3.1. Garlic
Garlic has been used as a therapeutic and medicinal agent in several cultures for centuries, specifically in Egyptian Cordex Ebers and in ancient Greece, Rome, India, China, and Japan
[88][89]. Garlic is mainly constituted by water, but it also contains carbohydrates, sulfur compounds, proteins, fibers, and free amino acids. In addition, it contains high levels of saponins, phosphorus, potassium, sulfur, zinc; moderate levels of selenium and vitamins A and C; and low levels of calcium, magnesium, sodium, iron, manganese, and B-complex vitamins
[90]. Furthermore, a substantial amount of evidence has shown that some of the compounds present in garlic have antioxidant properties with radical-scavenging functions and antioxidant enzyme modulation
[91][92].
Several garlic preparations, such as raw garlic homogenate, garlic powder, aged garlic extract, and garlic oil have been used in scientific studies to determine the effects of garlic. These may explain the diversity of the results concerning the effect of garlic in the male reproductive system. For example, Oi et al. used garlic powder to evaluate its effect on testosterone production in rats on a casein-based diet, a high protein level diet
[93]. After 28 days of supplementation, the testosterone levels were increased in the rats fed 40 and 25% casein diets, indicating that garlic enhanced testosterone production in high protein level diets
[93].
On the other hand, the effect of garlic extract on sperm characteristics and testicular oxidative damage after cadmium exposure showed that garlic extract improved epididymal sperm parameters (concentration, motility and counts) and reduced the number of abnormal sperm. It increased GSH, SOD, CAT, and alkaline phosphate (ALP) and decreased MDA and GST levels, improving antioxidant status after cadmium exposure
[94]. Concerning other environmental contaminants, Furan is a contaminant found in a wide variety of foods that have been heat-treated via thermal degradation that can induce damage in the testis. Garlic oil has been shown to ameliorate the effect of furan on histopathological alterations and the reduction of testosterone levels. Garlic oil also increased SOD, CAT, and GSH levels and decreased the MDA, CYP2E1, and caspase-3 levels
[95].
The antibiotic Adriamycin has been shown to induce reproductive toxicity. Aged garlic extract attenuates the toxic effects of Adriamycin, improving all sperm parameters (count, motility, viability and morphology) as well as the histological, biochemical, and ultrastructural findings in testicular sections. Moreover, it increases the levels of antioxidant defenses (GSH, GSH-Px, CAT, and SOD) and decreased MDA levels
[96]. Although garlic has several beneficial effects and is considered safe, care should be taken in terms of its therapeutic use, as some studies have shown its potential toxicity in the male reproductive system
[88][97]. In addition, a study showed that garlic might cause gastric irritation, nausea, vomiting, flushing, tachycardia, headache, insomnia, sweating, and dizziness, among other symptoms
[97].
In Table 2, it is summarized the beneficial effects in male reproductive system.
Table 2. Bioactive compounds present in natural products with beneficial effects in male reproductive system.
3.2. Ginger
Ginger or
Zingiber officinale is a grayish-white rhizome with pale brown rings that is used worldwide as a cooking spice and can be used as a powder or fresh root
[98]. For generations, it has been used as a medicinal plant to treat several medical conditions, such as constipation, fever, indigestion, infectious diseases, muscle aches, nausea, rheumatoid arthritis, sore throat
[99], and disorders of the male reproductive system
[150]. In medieval Persia, medical texts such as
Qanoonfel-teb (The Canon) by Ebn-e-Sina (980–1037) described ginger as a very effective herb for erectile dysfunction
[151]. In Western Uganda, men drink ginger tea to treat sexual impotence and erectile dysfunction
[152]. Additionally, hot ginger remedies are used to increase sexual energy and semen volume
[150].
In terms of biological activity, ginger is an antioxidant and shows
[153], anti-inflammatory
[154], anti-cancer
[155][156] anti-microbial
[157], anti-diabetic, hypolipidemic properties
[158] as well as androgenic activity
[159]. The compounds present in ginger include acids, choline, folic acid, inositol, pantothenic acid, resins, sesquiterpenes, vitamin B3 and B6, vitamin C compounds, volatile oils, and bio-trace elements such as calcium, magnesium, phosphor, and potassium
[160]. However, the main bioactive compounds present in ginger are gingerdiol, gingerol, shogaols, zingerone, and zingibrene, which are responsible for the antioxidant activity of ginger
[161] and properties of free radical scavenging, inhibition of lipid peroxidation, and DNA protection
[100].
In the testis, ginger is a protective factor against oxidative stress-inducers, such as carbon tetrachloride, an industrial chemical that, when it is decomposed, creates sulfite salts (e.g., sodium metabisulfite). These sulfite salts are used as preservatives and disinfectants in foods and pharmaceutical agents, as they release sulfur dioxide that can cause oxidative stress. Ginger treatment in the presence of carbon tetrachloride or sodium metabisulfite improved histopathological findings
[101] and prevented the toxic effects in the SeT, epididymal tissue
[99], and in the sperm parameters (morphology and motility)
[101]. Additionally, ginger increased the enzymes GHS-Px,
[99][101], TAC, SOD, and CAT
[99]; GSH-Rx levels; and testosterone
[101] and decreased MDA levels
[99][101].
Alcohol consumption has been a cause of great concern in terms of male fertility since excessive consumption is associated with increased oxidative stress levels
[100][109]. Ginger can attenuate the effects of ethanol by increasing SOD, GSH-Px, and CAT activity and by decreasing MDA and total homocysteine concentrations. Moreover, ginger administration increased the levels of testosterone, sex hormone-binding globulin, and dehydroepiandrosterone sulfate
[100][102].
Other studies have shown that ginger also protects the male reproductive system from drugs that induce damage. Three different doses of ginger (50, 100, and 150 mg/kg) were used to attenuate the toxicity of busulfan, a drug used to treat chronic myelogenous leukemia and blood disorders. Sperm counts and motility were increased in all ginger extract doses, with the sperm motility increase being dose-dependent. At a dose of 50 and 100 mg/kg, ginger extract increased the SeT volume, and at a dose of 100 and 150 mg/kg, the testosterone levels increased
[103]. Additionally, two different ginger extract doses (300 and 600 mg/kg) were used to evaluate protective effects against the toxic effects of cyclophosphamide, an anti-neoplastic agent. Both doses led to histological improvement and increased germ cells counts and antioxidant levels, but only the dose of 300 mg/kg increased the epithelium thickness, and the 600 mg/kg dose increased testosterone levels
[104].
The co-administration of ginger with gentamicin, an antibiotic, and cisplatin decreased the number of apoptotic cells compared to the non-treated group
[12][98] and restored normal testicular morphology, spermatogenesis, and sperm parameters (counts, motility and morphology)
[105]. In addition, the MDA levels decreased in response to treatment with ginger
[12].
Several metabolic syndromes can induce damage in the testis, such as high-fructose diet-induced metabolic syndrome and diabetes. Fructose is a carbohydrate that is widely used as a food additive because of its sweetness. However, it is one of the main factors that is responsible for the progression to metabolic syndrome, leading to oxidative stress
[106]. In rats fed with a high-fructose diet, ginger decreased the total body weight but increased testicular weight. Additionally, it improved histopathological findings, increasing the epithelial height and SeT perimeter and proliferative cell nuclear antigen (PCNA) and Beclin 1 immunoreactivity. PCNA is considered to be a proliferation marker that can be used to analyse spermatogenesis, and Becilin 1 is a protein involved in autophagic pathways and is considered to be an important regulatory mechanism in spermatogenesis and steroidogenesis
[106]. The increased immunoreactivity of PCNA and Beclin 1 indicate an improvement in spermatogenesis and steroidogenesis in the presence of ginger treatment. Ginger increased the FSH, LH, testosterone, HDL, and SOD levels and decreased the triglycerides, LDL, MDA, and serum levels of glucose, insulin as well as the subsequent diminution of the homeostasis model assessment for insulin resistance (HOMA-IR)
[106].
Diabetes is a chronic metabolic disease that is associated with infertility
[107]. Ginger treatment in induced diabetic rats with streptozotocin improved histopathological findings; increased the TAC, androgen receptor, and the PCNA levels; and decreased the blood glucose level and caspase-3 expression
[107]. Additionally, a different study showed that in alloxan-induced diabetic rats, a ginger supplemented diet improved sperm parameters (counts and motility) and increased testis, epididymis, prostate, and seminal vesicles weights. Moreover, a ginger-supplemented diet in diabetic rats increased (i) the hormonal serum levels of testosterone, FSH and LH and (ii) the antioxidant enzymes SOD, CAT and GSH-Px levels and decreased (i) plasma glucose; (ii) the metabolic enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and ALP; and (iii) MDA levels in the testis
[108].
In Table 2, it is summarized the beneficial effects in male reproductive system.
3.3. Grape
Grape (
Vitis vinifera) is one of the most farmed and largely produced fruits in the world
[110] and has a history of use in Europe for traditional treatments
[162]. Dried grape seeds contain 35% fiber, 29% extractable components such as phenolic compounds, 11% proteins, 7% water, and 3% of minerals
[163] and can be used to produce grape seed extract. The phenolic compounds found in grape include non-flavonoids such as resveratrol and flavonoids (e.g., catechin, epicatechin, quercetin, anthocyanin, and pro-anthocyanidins)
[109][111].
Grape seed extract presents several biological activities, namely anti-apoptotic, anti-necrotic, cardiovascular
[164], anti-cancer
[165], anti-inflammatory
[166], and antioxidant
[167] effects. Its capacity to scavenge oxidants and free radicals is due to the presence of the phenolic compounds, especially the pro-anthocyanidins
[168], which present a higher antioxidant capacity than vitamin C or E
[169]. Both grape seed extract and grape seed pro-anthocyanidin extract present protective effects against male reproductive toxic inducers.
Several studies have identified grape seed extract, grape seed pro-anthocyanidin extract, and grape juice concentrate as protective factors against cadmium toxicity. Grape seed extract and grape seed pro-anthocyanidin extract improved histopathological findings
[112][113][114][115], increasing the diameter and normal SeT
[112][115], testicular weight
[112], and Johnsen’s mean testicular biopsy score and decreasing the apoptotic index
[115]. It was also observed to increase PCNA immunoreactivity
[112] and total antioxidant status (TAS)
[113] in the enzymes of the antioxidant defense system and genes associated with steroidogenesis and Ki-67 expression
[114], and it decreased MDA levels
[113][114] and the immunoreactivity of the apoptotic regulator Bax
[114]. Grape juice concentrate treatment against cadmium toxicity demonstrated that co-administration restored the testis, epididymis, and ventral prostate weight
[116] to normal levels, ameliorating tissue architecture
[111][116][117], epididymis epithelium height (
caput and
cauda regions)
[111] and improving sperm parameters such as production, counts, transit time
[111], and morphology
[116]. Additionally, it increased testosterone and GSH levels and decreased cadmium accumulation, MDA levels
[111], and SOD and mitochondrial SOD activity
[116].
Grape seed extract can also protect the testis against the toxic effects of drugs such as dexamethasone, an immunosuppressive and anti-inflammatory glucocorticoid drug
[118]. Using two doses (200 or 400 mg/kg body weight) of grape seed extract administrated with dexamethasone, it was possible to observe histopathological improvement, especially at a dose of 400 mg/kg, which increased body, testis weight, and serum testosterone. It also increased thyroid hormones, (free T3, T4 and thyroid-stimulating hormone); antioxidant defenses (CAT and GSH); total protein content; acid phosphatase (ACP), a specific marker for spermatogenesis; and glucose-6-phosphate dehydrogenase (G-6-PDH). Thyroid hormones are essential in the regulation of the reproductive system, and G-6-PDH is associated with GSH synthesis that when decreased can indicate testicular degeneration
[118].
Additionally, grape seed extract seems to attenuate the effects of ethanol by increasing the weight of the testis, epididymis and accessory sex organs, sperm parameters (counts, motility, and morphology), testosterone, and GSH levels and decreasing the MDA levels in the testis
[109].
Plant growth regulators, namely gibberellic acid and indoleacetic acid, are chemicals that are used worldwide in agriculture that can induce toxic effects on the male reproductive system
[110]. Grape seed pro-anthocyanidin extract co-treatment with different plant growth regulators improved histopathological architecture and the spermatogenesis process and decreased apoptotic cells
[110].
Several events/incidents can induce damage in the testis, such as varicocele and testicular torsion. Varicocele is a dilatation of the pampiniform plexus, draining the testes and inducing male infertility
[119]. The administration of grape seed pro-anthocyanidin extract in a varicocele model rats improved histological and sperm parameters (concentration and motility). In addition, an increase of the antioxidant enzymes (SOD and GSH-Px), the apoptotic regulator’s ratio Bax/Bcl-2, Nrf2 and HO-1 was observed as were decreased levels of MDA, apoptotic cells, and caspase-3
[119]. Grape seed pro-anthocyanidin extract was administrated 7 days prior to the surgical procedure for induced testicular torsion in rats for 2 h followed by administration 2 h after detorsion. Grape seed pro-anthocyanidin extract ameliorated histopathological damage, increasing Johnsen’s mean testicular biopsy score and decreasing apoptotic cells, iNOS immunoreactivity, and MDA levels
[120].
Trans-Resveratrol (trans-3,4,5-trihydroxystilbene) is a natural antioxidant present in grapes. A study with rats treated with
trans-resveratrol, which was detected in plasma after 24 h of treatment, showed that it did not have adverse effects. The testicular weight was similar to the control group. However, the
trans-resveratrol groups showed a reduced SeT diameter but an increased SeT length, increasing the tubular density comparatively to the control group. In addition, it increased the sperm count and the hormonal levels of LH, FSH, and testosterone
[121].
In Table 2, it is summarized the beneficial effects in male reproductive system.
3.4. Green Tea
Green tea (
Camellia sinensis) is one of the oldest and most popular drinks worldwide
[170]. Green tea leaves contains 30% phenolic compounds, such as flavonols, of which epigallocatechin gallate, epigallocatechin, epicatechin gallate, catechin, epicatechin, and gallocatechin stand out; 15–20% protein; 5–7% carbohydrates; 5% minerals and trace elements; 3–4% methylxanthines; 2% lipids; 1–2% organic acids; and 1–4% amino acids
[171][172]. Moreover, it contains around 0.05–0.3% vitamin C
[173].
Green tea has several biological characteristics and health benefits, shpwing anti-cancer
[174][175], anti-cardiovascular diseases
[176], anti-inflammatory
[177], anti-arthritic
[178], anti-microbial
[179][180], neuroprotective
[181], cholesterol-lowering
[182] and antioxidant
[183] effects. Phenolic compounds are potent antioxidants with the ability to scagenge oxygen, hydroxyl, and anion superoxide radicals and have metal chelating functions
[122][184].
Green tea consumption is a common practice that is well accepted by modern society, and its beneficial effects are well recognized in our day to day lives. During a 52-day study period, the administration of green tea extract (2 and 5%) in male Wistar rats resulted in the body and reproductive organs weight remaining unchanged compared to control group. Liver weight also remained unchanged, but decreased levels of AST and ALT were observed, suggesting hepatoprotective properties. The testosterone level was similar to the control group as was the weight of the testosterone-dependent organs. Normal histological sections (except an increase in diameter of SeT) were observed between the green tea consumption group and control group. Concerning sperm parameters, green tea increased sperm concentration and viability, but the sperm motility and velocity functions remain similar to the control. However, a significant increase in spontaneous acrosome reactions was observed. Finally, the antioxidant defenses (CAT, GSH, MDA, and SOD levels) remain unchanged, indicating the safety of green tea consumption and a balance of the oxidative stress status of the tissues
[123].
Several studies identify green tea as a protective factor against environmental pollutants that are widely used in industry and that can induce oxidative damage. These includes para-nonylphenol, deltamethrin (a synthetic insecticide), cadmium, and nicotine (a volatile alkaloid that is the primary toxic component of cigarette smoking). Green tea extract ameliorated histopathologic damage
[122][124][125][126][127] by increasing the SeT diameter
[122][126], epithelium height, Johnson’s score
[122], and the volume of the SeT and testis
[124]. Additionally, green tea extract increased testis, body, and reproductive organ weight
[124][126][127]. In terms of the sperm parameters (concentration, motility, viability, morphology, production and counts), green tea extract co-administration with these environmental pollutants seemed to induce a beneficial effect
[122][124][125][126][127]. Green tea extract increased testosterone levels
[122][126][127] and antioxidant defenses (SOD, CAT, and GSH)
[126][127], and decreased caspase-3
[122][126] and cholesterol levels
[126]. Regarding the lipid peroxidation, green tea extract decreased MDA
[122][124][125] and TBARS levels
[127] compared to the environmental pollutants groups.
Green tea can also protect against the toxic effects of some drugs, such as doxorubicin, an anthracycline antibiotic
[128]. The administrations of two different green tea extract concentrations (200 mg/kg and 500 mg/kg) against doxorubicin-induced toxicity seemed to ameliorate the histological findings and increased sperm parameters (concentration and mobility), the Sertoli cell index (ratio between germ cells number and Sertoli cells number), and telomerase activity in both concentrations
[128]. Several studies have indicated the beneficial effects of green tea, though there are also reports of relevant side effects, such as hepatotoxicity and gastrointestinal disorders as well as drug interactions
[185].
In Table 2, it is summarized the beneficial effects in male reproductive system.
3.5. Microalgae and Algae
Microalgae are a natural source of various bioactive compounds, such as phycobilins, carotenoids, PUFA, polysaccharides, sterols, and vitamins, which have many applications from animal feed to human nutrition
[186]. PUFA are abundant in microalgae, and they are one of the major compounds responsible for its bioactivities
[187]. Therefore, their effects on male infertility have been explored because oxidative stress is a major contributor to defective spermatogenesis
[188]. Moreover, elevated oxidative stress within semen is also associated with infection/inflammation of the male reproductive system, which compromises sperm quality
[189]. After several studies indicating its safety and beneficial effects for human health, namely antitoxic, antigenotoxic, antioxidant effects, and reporting no reproductive and teratogenic toxicity, the microalgae
Chlorella vulgaris and
Spirulina platensis were classified as Generally Regarded as Safe (GRAS) substances by the United States Food and Drug Administration (FDA)
[190][191]. Additionally, some studies have reported the protective properties of
C. vulgaris against various noxious stimuli
[192][193][194], and it has been suggested that
C. vulgaris might be helpful in diseases where the maintenance of antioxidant status is crucial
[193].
In deltamethrin-intoxicated rats,
C. vulgaris administered orally for 8 weeks was able to re-establish the serum testosterone concentration, sperm counts, sperm viability, sperm motility, and sperm abnormalities as well as the testicular levels of SOD and CAT antioxidant enzymes and the lipid peroxidation marker MDA to levels similar to the control group
[129]. More recently, Eissa et al., demonstrated that pre- and co-treatment with
C. vulgaris was helpful against sodium nitrite-induced reproductive dysfunction via the partial prevention of negative changes in sperm quality, serum testosterone and FSH levels, testicular oxidant/antioxidant balance, and testicular histological architecture
[130].
S. platensis was also pointed as a promising protective agent to ameliorate diseases and toxicities involving oxidative stress
[195], having recognized antioxidant, anti-diabetic, anti-inflammatory and anti-apoptotic properties
[196]. At the reproductive level,
S. platensis has been shown to be beneficial in improving spermatogenesis and steroidogenesis after cadmium intoxication
[131] and counteracted furan toxicity in rat testis
[132]. Furthermore,
S. platensis reduced the deterioration induced by mercuric chloride in the sperm quality and testis of rats through the decrease of (i) lipid peroxidation, (ii) mercury accumulation in the testis, (iii) testicular histopathological changes, and iv) sperm abnormalities
[133].
S. platensis also reverted the mercuric chloride-induced inhibition in the activity of key antioxidant enzymes (SOD, CAT, and GSH-Px) back to normal levels
[133]. Moreover, the in vivo protective action of
S. platensis against bifenthrin-induced reprotoxicity has been documented. In that study,
S. platensis administrated before bifenthrin partially re-established the oxidant/antioxidant equilibrium, testosterone production, testicular mRNA, and microRNA levels of the genes involved in spermatogenesis as well as sperm motility and viability
[134].
Recently, it was highlighted that
C. vulgaris or
S. platensis can have positive effects on testicular dysfunction provoked by lead acetate due to their antioxidant activity, immunomodulatory ability, and anti-apoptotic activity
[135].
Spirulina maxima has been shown to improve spermatogenesis and steroidogenesis in diabetic rat testis
[136] and also mitigated benzo[alpha]pyrene- and cyclophosphamide-induced injury to male mouse germ cells
[137][138].
Although fewer works that compare the effects of microalgae are available, some algae also seem to have garnered interest in terms of reproductive purposes. Such is the case of
Halopteris scoparia, a brown alga that is generally consumed as a salad in Far East countries, which ha sbeen reported to protect against cadmium chloride-induced testicular damage in mice
[139]. In another study, fucoxanthin extract from brown algae
Laminaria japonica ameliorated male reproductive function in diabetic rats by (i) decreasing the glucose level, (ii) restoring sperm motility, (iii) reducing sperm abnormalities, (iv) enhancing enzymatic antioxidant activity, (v) reducing proinflammatory cytokine levels, and (vi) recovering LH and testosterone levels
[140]. Indeed, fucoxanthin is a natural agent with the potential to be considered an anti-diabetic candidate and a functional food to improve male fertility affected by diabetes mellitus
[140]. Furthermore, fucoxanthin extract from brown algae
Sargassum glaucescens increased sperm count, decreased sperm abnormalities, and improved the morphology of SeT as well as improved testosterone levels in hamsters treated with the chemotherapeutic drug cisplatin
[141].
In Table 2, it is summarized the beneficial effects in male reproductive system.
3.6. Propolis
Propolis or bee glue is a natural resinous mixture produced by honeybees that is used to seal holes in their honeycombs, smooth out the internal walls, and protect the entrance against intruders
[197].
Propolis is a complex mixture of several compounds derived from plants and is processed by the salivary enzymes of bees
[198], and for this reason, propolis content can vary depending on the plant source used by the bees
[142]. Usually, the propolis of Northern temperate climates contains approximately 50% resins and vegetable balsams, 30% waxes, 10% essential oils, 5% pollen, and 5% other organic substances
[143][199]. This composition can also change depending on the hive, district, and season
[199]. Due to this variability, propolis can have more than 300 compounds with pharmacological activity, such as polyphenolic compounds (e.g., flavonoids), terpenoids, various steroids, amino acids, glucose, fructose, vitamins such as vitamin B1, B2, C, and E, and essential elements such as magnesium, calcium, nickel, iron, and zinc
[197][200].
In fact, it has been used in folk medicine
[201], and no side effects have been described after propolis administration in humans and mice
[202]. Several biological activities with pharmaceutical interest have been described for propolis, such as anti-hyperglycemic, antioxidant, anti-inflammatory, anti-apoptotic
[202][203], and anti-microbial
[202][204] effects.
Phenolic compounds, such as flavonoids, are the main bioactive components responsible for the biological activity of propolis, specifically antioxidant activity. Flavonoids are capable of scavenging free radicals associated with several diseases, ageing, and toxic substances
[145][205]. Additionally, propolis antioxidant activity includes the capacity to activate antioxidant enzymes such as CAT
[206] and SOD
[207]. Moreover, propolis can inhibit the generation of superoxide anions and can reverse the consumption of glutathione, an enzyme with radical scavenging activity
[145][208].
In testis, several studies have described the use of propolis as a protective factor against many different oxidative stress inducers, showing significant improvements in male fertility
[209]. In addition, it has been found to have a protective role against oxidative stress-inducers such as copper, cadmium, and aluminum in the reproductive tissues of rats
[142][145][146]. Propolis co-treatment improved histopathological changes
[142][145][146] by decreasing the number of apoptotic cells
[142] and degenerative changes in the tubular epithelium
[146] and increasing Johnsen’s testicular score
[142]. Additionally, propolis coadministration induced an increase in CAT and GSH levels
[142][145], SOD
[142], testosterone, 17-ketosteroid reductase, and GST levels
[145], and it decreased MDA
[142][146] and TBARS levels
[145] and immunoreactivity of testicular HIF-1α
[146]. In terms of sperm parameters, propolis co-treatment increased sperm concentration and motility and decreased abnormal sperm
[142][145] and sperm death
[145]. Finally, it also increased the weight of the testis
[145][146] and epididymis
[145].
Diabetes mellitus has been associated with male infertility
[143]. Propolis may regulate the testicular and epididymal oxidative stress levels in induced-streptozotocin diabetic rats. Improved histopathologic changes have been found, namely increased SeT diameter and seminiferous epithelial height and decreased germ cells loss and epididymal epithelial height. Propolis co-administration increased the weight of the testes, epididymis, prostate, and seminal vesicles. Additionally, it demonstrated an increase of
Nrf2, SOD, CAT, GSH-Px, GSH-Rx, GST, and TAC levels, and it decreased NO and TBARS levels, supporting the antioxidant properties of propolis. Concerning the pro-inflammatory mediators and apoptosis-related genes, propolis increased the protein levels of NF-kB, tumour necrosis factor-α, interleukin (IL)-1β, and IL-10 and decreased testicular levels of Bax/Bcl-2 ratio, p53, caspase-8, caspase-9, and caspase-3
[143], demonstrating the anti-inflammatory and anti-apoptotic properties of propolis. Recently, it has also been shown that propolis treatment in diabetic rats ameliorated sperm parameters (counts, motility, viability and morphology) and diminished non-motile spermatozoa and sperm DNA fragmentation. Additionally, it improved steroidogenesis through the increase of testosterone levels,
StAR, CYP11A1, CYP17A1, 3β-HSD, and 17β-HSD. Relative to the metabolic pathways, propolis increased glucose transporter 3 (GLUT3), MCT2, MCT4, and decreased LDH, intra-testicular glucose, and lactate levels
[144].
In the presence of some drugs (paclitaxel, methotrexate and doxorubicin), propolis supplementation seems to a have a beneficial protective effects on the male reproductive system, improving histopathological changes by increasing the Johnsen testicular biopsy score
[147] and the diameter of SeT
[147][148]; sperm motility, viability
[149], and counts
[148][149]; and decreasing sperm abnormalities
[149]. Moreover, propolis co-administration increases GSH levels
[148][149], LDH, sorbitol dehydrogenase, ACP, ALP, G-6-PDH, testosterone, FSH, LH, IL-4, 3β-HSD, 17β-HSD, and
StAR [148] and decreases MDA
[148][149], 8-hydroxy-2-deoxyguanosine (8-OHdG)
[149], ALT, AST, MPO, tumor necrosis factor-alpha (TNF-α), Fas-L, and caspase-3 levels
[148]. Propolis also increases the ATP level in testis homogenate and decreases ADP and AMP levels
[149]. The existing data show that propolis presents beneficial effects against several diseases. However, it should be considered that there is no standardized propolis extraction method, which causes problems in terms of establishing its safe use. There have also been reports of its toxicity as well. Additionally, propolis has been identified as an allergen with immunological stimulating properties, which may affect human health
[197].
In Table 2, it is summarized the beneficial effects in male reproductive system.