Gallic acid regulates adipocyte hypertrophy and suppresses inflammatory gene expression induced by the paracrine interaction between adipocytes and macrophages in vitro and in vivo

A Comprehensive Review of Phytonutrients as a Dietary Therapy for Obesity

Obesity is a complex medical condition mainly caused by eating habits, genetics, lifestyle, and medicine. The present study deals with traditional diets like the Mediterranean diet, Nordic diet, African Heritage diet, Asian diet, and DASH, as these are considered to be sustainable diets for curing obesity. However, the bioavailability of phytonutrients consumed in the diet may vary, depending on several factors such as digestion and absorption of phytonutrients, interaction with other substances, cooking processes, and individual differences. Hence, several phytochemicals, like polyphenols, alkaloids, saponins, terpenoids, etc., have been investigated to assess their efficiencies and safety in the prevention and treatment of obesity. These phytochemicals have anti-obesity effects, mediated via modulation of many pathways, such as decreased lipogenesis, lipid absorption, accelerated lipolysis, energy intake, expenditure, and preadipocyte differentiation and proliferation. Owing to these anti-obesity effects, new food formulations incorporating these phytonutrients were introduced that can be beneficial in reducing the prevalence of obesity and promoting public health.

Ameliorative effects of gallic acid on GLUT-4 expression and insulin resistance in high fat diet-induced obesity animal model mice, Mus musculus

Reduced activity of glucose transporter type 4 isoform (GLUT-4), an insulin-sensitive glucose transporter distributed on the adipocytes, is associated with impaired insulin signaling. Insulin resistance resulting from alteration in glucose transport is responsible for exacerbating the emergence of metabolic abnormalities. The present study aimed to investigate the effects of the antidote gallic acid (GA) on expression-related changes in GLUT-4 and insulin receptor substrate-1 (IRS-1) in the visceral adipose tissue and on the subsequent development of insulin resistance in a high-fat diet (HFD)-induced obesity animal model. Methods: Twenty-four female Swiss albino mice were used and separated into the following four groups (six animals in each group): control group (standard pellet diet), HFD group, (60% HFD), HFD + GA group (60% HFD and GA 50 mg/kg body weight for 60 days), and GA group (GA 50 mg/kg body weight for 60 days). The effect of HFD on serum glucose, total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL), low-density lipoprotein (LDL) cholesterol, and insulin was evaluated. Additionally, homeostasis model assessment for insulin resistance (HOMA-IR) and glucose tolerance test (GTT) was performed. The serum antioxidative profile, which comprises oxidative parameters (superoxide dismutase [SOD], catalase [CAT], and glutathione peroxidase [GPx]) was measured. The effectiveness of GA against HFD-induced alteration in GLUT-4 and IRS-1 expression was also evaluated. Results: The experimental group that fed on GA + HFD had improved levels of serum triglycerides (p˂0.001), cholesterol (p˂0.05), and LDL cholesterol. GA administration also significantly improved hyperinsulinemia and HOMA-IR index (p˂0.001) in HFD mice. GA improved GTT results (p˂0.05); activity of SOD, CAT, and GPx (p˂0.05); and upregulated mRNA expression of GLUT-4 and IRS-1(p˂0.05) in the visceral adipose tissue in the HFD + GA experimental group. Conclusion: A link exists between insulin resistance, GLUT-4, and IRS-1 expression in the adipose tissue, and the initiation of metabolic syndrome, a condition characterized by obesity. GA may promote insulin signaling, glucose uptake, and lipid metabolism in the adipose tissues by mitigating oxidative stress. GA can also be used to manage obesity-related comorbidities including type 2 diabetes and dyslipidemia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01194-5.

Inhibition Effect of Adipogenesis and Lipogenesis via Activation of AMPK in Preadipocytes Treated with Canavalia gladiata Extract

The aim of this study was to investigate the effect of Canavalia gladiata extract (CGE) on the regulation of AMP-activated protein kinase (AMPK) in 3T3-L1 preadipocytes and evaluate the adipogenesis and lipogenesis mechanisms. In 3T3-L1 preadipocytes, lipid accumulation and differentiation were suppressed by 1.1, 1.3, and 1.4 times under the CGE treatment at 0.25, 0.5, and 1.0 mg/mL, respectively. The expression of the main genes involved in the inhibition of adipogenesis was evaluated at the mRNA level via a transcription-polymerase chain reaction. The extract at 1.0 mg/mL increased the mRNA expressions of AMPK and carnitine palmitoyl transferase-1 (CPT-1) by 1.9 and 1.2 times, respectively, while it decreased the expression of sterol regulatory element binding proteins-1c (SREBP-1c), peroxisome proliferator activated receptor-γ (PPAR-γ), CCAAT enhancer binding protein-α (C/EBP-α), and fatty acid synthase (FAS) by 1.1, 1.2, 1.8, and 1.5 times, respectively, indicating inhibition of the adipogenesis and lipogenesis potential of CGE. Gallic acid (4.02 mg/g) was identified as the main component of the CGE via LC-MS/MS and HPLC analysis. The results of this study suggested that CGE can be utilized as an anti-obesity food additive or medication by activating the AMPK-induced regulation and suppressing adipogenesis transcription factors.

Natural polyphenols: a potential prevention and treatment strategy for metabolic syndrome

Metabolic syndrome (MS) is the term for a combination of hypertension, dyslipidemia, insulin resistance, and central obesity as factors leading to cardiovascular and metabolic disease. Epidemiological investigation has shown that polyphenol intake is negatively correlated with the incidence of MS. Natural polyphenols are widely found in cocoa beans, tea, vegetables, fruits, and some Chinese herbal medicines; they are a class of plant compounds containing a variety of phenolic structural units, which are potent antioxidants and anti-inflammatory agents in plants. Polyphenols are composed of flavonoids (such as flavanols, anthocyanidins, anthocyanins, isoflavones, etc.) and non-flavonoids (such as phenolic acids, stilbenes, and lignans). Modern pharmacological studies have proved that polyphenols can reduce blood pressure, improve lipid metabolism, lower blood glucose, and reduce body weight, thereby preventing and improving MS. Due to the unique characteristics and potential development and application value of polyphenols, this review summarizes some natural polyphenols that could treat MS, including their chemical properties, plant sources, and pharmacological action against MS, to provide a basis for the further study of polyphenols in MS.

Phenolic Characterization Using cLC-DAD Analysis and Evaluation of In Vitro and In Vivo Pharmacological Activities of Ruta tuberculata Forssk

The perennial aromatic plant Ruta tuberculata Forssk (Rutaceae) has been traditionally used by Mediterranean peoples as folk medicine against several types of disease to treat diverse illness. The objective of this work is to evaluate the in vitro and in vivo pharmacological activities of the aqueous (RAE) and methanolic (MeOH) 80% (RME) extracts of Algerian R. tuberculata aerial parts. Antioxidant potential, neuro-protective and anti-arthritic activities were investigated in vitro using six antioxidant approaches and by determining acetyl-cholinesterase and bovine albumin denaturation inhibitory capacities, respectively. Furthermore, in vivo anti-ulcer and anti-inflammatory activities were evaluated on EtOH-induced gastric mucosal damage and carrageenan-induced paw edema models in mice. Moreover, bio-compounds’ contents were also quantified using spectrophotometric and cLC-DAD methods. Both in vivo and in vitro investigations showed remarkable antioxidant activity of Ruta tuberculata Forssk, while methanolic extract (RME) of Ruta tuberculata Forssk exhibited more significant neuro-protective and anti-inflammatory effects. However, the antiulcer activity was more pronounced with RAE of R. tuberculata, which suggests that this plant can be considered as a natural resource of potent bioactive compounds that may act as antioxidant and anti-inflammatory agents, which underlines the importance of incorporating them in therapies in order to treat various diseases linked to oxidative stress, and they may also provide crucial data for the development of new anticholinesterase drugs to improve neurodegenerative diseases, such as Alzheimer’s.

Aqueous Extract of Psiloxylon mauritianum, Rich in Gallic Acid, Prevents Obesity and Associated Deleterious Effects in Zebrafish

Obesity has reached epidemic proportions, and its prevalence tripled worldwide between 1975 and 2016, especially in Reunion Island, a French overseas region. Psiloxylon mauritianum, an endemic medicinal plant from Reunion Island registered in the French pharmacopeia, has recently gained interest in combating metabolic disorders because of its traditional lipid-lowering and “anti-diabetic” use. However, scientific data are lacking regarding its toxicity and its real benefits on metabolic diseases. In this study, we aim to determine the toxicity of an aqueous extract of P. mauritianum on zebrafish eleutheroembryos following the OECD toxicity assay (Organization for Economic Cooperation and Development, guidelines 36). After defining a non-toxic dose, we determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) that this extract is rich in gallic acid but contains also caffeoylquinic acid, kaempferol and quercetin, as well as their respective derivatives. We also showed that the non-toxic dose exhibits lipid-lowering effects in a high-fat-diet zebrafish larvae model. In a next step, we demonstrated its preventive effects on body weight gain, hyperglycemia and liver steatosis in a diet-induced obesity model (DIO) performed in adults. It also limited the deleterious effects of overfeeding on the central nervous system (i.e., cerebral oxidative stress, blood-brain barrier breakdown, neuro-inflammation and blunted neurogenesis). Interestingly, adult DIO fish treated with P. mauritianum display normal feeding behavior but higher feces production. This indicates that the “anti-weight-gain” effect is probably due to the action of P. mauritianum on the intestinal lipid absorption and/or on the microbiota, leading to the increase in feces production. Therefore, in our experimental conditions, the aqueous extract of P. mauritianum exhibited “anti-weight-gain” properties, which prevented the development of obesity and its deleterious effects at the peripheral and central levels. These effects should be further investigated in preclinical models of obese/diabetic mice, as well as the impact of P. mauritianum on the gut microbiota.

Serum Metabolomics Analysis of the Anti-Inflammatory Effects of Gallic Acid on Rats With Acute Inflammation

Background: Gallic acid (GA) is a natural small-molecule polyphenol having a wide range of pharmacological activities. Until now, some works have studied the effect and the mechanisms of GA against inflammation. However, whether or how gallic acid regulates the downstream metabolic disorder against acute inflammation remains unclear. The present study explored the protective effect and the potential mechanism of GA on acute inflammation through the metabolomics approach.

Methods: An acute inflammation rat model was induced by local injection of carrageenin. Local swelling on paw and serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) were assessed in Control, Model and Gallic acid groups, respectively. Serum metabolomics based on high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) was also established to collect rats’ metabolic profiles and explore the metabolic changes related to GA pretreatment.

Results: Compared to the Modal group, local pain, redness, and swelling induced by carrageenin were significantly alleviated in GA groups in addition to the dose-dependent decreases of TNF-α and IL-6. Metabolomics analysis found significant alterations in metabolic signatures between the carrageenin-induced inflammation and control groups. Twelve potential biomarkers were further identified in acute inflammation by principal component analysis (PCA) and partial least squares discrimination analysis (PLS-DA). In addition, when rats were pretreated with gallic acid, serum levels of eleven biomarkers were observed to restore partially. Metabolic pathway and networks analysis revealed that GA might invert the pathological process of acute inflammation by regulating the key biomarkers involved in linoleic acid metabolism, ascorbate and aldarate metabolism, pentose and glucuronate interconversions, and arachidonic acid (AA) metabolism pathways.

Conclusion: The study elucidates the protective effect of gallic acid against acute inflammation and its possible regulating mechanism from a metabolomic perspective. These results could provide a theoretical basis for clarifying gallic acid’s mechanism and potential medicinal value in curing inflammation disorder in the clinic.

Bio-Waste Products of Mangifera indica L. Reduce Adipogenesis and Exert Antioxidant Effects on 3T3-L1 Cells

Several studies highlighted the beneficial value of natural compounds in the prevention and treatment of obesity. Here, we investigated the anti-obesity effects of extracts of peel and seed of mango (Mangifera indica L.) cultivated in Sicily (Italy) in 3T3-L1 cells. Mango Peel (MPE) and Mango Seed (MSE) extracts at a 100 µg/mL concentration significantly reduced lipid accumulation and triacylglycerol contents during 3T3-L1 adipocyte differentiation without toxicity. HPLC-ESI-MS analysis showed that both the extracts contain some polyphenolic compounds that can account for the observed biological effects. The anti-adipogenic effect of MPE and MSE was the result of down-regulation of the key adipogenic transcription factor PPARγ and its downstream targets FABP4/aP2, GLUT4 and Adipsin, as well SREBP-1c, a transcription factor which promotes lipogenesis. In addition, both MPE and MSE significantly activated AMPK with the consequent inhibition of Acetyl-CoA-carboxylase (ACC) and up-regulated PPARα. The addition of compound C, a specific AMPK inhibitor, reduced the effects of MPE and MSE on AMPK and ACC phosphorylation, suggesting a role of AMPK in mediating MPE and MSE anti-lipogenic effects. Notably, MPE and MSE possess an elevated radical scavenging activity, as demonstrated by DPPH radical scavenging assay, and reduced ROS content produced during adipocyte differentiation. This last effect could be a consequence of the increase in the antioxidant factors Nrf2, MnSOD and HO-1. In conclusion, MPE and MSE possesses both anti-adipogenic and antioxidant potential, thus suggesting that the bio-waste products of mango are promising anti-obesity natural compounds.

Gallic Acid and Diabetes Mellitus: Its Association with Oxidative Stress

Diabetes mellitus (DM) is a severe chronic metabolic disease with increased mortality and morbidity. The pathological progression of DM is intimately connected with the formation and activation of oxidative stress (OS). Especially, the involvement of OS with hyperglycemia, insulin resistance, and inflammation has shown a vital role in the pathophysiological development of DM and related complications. Interestingly, accumulating studies have focused on the exploration of natural antioxidants for their improvement on DM. Of specific interest is gallic acid (GA), which is rich in many edible and herbal plants and has progressively demonstrated robust antioxidative and anti-inflammatory effects on metabolic disorders. To provide a better understanding of its potential therapeutic impacts and enhancement of human health care, the available research evidence supporting the effective antidiabetic properties of GA and relevant derivatives are needed to be summarized and discussed, with emphasis on its regulation on OS and inflammation against DM. This review aims to highlight the latest viewpoints and current research information on the role of OS in diabetes and to provide scientific support for GA as a potential antihypoglycemic agent for DM and its complications.

Chimarrão, terere and mate-tea in legitimate technology modes of preparation and consume: A comparative study of chemical composition, antioxidant, anti-inflammatory and anti-anxiety properties of the mostly consumed beverages of Ilex paraguariensis St. Hil

ETHNOPHARMACOLOGICAL RELEVANCE

Ilex paraguariensis St. Hil. (Aquifoliaceae) is a medicinal plant widely used by South American populations for centuries and is popularly attributed to stimulating and detoxifying properties. Nowadays, their consume traditionally occurs through three different beverages: chimarrão, terere and mate-tea.

AIM OF THE STUDY

Although its composition and properties are well studied, literature lacks work comparing the potential of their extracts obtained by a legitimate preparation mode of their popular beverages. Therefore, the purpose of this research is to investigate changes in chemical composition, antioxidant activity, anti-inflammatory efficacy and anxiolytic effect from lyophilized aqueous extracts obtained simulating the legitimate popular preparation mode of chimarrão, terere and mate-tea.

MATERIALS AND METHODS

In this work, were investigated differences related to preparation technology and dry material used through chemical composition analysis, with the lyophilized aqueous extracts obtained simulating the chimarrão, terere and mate-tea preparation. The chemical composition analysis comprises the total soluble phenolics content, chemical profiles by HPLC-ESI-MS/MS, and quantitative component detection by HPLC-UV/DAD. Moreover, evaluations of comparative antioxidant activity of the extracts (DPPH and ORAC_FL assays), anti-inflammatory efficacy and anxiolytic effect were performed in vivo.

RESULTS

Our results showed that chimarrão extracts presented a richer composition in terms of phenolic compounds and purine alkaloids, and better antioxidant activity when compared to the other extracts. In pleurisy test, all products showed anti-inflammatory properties in the dose of 60 mg/kg. In the anxiolytic evaluation, although all extracts presented some effect, chimarrão and terere were better than mate-tea in general. No sign of toxicity was observed.

CONCLUSIONS

Our findings support that the beverage made as chimarrão has the best composition and the most promising properties overall.

Gallic acid for cancer therapy: Molecular mechanisms and boosting efficacy by nanoscopical delivery

Cancer is the second leading cause of death worldwide. Majority of recent research efforts in the field aim to address why cancer resistance to therapy develops and how to overcome or prevent it. In line with this, novel anti-cancer compounds are desperately needed for chemoresistant cancer cells. Phytochemicals, in view of their pharmacological activities and capacity to target various molecular pathways, are of great interest in the development of therapeutics against cancer. Plant-derived-natural products have poor bioavailability which restricts their anti-tumor activity. Gallic acid (GA) is a phenolic acid exclusively found in natural sources such as gallnut, sumac, tea leaves, and oak bark. In this review, we report on the most recent research related to anti-tumor activities of GA in various cancers with a focus on its underlying molecular mechanisms and cellular pathwaysthat that lead to apoptosis and migration of cancer cells. GA down-regulates the expression of molecular pathways involved in cancer progression such as PI3K/Akt. The co-administration of GA with chemotherapeutic agents shows improvements in suppressing cancer malignancy. Various nano-vehicles such as organic- and inorganic nano-materials have been developed for targeted delivery of GA at the tumor site. Here, we suggest that nano-vehicles improve GA bioavailability and its ability for tumor suppression.

Natural Polyphenols in Metabolic Syndrome: Protective Mechanisms and Clinical Applications

Metabolic syndrome (MetS) is a chronic disease, including abdominal obesity, dyslipidemia, hyperglycemia, and hypertension. It should be noted that the occurrence of MetS is closely related to oxidative stress-induced mitochondrial dysfunction, ectopic fat accumulation, and the impairment of the antioxidant system, which in turn further aggravates the intracellular oxidative imbalance and inflammatory response. As enriched anti-inflammatory and antioxidant components in plants, natural polyphenols exhibit beneficial effects, including improving liver fat accumulation and dyslipidemia, reducing blood pressure. Hence, they are expected to be useful in the prevention and management of MetS. At present, epidemiological studies indicate a negative correlation between polyphenol intake and MetS incidence. In this review, we summarized and discussed the most promising natural polyphenols (including flavonoid and non-flavonoid drugs) in the precaution and treatment of MetS, including their anti-inflammatory and antioxidant properties, as well as their regulatory functions involved in glycolipid homeostasis.

Phenethyl Isothiocyanate Improves Lipid Metabolism and Inflammation via mTOR/PPARγ/AMPK Signaling in the Adipose Tissue of Obese Mice

Obesity is defined as excess adipose mass that causes serious health problems. Phenethyl isothiocyanate (PEITC) is a major and relatively nontoxic compound of the isothiocyanates. Although many studies have demonstrated that PEITC is a potent substance with physiological activities, such as anticancer activity, the precise mechanism for the effects of PEITC on inflammation and lipid metabolism in adipose tissue is not clear. Our study aimed to clarify the effects of PEITC supplements on the adipose tissue in obesity induced with a high-fat/cholesterol diet, and the underlying mechanisms. We induced obesity by feeding the mice with high fat with 1% cholesterol diet (HFCD) for 13 weeks. Mice were divided into five groups: normal diet (CON), HFCD, HFCD with 3 mg/(kg·d) gallic acid (HFCD+G), and HFCD with 30 and 75 mg/(kg·d) PEITC (HFCD+P30 and HFCD+P75, respectively). Using western blotting and quantitative polymerase chain reaction (qPCR) analysis of the adipose tissue, we determined the expression of lipid metabolism-related genes and inflammation-related genes. In the HFCD, the expression level of nuclear factor-κB (NF-κB), lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1), and cyclooxygenase-2 (COX-2), was higher compared with that in the CON. Moreover, in the HFCD, the expression of p-mechanical targets of the rapamycin (mTOR) was increased, whereas that of p-AMP-activated protein kinase (AMPK) was decreased compared with that in the CON. Nevertheless, these decreased expression levels of p-AMPK and increased levels of LOX-1, p-mTOR, peroxisome proliferator-activated receptor gamma (PPARγ), NF-κB, and COX-2, were alleviated by PEITC supplementation. Therefore, we suggest that PEITC might be a potential preventive agent for ameliorating obesity-induced inflammation and adipogenesis by modulating the mTOR/AMPK/PPARγ pathway.

Anti-NAFLD effect of defatted walnut powder extract in high fat diet-induced C57BL/6 mice by modulating the gut microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

Walnut kernel has the actions of removing meteorism, dissipating stagnation and removing blood stasis and is used after being defatted in TCM. Defatted walnut powder extract (DWPE) has the abilities of anti-oxidation and lowering lipid levels in vivo. However, the effects and the potential mechanisms of DWPE on NAFLD have not been explored.

AIM OF THE STUDY

The study were to investigate the anti-NAFLD effect of DWPE in high fat diet-induced C57BL/6 mice and demonstrate that whether DWPE developed the effect on anti-NAFLD by remodeling the compositions and abundances of gut microbiota.

MATERIALS AND METHODS

The inhibitory effect of DWPE on the development of NAFLD was conducted on C57BL/6 mice with a high fat diet and the regulation effect of DWPE on gut microbiota was verified on pseudo-sterile mice with treatment of broad spectrum antibiotics.

RESULTS

The results showed that the oral administration of DWPE remarkably alleviated hepatic lipid accumulation by decreasing the levels of TG, TC, LDL, MDA and increasing HDL. Meanwhile, the expressions of NF-κB and MAPKs family proteins were reduced by DWPE compared with HFD group. Otherwise, the efficacy of anti-NAFLD of DWPE was significantly decreased after treatment of antibiotics, which indicated the key role of gut microbiota in the therapeutic process. Furthermore, sequencing of 16S rRNA gene revealed that DWPE could revert the decreased relative abundance of gut microbiota caused by the long term of a high fat diet. And the disordered microflora was remodeled by DWPE including the reduction of Erysipelotrichia, Firmicutes and Actinobacteria as well as the increment of Bacteroidetes, Clostridiales, Bacteroidales S24-7, Prevotellaceae and Bacteroides.

CONCLUSION

Taken together, DWPE had a preventing effect on NAFLD, which might be associated with the regulation of gut microbiota.

Long-term supplementation with phenolic compounds from jaboticaba (Plinia jaboticaba (Vell.) Berg) reduces adiposophaty and improves glucose, lipid, and energy metabolism

Obesity is a critical public health problem worldwide that has been associated to non-communicable diseases (NCD), such as type 2 diabetes (T2DM), non-alcoholic fatty lipid diseases (NAFLD) and inflammatory diseases. Polyphenols from several food sources have been studied as one option against these health problems. Sabara jaboticaba (Plinia jaboticaba (Vell.) Berg) is a Brazilian berry rich in ellagic acid derivatives and anthocyanins. Here we investigated the effects of a phenolic-rich extract from Sabara jaboticaba (PEJ) in a diet-induced obesity animal model. PEJ at two doses, 50 mg gallic acid equivalent (GAE)/kg body weight (BW) and 100 mg GAE/kg BW, were administered by daily gavage to obese C57BL/6J mice for 14 weeks. PEJ prevented the excessive body weight and adiposity, adipocyte hypertrophy, inflammation, hyperglycemia, glucose intolerance, insulin resistance, hypercholesterolemia, and hepatic lipid accumulation, as well as increased energy expenditure. In conclusion, polyphenols from Sabara jaboticaba presented several powerful therapeutic properties relevant for fighting obesity and associated health problems.

Facial Fat Fitness: A New Paradigm to Understand Facial Aging and Aesthetics

Traditionally, facial adipose tissue has been perceived and treated as a homogenous volume-occupying subcutaneous depot. However, recent research from across disciplines is converging to reveal a far more anatomically organized and functionally dynamic role of facial adipose tissue. In this narrative review, we will discuss new insights into adipocyte function and facial adipose anatomy that have far-reaching implications for the practice of aesthetic facial plastic surgery. These concepts are synthesized into a "facial fat fitness" model which can be used to explain clinical observations in facial aging and aesthetic surgery. Fat fitness relates to the quality of facial adipose tissue, as opposed to quantity, and describes whether adipose tissue is in a predominantly healthy hyperplastic or unhealthy hypertrophic state. Fat fitness is modulated by lifestyle factors, and may be impacted positively or negatively by facial aesthetic treatments. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Gallic Acid Inhibits Lipid Accumulation via AMPK Pathway and Suppresses Apoptosis and Macrophage-Mediated Inflammation in Hepatocytes

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease, sometimes ranges from simple steatosis to nonalcoholic steatohepatitis (NASH). Various hits including excessive hepatic steatosis, oxidative stress, apoptosis, and inflammation, contribute to NASH development. Gallic acid (GA), a natural polyphenol, was reported to exert a protective effect on hepatic steatosis in animal models, but the precise molecular mechanisms remain unclear. Here, we examined the effect of GA on hepatic lipid accumulation, apoptosis, and inflammatory response caused by hepatocyte–macrophage crosstalk. We demonstrated that GA attenuated palmitic acid (PA)-induced fat accumulation via the activation of AMP-activated protein kinase (AMPK) in HepG2 cells. GA also ameliorated cell viability and suppressed apoptosis-related gene expression and caspase 3/7 activity induced by PA and H₂O₂. In a co-culture of lipid-laden Hepa 1-6 hepatocytes and RAW 264 macrophages, GA reduced inflammatory mediator expression and induced antioxidant enzyme expression. These results indicate that GA suppresses hepatic lipid accumulation, apoptosis, and inflammation caused by the interaction between hepatocytes and macrophages. The potential effects of GA observed in our study could be effective in preventing NASH and its complications.