Gallic acid induces apoptosis in 3T3-L1 pre-adipocytes via a Fas- and mitochondrial-mediated pathway

Gallic Acid: A Potential Anti-Cancer Agent

Cancer is one of the most devastating diseases worldwide and definitive therapeutics for treating cancer are not yet available despite extensive research efforts. The key challenges include limiting factors connected with traditional chemotherapeutics, primarily drug resistance, low response rates, and adverse side-effects. Therefore, there is a high demand for novel anti-cancer drugs that are both potent and safe for cancer prevention and treatment. Gallic acid (GA), a natural botanic phenolic compound, can mediate various therapeutic properties that are involved in anti-inflammation, anti-obesity, and anti-cancer activities. More recently, GA has been shown to exert anti-cancer activities via several biological pathways that include migration, metastasis, apoptosis, cell cycle arrest, angiogenesis, and oncogene expression. This review discusses two aspects, one is the anti-cancer potential of GA against different types of cancer and the underlying molecular mechanisms, the other is the bibliometric analysis of GA in cancer and tumor research. The results indicated that lung cancer, prostate cancer, stomach cancer, and colon adenocarcinoma may become a hot topic in further research. Overall, this review provides evidence that GA represents a promising novel, potent, and safe anti-cancer drug candidate for treating cancer.

The Mechanism of Honey in Reversing Metabolic Syndrome

Metabolic syndrome is a constellation of five risk factors comprising central obesity, hyperglycaemia, dyslipidaemia, and hypertension, which predispose a person to cardiometabolic diseases. Many studies reported the beneficial effects of honey in reversing metabolic syndrome through its antiobesity, hypoglycaemic, hypolipidaemic, and hypotensive actions. This review aims to provide an overview of the mechanism of honey in reversing metabolic syndrome. The therapeutic effects of honey largely depend on the antioxidant and anti-inflammatory properties of its polyphenol and flavonoid contents. Polyphenols, such as caffeic acid, p-coumaric acid, and gallic acid, are some of the phenolic acids known to have antiobesity and antihyperlipidaemic properties. They could inhibit the gene expression of sterol regulatory element-binding transcription factor 1 and its target lipogenic enzyme, fatty acid synthase (FAS). Meanwhile, caffeic acid and quercetin in honey are also known to reduce body weight and fat mass. In addition, fructooligosaccharides in honey are also known to alter lipid metabolism by reducing FAS activity. The fructose and phenolic acids might contribute to the hypoglycaemic properties of honey through the phosphatidylinositol 3-kinase/protein kinase B insulin signalling pathway. Honey can increase the expression of Akt and decrease the expression of nuclear factor-kappa B. Quercetin, a component of honey, can improve vasodilation by enhancing nitric oxide production via endothelial nitric oxide synthase and stimulate calcium-activated potassium channels. In conclusion, honey can be used as a functional food or adjuvant therapy to prevent and manage metabolic syndrome.

Gallic acid as a key substance to inhibit proliferation and adipogenesis in bovine subcutaneous adipocyte

Gallic acid (GA) is a widespread naturally occurring phenolic acid and one of the main active monomers that forms polyphenols such as tannins. In recent years, GA has been found as a potential regulator in lipid metabolism. However, effects and possible mechanisms of GA on cell growth and lipid metabolism of bovine subcutaneous adipocytes remain unknown. In this study, we investigated whether GA could affect proliferation and adipogenesis of subcutaneous adipocyte in beef cattle. We found that GA possesses inhibitive effects on proliferation and adipogenesis of bovine subcutaneous adipocyte via activating the metabolic master factor AMP-activated protein kinase alpha (AMPKα) to promote programmed cell death and lipolysis. The findings prove GA is a key substance to inhibit proliferation and adipogenesis of bovine subcutaneous adipocyte in vitro. Further in vivo study needs conducted to verify the reductive effects of GA on subcutaneous fat in beef cattle.

Polyphenol-Enriched Extracts from Trapa acornis Husks Inhibit Her2-Positive SK-BR-3 Breast Cancer Cell Proliferation and In Vivo Tumor Angiogenesis

The study aimed to investigate the antitumor effects of Trapa acornis husks (TAH) extract on SK-BR-3 cells of Her2-positive breast cancer. The bioactive compounds of TAH extracts were analyzed qualitatively and quantitatively by Ultra-Performance Liquid Chromatography/Mass Spectrometry (UPLC-MS)/high-performance liquid chromatographic system (HPLC). The effects of TAH extracts on cell proliferation, cell cycle, and apoptosis of SK-BR-3 cells were determined by CCK-8 and flow cytometry. Besides, the In Vivo antitumor effect of TAH extracts was detected. UPLC-MS/HPLC showed that the main bioactive compounds of TAH were gallic acid and galloylglucose derivatives. TAH extracts significantly inhibited the proliferation of SK-BR-3 cells in a dose- and time-dependent manner (P < 0.01). With the increase of TAH extracts concentration, cells in G2/M stage were increased and cell apoptosis was significantly increased. Immunohistochemical analysis showed that TAH extracts can significantly reduce the positive expression rate of Ki67 and Factor VIII index in tumor tissues. The mRNA expression levels of VEGF, MMP2, MMP9, and uPA were reduced after TAH extracts intervention (P < 0.01). TAH extracts also decreased the protein expression of p-Her2, p-ERK1/2, VEGF, MMP2, MMP9, and uPA (P < 0.01). In conclusion, polyphenol-enriched extracts from TAH might inhibit breast cancer cell proliferation and In Vivo tumor angiogenesis.

Preventive Effect of Fermented Chestnut Inner Shell Extract on Obesity-Induced Hepatic Steatosis

This study aimed to investigate the effects of the gallic acid-enriched fermented chestnut inner shell extract (FCCE) by Saccharomyces cerevisiae on a high fat diet (HFD)-induced obesity and hepatic steatosis in vivo mouse model. Mice feeding FCCE exhibited reduced body weight gain compared to those in the HFD-fed group, and showed lower abdominal fat pad weight including epididymal, retroperitoneal, and mesenteric adipose tissue. Further, FCCE administration decreased adipocyte size by suppressing adipogenic factors such as peroxisome proliferator activated receptor γ and CCAAT/ enhancer-binding protein α, and lipogenic factors such as sterol regulatory element-binding protein-1c, fatty acid synthase, and stearoyl CoA desaturase-1. Moreover, FCCE decreased levels of lipids in serum and liver as well as serum alanine aminotransferase and aspartate aminotransferase levels, markers of liver injury. Histological observations of the liver showed that FCCE significantly attenuated HFD-induced hepatic steatosis. The effect of FCCE on hepatic lipid regulatory factors may be partly associated with adenosine monophosphate-activated protein kinase activation. These results suggest that gallic acid-enriched FCCE has potential to be a promising functional food for prevention of obesity and obesity-related fatty liver disease.

Screening of secondary metabolites in cladodes to further decode the domestication process in the genus Opuntia (Cactaceae)

During their domestication process, the species of the genus Opuntia lose their ability to survive in the wild. Presence and concentration of secondary metabolites which play a role in the interaction with their surroundings are modified but without an identifiable pattern. A domestication gradient based on morphological characteristics has been previously described for the species in the Opuntia genus. Secondary metabolites are a diverse group of bioactive compounds that relate to a species evolution, both in their natural and artificial (domestication process) selection environments. In addition, these compounds are associated with plant resistance to stress when growing in the wild. A comprehensive characterization of secondary metabolite profiles in the Opuntia genus that accounts for the genotypic differences related to the degree of domestication has not previously been conducted. This study evaluated the phytochemical composition of young cladodes from fifteen variants, of O. ficus-indica, O. albicarpa Sheinvar, and O. megacantha Salm-Dyck, identified as species with a highly advanced, advanced and intermediate degree of domestication, respectively, and O. hyptiacantha A. Web, and O. streptacantha Lem. identified as wild-intermediate and wild species. Analyses were carried out using a HPLC-diode array detection technique. Out of the 13 identified and quantified phenolic molecules and terpenoids, only the caffeic, ferulic and syringic acids, and the terpenoid β-amyrin were present in all variants. The flavonoid luteolin was absent in all five species. Gallic, vallinic, p-hydroxybenzoic, chlorogenic and p-coumaric acids were only present in 53-87% of variants; flavonoids quercetin, isorhamnetin, rutin and apigenin in 47-87% of the variants. Both, oleanolic acid and peniocerol, were present only in 60% of variants. Isorhamnetin was absent in O. hyptiacantha and quercetin in O. streptacntha. Differences and similarities in the secondary metabolites content showed no recognizable trend relating to the degree of domestication across the species in this genus.

Metal nanoparticles synthesis through natural phenolic acids

For being applied in medicine as therapeutic agents, nanostructures need to be biocompatible and eco-friendly. Plant-derived phenolic acids have been utilised for green synthesis of metallic or metallic oxide nanoparticles (NPs). The phenolic acids play role as both reducing agents and stabilisers in the process of NPs synthesis. Many experiments have been dedicated to develop efficient green synthesis techniques for producing metal NPs. Using phenolic acids represents a reproducible, simple, profitable, and cost-effective strategy to synthesise metal NPs. As a phytochemical for metal NPs synthesis, phenolic acids are antioxidants that represent many health benefits. However, limited studies have been dedicated to the synthesis and characterisation of NPs produced by phenolic acids. Thus, this review focused on phenolic acids mediated nanomaterial synthesis and its biomedical applications. It should be noted the mechanism of metal ion bioreduction, phenolic acids surface adsorption, characterisation, and toxicity of metal NPs made with different phenolic acids have been discussed in this review.

Phenolic Compounds Inhibit 3T3-L1 Adipogenesis Depending on the Stage of Differentiation and Their Binding Affinity to PPARγ

Phenolic compounds might modulate adiposity. Here, we report our observation that polyphenols and phenolic acids inhibit adipogenesis in 3T3-L1 with different intensity depending on the family and the stage of differentiation. While quercetin and resveratrol inhibited lipid accumulation along the whole process of differentiation, apigenin and myricetin were active during the early and latest stages, but not intermediate, contrary to hesperidin. The activity of phenolic acids was limited to the early stages of the differentiation process, except p-coumaric and ellagic acids. This anti-adipogenic effect was accompanied by down-regulation of Scd1 and Lpl. Molecular docking analysis revealed that the inhibitory activity of these phenolic compounds over the early stages of adipogenesis exhibits a significant correlation (r = 0.7034; p = 0.005) with their binding affinity to the ligand-binding domain of PPARγ. Results show that polyphenols and phenolic acids would interact with specific residues of the receptor, which could determine their potential anti-adipogenic activity during the early stages of the differentiation. Residues Phe264, His266, Ile281, Cys285 and Met348 are the most frequently involved in these interactions, which might suggest a crucial role for these amino acids modulating the activity of the receptor. These data contribute to elucidate the possible mechanisms of phenolic compounds in the control of adipogenesis.

Inflammation and Oxidative Stress in an Obese State and the Protective Effects of Gallic Acid

Metabolic complications in an obese state can be aggravated by an abnormal inflammatory response and enhanced production of reactive oxygen species. Pro-inflammatory response is known to be associated with the formation of toxic reactive oxygen species and subsequent generation of oxidative stress. Indeed, adipocytes from obese individuals display an altered adipokine profile, with upregulated expression and secretion of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin (IL-6). Interestingly, natural compounds, including phenolic enriched foods are increasingly explored for their ameliorative effects against various metabolic diseases. Of interest is gallic acid, a trihydroxybenzoic acid that has progressively demonstrated robust anti-obesity capabilities in various experimental models. In addition to reducing excessive lipid storage in obese subjects, gallic acid has been shown to specifically target the adipose tissue to suppress lipogenesis, improve insulin signaling, and concomitantly combat raised pro-inflammatory response and oxidative stress. This review will revise mechanisms involved in the pathophysiological effects of inflammation and oxidative stress in an obese state. To better inform on its therapeutic potential and improvement of human health, available evidence reporting on the anti-obesity properties of gallic acid and its derivatives will be discussed, with emphases on its modulatory effect on molecular mechanisms involved in insulin signaling, inflammation and oxidative stress.

Optimization of Process Parameters for Reactive Separation of Gallic Acid

Reactive extraction of gallic acid (GA) from aqueous solution was studied using extractant TOA and Aliquat 336 in hexanol and a comparative analysis were made for optimum extractant-diluent system with two factor central composite design. The model equations were developed using 13 experimentations, each with TOA and Aliquat 336. TOA and Aliquat 336 gave antagonistic and synergistic effects respectively for extraction of GA. The optimum conditions were observed as CTOA= 8.6 %, CGA0= 2.9 g/L and CALQ= 33.2 %, CGA0= 3 g/L with experimental extraction of 92.2 % and 96.5 % respectively. Lesser TOA and its non-toxicity for extraction of GA as compared to Aliquat 336 suggest TOA as better candidate in the prevailing conditions.

Gallic Acid Alleviates Hypertriglyceridemia and Fat Accumulation via Modulating Glycolysis and Lipolysis Pathways in Perirenal Adipose Tissues of Rats Fed a High-Fructose Diet

This study investigated the ameliorative effect of gallic acid (GA) on hypertriglyceridemia and fat accumulation in perirenal adipose tissues of high-fructose diet (HFD)-induced diabetic rats. The previous results showed that orally administered GA (30 mg/kg body weight) for four weeks significantly reduced the levels of plasma glucose and triglyceride (TG) in HFD rats. GA also markedly decreased the perirenal adipose tissues weight of HFD rats in present study (p < 0.05). Western blot assay indicated that GA restored expression of insulin signaling-related proteins, such as insulin receptor (IR), protein kinase C-zeta (PKC-ζ), and glucose transporter-4 (GLUT4) in the perirenal adipose tissues of HFD rats. Moreover, GA enhanced expression of glycolysis-related proteins, such as phosphofructokinase (PFK) and pyruvate kinase (PK), and increased the expression of lipolysis-related proteins, such as adipose triglyceride lipase (ATGL), which is involved in lipolysis in the perirenal adipose tissues of HFD rats. This study revealed that GA may alleviate hypertriglyceridemia and fat accumulation through enhancing glycolysis and lipolysis pathways in perirenal adipose tissues of HFD rats. These findings also suggest the potential of GA in preventing the progression of diabetes mellitus (DM) complications.

Antioxidant activity and anticancer effect of ethanolic and aqueous extracts of the roots of Ficus beecheyana and their phenolic components

This study aimed to investigate the antioxidant and anticancer effects of ethanolic and aqueous extracts of the roots of Ficus beecheyana (EERFB and AERFB) and their phenolic components. In this study, total phenolic content and antioxidant activity of EERFB were higher than those of AERFB. Major phenolic compounds in the extracts were gallic acid, p-hydroxybenzoic acid, caffeic acid, chlorogenic acid, p-coumaric acid, and rutin; which were identified by high-performance liquid chromatography. Flow cytometric analysis of HL-60 cells exposed to EERFB showed that the percentage of apoptotic cells increased in a dose-dependent manner. EERFB treatment resulted in the loss of mitochondrial membrane potential and induced the apoptosis of HL-60 cells through a Fas- and mitochondrial-mediated pathway. Finally, pretreatment with general caspase-9/−3 inhibitors prevented EERFB from inhibiting cell viability in HL-60 cells. Our finding suggests that EERFB is an agent that may have antioxidant activity and inhibit the growth of cancer cells.

Interaction between Gallic acid and Asparaginase to potentiate anti-proliferative effect on lymphoblastic leukemia cell line

BACKGROUND

Treatment of acute lymphoblastic leukemia (ALL) fails in some cases and the side effects cause mortality in certain patients. Gallic acid (GA), a polyhydroxyphenolic compound has biological functions including anti-proliferative properties. The aim of the present study was to investigate the growth inhibition effects of GA in combination with asparaginase (ASP), as a component of combination chemotherapy, in a lymphoblastic leukemia cell line.

METHODS

Jurkat cells were incubated with different concentrations of GA with or without ASP. Proliferation inhibition was investigated using MTS test. The level of apoptosis alterations were evaluated using flow cytometry. The expression of Fas gene level and surface expression were investigated by quantitative real time PCR and flow cytometry respectively.

RESULTS

GA at 50μM concentration and ASP at 0.5 IU/ml inhibited 50% cell proliferation in 48 hours. GA also increased the inhibitory effect of ASP and some combinations had synergistic results. The increase of cell apoptosis and Fas expression were observed in GA-treated cells compared to control. GA increased the effect of ASP on proliferation inhibition, induction of apoptosis and Fas expression.

CONCLUSION

GA is an effective component in proliferation inhibition, apoptosis induction and enhancement of Fas expression level in Jurkat cell line. GA in some combination with ASP increases the effect of the latter on the cells. The study of the mechanism of these effects could be a further step towards target therapy. This study is a preliminary phase to the use of GA and should be carried out by more comprehensive study and animal models.

The Study of Apoptosis-inducing Effects of Three Pre-apoptotic Factors by Gallic Acid, Using Simulation Analysis and the Comet Assay Technique on the Prostatic Cancer Cell Line PC3

BACKGROUND

In this study, we demonstrated the effects of the Gallic Acid (GA) molecule on the prostate cancer cells line PC3 using the comet assay (Alkaline electrophoresis) technique and its effects on some important apoptotic factors including BAD (Bcl-2-Associated Death promoter), BAK (Bcl-2 homologous Antagonist/Killer), and BIM (Bcl-2-like protein 11) via simulation analysis by using the Auto Dock and Gromacs software.

METHODS

Following the MTT assay on the PC3 cells, and determining IC50, we used three concentrations of GA to around IC50 to treat PC3 cells. 100 comet pictures were obtained by alkaline electrophoresis and have been analysed with the CASP version 1.2.2 software; all the results were thereafter analysed by the SPSS version 21 statistical software.

RESULTS

The IC50 value for GA was determined to be 35 μM. The ratio of tail to head in alkaline electrophoresis for the three concentrations below the IC50 of GA in 25, 30, and 35 μM were measured as 24.7 (2.7), 44.5 (1.8), and 57.3 (1.3) percent, respectively. The results of the preapoptotic factors (BAD, BAK, and BIM) in the performed simulation in the absence and presence of GA showed that the GA protein causes the structural instability in the BAD protein, and the effect of GA can be explained by the creation of hydrogen bonds with proteins.

CONCLUSION

GA is a polyphenol compound in plants that can suppress cell growth and induce apoptosis in PC3 cells in prostate cancer in the range of IC50 concentrations. The apoptotic properties of GA induce pre-apoptotic factors.

Phycoerythrin averts intracellular ROS generation and physiological functional decline in eukaryotes under oxidative stress

In vitro antioxidant virtue and life-prolonging effect of phycoerythrin (PE; a pigment protein isolated from Phormidium sp. A09DM) have been revealed in our previous reports (Sonani et al. in Age 36:9717, 2014a; Sonani et al. in Process Biochem 49:1757-1766, 2014b). It has been hypothesized that the PE expands life span of Caenorhabditis elegans (bears large resemblance with human aging pathways) due to its antioxidant virtue. This hypothesis is tested in present study by checking the effect of PE on intracellular reactive oxygen species (ROS) generation and associated physiological deformities using mouse and human skin fibroblasts, C. elegans, and Drosophila melanogaster Oregon R ⁺ and by divulging PE's structural attributes responsible for its antioxidant asset. PE treatment displayed noteworthy decrease of 67, 48, and 77 % in ROS level in mouse fibroblast (3T3-L1), human fibroblast, and C. elegans N2, respectively, arisen under chemical-induced oxidative stress. PE treatment delayed the development of paraquat-induced Alzheimer phenotype by 14.5 % in C. elegans CL4176. Furthermore, PE improved the locomotion of D. melanogaster Oregon R ⁺ under oxidative stress with simultaneous up-regulation in super-oxide dismutase and catalase activities. The existence of 52 Glu + Asp + His + Thr residues (having metal ion sequestration capacity), 5 phycoerythrobilin chromophores (potential electron exchangers) in PE's primary structure, and significant hydrophobic patches on the surface of its α- and β-subunits are supposed to collectively contribute in the antioxidant virtues of PE. Altogether, results support the hypothesis that it is the PE's antioxidant asset, which is responsible for its life-prolonging effect and thus could be exploited in the therapeutics of ROS-associated abnormalities including aging and neurodegeneration in eukaryotes.

Gallic Acid, the Active Ingredient of Terminalia bellirica, Enhances Adipocyte Differentiation and Adiponectin Secretion

Visceral obesity induces the onset of metabolic disorders such as insulin resistance and diabetes mellitus. Adipose tissue is considered as a potential pharmacological target for treating metabolic disorders. The fruit of Terminalia bellirica is extensively used in Ayurvedic medicine to treat patients with diseases such as diabetes mellitus. We previously investigated the effects of a hot water extract of T. bellirica fruit (TB) on obesity and insulin resistance in spontaneously obese type 2 diabetic mice. To determine the active ingredients of TB and their molecular mechanisms, we focused on adipocyte differentiation using mouse 3T3-L1 cells, which are widely used to study adipocyte physiology. We show here that TB enhanced the differentiation of 3T3-L1 cells to mature adipocytes and that one of the active main components was identified as gallic acid. Gallic acid (10-30 µM) enhanced the expression and secretion of adiponectin via adipocyte differentiation and also that of fatty acid binding protein-4, which is the target of peroxisome proliferator-activated receptor gamma (PPARγ), although it does not alter the expression of the upstream genes PPARγ and CCAAT enhancer binding protein alpha. In the PPARγ ligand assay, the binding of gallic acid to PPARγ was undetectable. These findings indicate that gallic acid mediates the therapeutic effects of TB on metabolic disorders by regulating adipocyte differentiation. Therefore, TB shows promise as a candidate for preventing and treating patients with metabolic syndrome.

EGFR-dependent signalling reduced and p38 dependent apoptosis required by Gallic acid in Malignant Mesothelioma cells

The unrestrained EGFR signalling contributes to malignant phenotype in a number of cancers including Malignant Mesotheliomas. Present study was designed to evaluate EGFR-dependent anti-proliferative and apoptotic effects of Gallic acid in transformed Mesothelial (MeT-5A) and Malignant Mesothelioma (SPC212) cells. Gallic acid reduced the viability of Malignant Mesothelioma cells in a concentration and time-dependent manner. However, viability of mesothelial cells reduced only at high concentration and longer time periods. Gallic acid restrained the activation of EGFR, ERK1/2 and AKT proteins and down regulated expression of Cyclin D and Bcl-2 genes, but upregulated the expression of p21 gene in EGF-induced SPC212 cells. GA-induced transitory G1 arrest and triggered mitochondrial and death receptor mediated apoptosis, which requires p38MAPK activation. The data provided here indicate that GA is able to inhibit EGFR dependent proliferation and survival signals and induces p38 pathway dependent apoptosis in Malignant Mesothelioma cells. On the basis of these experimental findings it is worthwhile to investigate further the biological activity of Gallic acid on other Mesothelioma cell lines harbouring aberrant EGFR signals.

Gallic Acid Inhibits Proliferation and Induces Apoptosis in Lymphoblastic Leukemia Cell Line (C121)

Leukemia is known as the world's fifth most prevalent cancer. New cytotoxic drugs have created considerable progress in the treatment, but side effects are still the important cause of mortality. Plant derivatives have been recently considered as important sources for the treatment of various diseases, including cancer. Gallic acid (GA) is a polyhydroxyphenolic compound with a wide range of biological functions. The aim of the present study was to evaluate the effect of GA on proliferation inhibition and apoptosis induction of a lymphoblastic leukemia cell line. Jurkat cell (C121) line was cultured in RPMI 1640 supplemented with 10% heat-inactivated fetal bovine serum (FBS) with different concentrations of GA (10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 μM) for 24, 48 and 72 hours. The effect of GA on cell viability was measured using MTS assay. Induction of apoptosis was evaluated with Annexin V-FITC/PI kit and flow cytometry. Data were analyzed by SPSS version 20 using Kruskal-Wallis and Dunn's multiple comparison tests. Decline of cell viability to less than 50% was observed at 60.3±1.6, 50.9±1.5, and 30.9±2.8 μM concentration after 24, 48, and 72 hours incubation, respectively. All concentrations of GA (10, 30, 50 and 80 μM) enhanced apoptosis compared to the control (P<0.05). The results demonstrate that the polyphenolic compound, GA, is effective in inhibition of proliferation and induction of apoptosis in Jurkat cell line. It is recommended to study the mechanism of apoptosis induction in future investigations.

Anti-oxidant and anti-adipogenic effects of acorn (Quercus acutissima CARR.) shell extracts via regulation of wnt signaling in 3T3-L1 cells

Acorn (Quercus acutissima CARR.) is a nut from the Fagaceae family that has been used in traditional medicine for many years. However, shells from acorns are regarded as a by-product and are mostly discarded. Anti-adipogenic activities of acorn shells were investigated using 3T3-L1 cells and methanol shell extracts (AE-M). AE-M demonstrated Cu²⁺-chelation activities and anti-oxidant activities via reduction of oxidative stress levels induced using AAPH. Six days after adipocyte differentiation, 50 and 100 μg/mL AE-M completely suppressed 3T3-L1 adipogenesis and the anti-adipogenic effect was stronger than for the positive control 50 μM quercetin. Treatment with AE-M in 3T3-L1 cells reduced mRNA expression levels of adipogenic genes. AE-M-inhibition was found in pre-adipogenic, early, and intermediate stages of adipogenesis in 3T3-L1 cells. The Wnt/β-catenin signaling pathway is required for AE-M-inhibition of 3T3-L1 adipogenesis.

A class of sulfonamides as carbonic anhydrase I and II inhibitors

Four groups of novel sulfonamide derivatives: (i) acetoxybenzamide, (ii) triacetoxybenzamide, (iii) hydroxybenzamide and (iv) trihydroxybenzamide, all having thiazole, pyrimidine, pyridine, isoxazole and thiadiazole moieties were prepared and their inhibitory effects were studied on two metalloenzymes, i.e. carbonic anhydrase isozymes (hCA I and II), purified from human erythrocyte cells by Sepharose-4B-l-tyrosine-sulfanilamide affinity chromatography. These enzymes are present in almost all living organisms to catalyse the synthesis of bicarbonate ion (HCO₃^-) from carbon dioxide and water. The sulfonamide derivatives were found to be active against hCA I and II in the range of 2.62-136.54 and 5.74-210.58 nM, respectively.

Caffeoylquinic Acid Derivatives Protect SH-SY5Y Neuroblastoma Cells from Hydrogen Peroxide-Induced Injury Through Modulating Oxidative Status

Oxidative stress has been confirmed as a contribution to the pathogenesis and pathophysiology of many neurological disorders such as Alzheimer's disease and Parkinson's disease. Caffeoylquinic acids (CQAs) are considered to have anti-oxidative stress ability in a previous study, but the structure-activity relationships (SARs) of CQAs in neuroprotective effects are still unclear. In the present study, we primarily expound the SARs of CQAs in counteracting H₂O₂-induced injury in SH-SY5Y cells. We found that CQAs (1-10) represented the protection of SH-SY5Y cells against H₂O₂-induced injury in varying degrees and malonyl groups could obviously increase the anti-oxidative stress ability of CQAs. Intensive studies of 4,5-O-dicaffeoyl-1-O-(malic acid methyl ester)-quinic acid (MDCQA) indicated that the mechanisms could potentially involve activation of endogenous antioxidant enzymes and the regulation of the phosphorylation of MAPKs and AKT. In conclusion, MDCQA could serve as a neuroprotective agent with a potential to attenuate oxidative stress.

Dodecyl gallate induces apoptosis by upregulating the caspase-dependent apoptotic pathway and inhibiting the expression of anti-apoptotic Bcl-2 family proteins in human osteosarcoma cells

Dodecyl gallate (DG) is a gallic acid ester that has been shown to inhibit tumor growth. The aim of this study was to investigate the mechanism by which DG induces antiproliferative and apoptotic effects in MG-63 human osteosarcoma cells. Dose- and time-dependent cytotoxic effects of DG were determined using an MTT assay. The results showed that the half-maximal inhibitory concentration (IC₅₀) of DG in MG-63 cells was 31.15 µM at 24 h, 10.66 µM at 48 h, and 9.06 µM at 72 h. Flow cytometric analysis demonstrated that exposure to 20 and 40 µM DG resulted in an increase in the sub-G1 phase population and in S-phase cell cycle arrest. Furthermore, western blot analysis of apoptosis-related protein expression revealed an increase in the activation of caspases 8 and 3, cleavage of poly (ADPribose) polymerase (PARP), and disruption of mitochondrial membrane permeability was measured by flow cytometry. An increase in the Bax/Bcl-2 ratio and a decrease in the expression of inhibitor of apoptosis protein (IAP) family members, namely X-linked inhibitor of apoptosis protein and survivin, were also observed following DG treatment. These data provide insight into the molecular mechanisms governing the ability of DG to induce apoptosis in human osteosarcoma cells in vitro.

Synthesis, antiproliferative activity and molecular properties predictions of galloyl derivatives

The present study was designed to investigate the in vitro antiproliferative activity against ten human cancer cell lines of a series of galloyl derivatives bearing substituted-1,3,4-oxadiazole and carbohydrazide moieties. The compounds were also assessed in an in silico study of the absorption, distribution, metabolism and excretion (ADME) in the human body using Lipinski’s parameters, the topological polar surface area (TPSA) and percentage of absorption (%ABS). In general, the introduction of N'-(substituted)-arylidene galloyl hydrazides 4–8 showed a moderate antitumor activity, while the 2-methylthio- and 2-thioxo-1,3,4-oxadiazol-5-yl derivatives 9 and 10 led to increased inhibition of cancer cell proliferation. The precursor compound methyl gallate 2 and the intermediary galloyl hydrazide 3 showed greater antiproliferative activity with GI₅₀ values < 5.54 µM against all human tumor cell lines tested. A higher inhibition effect against ovarian cancer (OVCAR-3) (GI₅₀ = 0.05–5.98 µM) was also shown, with compounds 2, 3, 9 and 10 with GI₅₀ ≤ 0.89 µM standing out in this respect. The in silico study revealed that the compounds showed good intestinal absorption.

Antioxidant polyphenol-rich extracts from the medicinal plants Antirhea borbonica, Doratoxylon apetalum and Gouania mauritiana protect 3T3-L1 preadipocytes against H2O2, TNFα and LPS inflammatory mediators by regulating the expression of superoxide dismutase and NF-κB genes

Background

Adipose cells responsible for fat storage are the targets of reactive oxygen species (ROS) like H₂O₂ and pro-inflammatory agents including TNFα and LPS. Such mediators contribute to oxidative stress and alter inflammatory processes in adipose tissue, leading to insulin resistance during obesity. Thus, the identification of natural compounds such as plant polyphenols able to increase the antioxidant and anti-inflammatory capacity of the body is of high interest. We aimed to evaluate the biological properties of polyphenol-rich extracts from the medicinal plants A. borbonica, D. apetalum and G. mauritiana on preadipocytes exposed to H₂O₂, TNFα or LPS mediators.

Methods

Medicinal plant extracts were analysed for their polyphenol contents by Folin-Ciocalteu and UPLC-ESI-MS methods as well as for their free radical-scavenging activities by DPPH and ORAC assays. To assess the ability of polyphenol-rich extracts to protect 3T3-L1 preadipocytes against H₂O₂, TNFα or LPS mediators, several parameters including cell viability (MTT and LDH assays), ROS production (DCFH-DA test), IL-6 and MCP-1 secretion (ELISA) were evaluated. Moreover, the expression of superoxide dismutase, catalase and NF-κB genes was explored (RT-QPCR).

Results

All medicinal plants exhibited high levels of polyphenols with free radical-scavenging capacities. Flavonoids such as quercetin, kaempferol, epicatechin and procyanidins, and phenolic acids derived from caffeic acid including chlorogenic acid, were detected. Polyphenol-rich plant extracts did not exert a cytotoxic effect on preadipocytes but protected them against H₂O₂ anti-proliferative action. Importantly, they down-regulated ROS production and the secretion of IL-6 and MCP-1 pro-inflammatory markers induced by H₂O₂, TNFα and LPS mediators. Such a protective action was associated with an increase in superoxide dismutase antioxidant enzyme gene expression and a decrease in mRNA levels of NF-κB pro-inflammatory transcription factor.

Conclusion

This study highlights that antioxidant strategies based on polyphenols derived from medicinal plants tested could contribute to regulate adipose tissue redox status and immune process, and thus participate to the improvement of obesity-related oxidative stress and inflammation.

Gallic acid and methyl-3-O-methyl gallate: a comparative study on their effects on prostate cancer stem cells

The study shows the different ability of gallic acid and methyl-3-O-methyl gallate to inhibit NF-κB activity and the growth of PCa cells with stem-like properties.

Gallic acid: a versatile antioxidant with promising therapeutic and industrial applications

Oxidative stress, a result of an overproduction and accumulation of free radicals, is the leading cause of several degenerative diseases such as cancer, atherosclerosis, cardiovascular diseases, ageing and inflammatory diseases.

Identification of KMU-3, a novel derivative of gallic acid, as an inhibitor of adipogenesis

Differentiation of preadipocyte, also called adipogenesis, leads to the phenotype of mature adipocyte. Excessive adipogenesis, however, is largely linked to the development of obesity. Herein we investigated a library of 53 novel chemicals, generated from a number of polyphenolic natural compounds, on adipogenesis. Strikingly, among the chemicals tested, KMU-3, a derivative of gallic acid, strongly suppressed lipid accumulation during the differentiation of 3T3-L1 preadipocytes into adipocytes. On mechanistic levels, KMU-3 inhibited expressions of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), and fatty acid synthase (FAS) during adipocyte differentiation. Moreover, KMU-3 reduced expressions of adipokines, including retinol binding protein-4 (RBP-4), leptin, and regulated on activation, normal T cell expressed and secreted (RANTES) during adipocyte differentiation. Of further note, KMU-3 rapidly blocked the phosphorylation of signal transducer and activator of transcription-3 (STAT-3) during the early stage of adipogenesis. Importantly, pharmacological inhibition studies revealed that AG490, a JAK-2/STAT-3 inhibitor suppressed adipogenesis and STAT-3 phosphorylation, implying that early blockage of STAT-3 activity is crucial for the KMU-3-mediated anti-adipogenesis. These findings demonstrate firstly that KMU-3 inhibits adipogenesis by down-regulating STAT-3, PPAR-γ, C/EBP-α, and FAS. This work shows that KMU-3 is an inhibitor of adipogenesis and thus may have therapeutic potential against obesity.

Gallic acid selectively induces the necrosis of activated hepatic stellate cells via a calcium-dependent calpain I activation pathway

AIMS

The activation of hepatic stellate cells (HSCs) in response to liver injury is critical to the development of liver fibrosis, thus, the blockage of the activation of HSCs is considered as a rational approach for anti-fibrotic treatment. In this report, we investigated the effects and the underlying mechanisms of gallic acid (GA) in interfering with the activation of HSCs.

MAIN METHODS

The primary cultured rat HSCs were treated with various doses of GA for different time intervals. The morphology, viability, caspase activity, calcium ion flux, calpain I activity, reactive oxygen species generation and lysosomal functions were then investigated.

KEY FINDINGS

GA selectively killed HSCs in both dose- and time-dependent manners, while remained no harm to hepatocytes. Besides, caspases were not involved in GA-induced cell death of HSCs. Further results showed that GA toxicity was associated with a rapid burst of reactive oxygen species (ROS) and a subsequent increase of intracellular Ca(2+) and calpain activity. Addition of calpain I but not calpain II inhibitor rescued HSCs from GA-induced death. In parallel, pretreatment with antioxidants or an intracellular Ca(2+) chelator eradicated GA responses, implying that GA-mediated cytotoxicity was dependent on its pro-oxidative properties and its effect on Ca(2+) flux. Furthermore, application of ROS scavengers also reversed Ca(2+) release and the disruption of lysosomal membranes in GA-treated HSCs.

SIGNIFICANCE

These results provide evidence for the first time that GA causes selective HSC death through a Ca(2+)/calpain I-mediated necrosis cascade, suggesting that GA may represent a potential therapeutic agent to combat liver fibrosis.

Histone deacetylase (HDAC) inhibitory and antiproliferative activities of phenolic-rich extracts derived from the rhizome of Hydnophytum formicarum Jack.: sinapinic acid acts as HDAC inhibitor

Background

The rhizome of Hydnophytum formicarum Jack., a medicinal plant known in Thai as Hua-Roi-Roo, has been used in Thai traditional herbal medicine for treatment of cancer. We assessed the ability of its ethanolic and phenolic-rich extracts and its major phenolic compound, sinapinic acid, possessing histone deacetylase (HDAC) inhibitory activity to inhibit proliferation of 5 human cancer cell lines.

Methods

HeLa cells were used to study HDAC inhibitory activity of the extracts, sinapinic acid, and a well-known HDAC inhibitor sodium butyrate. Five human cancer cell lines and one non-cancer cell line were used to study antiproliferative activities of the plant extracts, sinapinic acid and sodium butyrate, comparatively.

Results

Results indicated that ethanolic and phenolic-rich extracts of H. formicarum Jack. rhizome possessed both antiproliferative activity and HDAC inhibitory activity in HeLa cells. Sinapinic acid, despite its lower HDAC inhibitory activity than the well-known HDAC inhibitor sodium butyrate, inhibited the growth of HeLa and HT29 cells more effectively than sodium butyrate. However, sinapinic acid inhibited the growth of HCT116 and Jurkat cells less effectively than sodium butyrate. The non-cancer cell line (Vero cells) and breast cancer cell line (MCF-7 cells) appeared to be resistant to both sinapinic acid and sodium butyrate. The growth inhibitory effects of the ethanolic and phenolic-rich extracts and sinapinic acid in HeLa cells were mediated by induction of apoptosis.

Conclusions

The results of this study support the efficacy of H. formicarum Jack. rhizome ethanolic and phenolic-rich extracts for the treatment of cervical cancer, colon cancer, and T- cell leukemia in an alternative medicine. Further studies of other active ingredients from this plant are needed.

Attenuation of oxidative stress in U937 cells by polyphenolic-rich bark fractions of Burkea africana and Syzygium cordatum

Background

Oxidative stress has been implicated in the progression of various diseases, which may result in the depletion of endogenous antioxidants. Exogenous supplementation with antioxidants could result in increased protection against oxidative stress. As concerns have been raised regarding synthetic antioxidant usage, the identification of alternative treatments is justified. The aim of the present study was to determine the antioxidant efficacy of Burkea africana and Syzygium cordatum bark extracts in an in vitro oxidative stress model.

Methods

Cytotoxicity of crude aqueous and methanolic extracts, as well as polyphenolic-rich fractions, was determined in C2C12 myoblasts, 3T3-L1 pre-adipocytes, normal human dermal fibroblasts and U937 macrophage-like cells using the neutral red uptake assay. Polyphenolic content was determined using the Folin-Ciocalteau and aluminium trichloride assays, and antioxidant activity using the Trolox Equivalence Antioxidant Capacity and DPPH assays. The extracts efficacy against oxidative stress in AAPH-exposed U937 cells was assessed with regards to reactive oxygen species generation, cytotoxicity, apoptosis, lipid peroxidation and reduced glutathione depletion.

Results

B. africana and S. cordatum showed enrichment of polyphenols from the aqueous extract, to methanolic extract, to polyphenolic-rich fractions. Antioxidant activity followed the same trend, which correlated well with the increased concentration of polyphenols, and was between two- to three-fold stronger than the Trolox antioxidant control. Both plants had superior activity compared to ascorbic acid in the DPPH assay. Polyphenolic-rich fractions were most toxic to the 3T3-L1 (IC₅₀’s between 13 and 21 μg/ml) and C2C12 (IC₅₀’s approximately 25 μg/ml) cell lines, but were not cytotoxic in the U937 and normal human dermal fibroblasts cultures. Free radical-induced generation of reactive oxygen species (up to 80%), cytotoxicity (up to 20%), lipid peroxidation (up to 200%) and apoptosis (up to 60%) was successfully reduced by crude extracts of B. africana and the polyphenolic-rich fractions of both plants. The crude extracts of S. cordatum were not as effective in reducing cytotoxic parameters.

Conclusion

Although oxidative stress was attenuated in U937 cells, cytotoxicity was observed in the 3T3-L1 and C2C12 cell lines. Further isolation and purification of polyphenolic-fractions could increase the potential use of these extracts as supplements by decreasing cytotoxicity and maintaining antioxidant quality.

Gallic acid: molecular rival of cancer

Gallic acid, a predominant polyphenol, has been shown to inhibit carcinogenesis in animal models and in vitro cancerous cell lines. The inhibitory effect of gallic acid on cancer cell growth is mediated via the modulation of genes which encodes for cell cycle, metastasis, angiogenesis and apoptosis. Gallic acid inhibits activation of NF-κB and Akt signaling pathways along with the activity of COX, ribonucleotide reductase and GSH. Moreover, gallic acid activates ATM kinase signaling pathways to prevent the processes of carcinogenesis. The data so far available, both from in vivo and in vitro studies, indicate that this dietary polyphenol could be promising agent in the field of cancer chemoprevention.

Chicoric acid induces apoptosis in 3T3-L1 preadipocytes through ROS-mediated PI3K/Akt and MAPK signaling pathways

Chicoric acid has been reported to possess various bioactivities. However, the antiobesity effects of chicoric acid remain poorly understood. In this study, we investigated the effects of chicoric acid on 3T3-L1 preadipocytes and its molecular mechanisms of apoptosis. Chicoric acid inhibited cell viability and induced apoptosis in 3T3-L1 preadipocytes which was characterized by chromatin condensation and poly ADP-ribose-polymerase (PARP) cleavage. Mitochondrial membrane potential (MMP) loss, Bax/Bcl-2 dysregulation, cytochrome c release, and caspase-3 activation were observed, indicating mitochondria-dependent apoptosis induced by chicoric acid. Furthermore, PI3K/Akt and MAPK (p38 MAPK, JNK, and ERK1/2) signaling pathways were involved in chicoric acid-induced apoptosis. The employment of protein kinase inhibitors LY294002, SB203580, SP600125, and U0126 revealed that PI3K/Akt signaling pathway interplayed with MAPK signaling pathways. Moreover, chicoric acid induced reactive oxygen species (ROS) generation. Pretreatment with the antioxidant N-acetylcysteine (NAC) significantly blocked cell death and changes of Akt and MAPK signalings induced by chicoric acid. In addition, chicoric acid down regulated HO-1 and COX-2 via the PI3K/Akt pathway.

Gallic Acid Induces a Reactive Oxygen Species-Provoked c-Jun NH2-Terminal Kinase-Dependent Apoptosis in Lung Fibroblasts

Idiopathic pulmonary fibrosis is a chronic lung disorder characterized by fibroblasts proliferation and extracellular matrix accumulation. Induction of fibroblast apoptosis therefore plays a crucial role in the resolution of this disease. Gallic acid (3,4,5-trihydroxybenzoic acid), a common botanic phenolic compound, has been reported to induce apoptosis in tumor cell lines and renal fibroblasts. The present study was undertaken to examine the role of mitogen-activated protein kinases (MAPKs) in lung fibroblasts apoptosis induced by gallic acid. We found that treatment with gallic acid resulted in activation of c-Jun NH₂-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and protein kinase B (PKB, Akt), but not p38MAPK, in mouse lung fibroblasts. Inhibition of JNK using pharmacologic inhibitor (SP600125) and genetic knockdown (JNK specific siRNA) significantly inhibited p53 accumulation, reduced PUMA and Fas expression, and abolished apoptosis induced by gallic acid. Moreover, treatment with antioxidants (vitamin C, N-acetyl cysteine, and catalase) effectively diminished gallic acid-induced hydrogen peroxide production, JNK and p53 activation, and cell death. These observations imply that gallic acid-mediated hydrogen peroxide formation acts as an initiator of JNK signaling pathways, leading to p53 activation and apoptosis in mouse lung fibroblasts.

Dietary polyphenols preconditioning protects 3T3-L1 preadipocytes from mitochondrial alterations induced by oxidative stress

Numerous studies indicate that an increase in reactive oxygen species (ROS) significantly affects white adipose tissue biology and leads to an inflammatory profile and insulin resistance, which could contribute to obesity-associated diabetes and cardiovascular diseases. Mitochondria play a key role in adipose tissue energy metabolism and constitute the main source of cellular ROS such as H(2)O(2). Polyphenols constitute the most abundant antioxidants provided by the human diet. Indeed, they are widely distributed in fruits, vegetables and some plant-derived beverages such as coffee and tea. Thus, the biological effects of dietary polyphenols that may increase the antioxidant capacity of the body against obesity-induced oxidative stress are of high interest. Here, we studied the capacity of polyphenols to modulate the impact of oxidative stress on the mitochondria of preadipocytes, which are important cells governing the adipose tissue development for energy homeostasis. Whereas H(2)O(2) treatment induces a proliferation arrest associated with an increase in mitochondrial content in 3T3-L1 preadipocytes, preconditioning with some major dietary polyphenols totally or partially protects the cells against oxidative stress consequences. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.

Plant-derived phenolics inhibit the accrual of structurally characterised protein and lipid oxidative modifications

Epidemiological data suggest that plant-derived phenolics beneficial effects include an inhibition of LDL oxidation. After applying a screening method based on 2,4-dinitrophenyl hydrazine-protein carbonyl reaction to 21 different plant-derived phenolic acids, we selected the most antioxidant ones. Their effect was assessed in 5 different oxidation systems, as well as in other model proteins. Mass-spectrometry was then used, evidencing a heterogeneous effect on the accumulation of the structurally characterized protein carbonyl glutamic and aminoadipic semialdehydes as well as for malondialdehyde-lysine in LDL apoprotein. After TOF based lipidomics, we identified the most abundant differential lipids in Cu(++)-incubated LDL as 1-palmitoyllysophosphatidylcholine and 1-stearoyl-sn-glycero-3-phosphocholine. Most of selected phenolic compounds prevented the accumulation of those phospholipids and the cellular impairment induced by oxidized LDL. Finally, to validate these effects in vivo, we evaluated the effect of the intake of a phenolic-enriched extract in plasma protein and lipid modifications in a well-established model of atherosclerosis (diet-induced hypercholesterolemia in hamsters). This showed that a dietary supplement with a phenolic-enriched extract diminished plasma protein oxidative and lipid damage. Globally, these data show structural basis of antioxidant properties of plant-derived phenolic acids in protein oxidation that may be relevant for the health-promoting effects of its dietary intake.