Pharmacological Activities of Hovenia dulcis Extracts: Comparison
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Please note this is a comparison between Version 2 by Catherine Yang and Version 1 by Gloria Brusotti.

Hovenia dulcis Thunberg is an herbal plant, belonging to the Rhamnaceae family, widespread in west Asia, USA, Australia and New Zealand, but still almost unknown in Western countries. H. dulcis has been described to possess several pharmacological properties, such as antidiabetic, anticancer, antioxidant, anti-inflammatory and hepatoprotective, especially in the hangover treatment, validating its use as an herbal remedy in the Chinese Traditional Medicine. The biological activities of H. dulcis crude extracts and secondary metabolites isolated from them highlighted promising pharmacological effects in vitro and in vivo.

  • Hovenia dulcis
  • traditional medicine
  • phytochemistry

1. Acute Alcohol Detoxification Effect and Anti-Hangover Activity

For a long time, H. dulcis has been utilized in Chinese and Korean traditional medicine to treat acute alcohol intoxication. This biological activity has been extensively studied, demonstrating that H. Dulcis extracts reduce alcohol concentration in blood [1]. Earlier studies in East Asia demonstrated that H. Dulcis extracts increase the activity of ADH and ALDH, contributing to reduce alcohol concentration after ingestion. A rapid in vitro screening performed by Xu et al. showed that H. dulcis fruits and stem extracts increase both ADH and ALDH activity measured through microplate reader assay [33][2]. This biological effect was also confirmed by another study that compared the detoxification activity of H. dulcis from China and Korea. The administration of crude seeds’ hot water extracts to CD® (Sprague Dawley) rats, 30 min prior to alcohol ingestion, enhances the activity of ADH and ALDH more than control groups, reducing blood alcohol concentration. This effect was further enhanced when the crude extracts were partitioned with solvents. Interestingly, the partition of crude extracts improves the activity of ADH by 60% compared to the control. Contrarily, the ALDH activity was most affected by crude extracts. No significant differences in efficacy were observed between Korea and China H. dulcis extracts [34][3]. Similar results were obtained by two other in vivo experiments conducted by Okuma et al. [35][4] and Chen et al. [36][5] Both studies showed a decrease of blood alcohol and acetaldehyde levels in rats and mice [35][4]. Specifically, the administration of H. dulcis aqueous extract [36][5] significantly increased ADH activity in the liver of mice compared to the control group. The same results were obtained by Du et al. [37][6] when mice were treated orally with 60% ethanol (10 mL/kg) and H. dulcis semen extracts (150, 300, 600 mg/kg/day), for 4 consecutive days. The middle and higher dose of H. dulcis extracts significantly decreased the blood alcohol level at 300 and 600 mg/kg [37][6]. This evidence led Korean researchers to fill a patent application that covers technical aspects related to extraction and isolation of hovenodulinol from H. dulcis fruits and its bioactivity against alcohol toxicity [8][7]. The patent describes the isolation and identification of hovenodulinol from water and ethanol fruits extracts. A preliminary in vitro test on human hepatic cell line WRL-68 showed no toxic effect. The administration of 1 mg/kg of hovenodulinol to Sprague-Dawley rats, after alcohol ingestion, showed good properties in reducing blood alcohol and aldehyde concentration, from 30 min to 6 h, after alcohol ingestion, compared to the control group. The effect on ADH and ALDH activity in liver was also confirmed with an increasing enzymes activity of 42.6% and 59.8%, respectively. The enzymes activity in the control group was 28.3% for ADH and 29.1% for ALDH. Also, the GST activity was enhanced by 179% after the treatment with 1 mg/L of hovenodulinol. The authors demonstrated a similar effect when the test compound was administered to 20 healthy men. A reduction of alcohol and aldehyde was observed in saliva and exhaled breath in the treatment (5 mg/kg of hovenodulinol) versus control group [8][7]. Recently, a randomized controlled crossover trial evaluating the anti-hangover effect of freeze-dried aqueous extract of H. dulcis fruit was conducted [38][8]. Fruits were boiled with distilled water for 4 h, filtered, and concentrated. The extract was standardized with quercetin at 5.9–8.9 mg/g. Twenty-six eligible male adults were enrolled and allocated to placebo or treatment group with subsequent crossover. Hangover was induced with the administration of 360 mL of Korean Soju (50 g alcohol). In order to explore the mechanism underlying the anti-hangover effect, only subjects with heterozygous ALDH2 were included. Furthermore, blood alcohol, acetaldehyde and inflammatory cytokines were measured over time, evaluating the potential association with a score obtained through the administration of a questionnaire that evaluates hangover symptoms. The authors also evaluated the possible influence of CYP2E1 polymorphism on the relationships explored. The results demonstrated no difference between groups for blood alcohol and acetaldehyde concentrations, while a significant decrease in hangover symptom scores was observed in the treatment group compared to the placebo group. Significant differences between groups were also observed on IL-6, IL-10, IL-10/IL-6 ratio and AST levels. Cytokines level was positively correlated with total hangover symptom scores while the presence of CYP2E1 polymorphism can modify it. The authors concluded by stating that the pharmacological effect of H. dulcis extract on alcohol hangovers might be associated with the regulation of inflammatory response [38][8].

2. Hepatoprotective and Antifibrotic Activities

Several in vivo studies have been conducted to evaluate the hepatoprotective effect of H. Dulcis extract in various models of liver injuries induced by chemicals toxins [14,59,60][9][10][11].

2.1. Effect on CCl4 Liver Injury

Hase et al. [14][9] conducted a bio-guided study of H. dulcis fruits extracts in order to evaluate the hepatoprotective effect of this plant. Male Sprague-Dawley rats were treated with 100 mg/kg of methanol or water H. dulcis fruits extracts twice daily for 1 week, before CCl4 administration. Only methanol extract showed a significant hepatoprotective effect compared to the CCl4-treated group. Serum AST and ALT levels, 24 h after CCl4 intoxication, were 933 ± 114 and 730 ± 212 U/L respectively, for water and methanol extract-treated groups. In the methanol-treated group, AST and ALT levels were significantly lower, 311 ± 94 and 175 ± 65 U/L, respectively. Methanol extract was further suspended in water and partitioned with EtOAc (ethyl acetate), obtaining EtOAc soluble and insoluble fractions. The hepatoprotective effect of these two fractions were evaluated in CCl4-induced rat hepatocyte injury in vitro. The EtOAc soluble fraction was more active than insoluble and methanol extract. Therefore, it was subjected to chromatographic separation in order to obtain 7 fractions; fraction 4, the most active, was further purified, allowing the isolation of 2 compounds, identified as Myricetin and DHM. Only DHM showed a hepatoprotective effect in the same in vitro model indicated above [14][9]. Similar results were obtained by Kim et al. in an in vivo model of acute liver injury induced by CCl4. The authors demonstrated a significant reduction in AST and ALT levels in rats treated with H. dulcis extract compared to the control group [59][10]. The same pharmacological activity was highlighted in a chronic in vivo model of hepatic fibrosis induced by CCl4 administered for 6 weeks in 48 male Sprague-Dawley rats. The potential mechanism of action of the of H. dulcis extract hepatoprotective effect was determined through the evaluation of mRNA expression of MMP-13 and TIMP-1 in hepatic tissue. Results obtained showed that the mRNA expression of TIMP-1 was statistically reduced by the plant extract, and this effect is correlated with the reversion of hepatic fibrosis in the experimental group [39,40][12][13]. A more detailed study on the anti-fibrotic effect of H. dulcis fruit extract in rats was conducted by Lee et al [60][11]. The administration of 4.0 mL/kg of methanol fruit extract, diluted in distilled water at a final concentration of 20%, five times a week (for 6 weeks), reduced ALT, AST and bilirubin levels and expression volume of collagen I and III, compared to the control group. Furthermore, the treatment reduced the expression and accumulation of collagen I and III in liver tissue. Pathological images confirmed that in rats treated with extract + CCl4, the progression of fibrosis was inhibited more than in rats treated with CCl4 alone. Moreover, the in vitro test demonstrated that methanol extract inhibited hepatic stellate cell proliferation at all the concentrations tested (from 6 to 180 mcg/mL), without cytotoxic effects on cell viability [60][11]. The same antifibrotic effect was also reported from four ceanothane-type and lupane-type triterpenoids isolated from H. dulcis roots methanol extract, with IC50 values in the range of 15–50 µM [12][14]. The hepatoprotective activity of H. dulcis fruit ethanol extract was also demonstrated in a chronic hepatitis model induced by CCl4 administration in mice [61][15]. Molecular and histopathological alteration in liver, induced by CCl4, were reduced in mice treated with 0.5 or 1 mg/kg of extract. Histological analysis demonstrated that H. dulcis attenuates fibrosis and necrosis, inhibits hepatic lipid peroxidation and induces a significant reduction of biochemical markers of hepatocellular necrosis and hepatic levels of malondialdehyde (MDA), compared to mice treated with CCl4 alone. At the molecular level, the effect of H. dulcis on mRNA expression of hepatic collagen (α1) (I) and collagen (α1) (III) was confirmed by RT-qPCR analysis. Finally, the treatment increases the expression of methionine adenosyltransferase 2a (MAT2A), an enzyme involved in hepatic regeneration [61][15].

2.2. Effect on Alcohol-Induced Liver Injury

The protective effect of H. dulcis extract on alcohol toxicity was demonstrated both for semen and fruit extracts. The administration of semen extract, at the concentration of 150, 300 and 600 mg/kg/day for 4 days, exerts a hepatoprotective effect in mice with acute alcohol-induced liver injury, without inducing toxic side effects. In H. dulcis-treated mice, the levels of ALT and AST were significantly decreased in concomitance with an increased activity of ADH, SOD, GST and GSH that contributed to metabolize alcohol, rapidly. Furthermore, an acute toxicity test was conducted to assess safety and lethal dose of oral semen extract administration. A single dose, up to 22 g/kg, did not cause death or toxic effects during the 14 days of observation [37][6]. A study conducted by Wang et al. [6][16] focused the attention on the assessment of antioxidant activity of low molecular weight constituents of H. dulcis peduncles extract, characterized by the presence of polysaccharides. A first extraction with ethanol was performed in order to remove small molecules and oligosaccharides. The residues were then extracted with hot water followed by treatment with ethanol and macroporous resin. Galactose, arabinose, rhamnose and galacturonic acid were found to be the main components of the obtained fraction. Three different concentrations were administered: 100, 350 and 600 mg/kg, once daily for 20 days. Results demonstrated strong antioxidant activity properties both in vitro, due to high superoxide radical scavenging activity and significant inhibition effect on lipid peroxidation, and in vivo, restoring SOD and glutathione peroxidase (GSH-Px) activities in liver of mice injured by ethanol. Serum ALT and AST concentration and liver level of MDA were significantly lower than in mice treated with ethanol only. These results suggest that the hepatoprotective effect of H. dulcis peduncles extract is mediated via the antioxidant action. The polysaccharide fraction is one of the active principles contributing to the biological activities and traditional uses described for H. dulcis [6][16]. The same biological activity of polysaccharides fraction of H. dulcis was described and patented by Na et al. [62][17], where the hepatoprotective effect was demonstrated in an ex vivo model of liver toxicity induced by bromobenzene [60][11]. A study conducted by Yoshikawa et al. on Hoveniae semen seu fructus extracts reported an inhibitory action on the alcohol-induced muscular relaxation and a hepatoprotective effect on the d-galactosamine/lipopolysaccharide or CCl4-induced liver toxicity. Through the application of a bio-guided method, the authors reported DHM and hovenitin 1 as the molecules responsible for the biological activity on alcohol-induced muscular relaxation, but only hovenitin 1 demonstrated a hepatoprotective effect on liver toxicity induced by lipopolysaccharide (LPS) [18]. Cho et al. conducted a detailed study aimed to elucidate the molecular mechanisms supporting the hepatoprotective effect of H. dulcis extract on alcohol-induced liver toxicity [41][19]. Hoveniae semen seu fructus were extracted with hot water and three doses were selected (500, 250 and 125 mg/kg) and orally administered once a day, after 1 h of ethanol treatment for 14 days. The pharmacological effect of the extract was proved to exert statistically significant anti-inflammatory, anti-steatosis and antioxidant activities, at all dosages, in a dose-dependent manner. All molecular and histopathological markers related with alcohol intoxication were substantially improved by the experimental treatment compared to mice fed only with ethanol. Specifically, H. dulcis extract decreased AST, ALT, albumin, ALP, TG and γ-GTP levels in serum, and TG, TNF-α contents and CYP4502E1 activity in liver. The administration of H. dulcis extract enhanced hepatic GSH contents, SOD and CAT activities and modified mRNA expression of genes involved in hepatic lipogenic process, such as SREBP-1c, SCD1, ACC1, FAS, PPARγ and DGAT2, in fatty acid oxidation, including PPARα, ACO1 and CPT1, compared to the ethanol group. Oxidative stress and lipid peroxidation processes induced by ethanol were also normalized by the treatment through the decrease of immunoreactive hepatocytes cells positive to 4-hydroxynonenal and nitrotyrosine. Histopathological analysis revealed a significant and dose-dependent inhibition of steatosis, compared with the ethanol control mice. The molecular mechanism, underlying the hepatoprotective effect of H. dulcis extract in this model, is related to the strong antioxidant action and the regulation of genes involved in the lipogenic process and fatty acid oxidation in liver [41][19]. In a further model of liver hepatotoxicity, induced by chronic alcohol administration in rats, fruit water extract and seed ethanol extract of H. dulcis demonstrated anti-steatotic and anti-inflammatory effects at the concentrations of 300 and 500 mg/kg/day, respectively [63][20]. Both the extracts reduced hepatic and serum lipid contents and inflammatory markers, CRP, TNF-α and IL-6, compared to rats in the alcohol group. The decrease of hepatic fatty acid oxidative genes (Ppargc1a, Cpt1a and Acsl1) levels and the increase of myeloid differentiation primary response 88 (Myd88), TNF-α and CRP gene levels were positively regulated in the H. dulcis group. Both extracts also significantly reduce hepatic activities of fatty acid synthase and phosphatidate phosphohydrolase, plasma alcohol and acetaldehyde levels, hepatic enzyme activity and protein expression of CYP2E1, compared to the control group. This study provided further evidence that hepatoprotective action of H. dulcis extracts is exerted through the regulation of lipid and inflammation metabolism [63][20]. A further step to explain the therapeutic effect of H. dulcis in ethanol liver disease was recently provided by Ping et al. [64][21].
The authors explored the pharmacological effect on new molecular mechanisms characterizing the development of alcoholic liver disease. Recent findings attribute a central role to the gut–liver axis and its connection with microbiota. Ethanol assumption altered intestinal barrier function and gut microbiota, leading to an increase of endotoxin release, such as LPS, that promotes a critical crosstalk between liver and gut, exacerbating steatosis, inflammation and fibrosis in liver. LPS activates macrophage through activating the tool-like receptor 4 (TLR4) pathway and induces the release of NFkB and TNF-α. Sprague-Dawley rats were fed with a diet containing alcohol with or without semen H. dulcis water extract (300 and 600 mg/kg/d) for 8 weeks. The content of total flavonoid in semen was quantified and results showed that the extract contained 1.08% of DHM, 0.425% of dihydroquercetin and 1.4% of quercetin. Authors suggested that the therapeutic effect of the extract is due to the presence of these flavonoids, in accordance with literature data on their pharmacological effect on liver diseases. Results showed that the extract significantly ameliorated biochemical and histopathological markers such as ALT, AST, LDH and LPS. The increase of inflammatory molecules expression (TLR4, MyD88, NF-κB, Iκ-B, P-Iκ-B and TNF-α) in liver, induced by the activation of TLR4 receptor, were inhibited by experimental treatment compared to control group. Furthermore, the extract upregulated the expressions of zonula occludens-1 and occludin in the intestine, improved the barrier function and reduced the absorption of endotoxin, inhibiting the negative crosstalk induced by LPS between the gut and liver. For the first time, it was also demonstrated that H. dulcis modulates abnormalities of the gut–liver axis and regulates microbiota, promoting diversity and abundance of bacterial community and reducing microorganisms that release endotoxin into the enterohepatic circulation [64][21].

2.3. Effect on Paracetamol-Induced Hepatotoxicity

A recent study conducted by Bui [65][22] demonstrated the acute hepatoprotective activity of H. dulcis extract on liver injuries induced by paracetamol in swiss albino mice. The experimental group was treated with 10 g/kg/day of H. dulcis ethanol fruit extract and paracetamol 400 mg/kg for a total of 8 days. Results demonstrated the hepatoprotective effect of the extract on paracetamol-induced toxicity through the reduction of AST, ALT, inflammation and necrosis compared to the control group [65][22]. In another study, conducted by Dong et al. [22][23] the hepatoprotective effect of ethanol fruit extract was evaluated on liver toxicity induced by paracetamol. Male C57BL/6 mice were allocated in different groups that included: control group, paracetamol group and experimental groups treated with 200, 400 or 800 mg/kg body weight, together with a single dose of paracetamol (300 mg/kg) to induce acute liver injury. The treatment was repeated every day, for five consecutive days. The pharmacological effect was evaluated by histopathological and biochemical analysis. Results demonstrated that H. dulcis extract reduced liver injury in a dose-dependent manner through multiple mechanisms of action. The extract reduced (a) the oxidative stress, increasing the expression of MDA, SOD and the concentration of GSH, (b) apoptosis of hepatocytes, decreasing cytochrome c, cleaved caspase-3 and caspase-9 expression, and increased B-cell lymphoma-2 (Bcl-2) expression, (c) the inhibition of CYP2E1, one of the enzymes that regulates the bioconversion of the drug that induces liver toxicity, and (d) serum marker enzymes ALT, AST and LDH. Finally, the extract also regulated bile acid and lipid homeostasis altered by paracetamol [22][23].

2.4. Effect on lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-Induced Liver Injury

The hepatoprotective effect of H. dulcis extract was also reported in immunological liver toxicity. Hase et al. [66][24] evaluated the pharmacological effect of H. dulcis water and methanol fruit extracts on LPS-induced liver injury in chronic ethanol-fed rats. A significant decrease of blood ALT and AST levels, accumulation of hepatic triglyceride, total cholesterol and malondialdehyde was demonstrated compared to the control group. Instead, no difference was observed between control and methanol extract-treated groups [66][24]. In another similar experimental study, however, the same authors reported that only methanol H. dulcis fruit extract exerts a hepatoprotective effect on LPS-induced rats’ liver toxicity. The results showed that treatment with methanol extract reduced ALT level by 75.9% compared to the control group. Furthermore, only 27.2% mice died in the methanol extract-treated group compared to 62.6% in the control group. No significant effect for both parameters was observed in the water extract-treated group [14][9]. Concerning the investigation of molecules contributing to the hepatoprotective action on immunological liver toxicity, Yoshikawa et al. [18] reported that the active compound was hovenitin I, a molecule isolated from Hoveniae semen seu fructus extracts.

3. Anticancer Activity

In vitro studies on the cytotoxic activity of H. dulcis extracts demonstrate antitumor properties in different cell lines. Castro et al. [42][25] reported a specific cytotoxicity, against P2/0 mouse myeloma and lymphoma cells, belonging to H. dulcis pseudo-fruits ethanol extract. Morales et al. [3][26] investigated the anticancer and hepatotoxicity activity of hydro-methanolic extracts of H. dulcis pseudo-fruits at different maturation stages. Cancer cell lines used in this study included: MCF-7 (breast carcinoma), NCI-H460 (non-small cell lung cancer), HeLa (cervical carcinoma), HepG2 (hepatocellular carcinoma) and HCT15 (colon carcinoma). Results demonstrated that only extracts obtained by immature pseudo-fruits showed antitumor properties and HCT15 and HepG2 were the most sensible cell lines (50% growth inhibition at 8.58 and 82.34 µg/mL, respectively). No hepatotoxicity on non-tumor liver primary culture (PLP2) was observed for all tested extracts [3][26]. Park et al. demonstrated that H. dulcis leaves’ methanol extract significantly inhibited the growth of HT29 and HepG2 cell lines. The maximum inhibition rate was of 80% at 100 μg/mL. Chloroform and hexane fractions, obtained from methanol extract, showed similar activity. No cytotoxicity effect was observed on the human liver cell line under the same conditions [43][27]. A recent study investigated the anticancer effect of H. dulcis branches ethanol extract and DHM, using in vitro and in vivo angiogenesis assays. Human umbilical vein endothelial cells (HUVECs) were used to evaluate cytotoxicity and a potential mechanism underlying the antiangiogenic action. The viability of HUVECs was not affected by the H. dulcis extract up to 100 μg/mL. Contrarily, the proliferation of HUVECs stimulated by vascular-endothelial growth factor (VEGF) was significant, in a dose-dependent manner, when treated with 25, 50 and 100 μg/mL of the extract. Moreover, H. dulcis ethanol extract inhibited invasiveness, tube-forming ability and migration of HUVECs induced by VEGF. The anti-angiogenic activity was also confirmed in vivo through the chorioallantoic membrane (CAM) assay, without inducing cytotoxicity. The analysis of the molecular pathway involved in this action revealed that H. dulcis ethanol extract inhibited VEGFR2-mediated downstream signaling cascades, reducing STAT3, AKT, ERK1/2 phosphorylation and the protein expression of VEGFR2, MMP-2, MMP-9 and cyclin D1 in HUVECs. In HepG2 cells, at the concentration of 100 μg/mL, the extract inhibited the expression of HIF-1α. DHM, one of the main secondary metabolites secreted by H. dulcis, showed the same antiangiogenic activity of the extract, through the inhibition of VEGFR2 signal transduction and suppressing the expression of HIF-1α/VEGF [21][28]; thus, in this case, the claimed biological activity was linked to a specific compound and not to the whole phytocomplex.

4. Antiallergic Activity

Four bioactive triterpene glycosides, Hovenidulciosides A1, A2, B1 and B2, were isolated from Hovenia semen seu fructus methanol extract. All compounds demonstrated inhibitory activity on the histamine release from rat mast cells induced by compound 48/80 and calcium ionophore A-23187 [44,45,46][29][30][31]. A recent study conducted by Lim et al. [47][32] investigated the anti-inflammatory and anti-allergic effect of three H. dulcis ethanol extracts obtained from fruits, branches and leaves. Antigen-stimulated mast cell-like cell line rat basophilic leukemia (RBL)-2H3 and a passive cutaneous anaphylaxis (PCA) mouse were chosen as in vitro and in vivo models. The RBL-2H3 cell line is a histamine-releasing cell line used in inflammation and immunological research. Cells were sensitized with dinitrophenol, then treated with the extract at the concentration of 5, 10 or 20 μg mL−1. Evaluation conducted at the molecular level revealed that H. dulcis branches extract inhibits inflammatory and allergic mediators in the RBL-2H3 cell line. Specifically, only H. dulcis branches extract showed anti-allergic activity both in vitro and in vivo. Results obtained in vitro demonstrated that the treatment induces the inhibition of β-hexosaminidase (that indicates the inhibition of degranulation) and histamine release. The production and expression of COX2, PGE2, interleukin-4, TNF-α and NFKB was also significantly inhibited. Furthermore, the authors investigated the effect of H. dulcis branches extract on FcεRI and MAPK, two molecular pathways known to be involved in inflammatory and allergic disease. The treatment with the extract was able to suppress the FcεRI pathway and the downstream signaling involved in mast cell activation and degranulation. Also, the inhibition of some components of the MAPK pathway, ERK and p38, involved in cytokine secretion, was proven. The anti-allergic activity of the extract was then investigated in a mast cell-dependent passive cutaneous anaphylaxis (PCA) mouse model induced by the administration of dinitrophenyl-IgE. The effect of H. dulcis branches extract, orally administered (100 or 300 mg kg−1), was compared to the antihistamine drug cetirizine (20 mg kg−1). Both treatments suppressed the antigen stimulated PCA response compared to the control group. The authors isolated 8 compounds from the extract, including: ferulic acid, vanillic acid, methyl vanillate, 2,3,4-trihydroxybenzoic acid, Taxifolin, Pinosylvin, 3,5-dihydrokaempferol and (−)-Gallotechin. They found that taxifolin, dihydro-kaempferol and pinosylvin inhibited β-hexosaminidase release in antigen-stimulated RBL-2H3 cells. Pinosylvin showed the most potent inhibitory effect. The mechanism of pinosylvin on IgE-sensitized RBL-2H3 cells was further investigated. No toxic effect on RBL-2H3 cell viability was observed at the concentration of 5–20 μg mL−1. Pinosylvin inhibited the release of proinflammatory mediators releasing IL-4, TNF-α and PGE2, and the expression of COX-2, IL-4, TNF-α, NFKB1 and NFKB2 in RBL-2H3 cells treated with IgE [47][32].

5. Anti-Inflammatory and Analgesic Activity

Different studies reported above highlighted the anti-inflammatory activity of H. dulcis extracts explicated through the inhibition of pathway and mediators known to be crucial for the development of inflammatory reaction, such as NFKB, TNF-α, IL-1, IL-10, etc. [48,49,67,68][33][34][35][36]. The anti-inflammatory effect of H. dulcis fruits ethanol extract in a mouse macrophage RAW 276.7 cells model was investigated. Results showed that H. dulcis extract significantly inhibited, in a dose-dependent manner, the expression of NO, nitric oxide synthase, COX-2, interleukin-1b, TNF-α, the nuclear translocation of NF-kB, p65 and the phosphorylation of IkB in the cytoplasm [67][35]. A similar in vitro study conducted by Jeong et al. [48][33] assessed the anti-inflammatory effect and the mechanism of action of Hoveniae semen seu fructus extracts in the murine macrophage cell line (RAW 264.7) and mouse primary macrophages. They demonstrated that H. dulcis ethanol extract (10, 30 and 50 mg/mL) strongly inhibited, in a concentration-dependent manner, the phosphorylation of MAPK and reduced the activation of activator protein-1 (AP-1), janus kinase-2 (JAK2)/STAT and NF-κB in LPS-stimulated RAW 264.7 cells. The expression of NO and iNOS, TNF-α, IL-6 and IL-1β was also significantly attenuated. In further analyses, DHM, taxifolin and myricetin were identified as the bioactive molecules responsible for the anti-inflammatory effect of the extract. In fact, each compound inhibited the inflammatory response in LPS-stimulated macrophages [48][33]. The anti-inflammatory action of H. dulcis extract was also confirmed in an in vivo model of atopic dermatitis-like skin lesions induced by 2,4-dinitrochlorobenzene (DNCB) in NC/Nga mice and TNF-α/interferon (IFN) gamma-induced chemokines production in spontaneously immortalized human keratinocytes (HaCaT) cell lines. The study design included 5 groups: control, DNCB, dexamethasone, H. dulcis branches (HDB) and extract (50 and 200 mg/kg plus DNCB). The extract and dexamethasone were oral administered once a day for 5 weeks. In vitro results showed that the extract significantly reduced MAPK signaling and cytokine production. The treatment also regulated the production of TARC (thymus and activation-regulated chemokine) and MDC (macrophage-derived chemokine) by HaCat cells stimulated by TNF-alfa and IFN-gamma. The anti-inflammatory effect of the extract’s main components (2,3,4-trihydroxybenzoic acid ferulic acid, vanillic acid, methyl vanillate, 3,5-dihydrokaempferol and pinosylvin) was evaluated in the same in vitro model. Methyl vanillate demonstrated the most potent anti-inflammatory action, inhibiting the expression of TNF-α, IL-6, TARC, MDC, ERK, c-jun N-terminal kinase and p38MAPK. In vivo data showed that HDB extract reduced epidermal thickness and dermal infiltration of cytokine-expressing inflammatory cells. Moreover, serum IgE and IgG2a levels and the expression of mRNA for Th1 and Th2-related mediators in skin lesions were significantly reduced. The authors concluded the study, suggesting that the mechanism of action of HDB in an atopic dermatitis model is mediated by the regulation of Th1 and Th2 responses and consequent expression of inflammatory mediators [49][34]. Another in vivo study conducted by Lee et al. [60][11] investigated the analgesic effect of H. dulcis extract on an inflammatory orofacial pain model induced by formalin. Rats were divided in four groups: (a) control, (b) 5% formalin, (c) 5% formalin + 4.5 mL/kg of H. dulcis extract and (d) 5% formalin + distilled water administration. Results obtained from the study reported a significant reduction of orofacial pain in H. dulcis-treated animals compared to other groups. Western blot analyses, conducted on markers involved in pain regulation and inflammation, revealed that the extract inhibited p38MAPK, iNOS and Nrf2 in the brain.

6. Laxative Activity

Evidence of laxative activity of H. dulcis extracts were derived from two recent in vivo studies. In the first study, Choi et al. [69][37] described the laxative properties of H. dulcis branches after extraction with water followed by partition in hexane, chloroform, ethyl acetate and butanol. The laxative effects were assessed on low-fiber diet-induced constipation in Sprague-Dawley rats by measuring spasmogenic activity and intestinal transit of charcoal meal and stool parameters. Results showed that only water extract (100 and 200 mg/kg) had a positive effect, improving the intestinal transit of charcoal meal and the frequency and weight of stools. Moreover, the contractile responses of isolated rat colon were significantly enhanced by the water extract. Finally, the authors identified vanillic acid as the active molecule of the extract with spasmogenic activity on an isolated rat colon test. The second in vivo study evaluated the laxative activity of hot-water extracts of H. dulcis, in two chronic constipation models: loperamide-induced constipation and low-fiber diet-induced constipation. Results showed an increase of stool parameters (fecal number, weight and water content), and intestinal transit compared to loperamide and low-fiber diet groups [50][38].

7. Antimicrobial Activity

The antimicrobial effect of H. dulcis was proven against Gram-positive bacteria, Gram-negative bacteria, parasites and yeasts [1]. A study conducted on methanol-soluble fraction of H. dulcis hot-water extracts lead to the isolation of vanillic and ferulic acids as active molecules with antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Micrococcus luteus, Streptococcus mutans, Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc mesenteroides and Pediococcus damnosus), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi) and yeast (Candida albicans) [51][39]. Cho et al. isolated 3(Z)-dodecenedioic acid from H. dulcis leaves and demonstrated its antimicrobial activity against Staphylococcus aureus and Escherichia coli [70][40]. The antimicrobial effect was also demonstrated for H. dulcis pseudo-fruits extracts [71][41]. A recent study conducted by Morales et al. reported that the antimicrobial activity of. H. dulcis pseudo-fruits extract is strictly correlated to the fruit development process. Extract of fruits in the immature stages showed high activity and low minimal inhibitory concentration values on Staphylococcus epidermidis, Sthaphylococcus aureus and Pseudomonas aeruginosa. The authors reported that the antimicrobial effect could be related to the flavonoids content. In fact, immature pseudo-fruits showed high content of catechin and quercetin derivatives [3][26]. The inhibitory activity against parasites was described by Gadelha et al. [72][42] and Castro et al. [42][25], demonstrating the ability of H. dulcis extracts to inhibit the growth of Giardia lamblia trophozoites (dichloromethane fraction from the methanol extract of leaves) and Trypanosoma cruzi, respectively.

8. Antidiabetic Activity

Both in vitro and in vivo studies have demonstrated the antidiabetic effect of H. dulcis extracts. Different in vitro studies reported the inhibitory effect of crude extracts against α-amylase and α-glucosidase [52,73,74,75][43][44][45][46]. Meng et al. [52][43] showed that total flavonoids, myricetin and quercetin obtained from H. dulcis ethanol seeds extract have an inhibitory effect on α-amylase and α-glucosidase. The IC50 related to the inhibitory activity of total flavonoids, myricetin and quercetin against that of α-amylase was 32.8, 662 and 770 μg mL−1, respectively. In the case of α-glucosidase, all three samples demonstrated a more potent inhibition with IC50 values of 8, 3 and 32 μg mL−1. The authors also demonstrated that the inhibition was reversible and competitive on α-amylase, while the effects on α-glucosidase were non-competitive. It was also reported that myricetin was the most promising compound since its activity was more effective than acarbose [52][43]. The in vitro inhibitory activity against α-amylase and α-glucosidase enzymes was also demonstrated for H. dulcis extract, mainly composed of polysaccharides, and their bioactivity was affected by the extraction method [73,74,75][44][45][46]. The antidiabetic effect was investigated and proven also on different in vivo models of diabetic mice and rats [53,76,77,78][47][48][49][50]. In an alloxan-induced diabetic model, the treatment of mice with glibenclamide or H. dulcis extract significantly lowered blood sugar levels and increased hepatic glycogen, compared to the control group [76][48]. The antidiabetic activity was also observed in streptozotocin-induced hyperglycemic mice and rats. Kim et al. demonstrated that the administration of H. dulcis peduncles water extract for 6 weeks at the concentration of 0.01 and 0.04 g/kg reduced blood glucose concentration and partially recovered pancreatic islets and pancreatic β-cells from the damage induced by streptozotocin. The authors correlated these effects with the antioxidant activity of the extract [53][47]. The same effect was shown in the study published by Lee et al. [60][11]. The treatment of streptozotocin-induced diabetic rats with 20 or 50 mg/kg−1 of ethyl acetate fraction from an 80% methanolic extract of H. dulcis fruits induced a decrease of plasma glucose, lipid peroxide, total cholesterol and triglycerides in liver microsomes and an increase of glutathione levels in the liver cytosol [77,78][49][50]. Furthermore, in a recent in silico analysis performed in order to identify potential pharmacological target of H. dulcis compounds (especially flavonoids) among the main pathways involved in diabetes mellitus, including insulin resistance, glucose level and chronic inflammation, it was suggested that H. dulcis flavonoids may exert their antidiabetic and anti-inflammatory activity through the modulation of AKT1 and glycogen synthase kinase 3 beta (GSK3β) [79][51].

9. Anti-Dyslipidemic and Antiadipogenic Activities

The anti-dyslipidemic and antiadipogenic activities of H. dulcis extracts were examined in a limited number of in vitro and in vivo models. Kim et al. assessed the antiadipogenic effect of H. dulcis fruit or stem water extracts in the 3T3-L1 preadipocytes cell line. The fruit extract (100 μg/mL−1) showed a significant dose-dependent inhibition of lipid accumulation, downregulating the expression of the PPARγ, CCAAT/enhancer-binding protein-α, adipocyte fatty acid-binding protein 2, adiponectin and resistin, with an inhibition rate of 29.33%, 54.36%, 34.5%, 55.69% and 60.39%, respectively. Moreover, the extract increases the phosphorylation of AMPK-α, liver kinase B1 and acetyl-CoA carboxylase [54][52]. In vivo studies also demonstrated the ability of H. dulcis extract to improve lipid metabolism. Pinto et al. [55][53] evaluated the effect of hydroalcoholic extract of H. dulcis fruit (50.0 and 100.0 mg/kg) and DHM (25.0 and 50.0 mg/kg) in hypercholesterolemic rats. The results demonstrated that both treatments significantly reduced total cholesterol and LDL-C, compared to the control. However, an increase of triglycerides and hepatic transaminases was observed only in rats treated with DHM, suggesting that the crude extract could be more useful than the compound alone [55][53]. The effect on lipid metabolism was also demonstrated by administering insoluble dietary fiber obtained from H. dulcis pomace and modified by ball milling and complex enzyme treatment. The treatment of mice with insoluble dietary fiber significantly slowed weight gain in hyperlipidemic mice, improved lipid metabolism (serum high-density lipoprotein cholesterol, total cholesterol, triglyceride and low-density lipoprotein cholesterol levels) and atherosclerosis and liver index, compared to the control group [74][45].

10. Antioxidant Activity

The antioxidant action of H. dulcis extracts has been demonstrated in numerous studies and this effect has been considered also as one of the mechanisms supporting the hepatoprotective and alcohol detoxification effects observed in various in vitro and in vivo studies [6,80][16][54]. A study conducted by Morales et al. [3][26] explored the antioxidant capacity of hydromethanolic extracts of H. dulcis pseudo-fruits through three in vitro assays: 2-2-diphenyl-1-picrylhdrazyl (DPPH) scavenging activity, reducing power (Ferricyanide/Prussian blue assay) and β-carotene/linoleate assay, in order to determine the inhibition of the lipid peroxidation process. The authors revealed that antioxidant effect was strongly correlated with the maturation process of pseudo-fruits. In fact, pseudo-fruits during the immature stage have higher antioxidant activity compared to those at the mature stage. This difference was explained due to the high presence of phenolic compounds during the immature stage. Similar results were observed when the antioxidant activity was evaluated through other antioxidant assays [3][26]. Other authors also confirmed the antioxidant activity of other botanical parts of H. dulcis, such as leaves and stem extracts [9,11][55][56]. Other studies exploring the antioxidant effect of the polysaccharide compounds and polyphenolic–protein–polysaccharide complexes extracted from peduncles or other parts reported a strong activity of these fractions, suggesting their applications in the functional food and medicine industries [6,56,57,81][16][57][58][59].

11. Anti-Osteoporotic Effect

An in vitro, ex vivo and in vivo study investigates the use of H. dulcis extract as potential treatment for osteoporosis [58][60]. Top-flash screening assay conducted on 350 plants indicated that H. dulcis water extract was an activator of Wnt/β-catenin signaling, one of the potential pharmacological targets for the development of anti-osteoporotic drugs. The activation of Wnt/β-catenin signaling promotes osteoblast differentiation, subsequent bone formation and suppresses osteoclastogenesis. H. dulcis water extract promotes bone formation in an ex vivo calvaria assay and activates Wnt/β-catenin signaling in a dose-dependent manner at the concentration of 5 and 50 μg/mL, without significant toxicity. Moreover, in primary calvarial osteoblasts treated with H. dulcis extract, the mRNA levels of the osteoblast differentiation markers such as RUNX2, BMP2, ALP and OCN were significantly increased. The expression of RANKL and OPG was reduced and increased, respectively. Hematoxylin and eosin staining showed a reduced calvaria thickness in a sample treated with the extract. The administration of H. dulcis extract (200 mg/kg for 4 weeks) in ICR mice induced an increase of femoral bone mass and thickness compared to in the control group. This activity was related to the activation of the Wnt/β-catenin pathway in trabecular and cortical bones of femurs. In order to identify the molecules activating Wnt/β-catenin, the authors tested 8 compounds in the same experiments, known to be part of H. dulcis extracts: vanillic acid, methyl vanillate, ferulic acid, myricetin, taxifolin, 2,3,4-trihydrobenzoic acid, dihydrokaempferol and gallocatechin. Methyl vanillate (20 uM) showed higher activity in all tests described above, demonstrating to induce osteogenesis promoting the expression of differentiation markers in a dose-dependent manner through the activation of the Wnt pathway. In fact, siRNA-mediated β-catenin knockdown suppressed the activation-regulated mediated by methyl vanillate. Further investigation confirmed the anabolic and anti-osteoporotic effect, reversing bone loss in ovariectomized mice through the increase of β-catenin expression in femoral trabecular and cortical bones. The effect was dose-dependent and did not induce toxicity [58][60].

12. Immunomodulatory Activity

Only one study, among those available in the literature, demonstrated the immunostimulatory activity of H. dulcis aqueous ethanol peduncle extract [10][61]. Wang et al. fractioned the extract and obtained three fractions (HDPS-1, HDPS-2 and HDPS-3) that were mainly composed by rhamnose, arabinose, galactose and galacturonic acid. However, HDPS-3 contained a higher content of galacturonic acid (40.5%) than HDPS-1 and HDPS-2 (1.8% and 7.6% respectively). Moreover, HDPS-1 had a much higher molecular weight than HDPS-2 or HDPS-3. In vitro studies demonstrated that all three fractions had immunostimulatory activities, stimulating the proliferation of splenocytes and activating peritoneal macrophages, enhancing phagocytosis, NO production and acid phosphatase activity. HDPS-1 was the most active fraction. The authors suggested that molecular weight, monosaccharide composition and uronic acid content were crucial for the immunostimulatory activity [10][61].

13. Neuroprotective Effect

A neuroprotective action of H. dulcis stem bark extract was reported by Li et al. [9][55]. Several fractions extracted from H. dulcis stem bark were assessed against glutamate-induced neurotoxicity in mouse hippocampal HT22 cells. EtOAc-soluble fraction from methanolic extract exhibited in vitro neuroprotective activity at the concentration of 5 μg/mL, increasing HT22 cell viability (71.3% ± 8.1%) compared to those treated with glutamate only (38.3% ± 4.1%). The fraction also possesses antioxidant activity against DPPH, ABTS and superoxide radical scavenging assay. A bioassay-guided method was applied leading to the identification of active compounds: (−)-catechin and (+)-afzelechin. Both molecules demonstrated neuroprotective and antioxidant activities [9][55].

References

  1. Hyun, T.K.; Eom, S.H.; Yu, C.Y.; Roitsch, T. Hovenia dulcis—An Asian traditional herb. Planta Med. 2010, 76, 943–949.
  2. Xu, B.J.; Deng, Y.Q.; Jia, X.Q.; Lee, J.H.; Mo, E.K.; Kang, H.J.; Sung, C.K. A rapid screening for alcohol detoxification constituents of Hovenia dulcis by microplate reader. Agric. Chem. Biotechnol. 2003, 46, 105–109.
  3. Kim, K.H.; Chung, Y.T.; Lee, J.H.; Park, Y.S.; Shin, M.K.; Kim, H.S.; Kim, D.H.; Lee, H.Y. Hepatic detoxification activity and reduction of serum alcohol concentration of Hovenia dulcis Thunb. from Korea and China. Korean J. Med. Crop Sci. 2000, 8, 225–233.
  4. Okuma, Y.; Ishikawa, H.; Ito, Y.; Hayashi, Y.; Endo, A.; Watanabe, T. Effect of extracts from Hovenia dulcis Thunb. on alcohol concentration in rats and men administered alcohol. Jpn. Nutr. Crop. Sci. Bull. 1995, 48, 167–172.
  5. Chen, S.H.; Zhong, G.S.; Li, A.L.; Li, S.H.; Wu, L.K. Influence of Hovenia dulcis on alcohol concentration in blood and activity of alcohol dehydrogenase (ADH) of animals after drinking. Zhongguo Zhong Yao Za Zhi 2006, 31, 1094–1096.
  6. Du, J.; He, D.; Sun, L.N.; Han, T.; Zhang, H.; Qin, L.P.; Rahman, K. Semen Hoveniae extract protects against acute alcohol-induced liver injury in mice. Pharm. Biol. 2010, 48, 953–958.
  7. Hovenodulinol, An Active Compound Extracted from Hovenia dulcis Thunb., A Process for Preparing the Same, And an Alcohol Decomposing Agent or an Agent for Alleviating Lingering Intoxication Containing the Same. Google Patent. Available online: https://patents.google.com/patent/WO2002024678A1/en (accessed on 7 December 2020).
  8. Kim, H.; Kim, Y.J.; Jeong, H.Y.; Kim, J.Y.; Choi, E.K.; Chae, S.W.; Kwon, O. A standardized extract of the fruit of Hovenia dulcis alleviated alcohol-induced hangover in healthy subjects with heterozygous ALDH2: A randomized, controlled, crossover trial. J. Ethnopharmacol. 2017, 209, 167–174.
  9. Hase, K.; Ohsugi, M.; Xiong, Q.; Basnet, P.; Kadota, S.; Namba, T. Hepatoprotective effect of Hovenia dulcis Thunb. on experimental liver injuries induced by carbon tetrachloride or d-galactosamine/lipopolysaccharide. Biol. Pharm. Bull. 1997, 20, 381–385.
  10. Kim, Y.S.; Park, J.; Kwon, Y.; Lim, D.W.; Song, M.K.; Choi, H.Y.; Kim, H. Hepatoprotective Effects of Hovenia dulcis Extract on Acute and Chronic Liver Injuries induced by Alcohol and Carbon Tetrachloride. Korean J. Herbol. 2013, 28, 25–32.
  11. Lee, J.J.; Yang, D.; Kim, H.; Hur, S.J.; Lee, J.D.; Yum, M.J.; Song, M.D. Liver Fibrosis Protective Effect of Hovenia dulcis fruit. Curr. Top. Nutraceutical Res. 2014, 12, 43–50.
  12. Liu, X.L.; Zhnag, H.; Wang, F. Effect of Hovenia dulcis Extract on Expression of MMP-13 and TIMP-1 in Hepatic Tissue. Zhongguo Zhong Yao Za Zhi 2006, 31, 1097–1100.
  13. Grünwald, B.; Schoeps, B.; Krüger, A. Recognizing the Molecular Multifunctionality and Interactome of TIMP-1. Trends Cell Biol. 2019, 29, 6–19.
  14. Kang, K.B.; Jun, J.B.; Kim, J.W.; Kim, H.W.; Sung, S.H. Ceanothane-and lupane-type triterpene esters from the roots of Hovenia dulcis and their antiproliferative activity on HSC-T6 cells. Phytochemistry 2017, 142, 60–67.
  15. Fang, H.; Lin, H.Y.; Chan, M.C.; Lin, W.L.; Lin, W.C. Treatment of Chronic Liver Injuries in Mice by Oral Administration of Ethanolic Extract of the Fruit of Hovenia dulcis. Am. J. Chin. Med. 2007, 35, 693–703.
  16. Wang, M.; Zhu, P.; Jiang, C.; Ma, L.; Zhang, Z.; Zeng, X. Preliminary characterization, antioxidant activity in vitro and hepatoprotective effect on acute alcohol-induced liver injury in mice of polysaccharides from the peduncles of Hovenia dulcis. Food Chem. Toxicol. 2012, 50, 2964–2970.
  17. Na, C.S.; Jung, N.C. Lower Alcohol-Insoluble Extract of Hovenia dulcis var. Koreana nakai, A Polysaccharide Isolated Thereform and an Antihepatotoxic Composition Containing Same. Google Patent. Available online: https://patents.google.com/patent/WO2002060463A1/en (accessed on 7 December 2020).
  18. Yoshikawa, M.; Murakami, T.; Ueda, T.; Yoshizumi, S.; Ninomiya, K.; Murakami, N.; Matsuda, H.; Saito, M.; Fujii, W. Bioactive constituents of Chinese natural medicines. III. Absolute stereostructures of new dihydroflavonols, hovenitins I, II, and III, isolated from Hoveniae Semen Seu Fructus, the seed and fruit of Hovenia dulcis Thunb. (Rhamnaceae): Inhibitory effect on alcohol-induced muscular relaxation and hepatoprotective activity. Yakugaku Zasshi 1997, 117, 108–118.
  19. Cho, I.; Kim, J.; Jung, J.; Sung, S.; Kim, J.; Lee, N.; Ku, S. Hepatoprotective effects of hoveniae semen cum fructus extracts in ethanol intoxicated mice. J. Exerc. Nutr. Biochem. 2016, 20, 49–64.
  20. Choi, R.Y.; Woo, M.J.; Ham, J.R.; Lee, M.K. Anti-steatotic and anti-inflammatory effects of Hovenia dulcis Thunb. extracts in chronic alcohol-fed rats. Biomed. Pharmacother. 2017, 90, 393–401.
  21. Ping, Q.; Yu, D.; Tao, Z.; Yun-yun, L.; Xian-jie, K.; Min-xia, P.; Huan-Zhou, L.; Hao, X.; Chao, G.; Su-hua, P.; et al. Semen hoveniae extract ameliorates alcohol-induced chronic liver damage in rats via modulation of the abnormalities of gut-liver axis. Phytomedicine 2019, 52, 40–50.
  22. Bui, N. Hepatoprotective Activity of Hovenia dulcis Thumb. on paracetamol Induced Liver Toxicity in Mice. Gut Liver 2019, 13, 92.
  23. Dong, S.; Ji, J.; Zhang, B.; Hu, L.; Cui, X.; Wang, H. Protective effects and possible molecular mechanism of Hovenia dulcis Thunb. extract on acetaminophen-induced hepatotoxicity. Pharmazie 2018, 73, 666–670.
  24. Hase, K.; Ohsugi, M.; Basnet, P.; Kadota, S.; Namba, T. Effect of Hovenia dulcis on lipopolysaceharide-induced liver injury in chronic alcohol-fed rats. J. Trad. Med. 1997, 14, 28–33.
  25. Castro, T.C.; Pelliccione, V.L.B.; Figueiredo, M.R.; Soares, R.O.A.; Bozza, M.T.; Viana, V.R.C.; Albarello, N.; Solange, F.L.F. Atividade antineoplásica e tripanocida de Hovenia dulcis Thunb. cultivada in vivo e in vitro. Rev. Bras. Farmacogn. 2002, 12, 96–99.
  26. Morales, P.; Maieves, H.A.; Dias, M.I.; Calhella, R.C.; Sánchez-Mata, M.C.; Santos-Buelga, C.; Barros, L.; Ferreira, I.C.F.R. Hovenia dulcis Thunb. pseudofruits as functional foods: Phytochemicals and bioactive properties in different maturity stages. J. Funct. Foods 2017, 29, 37–45.
  27. Park, S.H.; Chang, E.Y. Antimutagenic and cytotoxic effects of Hovenia dulcis Thumb. leaves extracts. Korean J. Soc. Food. Sci. Nutr. 2007, 36, 1371–1376.
  28. Mi, H.J.; Nim, L.H.; Jin, J.H. Hovenia dulcis Thunb. and its active compound ampelopsin inhibit angiogenesis through suppression of VEGFR2 signaling and HIF-1α expression. Oncol. Rep. 2017, 38, 3430–3438.
  29. Xu, B.J.; Deng, Y.Q.; Sung, C.K. Advances in Studies on Bioactivity of Hovenia dulcis. Agric. Chem. Biotechnol. 2004, 47, 1–5.
  30. Yoshikawa, M.; Ueda, T.; Muraoka, O.; Aoyama, H.; Matsuda, H.; Shimoda, H.; Yamahara, J.; Murakami, N. Absolute stereostructures of hovenidulciosides A1 and A2, bioactive novel triterpene glycosides from Hoveniae semen seu fructus, the seeds and fruit of Hovenia dulcis Thunb. Chem. Pharm. Bull. 1995, 43, 532–534.
  31. Yoshikawa, M.; Murakami, T.; Ueda, T.; Matsuda, H.; Yamahara, J.; Murakami, N. Bioactive saponins and glycosides. IV. Four methyl-migrated 16, 17-seco-damma-rane triterpene gylcosides from Chinese natural medicine, Hoveniae semen seu fructus, the seeds and fruit of Hovenia dulcis Thunb.: Absolute stereostructures and inhibitory activity on histamine release of hovenidulciosides A1, A2, B1, and B2. Chem. Pharm. Bull. 1996, 44, 1736–1743.
  32. Lim, S.J.; Kim, M.; Randy, A.; Nho, C.W. Inhibitory effect of the branches of Hovenia dulcis Thunb. and its constituent pinosylvin on the activities of IgE-mediated mast cells and passive cutaneous anaphylaxis in mice. Food Funct. 2015, 6, 1361–1370.
  33. Jeong, Y.H.; Oh, Y.C.; Cho, W.K.; Yim, N.H.; Ma, J.Y. Hoveniae Semen Seu Fructus Ethanol Extract Exhibits Anti-Inflammatory Activity via MAPK, AP-1, and STAT Signaling Pathways in LPS-Stimulated RAW 264.7 and Mouse Peritoneal Macrophages. Mediat. Inflamm. 2019, 4, 1–14.
  34. Lim, S.J.; Kim, M.; Randy, A.; Nam, E.J.; Nho, C.W. Effects of Hovenia dulcis Thunb. extract and methylvanillate on atopic dermatitis-like skin lesions and TNF-a/IFN-c-induced chemokines production in HaCaT cells. J. Pharm. Pharmacol. 2016, 68, 1465–1479.
  35. Park, J.Y.; Moon, J.Y.; Park, S.D.; Park, W.H.; Kim, H.; Kim, J.E. Fruits extracts of Hovenia dulcis Thunb. Suppresses lipopolysaccharide-stimulated inflammatory responses through nuclear factor-kappa B pathway in Raw 264.7 cells. Asian Pac. J. Trop. Med. 2016, 9, 357–365.
  36. Lee, J.S.; Lee, M.K.; Kim, Y.K.; Kim, K.E.; Hyun, K.Y. Attenuant effects of Hovenia dulcis extract on inflammatory orofacial pain in rats. J. Korea Acad. Ind. Coop. Soc. 2014, 15, 5088–5094.
  37. Choi, C.Y.; Cho, S.S.; Yoon, I.S. Hot-water extract of the branches of Hovenia dulcis Thunb. (Rhamnaceae) ameliorates low-fiber diet-induced constipation in rats. Drug Des. Devel. Ther. 2018, 12, 695–703.
  38. Oh, K.N.; Kim, Y.; Choi, E.J.; Lee, H.; Hong, J.A.; Kim, M.; Oh, D.R.; Jung, M.A.; Park, R.D.; Kim, S.I.; et al. Laxative activity of the hot-water extract mixture of Hovenia dulcis Thunb. and Phyllostachys pubescens Mazel in chronic constipation model SD rats. J. Microbiol. Biotechnol. 2020, 30, 649–661.
  39. Cho, J.Y.; Moon, J.H.; Park, K.H. Isolation and identification of 3-methoxy-4-hydroxybenzoic acid and 3-methoxy-4hydroxycinnamic acid from hot water extracts of Hovenia dulcis Thunb and confirmation of their antioxidative and antimicrobial activity. Korean J. Food. Sci. Technol. 2000, 32, 1403–1408.
  40. Cho, J.Y.; Moon, J.H.; Eun, J.B.; Chung, S.J.; Park, K.H. Isolation and characterization of 3(Z)-dodecenedioic acid as an antibacterial substance from Hovenia dulcis Thunb. Food Sci. Biotechnol. 2006, 13, 46–50.
  41. Basavegowda, N.; Idhayadhulla, A.; Lee, Y.R. Phyto-synthesis of gold nanoparticles using fruit extract of Hovenia dulcis and their biological activities. Ind. Crops Prod. 2014, 52, 745–751.
  42. Gadelha, A.P.R.; Vidal, F.; Castro, T.M.; Lopes, C.S.; Albarello, N.; Coelho, M.G.P.; Figueiredo, S.F.L.; Leal-Monteiro, L.H. Susceptibility of Giardia lamblia to Hovenia dulcis extracts. Parasitol. Res. 2005, 97, 399–407.
  43. Meng, Y.; Su, A.; Yuan, S.; Zhao, H.; Tan, S.; Hu, C.; Deng, H.; Guo, Y. Evaluation of total flavonoids, myricetin, and 1uercetin from Hovenia dulcis Thunb. as inhibitors of α-amylase and α-glucosidase. Plant Foods Hum. Nutr. 2016, 71, 444–449.
  44. Wu, D.T.; Liu, W.; Xian, M.L.; Du, G.; Liu, X.; He, J.J.; Wang, P.; Qin, W.; Zhao, L. Polyphenolic-protein-polysaccharide complexes from Hovenia dulcis: Insights into extraction methods on their physicochemical properties and in vitro bioactivities. Foods 2020, 9, 456.
  45. Yang, B.; Wu, Q.; Song, X.; Yang, Q.; Kan, J. Physicochemical properties and bioactive function of Japanese grape (Hovenia dulcis) pomace insoluble dietary fiber modified by ball milling and complex enzyme treatment. Int. J. Food Sci. Technol. 2019, 54, 2363–2373.
  46. Yang, B.; Wu, Q.; Luo, Y.; Yang, Q.; Chen, G.; Wei, X.; Kan, J. Japanese grape (Hovenia dulcis) polysaccharides: New insight into extraction, characterization, rheological properties, and bioactivities. Int. J. Biomacromol. 2019, 134, 631–644.
  47. Kim, J.S.; Na, C.S.; Eun, B.J. Effect of Hovenia dulcis Thunber extract on the hyperglycemic mice induced with streptozotocin. J. Korean Soc. Food Sci. Nutr. 2005, 34, 632–637.
  48. Ji, Y.; Chen, S.; Zhang, K.; Wan, W. Effects of Hovenia dulcis Thunb on blood sugar and hepatic glycogen in diabetic mice. Zhong Yao Cai 2002, 25, 190–191.
  49. Lee, Y.A.; Chae, H.J.; Moon, H.Y. Effect of Hovenia dulcis Thunb. var. koreana Nakai fruit extract on glucose, lipid metabolism and antioxidant activity in streptozotocin-induced diabetic rats. J. Exp. Biomed. Sci. 2005, 11, 533–538.
  50. Wu, L.; Zhang, J. Evaluation of anti-diabetic activities of Hovenia dulcis Thunb. Adv. Mater. Res. 2012, 554–556, 1827–1830.
  51. De Godoi, R.S.; Almera, M.P.; da Silva, F.R. In silico evaluation of the antidiabetic activity of natural compounds from Hovenia dulcis Thunberg. J. Herbal Med. 2020, 100349.
  52. Kim, H.L.; Sim, J.E.; Choi, H.M.; Choi, I.Y.; Jeong, M.Y.; Park, J.; Jung, Y.; Youn, D.H.; Cho, J.H.; Kim, J.H.; et al. The AMPK pathway mediates an anti-adipogenic effect of fruits of Hovenia dulcis Thunb. Food Funct. 2014, 5, 2961–2968.
  53. Pinto, J.T.; Toledo de Oliveira, T.; Alvarenga, L.F.; Barbosa, A.S.; Ramos Pizziolo, V.; Da Costa, M.R. Pharmacological activity of the hydroalcoholic extract from Hovenia dulcis thunberg fruit and the flavonoid dihydromyricetin during hypercholesterolemia induced in rats. Braz. J. Pharm. Sci. 2014, 50, 727–735.
  54. Cho, I.J.; Kim, J.W.; Jung, J.J.; Sung, S.H.; Ku, S.K.; Choi, J.S. In Vitro Protective Effects of Hoveniae Semen cum Fructus Extracts against Oxidative Stress. Toxicol. Environ. Health Sci. 2016, 8, 19–27.
  55. Li, G.; Min, B.S.; Zheng, C.; Lee, J.; Oh, S.R.; Ahn, K.S.; Lee, H.K. Neuroprotective and Free Radical Scavenging Activities of Phenolic Compounds from Hovenia dulcis. Arch. Pharm. Res. 2005, 28, 804–809.
  56. Cho, J.Y.; Hyun, S.H.; Moon, J.K.; Park, K.H. Isolation and Structural Determination of a Novel Flavonol Triglycoside and 7 Compounds from the leaves of oriental raisin tree (Hovenia dulcis) and their antioxidative activity. Food Sci. Biotechnol. 2013, 22, 115–123.
  57. Yang, B.; Luo, Y.; Wu, Q.; Yang, Q.; Kan, J. Hovenia dulcis polysaccharides: Influence of multi-frequency ultrasonic extraction on structure, functional properties, and biological activities. Int. J. Biol. Macromol. 2020, 148, 1010–1020.
  58. Liu, W.; Li, F.; Wang, P.; Liu, X.; He, J.J.; Xian, M.L.; Zhao, L.; Qin, W.; Gan, R.Y.; Wu, D.T. Effects of drying methods on the physicochemical characteristics and bioactivities of polyphenolic-protein-polysaccharide conjugates from Hovenia dulcis. Int. J. Biol. Macromol. 2020, 148, 1211–1221.
  59. Liu, Y.; Qiang, M.; Sun, Z.; Du, Y. Optimization of ultrasonic extraction of polysaccharides from Hovenia dulcis peduncles and their antioxidant potential. Int. J. Biol. Macromol. 2015, 80, 350–358.
  60. Cha, P.H.; Shin, W.; Zahoor, M.; Kim, H.Y.; Min, D.S.; Choi, K.Y. Hovenia dulcis Thunb extract and its ingredient methyl vanillate activate wnt/ β-catenin pathway and increase bone mass in growing or ovariectomized mice. PLoS ONE 2014, 22, e85546.
  61. Wang, M.; Jiang, C.; Ma, L.; Zhang, Z.; Cao, L.; Liu, J.; Zeng, X. Preparation, preliminary characterization and immunostimulatory activity of polysaccharide fractions from the peduncles of Hovenia dulcis. Food Chem. 2013, 138, 41–47.
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