Anti-Arthritic and Anti-Cancer Activities of Polyphenols: Comparison
Please note this is a comparison between Version 1 by Muhammad Ali and Version 2 by Lindsay Dong.

Polyphenols have gained widespread attention as they are effective in the prevention and management of various diseases, including cancer diseases (CD) and rheumatoid arthritis (RA). They are natural organic substances present in fruits, vegetables, and spices. Polyphenols interact with various kinds of receptors and membranes. They modulate different signal cascades and interact with the enzymes responsible for CD and RA. These interactions involve cellular machinery, from cell membranes to major nuclear components, and provide information on their beneficial effects on health.

  • polyphenols
  • rheumatoid arthritis
  • cancer
  • in vitro
  • metastasis

1. Introduction

Plants have been used as medicines for more than 5000 years to treat a variety of diseases in humans. These phytomedicines have been able to cure animals and humans due to their beneficial natural phytochemicals. Phytochemicals are secondary metabolites of plant sources and have unique bioactive organic compounds with multiple pharmacological activities, including antiviral, anti-inflammatory, antineoplastic, and antioxidant. These phytochemicals include polyphenols [1], which are naturally occurring organic compounds in grapes, berries, nuts, olives, coffee, tea, flaxseed, and spices such as rosmarinus officinalis, origanum vulgare, salvia officinalis, and majorana syriaca [2]. The chemical structure of polyphenols consists of aromatic rings to which one or more hydroxyl groups are attached. Flavonoids, xanthones, catechin, hesperetin, quercetin, ellagic acid, lignans, stilbenes, chalcones, polyphenolic amides, and resveratrol fall within the class of polyphenolic substances [3][4][3,4].
Polyphenols possess anticancer and anti-inflammatory properties which modulate signaling pathways, induce apoptosis in various kinds of cancer cells, and reduce nucleoside diphosphate kinase B activity in lung, bladder, and colon cancer cells. Nucleoside diphosphate kinase B (NME2) plays an important role in many cellular processes. As a transcription factor, NME2 acts on the oncogene c-MYC, which is involved in the development of cancer [5].
Similarly, in recent decades, medicinal plants have been investigated for anticancer activity. These phytochemicals play a crucial role in maintaining the molecular signaling pathways of cancer. They can inhibit fatty acid synthesis, topoisomerase I/II suppression and downregulation, p53 accumulation, cell cycle arrest, proteasome inhibition, and regulation of survival/proliferation events. Unlike common approaches to cancer treatment that require lengthy and painful procedures, they have fewer side effects. The development of allopathic drugs requires complex procedures, from selecting a molecule to the production of medicines that might lead to unexpected failure, side effects, and toxicity [6]. Thus, researchers are continuously searching for novel alternative strategies for dealing with such conditions in a more effective way.

23. Biological Basis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory joint disease that causes cartilage and bone damage. Initially, it affects the joints, but it progresses to the eyes, kidneys, skin, lungs, and heart [7]. The major symptoms of RA are swollen and warm joints, fatigue, fever, weight loss, and rheumatoid nodules under the skin [8][9]. The factors that initiate the cause of RA are poorly understood. Genetic factors, including class II major histocompatibility antigens/human leukocyte antigens (HLA-DR) and non-HLA genes, play a crucial role in the pathogenesis of RA. The HLA and a few non-HLA genes have also been linked to citrullinated proteins called anti-citrullinated protein antibodies (ACPA) [9][13]. Anti-citrullinated protein antibodies (ACPAs) are autoantibodies that attack peptides and proteins that contain citrulline. As a result of inflammation, the arginine amino acid in proteins can be converted into citrulline by the calcium-dependent enzyme peptidyl-arginine-deiminase (PAD); this process is called citrullination. When the shape of proteins is altered, the immune system recognizes those proteins as antigens and initiates a response [10][14]. Exposure to air pollution, including silica dust, smoke, and carbon-derived nanomaterials, can stimulate mucosal toll-like receptors (TLRs) that activate PADs and antigen-presenting cells (APCs). Citrullinated proteins are triggered by smoking in the context of the HLA-DR SE gene [11][15]. There are also pathogens that trigger RA, such as Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis [12][16]. The pathobiology of RA involves the innate and adaptive immune systems. Cytokines are released by the body, causing the expression of adhesion molecules on the synovium membrane to increase. This allows inflammatory cells such as lymphocytes, macrophages, and plasma cells to migrate to the synovium, where they multiply and activate similar fibroblast-like synoviocytes (FLS). FLS stimulates the expression of the receptor activator of nuclear factor kappa-B ligand (RANKL), and, consequently, a high expression of pro-inflammatory cytokines occurs, leading to the initiation of osteoclast activity. Osteoclast cells absorb bone tissues and eventually, bone erosion occurs. FLS cells also release matrix metalloproteinases (MMPS), which are proteases responsible for the degradation of cartilage. Inflammation of the synovial membrane and the presence of inflammatory cells cause synovial hyperplasia and pannus formation, which consists of the extra growth of the joints and cartilage. High expression of vascular endothelial growth factor (VEGF) causes angiogenesis, resulting in more blood flowing to assist the maintenance of the pannus. The formation of the pannus leads to chronic inflammation and is responsible for the production of collagenase and protease [13][18]. Reactive oxygen species (ROS) also contribute to RA development. This is due to the fact that macrophages activated by excessive production of proinflammatory cytokines secrete reactive oxygen species (ROS), leading to the destruction of cartilage and joints [14][15][10,11]. The innate immune system is the first line of defense against pathogens. Many factors play a role in innate immunity, such as antibacterial peptides, mannose-binding lectins, the alternate pathway of complement activation, and cytokines. Dendritic cells, neutrophils, macrophages, T lymphocytes, and natural killer cells have major roles in the host’s immune response. TNF-α is an inflammatory cytokine released by immune cells such as macrophages, natural killer cells, endothelial cells, activated lymphocytes, and neutrophils (Figure 1). It mediates the activation, migration, and adhesion of immune cells, and contributes to the processes of angiogenesis and osteoclastogenesis [16][20].
Figure 1. Schematic pathogenesis of RA. The process of immune activation and disease progression involves the activation of both the innate and adaptive immune systems.
IL-6 is produced by FLS cells and macrophages. It stimulates endothelial cells to release chemokines and activates B and T cells, as well as osteoclasts. IL-6 plays an active role in the production of VEGF, which is responsible for pannus formation. IL-1β is produced in the inflamed synovium by macrophages and monocytes, and has the same activities as TNF-α [17][21]. These inflammatory cytokines induce inflammation by activating various pathways such as mitogen-activated protein kinase (MAPks), c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), p38, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), and NF-κB, responses that are not antigen-specific, adaptive, or associated with immunologic memory. Inflammatory markers such as IL-6, IL-10, the neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR), TNF-α, and C-reactive protein (CRP) play important roles in the pathogenesis of RA and are highly expressed in serum and synovium fluid of RA patients [18][19][22,23].  There are some drugs available that decrease inflammation and reduce pain, e.g., disease-modifying anti-rheumatic drugs (DMARDs), such as methotrexate, hydroxychloroquine, steroids, and non-steroidal anti-inflammatory drugs (NSAID); TNF inhibitors; and IL-6 inhibitors [20][8]. DMARDs are classified into conventional synthetic DMARDs (csDMARDs), targeted synthetic DMARDs (tsDMARDs), and biological DMARDs (bDMARDs). csDMARDs consist of leflunomide (LEF), sulfasalazine (SASP), and methotrexate (MTX); bDMARDs include inhibitors targeting B cells (rituximab), tumor necrosis factor (e.g., adalimumab and etanercept) T cells (abatacept), and interleukin-6 (IL-6; tocilizumab); and tsDMARDs consist of inhibitors of Janus kinase, baricitinib, and tofacitinib [21][29]

34. Biological Basis of Cancer Disease

Cancer is caused by the uncontrolled proliferation of normal cells in the body. Old cells do not demolish and continue to grow uncontrollably, resulting in the formation of new, abnormal cells. These uncontrolled cell divisions combine to form a mass of tissue known as a tumor. There are some physiological and biochemical factors that cause cancer, such as ionized and ultraviolet radiations, viral infections (e.g., human papillomavirus HPV causes cervical tumor growth and hepatitis B causes liver cancer), smoking, lack of exercise, high consumption of simple sugar and meat, parasites (e.g., schistosomiasis causes bladder cancer), contamination of meals or beverages (e.g., liver cancer may be caused by aflatoxins), and consumption of alcohol, which can cause liver cancer and bacterial infections (e.g., gastric cancer caused by Helicobacter pylori). Lung, stomach, colon, breast, prostate, and cervical cancers killed roughly 10 million individuals in 2020 [22][23][24][25][26][30,31,32,33,34]. For this reason, cancer therapies and preventive studies are necessary. There are many different phytochemical compounds present in fruits and vegetables that have anti-cancer, anti-inflammatory, antioxidant, and anti-diabetic properties.

45. In Vitro Test with Polyphenols

The Mediterranean diet has been known to reduce the incidence of chronic inflammation [24][32]. Extra virgin olive oil (EVOO) is one component of the Mediterranean diet which helps to reduce inflammation [25][33]. Phenolic compounds including tyrosol, hydroxytyrosol (HTyr), and oleuropein are key active components present in EVOO and have antioxidant and anti-inflammatory properties [26][27][34,35]. Many in vitro and in vivo studies have been performed to analyze the anti-arthritis effects of HTyr against various types of malignant cells, with different mechanisms of action being proposed. The investigation was conducted by Rosillo et al. to evaluate the efficacy of HTyr in a human synovial cell line, SW982. SW982 cells treated with HTyr had significantly reduced expression of tumor necrosis factors, matrix metalloproteinases, and IL-6. NF-jB and MAPKs phosphorylation activation induced by IL-1b was also inhibited by HTyr treatment. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) and the mammalian target of rapamycin (mTOR) are signaling pathways involved in the regulation of cell growth and cell survival. These signaling pathways are activated by various stimuli and regulate various operations, such as transcription, translation, proliferation, growth and survival [28][37]. Polyphenols regulate the immune system by inhibiting the mitogen-activated protein kinase (MAPK), ERK, JNK, and p38 (Figure 2), as well as the PI3K/AKT, mTORC1, and JAK-STAT pathways (Figure 3). Polyphenolic compounds have been shown to affect the epithelial–mesenchymal transition (EMT) by upregulating epithelial markers, such as E-cadherin, and suppressing mesenchymal markers [29][30][38,39]. Natural polyphenols, including apigenin genistein, luteolin, resveratrol, and quercetin, have been proven to induce cell death in various cancerous cell lines [31][40]. In vitro studies have shown that polyphenol extracts modulate NF-κB and Nrf2 activation and regulate PI3K and MAPK function in cancer cell lines [32][41].
Figure 2. Potential sites of an inhibitory mechanism of polyphenols in MAPK signaling pathways. ERK, extracellular signal-related kinases; JNK, c-Jun amino-terminal kinases; p38, p38 mitogen-activated protein kinase.
Figure 3. Potential sites of an inhibitory mechanism of polyphenols in the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) and the mammalian target of rapamycin (mTOR) pathways.
Olive oil (Olea Europea L.) is a well-known Mediterranean evergreen tree derivative with a slow growth rate and a life expectancy of up to 1000 years [33][42]. It is one of the most valuable trees for the Mediterranean economy, offering numerous commercial uses, such as in food, lumber, and cosmetics. The Mediterranean diet’s (MD) health benefits are known worldwide. Extra-virgin olive oil (EVOO) is increasingly considered a symbol of the MD. One of the significant differences between MD and other healthy diets is the high consumption of EVOO, which ranges from 15.3 to 23 kg per person per year [34][43]. EVOO-rich diet, with its omega-3 fatty acid content, is effective against many diseases such as Type 2 diabetes, RA, CD, and neurodegenerative and cardiovascular diseases [35][36][44,45].
Flavonoids are made up of two benzene rings connected by three linear carbon chains. Further modifications, such as glycosylation, result in the formation of other compounds, which are classified as flavones, flavonols, flavanones, and flavanols. Flavones were the first flavonoids discovered in virgin olive oil; their free forms, luteolin, and apigenin are the most concentrated compounds [37][49]. Luteolin has anticancer properties under both in vitro and in vivo conditions. Luteolin hampers the processes of carcinogenesis, such as metastasis, cell transformation, and angiogenesis, through different pathways, e.g., inducing apoptotic cell death, regulating the cell cycle, reducing transcription factors, and suppressing kinases [38][50].

4.1. In Vitro Test with Olive Oil Polyphenols

5.1. In Vitro Test with Olive Oil Polyphenols

45.1.1. In Vitro Test with Tyrosol on Rheumatoid Arthritis Cellular Models

Tyrosol is phenethyl alcohol, and is present in olive oil. It has anti-inflammatory and antioxidant properties. Luo et al. found that tyrosol reduces the release of IL-6 and TNF-α in cerebral hippocampal astrocytes isolated from post-neonatal pups of C57BL/6j mice. The decreased expression of cytokines is due to astrocyte inhibition and STAT3 signaling pathway regulation. Tyrosol also inhibits the IκBα degradation and enhances the phosphorylation of IκBα, leading to the downregulation of NF-κB expression [39][66]. Kim et al. concluded that tyrosol decreased the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, and phosphorylated-IκBα in LPS-stimulated RAW 264.7 macrophages [40][67]. These outcomes show that tyrosol modulates the inflammatory response and can be used as a treatment compound for RA.

45.1.2. In Vitro Test with Oleocanthal on Rheumatoid Arthritis Cellular Models

Oleocanthal is a polyphenolic compound, an important constituent of extra virgin olive oil, with anti-inflammatory properties. Studies by Scotece et al. (2012) examined that oleocanthal inhibits lipopolysaccharide-induced nitric oxide production and expression of iNOS, and suppresses the expression of macrophage inflammatory protein-1α. Oleocanthal also inhibits the production of IL-6 in J774 macrophages and ATDC5 chondrocytes, as well as the production of IL-1β, TNF-α, GM-CSF, and NO in J774. These cytokines play a significant role in the inflammatory process and destruction of cartilage in RA [41][68]. This research indicates that oleocanthal has anti-inflammatory properties and can be used for the treatment of RA.

45.1.3. In Vitro Test with Oleuropein on Rheumatoid Arthritis Cellular Models

Oleuropein is the most important phenolic compound in olive oil, with antioxidant and anti-inflammatory properties. It is used as a food supplement in Mediterranean countries. Its anti-inflammatory characteristics were evaluated by Castejón et al. The effects of oleuropein were evaluated on the IL-1β-induced human synovial sarcoma cell line (SW982). It was observed that the expression of inflammatory cytokines IL-6, TNF-α, MMP-1, MMP-3, mPGES-1, and COX-2 were decreasing. This outcome proves that oleuropein can be used for the management and prevention of RA [42][69].

45.1.4. In Vitro Test with Hydroxytyrosol on Cancer Cell Lines

The authors in [43][70] showed that hydroxytyrosol induces apoptosis in the LS180 colorectal cancer cell line by upregulation of pro-apoptotic genes such as BAX, CASP3, and P53, and also increases the BAX:BCL2 ratio and decreases nuclear factor erythroid 2-related factor 2 (NFE2L2) expression. Furthermore, hydroxytyrosol treatment increases antioxidative activity in colorectal cancer-cell lines, as evidenced by increased antioxidant enzymes. In another study [38][50], the authors demonstrated that HTyr can induce apoptosis in DLD1 colon cancer cells by producing ROSs. ROSs activated the PI3K/AKT/FOXO3 pathway, which regulated FOXO3 targets such as SOD and catalase, contributing to a reduction in cellular antioxidant defenses. In vitro studies of HTyr’s effects on colon cancer proliferation proposed that olive oil phenolic extracts regulate epigenetic mechanisms. CpG island methylation on the promoter of the Type I Cannabinoid Receptor (CB1), which could function as a tumor suppressor, has been frequently reported in the context of various cancers, including colon cancer.

45.1.5. In Vitro Test with Luteolin on Cancer Cell Lines

An investigation conducted in 2015 by Sun et al. demonstrated that the luteolin inhibits MDA-MB-231 breast cancer cell survival, as well as the expression of Notch signaling-related protein and mRNAs [44][73]. The 2015 study conducted by Jeon et al. showed that luteolin expresses chemopreventive properties in MCF-7, HER18, MDA-MB-231, and SkBr3 cells by inhibition of extracellular signal-regulated kinase (ERK) via Akt inactivation [45][74]. In another study, the authors revealed that luteolin inhibits the activation of MAPK signaling pathway 9 in 12-o-tetradecanoylphorbol-13-acetate (TPA)-treated breast cancer cells (MCF-7), leading to downregulation of the expressions of IL-8 and MMP. Luteolin also downregulates the activation of the AP-1 and NF-κB pathways [46][75].

4.2. In Vitro Test with Spice Polyphenols

5.2. In Vitro Test with Spice Polyphenols

45.2.1. In Vitro Test with Curcumin Polyphenols on Rheumatoid Arthritis Cellular Models

Curcumin is a bright yellow chemical produced by the Curcuma longa species which is a natural anti-inflammatory agent. Curcumin has been demonstrated to have anti-inflammatory activities by blocking the COX-2 pathway. It has also been observed that curcumin decreases the production of vascular endothelial growth factor (VEGF) and IL-6. It also inhibits the extracellular signal-regulated kinase (ERK1/2) and NF-κB inflammatory pathways [47][79]. The production of receptor activators of nuclear factor κB ligand (RANKL) and osteoclast-associated RANK is important for the process of osteoclastogenesis. RANK binds to RANKL, and as a result, osteoclast differentiation begins. Inflammatory cytokines upregulate the expression levels of RANK, enhance osteoclast precursors, and increase their sensitivity to RANKL, which may result in bone erosion in RA. Curcumin may inhibit the osteoclastogenic potential of PBMCs in patients with RA through the suppression of the mitogen-activated protein kinase/RANK/c-Fos/NFATc1 signaling pathways. NFATc1 is a crucial transcription factor that is expressed in osteoclast precursors through Ca2+ oscillation, MAPKs, and c-Fos or RANK in response to RANKL [48][80].

45.2.2. In Vitro Test with Curcumin Polyphenols on Cancer Cell Lines

Curcumin is an essential natural chemical that has anti-inflammatory and anti-tumor activities. The chemopreventive effects of curcumin were investigated in cultured breast cancer cells. Specifically, curcumin was found to suppress the proliferation of several breast cancer cell lines, including T47D, MCF7, MDA-MB-231, and MDA-MB-468 [49][84]. Curcumin also suppressed protein kinase B (Akt)/mammalian target of rapamycin (mTOR) phosphorylation, decreased B-cell lymphoma 2 (BCL2), and enhanced BCL-2-associated X protein (BAX) and caspase 3 cleavage, resulting in apoptosis in breast cancer cells [50][85]. Curcumin suppressed breast cancer cell growth and triggered G2/M phase cell cycle arrest and apoptosis, which could be linked to decreased CDC25 and CDC2 protein levels, increased P21 protein levels, suppression of Akt/mTOR phosphorylation, and stimulation of the mitochondrial apoptotic pathway [51][86].

45.2.3. In Vitro Test with Ginger Polyphenols on Cancer Cell Lines

Ginger (Zingiber officinale) is a domesticated spice that is used as a food additive. It is used in herbal medicine and has many medicinal properties. Ginger has many bioactive components, including anthocyanins, volatile oils, tannins, sesquiterpenes, and gingerols [52][88]. Gingerol is an active ingredient in ginger with anti-cancer properties, and it modulates various signal pathways in cancerous cells, i.e., nuclear factors (NF-KB), signal transducer and activator of transcription 3 (STAT3), activator protein-1 (AP-1), wnt/β-catenin, growth factor receptors (EGFR, VEGFR), mitogen-activated protein kinases (MAPK), and pro-inflammatory mediators [53][89].

45.2.4. In Vitro Test with Stilbenes on Rheumatoid Arthritis Cellular Models

Stilbenes are polyphenolic non-flavonoid compounds found in berries, grapes, red wine, peanuts, etc., which have anti-inflammatory and antioxidant properties. More than 400 stilbene compounds have been identified. Resveratrol is an important compound of stilbenes that is present in the outer layer of the skin of grapes [54][93] and that increases the expression of heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor 2 in H2O2 treated (RA-FLS) RA fibroblast-like synoviocyte cells. Furthermore, it also downregulates the expression of kelch-like ECH-related protein 1 (keap1), ROS, and MDA. It also blocks the expression of nuclear factor-κB (NF-κB) p65 and enhances the expression of Bcl-2/Bax, which leads to inhibition of cell proliferation and apoptosis [55][94]. It has been determined that resveratrol induces cell apoptosis in the MH7A cell line by activation of caspase-9 and caspase-3 and disruption of mitochondria. Disruption of mitochondria causes the downregulation of the expression of Bcl-XL and the release of cytochrome c into the cytosol from mitochondria [56][95]. It has also been proven that resveratrol modulates the production of cytokines and inhibits the protein expression of MMP-3 and IL-1b in fibroblast-like synoviocytes.

4.3. In Vitro Test with Grapes Polyphenols

5.3. In Vitro Test with Grapes Polyphenols

Studies by Jang et al. examined the anti-tumor activity of resveratrol on androgen-sensitive human prostate adenocarcinoma cells (LNCaP), a human prostate cancer cell line. Prostate cancer is the second-most common cause of cancer-related mortality. Studies have shown that prostate cancer is affected by the action of dihydrotestosterone on androgen receptors. C-X-C chemokine receptor type 4 (CXCR4) is a receptor that is highly expressed in prostate cancer cells. Dihydrotestosterone proliferates LNCaP prostate cancer cells. The results showed that resveratrol and its combination with AMD3100 (CXCR4 inhibitor) reduced the cell viability promoted by dihydrotestosterone [57][105]. Studies conducted by Aires et al. concluded that 3-o-sulfate-Resveratrol, a metabolite of resveratrol, inhibits human colon cancer cell lines due to S-phase stem cell accumulation, the apoptosis process, and DNA damage to the colon [58][106]

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