Methyl Gallate Suppresses Canine Mammary Gland Tumors by Inducing Apoptosis and Anti-angiogenesis.

BACKGROUND/AIM: Methyl gallate (MG), a plant phenolic compound, has known anticancer properties. However, its effects on canine mammary gland tumors (CMTs) are unclear. This study evaluated the impact of MG on cell viability, migration, and apoptosis in two CMT cell lines. MATERIALS AND METHODS: CMT-U27 and CF41.mg cells were used. In vitro experiments included MTT and scratch assays, Annexin-V/propidium iodide double staining, immunocytochemistry, and western blot analyses. An in vivo CMT xenograft mouse model was also used to observe the effects of MG on tumor growth and vasculature. Immunohistochemistry was performed to analyze vessel density and apoptosis in tumor tissues. Cell migration and tube formation assays with canine aortic endothelial cells assessed the anti-angiogenic effects of MG. RESULTS: Data showed a significant decrease in cell viability and migration in both CMT cell lines after 24 h exposure to various MG concentrations. MG treatment induced dose-dependent apoptotic cell death and elevated cleaved caspase-3 expression. In vivo experiments confirmed tumor growth suppression 21 days post-treatment with 40 mg/kg MG. Tumor tissues displayed increased cleaved caspase-3 and reduced vessel density. MG also inhibited cell migration and disrupted tube formation in canine endothelial cells. CONCLUSION: MG has potential as an anticancer drug for CMTs by promoting apoptotic cell death and reducing angiogenesis, highlighting its therapeutic promise.

Biosensor-based active ingredient recognition system for screening potential small molecular Severe acute respiratory syndrome coronavirus 2 entry blockers targeting the spike protein from Rugosa rose.

The traditional formulation Hanchuan zupa granules (HCZPs) have been widely used for controlling coronavirus disease 2019 (COVID-19). However, its active components remain unknown. Here, HCZP components targeting the spike receptor-binding domain (S-RBD) of SARS-CoV-2 were investigated using a surface plasmon resonance (SPR) biosensor-based active ingredient recognition system (SPR-AIRS). Recombinant S-RBD proteins were immobilized on the SPR chip by amine coupling for the prescreening of nine HCZP medicinal herbs. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) identified gallic acid (GA) and methyl gallate (MG) from Rosa rugosa as S-RBD ligands, with KD values of 2.69 and 0.95 µM, respectively, as shown by SPR. Molecular dynamics indicated that GA formed hydrogen bonds with G496, N501, and Y505 of S-RBD, and MG with G496 and Y505, inhibiting S-RBD binding to angiotensin-converting enzyme 2 (ACE2). SPR-based competition analysis verified that both compounds blocked S-RBD and ACE2 binding, and SPR demonstrated that GA and MG bound to ACE2 (KD = 5.10 and 4.05 µM, respectively), suggesting that they blocked the receptor and neutralized SARS-CoV-2. Infection with SARS-CoV-2 pseudovirus showed that GA and MG suppressed viral entry into 293T-ACE2 cells. These S-RBD inhibitors have potential for drug design, while the findings provide a reference on HCZP composition and its use for treating COVID-19.

Assay Analysis of Tannase from Lactobacillus plantarum.

Tannin, which is an astringent taste in the mouth, is a polyphenol compound contained in some plants. Tannin causes denaturation of proteins of the tongue or oral mucosa. Tannase, a hydrolase that cleaves carboxylic ester bonds specifically, is used in many industrial fields. Some tannase (tannin acyl hydrolase, EC3.1.1.20) is used widely to prevent or reduce creaming of some foods and beverages. Because some tannins are formed of insoluble salts combined with protein, they reduce creaming such as the white hazing of iced tea. Moreover, they can clarify beverages such as fruit juices during wine and beer production. Tannase is produced by microorganisms under conditions with tannic acid present, mainly from plants. Tannase characteristics differ according to its microorganism of origin. Therefore, it is important to study the microbes used as lactic acid bacteria (LAB), evaluate new methods of tannase assay, and apply them in food or other industries. In this chapter, assay of tannase in LAB is demonstrated using methyl gallate as substrate, with color development by rhodanine and potassium hydroxide solution, using a spectrophotometer. Actual data of high tannase-producing LAB, Lactobacillus plantarum, and enzyme characteristics in optimum conditions are presented in this chapter.

Isolation and Characterization of Cytotoxic Compounds from Detarium microcarpum Guill. and Perr. Stem Bark.

INTRODUCTION: Globally, about 8.2 million cancer-related deaths are recorded annually. Sadly, most of the deaths result from the toxicity of most chemotherapeutic agents. Hence, there are growing demands for chemotherapeutic agents with high specificity and selectivity. This study was designed to assess the cytotoxic potential of Detarium microcarpum and isolate cytotoxic compounds with better selectivity profiles. METHODS: Detarium microcarpum Stem bark (DMS) was collected and authenticated at the Forest Herbarium Ibadan (FHI), and a voucher (FHI-111954) was issued. Dried DMS was pulverized and extracted into 70% methanol. The extract was partitioned into hexane, dichloromethane, and ethyl acetate fractions. The cytotoxicities of the extract, fractions, and isolated compounds were determined. The cytotoxicity of the isolated compounds was tested against different cell lines, including human breast (AU565 and MDA MB231), oral adenosquamous (CAL27), and cervical (HeLa) cancer cells, as well as healthy (3T3) non-cancer cells. RESULTS: Methyl gallate, eriodictyol, quercetin, quebrachitol, catechin, catechin gallate, and gallic acid, isolated from dichloromethane and ethyl acetate fractions, displayed weak cytotoxicity against breast (AU565 and MDAMD- 231) and cervical (HeLa) cancer cell lines. Interestingly, all the compounds, except gallic acid (48.91±4.51% inhibition), displayed potent cytotoxicity on oral cancer cells. Methyl gallate and quercetin displayed the highest activity, with IC50 values of 89.57±1.98µM and 78.19±1.49µM, respectively. Interestingly, all the compounds were not toxic to healthy non-cancer (3T3) cells. CONCLUSION: The compounds displayed anticancer activity specific to oral cancer cells and were highly selective for cancer cells without causing significant toxicity to healthy non-cancer cells.

Methyl gallate attenuates virulence and decreases antibiotic resistance in extensively drug-resistant Pseudomonasaeruginosa.

Pseudomonas aeruginosa infections have become a serious threat to public health due to the increasing emergence of extensively antibiotic-resistant strains and high mortality rates. Therefore, the search for new therapeutic alternatives has become crucial. In this study, the antivirulence and antibacterial activity of methyl gallate was evaluated against six clinical isolates of extensively antibiotic-resistant P. aeruginosa. Methyl gallate exhibited minimal inhibitory concentrations of 256-384 µg/mL; moreover, the use of subinhibitory concentrations of the compound inhibited biofilm formation, swimming, swarming, proteolytic activity, and pyocyanin production. Methyl gallate plus antipseudomonal antibiotics showed a synergistic effect by reduced the MICs of ceftazidime, gentamicin and meropenem. Furthermore, the potential therapeutic effect of methyl gallate was demonstrated in an infection model. This study evidenced the antivirulence and antimicrobial activity of methyl gallate as a therapeutic alternative against P. aeruginosa.

Piperine Enhances Antimalarial Activity of Methyl Gallate and Palmatine Combination.

PURPOSE: Artemisinin combination therapies, the first-line antimalarials in Nigeria, have reportedly suffered multiple failures in malaria treatment, hence the search for novel combination of other compounds. Methyl gallate and palmatine have been reported to exhibit antiplasmodial activities but the antimalarial activity of their combination has not been evaluated. Therefore, the evaluation of the combination of methyl gallate and palmatine for antimalarial activity in vitro and in vivo in the presence of piperine was carried out. MATERIALS AND METHODS: The inhibitory potential of methyl gallate and palmatine combination on ß-hematin (hemozoin) formation was studied in vitro. Also, the antimalarial activity of methyl gallate and palmatine combination with/without a bioenhancer (piperine) was evaluated in Plasmodium berghei NK65-infected mice. RESULTS: Methyl gallate and palmatine in the ratio 3:2 acted synergistically in vitro and had the highest inhibitory effect (IC50 = 0.73 µg/mL) on ß-hematin (hemozoin) formation. The 3:2 combination of methyl gallate and palmatine exhibited no antimalarial activity in vivo in the absence of piperine but caused reduction in parasitemia that exceeded 40% in the presence of piperine at the dose of 25 mg/kg body weight on days 6 and 8 post-inoculation in mice. CONCLUSION: The 3:2 combination of methyl gallate and palmatine in the presence of piperine exhibited antimalarial activity in vivo, possibly by synergistic inhibition of hemozoin formation which may cause accumulation of haem within the food vacuole of Plasmodium spp. and its death.

Methyl gallate from Camellia nitidissima Chi flowers reduces quorum sensing related virulence and biofilm formation against Aeromonas hydrophila.

Aeromonas hydrophila, a Gram-negative zoonotic bacterium, causes high mortality in fish farming and immunocompromised patients. This study aimed to extract methyl gallate (MG) from the flowers of Camellia nitidissima Chi and evaluate its potential as a quorum sensing inhibitor (QSI) against Aeromonas hydrophila SHAe 115. MG reduced QS-associated virulence factors, including hemolysis, protease, and lipase, while impairing swimming motility and biofilm formation. Additionally, MG down-regulated positive regulatory genes (ahyR, fleQ) and up-regulated negative regulators (litR, fleN). This highlights MG's promise as a potent QSI for A. hydrophila SHAe 115, advancing strategies against infections in aquaculture and human health.

Assessing the Potential of Gallic Acid and Methyl Gallate to Enhance the Efficacy of ß-Lactam Antibiotics against Methicillin-Resistant Staphylococcus aureus by Targeting ß-Lactamase: In Silico and In Vitro Studies.

Methicillin-resistant Staphylococcus aureus (MRSA), a global health concern, has prompted research into antibiotic adjuvants as a potential solution. Although our group previously reported the enhancing effects of gallic acid (GA) and methyl gallate (MG) on penicillin G activity against MRSA, the synergistic potential with other ß-lactam antibiotics and the underlying mechanism have not been fully explored. Therefore, this study primarily aimed to investigate the antibacterial synergism with ß-lactam antibiotics through disc diffusion, checkerboard, and time-kill assays. The ß-lactamase inhibition was also examined through both molecular modeling and in vitro experiments. Additionally, bacterial morphology changes were studied using a scanning electron microscopy (SEM). The results revealed that both GA and MG exhibited anti-MRSA activity and showed indifferent effects when combined with ß-lactam antibiotics against methicillin susceptible S. aureus (MSSA). Interestingly, MG demonstrated synergism with only the ß-lactamase-unstable antibiotics against MRSA with the lowest fractional inhibitory concentration (FIC) indexes of ≤3.75. However, GA and MG exhibited weak ß-lactamase inhibition. Furthermore, GA, MG, and the combination with ampicillin induced the morphological changes in MRSA, suggesting a possible mechanism affecting the cell membrane. These findings suggest that MG could potentially serve as an adjunct to ß-lactam antibiotics to combat MRSA infections.

Frying Performance of Gallic Acid and/or Methyl Gallate Accompanied by Phosphatidylcholine.

This study shows the possibility of using gallic acid (GA) and/or methyl gallate (MG) accompanied by phosphatidylcholine (PC) instead of tert-butylhydoquinone (TBHQ) for frying purposes. The antioxidants and PC were added in the concentrations of 1.2 mM and 500-2000 mg/kg, respectively. Oxidative stability index (OSI) and the kinetics of change in conjugated dienes (LCD), carbonyls (LCO), and acid value (AV) were used to assess the antioxidative treatments. GA alone and GA/MG (50:50) plus PC at 2000 mg/kg yielded the same OSI as that of TBHQ (18.4 h). The latter was of the highest frying performance in preventing the formation of LCD (rn = 0.0517/h and tT = 10.6 h vs. rn = 0.0976/h and tT = 4.5 h for TBHQ), LCO (rn = 0.0411/h and tT = 12.7 h vs. rn = 0.15/h and tT = 4.3 h for TBHQ), and hydrolytic products (AVm = 37.8 vs. 24.0 for TBHQ); rn: normalized the maximum rate of LCD/LCO accumulation; tT: the time at which the rate of LCD/LCO accumulation is maximized; AVm: quantitative measure of hydrolytic stability.

Methyl gallate: Review of pharmacological activity.

Methyl gallate (MG) is a polyphenolic compound widely found in natural plants. MG has been shown to have a variety of biological functions, including anti-tumor, anti-inflammatory, anti-oxidant, neuroprotective, hepatoprotective and anti-microbial activities, and has broad research and development prospects. A total of 88 articles related to MG were searched using the PubMed, Science Direct, and Google Scholar databases, systematically investigating the pharmacological activity and molecular mechanisms of MG. There were no restrictions on the publication years, and the last search was conducted on June 5, 2023. MG can exert pharmacological effects through multiple pathways and targets, such as PI3K/Akt, ERK1/2, Caspase, AMPK/NF-κB, Wnt/ß-catenin, TLR4/NF-κB, MAPK, p53, NLRP3, ROS, EMT. According to the literature, MG has the potential to be a prospective adjuvant for anticancer therapy and deserves further study.

A Deadly Liaison between Oxidative Injury and p53 Drives Methyl-Gallate-Induced Autophagy and Apoptosis in HCT116 Colon Cancer Cells.

Methyl gallate (MG), which is a gallotannin widely found in plants, is a polyphenol used in traditional Chinese phytotherapy to alleviate several cancer symptoms. Our studies provided evidence that MG is capable of reducing the viability of HCT116 colon cancer cells, while it was found to be ineffective on differentiated Caco-2 cells, which is a model of polarized colon cells. In the first phase of treatment, MG promoted both early ROS generation and endoplasmic reticulum (ER) stress, sustained by elevated PERK, Grp78 and CHOP expression levels, as well as an upregulation in intracellular calcium content. Such events were accompanied by an autophagic process (16-24 h), where prolonging the time (48 h) of MG exposure led to cellular homeostasis collapse and apoptotic cell death with DNA fragmentation and p53 and γH2Ax activation. Our data demonstrated that a crucial role in the MG-induced mechanism is played by p53. Its level, which increased precociously (4 h) in MG-treated cells, was tightly intertwined with oxidative injury. Indeed, the addition of N-acetylcysteine (NAC), which is a ROS scavenger, counteracted the p53 increase, as well as the MG effect on cell viability. Moreover, MG promoted p53 accumulation into the nucleus and its inhibition by pifithrin-α (PFT-α), which is a negative modulator of p53 transcriptional activity, enhanced autophagy, increased the LC3-II level and inhibited apoptotic cell death. These findings provide new clues to the potential action of MG as a possible anti-tumor phytomolecule for colon cancer treatment.

Natural Gallic Acid and Methyl Gallate Induces Apoptosis in Hela Cells through Regulation of Intrinsic and Extrinsic Protein Expression.

Induction of apoptosis is one of the targeted approaches in cancer therapies. As previously reported, natural products can induce apoptosis in in vitro cancer treatments. However, the underlying mechanisms of cancer cell death are poorly understood. The present study aimed to elucidate cell death mechanisms of gallic acid (GA) and methyl gallate (MG) from Quercus infectoria toward human cervical cancer cell lines (HeLa). The antiproliferative activity of GA and MG was characterised by an inhibitory concentration using 50% cell populations (IC50) by an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. Cervical cancer cells, HeLa, were treated with GA and MG for 72 h and calculated for IC50 values. The IC50 concentration of both compounds was used to elucidate the apoptotic mechanism using acridine orange/propidium iodide (AO/PI) staining, cell cycle analysis, the Annexin-V FITC dual staining assay, apoptotic proteins expressions (p53, Bax and Bcl-2) and caspase activation analysis. GA and MG inhibited the growth of HeLa cells with an IC50 value of 10.00 ± 0.67 µg/mL and 11.00 ± 0.58 µg/mL, respectively. AO/PI staining revealed incremental apoptotic cells. Cell cycle analysis revealed an accumulation of cells at the sub-G1 phase. The Annexin-V FITC assay showed that cell populations shifted from the viable to apoptotic quadrant. Moreover, p53 and Bax were upregulated, whereas Bcl-2 was markedly downregulated. Activation of caspase 8 and 9 showed an ultimate apoptotic event in HeLa cells treated with GA and MG. In conclusion, GA and MG significantly inhibited HeLa cell growth through apoptosis induction by the activation of the cell death mechanism via extrinsic and extrinsic pathways.

Vachellia farnesiana Pods or a Polyphenolic Extract Derived from Them Exert Immunomodulatory, Metabolic, Renoprotective, and Prebiotic Effects in Mice Fed a High-Fat Diet.

Obesity causes systemic inflammation, hepatic and renal damage, as well as gut microbiota dysbiosis. Alternative vegetable sources rich in polyphenols are known to prevent or delay the progression of metabolic abnormalities during obesity. Vachellia farnesiana (VF) is a potent source of polyphenols with antioxidant and anti-inflammatory activities with potential anti-obesity effects. We performed an in vivo preventive or an interventional experimental study in mice and in vitro experiments with different cell types. In the preventive study, male C57BL/6 mice were fed with a Control diet, a high-fat diet, or a high-fat diet containing either 0.1% methyl gallate, 10% powdered VFP, or 0.5%, 1%, or 2% of a polyphenolic extract (PE) derived from VFP (Vachellia farnesiana pods) for 14 weeks. In the intervention study, two groups of mice were fed for 14 weeks with a high-fat diet and then one switched to a high-fat diet with 10% powdered VFP for ten additional weeks. In the in vitro studies, we evaluated the effect of a VFPE (Vachellia farnesiana polyphenolic extract) on glucose-stimulated insulin secretion in INS-1E cells or of naringenin or methyl gallate on mitochondrial activity in primary hepatocytes and C2C12 myotubes. VFP or a VFPE increased whole-body energy expenditure and mitochondrial activity in skeletal muscle; prevented insulin resistance, hepatic steatosis, and kidney damage; exerted immunomodulatory effects; and reshaped fecal gut microbiota composition in mice fed a high-fat diet. VFPE decreased insulin secretion in INS-1E cells, and its isolated compounds naringenin and methyl gallate increased mitochondrial activity in primary hepatocytes and C2C12 myotubes. In conclusion VFP or a VFPE prevented systemic inflammation, insulin resistance, and hepatic and renal damage in mice fed a high-fat diet associated with increased energy expenditure, improved mitochondrial function, and reduction in insulin secretion.

Effects of Leea indica leaf extracts and its phytoconstituents on natural killer cell-mediated cytotoxicity in human ovarian cancer.

BACKGROUND: The rich biodiversity of medicinal plants and their importance as sources of novel therapeutics and lead compounds warrant further research. Despite advances in debulking surgery and chemotherapy, the risks of recurrence of ovarian cancer and resistance to therapy are significant and the clinical outcomes of ovarian cancer remain poor or even incurable. OBJECTIVE: This study aims to investigate the effects of leaf extracts from a medicinal plant Leea indica and its selected phytoconstituents on human ovarian cancer cells and in combination with oxaliplatin and natural killer (NK) cells. METHODS: Fresh, healthy leaves of L. indica were harvested and extracted in 70% methanol by maceration. The crude extract was partitioned with n-hexane, dichloromethane and ethyl acetate. Selected extracts and compounds were analyzed for their effects on cell viability of human ovarian cancer cells, NK cell cytotoxicity, and stress ligands expression for NK cell receptors. They were also evaluated for their effects on TNF-α and IL-1ß production by enzyme-linked immunosorbent assay in lipopolysaccharide-stimulated human U937 macrophages. RESULTS: Leaf extracts of L. indica increased the susceptibility of human ovarian tumor cells to NK cell-mediated cytotoxicity. Treatment of cancer cells with methyl gallate but not gallic acid upregulated the expression of stress ligands. Tumor cells pretreated with combination of methyl gallate and low concentration of oxaliplatin displayed increased levels of stress ligands expression and concomitantly enhanced susceptibility to NK cell-mediated cytolysis. Further, NK cells completely abrogated the growth of methyl gallate-pretreated ovarian cancer cells. The leaf extracts suppressed TNF-α and IL-1ß production in human U937 macrophages. Methyl gallate was more potent than gallic acid in down-regulating these cytokine levels. CONCLUSIONS: We demonstrated for the first time that leaf extracts of L. indica and its phytoconstituent methyl gallate enhanced the susceptibility of ovarian tumor cells to NK cell cytolysis. These results suggest that the combined effect of methyl gallate, oxaliplatin and NK cells in ovarian cancer cells warrants further investigation, for example for refractory ovarian cancer. Our work is a step towards better scientific understanding of the traditional anticancer use of L. indica.

Methyl gallate prevents oxidative stress induced apoptosis and ECM degradation in chondrocytes via restoring Sirt3 mediated autophagy and ameliorates osteoarthritis progression.

Osteoarthritis (OA) is a common age-related degenerative disease involving various pathological processes, among which apoptosis in chondrocyte and extracellular matrix (ECM) degradation are the main pathologies. Previous studies have shown that autophagy has a protective effect on apoptosis and ECM degradation in chondrocytes. Methyl gallate (MG) is a natural polyphenol from various medicinal and edible plants. Moreover, several studies have demonstrated that MG exerts multiple pharmacological effects in various diseases, including anti-inflammatory, antioxidant, and anti-apoptosis. Hence, in this study, we investigate the protective effect of MG on the pathological process of OA in cellular and mice OA model to elucidate the underlying molecular mechanism. In vitro, MG treatment inhibits the expression of pro-apoptotic proteins and promotes the expression of anti-apoptotic proteins under TBHP stimulation. Meanwhile, MG treatment promotes the expression of Collagen II and Aggrecan and inhibits the expression of matrix-degrading enzymes thrombospondin motifs 5 (ADAMTS5) and matrix metalloproteinase-13 (MMP13), which lead to ECM degradation. Furthermore, in terms of mechanism, MG treatment enhances autophagy by upregulating SIRT3 expression, and inhibition of autophagy could eliminate the protective effect of MG on chondrocytes in terms of anti-apoptosis and ECM synthesis. The protective effect of MG on OA has also been observed in mice OA model. In brief, our study suggests that MG could be a potential candidate for the treatment of OA.

Bioassay-guided isolation and characterization of lead antimicrobial compounds from Acacia hydaspica plant extract.

Acacia hydaspica possesses varied pharmacological attributes. We aimed to examine the antimicrobial potential and isolate the active antimicrobial metabolites. The plant extract was fractionated and the antimicrobial activity of the crude extract, fractions and compounds was tested by agar well diffusion and agar tube dilution and broth dilution methods. Bacterial strains selected for bioactivity testing were Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii while selected strains from kingdom fungi were Candida albicans, Cryptococcus neoformans, Fusarium solani and Aspergillus. The active compounds were isolated from Acacia hydaspica by bioassay-guided fractionation and identified by nuclear magnetic resonance and spectroscopic techniques. S. aureus cell surface proteins, Autolysins (Atl), Clumping factor A (ClfA), and Fibronectin Binding Proteins (FnBP), were molecularly docked with Catechin 3-O-gallate (CG) and Methyl gallate (MG) and binding energy and molecular interactions between the proteins and compounds were analyzed. Ethyl acetate (AHE) and Butanol (AHB) fractions of A. hydaspica were the most active fractions against tested microbial strains. Therefore, both were subjected to bioassay-directed fractionation which led to the isolation of one pure active antimicrobial AHE and one active pure compound from AHB fraction besides active enriched isolates. Methyl-gallate (MG) and catechin-3-gallate (CG) are active compounds extracted from AHE and AHB fractions respectively. In antibacterial testing MG significantly inhibited the growth of E. coli (MIC50 = 21.5 µg/ml), B. subtilus (MIC50 = 23 µg/ml) and S. aureus (MIC50 = 39.1 µg/ml) while moderate to low activity was noticed against other tested bacterial strains. Antifungal testing reveals that MG showed potent antifungal activity against F. solani (MIC50 = 33.9 µg/ml) and A. niger (MIC50 = 41.5 µg/ml) while lower antifungal activity was seen in other tested strains. AHB fractions and pure compound (CG) showed specific antibacterial activity against S. aureus only (MIC50 = 10.1 µg/ml) while compound and enriched fractions showed moderate to no activity against other bacterial and fungal strains respectively. Molecular docking analysis revealed that CG interacted more strongly with the cell surface proteins than MG. Among these proteins, CG made a stronger complex with ClfA (binding affinity - 9.7) with nine hydrophobic interactions and five hydrogen bonds. Methyl gallate (MG) and catechin 3-O-gallate (CG) are the major antimicrobial compound from A. hydaspica that inhibit the growth of specific microbes. The occurrence of MG and CG endorse the traditional antimicrobial applicability of A. hydaspica, and it can be a legitimate alternative to control specific microbial infections.

Methyl Gallate Alleviates Acute Ulcerative Colitis by Modulating Gut Microbiota and Inhibiting TLR4/NF-κB Pathway.

Ulcerative colitis (UC) is a complex immune-mediated inflammatory disease. In recent years, the incidence of UC has increased rapidly, however, its exact etiology and mechanism are still unclear. Based on the definite anti-inflammatory and antibacterial activities of Sanguisorba officinalis L., we studied its monomer, methyl gallate (MG). In this study, we employed flow cytometry and detected nitric oxide production, finding MG regulated macrophage polarization and inhibited the expression of proinflammatory cytokines in vitro. MG also exhibited anti-inflammatory activity accompanying with ameliorating body weight loss, improving colon length and histological damage in dextran sulfate sodium-induced UC mice. Meanwhile, transcription sequencing and 16S rRNA sequencing analyzed the key signaling pathways and changes in the gut microbiota of MG for UC treatment, proving that MG could alleviate inflammation by regulating the TLR4/NF-κB pathway in vivo and in vitro. Additionally, MG altered the diversity and composition of the gut microbiota and changed the abundance of metabolic products. In conclusion, our results are the first to demonstrate that MG has obvious therapeutic effects against acute UC, which is related to macrophage polarization, improved intestinal flora dysbiosis and inhibition of TLR4/NF-κB signaling pathway, and MG may be a promising therapeutic agent for UC treatment.

Antioxidant activity and protective effect of methyl gallate against t-BHP induced oxidative stress through inhibiting ROS production.

Non-alcoholic fatty liver disease (NAFLD) is one of the major diseases of chronic liver damage caused by oxidative stress. In this study, we investigated hepatoprotective effect of methyl gallate (MG) against t-BHP induced oxidative stress. Our results revealed that MG possessed strong antioxidant activity and lipid peroxidation inhibitory activity. In addition, MG inhibited t-BHP induced cell cytotoxicity, ROS production and sub-G1 phase cells in Chang liver cells. MG attenuated also activated signal p38 and decreased mitochondrial-mediated cell death by regulating pro- and anti- apoptotic proteins. Our results indicate that MG could be potentially used as protective agent in NAFLD therapy by modulating oxidative stress.

Effect of Methyl Gallate on 1-Nitropyrene-Induced Keratinocyte Toxicity in a Human and Canine Skin Model.

The skin, which is the largest organ of the human body, is in direct contact with pollutants in the surrounding atmosphere. Meanwhile, 1-nitropyrene (1-NP), the most abundant nitro-polycyclic aromatic hydrocarbon found in particulate matter, is known to have carcinogenic effects; however, studies on its toxicity in human and canine skin are still needed. In this study, we investigated 1-NP-induced apoptosis and inflammatory pathways in HaCaT cells. In addition, we also measured the cytoprotective effect of methyl gallate (MG), which is widely distributed in medicinal and edible plants and is well known for its anti-inflammatory and antioxidant properties. MG inhibited 1-NP-induced cell death and apoptosis pathways, including the cleavage of PARP and activation of caspase-3, -7, and -9. MG also suppressed 1-NP-induced COX-2 expression and phosphorylation of mitogen-activated protein kinases (MAPKs) and MAPK kinases (MAPKKs). Our findings suggest that 1-NP induces skin toxicity in human and canine through apoptosis and inflammatory responses, and moreover, that this can be prevented by treatment with MG.

Methyl Gallate Suppresses the Migration, Invasion, and Epithelial-Mesenchymal Transition of Hepatocellular Carcinoma Cells via the AMPK/NF-κB Signaling Pathway in vitro and in vivo.

Methyl gallate (MG), a polyphenolic compound found in plants, is widely used in traditional Chinese medicine. MG is known to alleviate several cancer symptoms. However, most studies that have reported the antitumor effects of MG have done so at the cellular level, and the inhibitory effect and therapeutic mechanism of MG in hepatocellular carcinoma (HCC) have not been extensively explored in vivo. We aimed to understand the therapeutic mechanism of MG in HCC in vitro and in vivo. MTT and colony formation assays were used to determine the impact of MG on the proliferation of a human HCC cell line, BEL-7402; wound healing and transwell assays were used to quantify the migration and invasion of HCC cells. Western blotting was used to quantify the expression of the AMPK/NF-κB signaling pathway proteins. In vivo tumor growth was measured in a xenograft tumor nude mouse model treated with MG, and hematoxylin-eosin staining and immunohistochemistry (IHC) were used to visualize the histological changes in the tumor tissue. We found that MG showed anti-proliferative effects both in vitro and in vivo. MG downregulated the protein expression of AMPK, NF-κB, p-NF-κB, and vimentin and upregulated the expression of E-cadherin in a dose-dependent manner. Additionally, MG inhibited the migration and invasion of HCC cells by decreasing MMP9 and MMP2 expression and increasing TIMP-2 expression. These were consistent with the results of IHC in vivo. MG inhibited the proliferation, migration, and invasion of HCC cells. This effect potentially involves the regulation of the AMPK/NF-κB pathway, which in turn impacts epithelial-mesenchymal transition and MMP expression.