Protective effects of gallic acid on hepatic lipid peroxide metabolism, glycoprotein components and lipids in streptozotocin-induced type II diabetic Wistar rats

Metabolites of traditional Chinese medicine targeting PI3K/AKT signaling pathway for hypoglycemic effect in type 2 diabetes

Type 2 diabetes mellitus is a chronic metabolic disease characterized by insulin resistance, with high morbidity and mortality worldwide. Due to the tightly intertwined connection between the insulin resistance pathway and the PI3K/AKT signaling pathway, regulating the PI3K/AKT pathway and its associated targets is essential for hypoglycemia and the prevention of type 2 diabetes mellitus. In recent years, metabolites isolated from traditional Chinese medicine has received more attention and acceptance for its superior bioactivity, high safety, and fewer side effects. Meanwhile, numerous in vivo and in vitro studies have revealed that the metabolites present in traditional Chinese medicine possess better bioactivities in regulating the balance of glucose metabolism, ameliorating insulin resistance, and preventing type 2 diabetes mellitus via the PI3K/AKT signaling pathway. In this article, we reviewed the literature related to the metabolites of traditional Chinese medicine improving IR and possessing therapeutic potential for type 2 diabetes mellitus by targeting the PI3K/AKT signaling pathway, focusing on the hypoglycemic mechanism of the metabolites of traditional Chinese medicine in type 2 diabetes mellitus and elaborating on the significant role of the PI3K/AKT signaling pathway in type 2 diabetes mellitus. In order to provide reference for clinical prevention and treatment of type 2 diabetes mellitus.

Microbiome-Metabolome Analysis Insight into the Effects of the Extract of Phyllanthus emblica L. on High-Fat Diet-Induced Hyperlipidemia

The fruit of Phyllanthus emblica L. (FEPE) has a long history of use in Asian folk medicine. The main bioactive compounds in FEPE are polyphenols, known for their potent antioxidant, anti-inflammatory, and hypolipidemic activities. The present study aimed to investigate the intervention effect of FEPE (100 and 200 mg/kg) on hyperlipidemia for 8 weeks and preliminarily explored the potential mechanism by microbiome-metabolome analysis. The results showed that a high-dose FEPE (200 mg/kg) effectively alleviated dyslipidaemic symptoms and body weight gain in hyperlipidemic mice induced by a high-fat diet (HFD). Microbiome analysis showed that FEPE altered the structure of the intestinal microbiota, which included an increase in specific probiotics (such as Akkermansia, Anaerovorax, and Bacteroides) and a decrease in harmful bacteria (including A2, Acetitomaculum, Candidatus_Arthromitus, Lachnospiraceae_NK4A136_group, Lachnospiraceae_NK4B4_group, Rikenella, and Streptococcus), as well as a reduction in the level of short-chain fatty acids (SCFAs). In addition, significant changes in the hepatic metabolome were observed, and eight key metabolites associated with betaine metabolism, lysine degradation, methionine metabolism, and fatty acid metabolism pathways were primarily filtered. The correlated analysis identified several key "microbiota-metabolite" axes in the treatment of hyperlipidemia by FEPE extract. In conclusion, the present study is expected to provide a basis for treating hyperlipidemia with FEPE from the perspective of the microbiome-liver metabolome axis.

Extraction and Characterization of Bioactive Compounds from Diverse Marine Microalgae and Their Potential Antioxidant Activities

This study compared free and bound phenolic compounds in various marine microalgae species. It assessed total phenolic content (TPC), total flavonoid content (TFC) and total condensed tannin content (TCT) and their antioxidant capacities using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS⋅+ ) radical cation-based assay and ferric ion reducing antioxidant power assay. Liquid chromatography-mass spectrometry (LC-MS) was also employed to characterize the phenolic profiling. Results showed that free phenolic compounds ranged from 1.83-6.45 mg GAE/g d. w., while bound phenolic compounds ranged from 4.03-26.03 mg GAE/g d. w., indicating significant differences. These variations were consistent across assays, highlining unique profiles in different species. A total 10 phenolics were found in these seven microalgae, including 1 phenolic acid, 6 flavonoids, 1 other polyphenol and 2 lignans. 4'-O-methyl-(-)-epigallocatechin 7-O-glucuronide and chrysoeriol 7-O-glucoside in microalgae were firstly reported in microalgal samples. These findings have implications for future applications in industries.

Analysis of the Chemical Composition and Evaluation of the Antioxidant, Antimicrobial, Anticoagulant, and Antidiabetic Properties of Pistacia lentiscus from Boulemane as a Natural Nutraceutical Preservative

Pistacia lentiscus L. has traditionally been employed as a diuretic and stimulant in the treatment of hypertension. Our interest centered on analyzing the chemical profile of the plant's leaves and its in vitro, in vivo, and in silico antioxidant, antimicrobial, anticoagulant, and antidiabetic effects in order to valorize this species and prepare new high-value products that can be used in the agro-food and pharmaceutical industries. When this species' essential oil was hydrodistilled and subjected to GC-MS analysis, the results showed that the principal components were germacrene D (17.54%), spathulenol (17.38%), bicyclogermacrene (12.52%), and terpinen-4-ol (9.95%). The extraction of phenolic compounds was carried out by decoction and Soxhlet. The determination of total polyphenols, flavonoids, and tannins of aqueous and organic extracts by spectrophotometric methods demonstrated the richness of this species in phenolic compounds. Chromatographic analysis by HPLC/UV-ESI-MS of the aqueous extract of P. lentiscus revealed the presence of 3,5-di-O-galloyl quinic acid, gallic acid, and 3,4,5-tri-O-galloyl quinic acid specific to this species. The study of antioxidant activity by three methods (DPPH, FRAP, and Total Antioxidant Capacity) revealed that P. lentiscus is a very promising source of natural antioxidants. The antimicrobial activity of the essential oil and aqueous extract (E0) was studied by microdilution on the microplate. The results revealed the effectiveness of the aqueous extract compared to the essential oil against Gram-negative bacteria (K. pneumoniae, A. baumannii, E. aerogenes, E. cloacae, P. fluorescence, Salmonella sp., Shigella sp., and Y. enterolitica) and candidoses (C. krusei and C. albicans). The measurements of prothrombin time (PT) and activated partial thromboplastin time (aPTT) of the aqueous extract (E0) can significantly prolong these tests from concentrations of 2.875 and 5.750 mg/mL, respectively. The antihyperglycemic effect of the aqueous extract (E0) showed a strong in vitro inhibitory activity of α-amylase and α-glucosidase compared to acarbose. Thus, it significantly inhibited postprandial hyperglycemia in Wistar albino rats. The in-silico study of the major compounds of the essential oil and extract (E0) carried out using PASS, SwissADME, pkCSM, and molecular docking tools confirmed our in vitro and in vivo results. The studied compounds showed a strong ability to be absorbed by the gastrointestinal tract and to passively diffuse through the blood-brain barrier, a similarity to drugs, and water solubility. Molecular docking experiments deduced the probable mode of action of the identified compounds on their respective target proteins, such as NADPH oxidase, thrombin, α-amylase, and α-glucosidase. Furthermore, given the demonstrated antioxidant, antimicrobial, anticoagulant, and antidiabetic effects, we can affirm the richness of P. lentiscus in bioactive molecules and its use in traditional medicine as a source of preservative agent.

Dual actions of gallic acid and andrographolide trigger AdipoR1 to stimulate insulin secretion in a streptozotocin-induced diabetes rat model

Common treatments for the management of diabetes have limitations due to side effects, hence the need for continuous research to discover new remedies with better therapeutic efficacy. Previously, we have reported that the combination treatment of gallic acid (20 mg/kg) and andrographolide (10 mg/kg) for 15 days demonstrated synergistic hypoglycemic activity in the streptozotocin (STZ)-induced insulin-deficient diabetes rat model. Here, we attempt to further elucidate the effect of this combination therapy at the biochemical, histological and molecular levels. Our biochemical analyses showed that the combination treatment significantly increased the serum insulin level and decreased the total cholesterol and triglyceride level of the diabetic animals. Histological examinations of H&E stained pancreas, liver, kidney and adipose tissues of combination-treated diabetic animals showed restoration to the normalcy of the tissues. Besides, the combination treatment significantly enhanced the level of glucose transporter-4 (GLUT4) protein expression in the skeletal muscle of treated diabetic animals compared to single compound treated and untreated diabetic animals. The molecular docking analysis on the interaction of gallic acid and/or andrographolide with the adiponectin receptor 1 (AdipoR1), a key component in the regulation of pancreatic insulin secretion, revealed a greater binding affinity of AdipoR1 to both compounds compared to individual compounds. Taken together, these findings suggest the combination of gallic acid and andrographolide as a potent therapy for the management of diabetes mellitus.

The Role of Antioxidants in the Interplay between Oxidative Stress and Senescence

Cellular senescence is an irreversible state of cell cycle arrest occurring in response to stressful stimuli, such as telomere attrition, DNA damage, reactive oxygen species, and oncogenic proteins. Although beneficial and protective in several physiological processes, an excessive senescent cell burden has been involved in various pathological conditions including aging, tissue dysfunction and chronic diseases. Oxidative stress (OS) can drive senescence due to a loss of balance between pro-oxidant stimuli and antioxidant defences. Therefore, the identification and characterization of antioxidant compounds capable of preventing or counteracting the senescent phenotype is of major interest. However, despite the considerable number of studies, a comprehensive overview of the main antioxidant molecules capable of counteracting OS-induced senescence is still lacking. Here, besides a brief description of the molecular mechanisms implicated in OS-mediated aging, we review and discuss the role of enzymes, mitochondria-targeting compounds, vitamins, carotenoids, organosulfur compounds, nitrogen non-protein molecules, minerals, flavonoids, and non-flavonoids as antioxidant compounds with an anti-aging potential, therefore offering insights into innovative lifespan-extending approaches.

Combined effect of metformin and gallic acid on inflammation, antioxidant status, endoplasmic reticulum (ER) stress and glucose metabolism in fructose-fed streptozotocin-induced diabetic rats

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Metformin, gallic acid and a combination of both improved glucose metabolism and antioxidant status in diabetic rats.

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Metformin, gallic acid and a combination of both lowered levels of IL-6 and TNF-α in liver and pancreas of diabetic rats.

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Metformin, gallic acid and a combination of both decreased the expression of ATF4 in liver and pancreas of diabetic rats.

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Metformin/GA combination appeared more effective than metformin only and gallic acid only.

Over time, diabetes patients usually need combination therapy involving two or more agents, including phytonutrients to attain therapeutic targets. The purpose of this research is to elucidate the combined effect of metformin and gallic acid (GA) on glucose metabolism, inflammation as well as oxidative and endoplasmic reticulum (ER) stresses in fructose-fed diabetic rats. Thirty-five rats of Wistar strain were arbitrarily distributed into five groups, each containing seven animals as follows: normal control, diabetic control, groups administered 100 mg/kg bw metformin only, 50 mg/kg bw gallic acid only and a combination of both. Experimental animals were made diabetic by single injection of 40 mg/kg streptozotocin (intraperitoneally) subsequent to 14 days administration of 10 % fructose prior. Treatment of rats continued for 21 days following diabetes confirmation. Glucose and insulin levels as well as lipid profile were evaluated in the serum, while activities of catalase and superoxide dismutase were estimated in both liver and pancreas. In addition, levels of malondialdehyde, interleukin-6 and tumor necrosis factor-alpha, as well as expression of activating transcription factor-4 were evaluated in liver and pancreas of diabetic rats. Activities of glucose-6-phosphatase and glucokinase were also determined in liver of diabetic animals. Metformin only, GA only and combination of metformin and GA significantly improved antioxidant status and glucose homeostasis while inflammation and endoplasmic reticulum stress were significantly ameliorated in diabetic rats. Metformin/GA combination appeared to improve glucose metabolism by increasing insulin level and ameliorating the dysregulated activities of glucose metabolizing enzymes and ER stress better than either metformin only or GA only. It could be concluded that coadministration of metformin/GA produced a combined effect in ameliorating diabetes in Wistar rats and could be considered in treatment of diabetes.

A review of the phytochemical, pharmacological, pharmacokinetic, and toxicological evaluation of Quercus Infectoria galls

ETHNOPHARMACOLOGICAL RELEVANCE

Quercus Infectoria galls (QIG) have a long history of use in traditional Chinese medicine and traditional Uyghur medicine for the treatment of diarrhea, hemorrhage, skin disease, and many other human ailments. Medicinal applications of QIG have become increasingly popular in Greece, Asia Minor, Syria, and Iran.

AIM OF THE REVIEW

The present paper reviewed the ethnopharmacology, phytochemistry, analytical methods, biological activities, metabolism, pharmacokinetics, toxicology, and drug interactions of QIG to assess the ethnopharmacological uses, explore its therapeutic potential, and identify future opportunities for research.

MATERIALS AND METHODS

Information on QIG was gathered via the Internet (using Google Scholar, Baidu Scholar, Elsevier, ACS, Pubmed, Web of Science, CNKI, and EMBASE) and libraries. Additionally, information was also obtained from local books and PhD and MS dissertations.

RESULTS

QIG has played an important role in traditional Chinese medicine. The main bioactive metabolites of QIG include tannins, phenolic acids, flavonoids, triterpenoids, and steroids. Scientific studies on the QIG extract and its components have shown its wide range of pharmacological activities, such as cholinesterase- and monoamine oxidase-inhibitory, antitumor, anti-hypertension, antidiabetic, antimicrobial, insecticidal, antiparasitic, antioxidant, and anti-inflammatory.

CONCLUSIONS

The ethnopharmacological, phytochemical, pharmacological, and analytical methods of QIG were highlighted in this review, which provides information for future studies and commercial exploration. QIG has a huge potential for pharmaceutical and nutraceutical applications. Moreover, comprehensive toxicity studies of this plant must be conducted to ensure its safety. Additional investigations are recommended to transmute the ethnopharmacological claims of this plant in folklore medicines into scientific rationale-based information. Research on pharmacokinetics studies and potential drug interactions with standard-of-care medications is still limited, which calls for additional studies particularly on humans. Further assessments and clinical trials should be performed before it can be integrated into medicinal practices.

Gallic Acid Ameliorated Impaired Lipid Homeostasis in a Mouse Model of High-Fat Diet-and Streptozotocin-Induced NAFLD and Diabetes through Improvement of β-oxidation and Ketogenesis

Gallic acid (GA) is a simple polyphenol found in food and traditional Chinese medicine. Here, we determined the effects of GA administration in a combined mouse model of high-fat diet (HFD)-induced obesity and low-dose streptozotocin (STZ)-induced hyperglycemia, which mimics the concurrent non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes pathological condition. By combining the results of physiological assessments, pathological examinations, metabolomic studies of blood, urine, liver, and muscle, and measurements of gene expression, we attempted to elucidate the efficacy of GA and the underlying mechanism of action of GA in hyperglycemic and dyslipidemic mice. HFD and STZ induced severe diabetes, NAFLD, and other metabolic disorders in mice. However, the results of liver histopathology and serum biochemical examinations indicated that daily GA treatment alleviated the high blood glucose levels in the mice and decelerated the progression of NAFLD. In addition, our results show that the hepatoprotective effect of GA in diabetic mice occurs in part through a partially preventing disordered metabolic pathway related to glucose, lipids, amino acids, purines, and pyrimidines. Specifically, the mechanism responsible for alleviation of lipid accumulation is related to the upregulation of β-oxidation and ketogenesis. These findings indicate that GA alleviates metabolic diseases through novel mechanisms.

Therapeutic Effects of Gallic Acid in Regulating Senescence and Diabetes; an In Vitro Study

Gallic acid (GA), a plant-derived ubiquitous secondary polyphenol metabolite, can be a useful dietary supplement. This in vitro study’s primary purpose was to assess the anti-aging properties of GA using rat embryonic fibroblast (REF) cells, antidiabetic effects via pancreatic islet cells, and finally, elucidating the molecular mechanisms of this natural compound. REF and islet cells were isolated from fetuses and pancreas of rats, respectively. Then, several senescence-associated molecular and biochemical parameters, along with antidiabetic markers, were investigated. GA caused a significant decrease in the β-galactosidase activity and reduced inflammatory cytokines and oxidative stress markers in REF cells. GA reduced the G0/G1 phase in senescent REF cells that led cells to G2/M. Besides, GA improved the function of the β cells. Flow cytometry and spectrophotometric analysis showed that it reduces apoptosis via inhibiting caspase-9 activity. Taken together, based on the present findings, this polyphenol metabolite at low doses regulates different pathways of senescence and diabetes through its antioxidative stress potential and modulation of mitochondrial complexes activities.

Evaluation of the in vitro ⍺-amylase inhibitory, antiglycation, and antioxidant properties of Punica granatum L. (pomegranate) fruit peel acetone extract and its effect on glucose uptake and oxidative stress in hepatocytes

Punica granatum L. (pomegranate) is a widely eaten fruit. The antidiabetic, antioxidative, and antilipidemic properties of the hydroalcoholic extracts of the different plant's parts have been extensively studied, with scarce information on the acetone extract (ACE). This study investigated antidiabetic, antioxidative, and antiobesogenic properties of ACE of the fruit peel. Preliminary data showed that ACE showed stronger antioxidant (radical-scavenging IC₅₀  = 1.56 μg/ml) and ⍺-amylase inhibitory (IC₅₀  = 10.6 μg/ml) properties than the hydroalcoholic extracts and Acarbose. The ACE inhibited protein glycation and lipase activity. In hepatocytes, ACE impaired oxidative stress-induced lipid peroxidation and reduced glutathione depletion but increased glucose uptake without decreasing the cell viability. HPLC analysis showed predominant presence of bioactive phenolic acids (ferulic, caffeic, and gallic acids) in this extract. This study suggests that ACE of P. granatum fruit peel may be an understudied extract that contains potent antidiabetic and antioxidative bioactive principles with minimal toxicity. PRACTICAL APPLICATIONS: Plant derived medicines have been an affordable and effective alternative therapy for many metabolic diseases, including diabetes. The fruit juice and fruits of pomegranate is widely consumed for the palatable taste and cardiovascular benefits. This study provides preliminary experimental evidences confirming that of the acetone extracts of pomegranate fruit peel, which has been sparsely studied, may possess more potent antidiabetic and antioxidative property than to the routinely studied hydroalcoholic counterparts. Additionally, the acetone extract is rich in bioactive phenolic acids, suggesting that the acetone extract of pomegranate fruit peel may be a promising candidate for further antidiabetic study and a source of bioactive principles for the management of diabetes and oxidative complications.

A Role of Gallic Acid in Oxidative Damage Diseases: A Comprehensive Review

Gallic acid is a trihydroxybenzoic acid of plant metabolites widely spread throughout the plant kingdom. It has characteristics of the strong antioxidant and free radical scavenging activities, and can protect biological cells, tissues, and organs from damages caused by oxidative stress. This review aims to summarize the protective roles of gallic acid and the underlying pharmacological mechanisms in the pathophysiological process of the oxidative damage diseases, such as cancer, cardiovascular, degenerative, and metabolic diseases. The studies reviewed herein showed that the main therapeutic effects of gallic acid were attributed to its antioxidant properties. It modulated various signaling pathways through a wide range of inflammatory cytokines, and enzymic and nonenzymic antioxidants. However, the available data were limited to few studies assessing the treatment effects of gallic acid in human subjects to confirm its therapeutic outcomes. Therefore, the clinical trials were urgently needed to investigate the safety and efficacy of gallic acid treatment on human beings. The scientific data summarized in this review highlighted the therapeutic potentials of gallic acid for oxidative damage diseases. It could be developed as versatile adjuvant or therapeutically lead compound in future.

Pharmacological effects of gallic acid in health and diseases: A mechanistic review

OBJECTIVES

Gallic acid is a natural phenolic compound found in several fruits and medicinal plants. It is reported to have several health-promoting effects. This review aims to summarize the pharmacological and biological activities of gallic acid in vitro and animal models to depict the pharmacological status of this compound for future studies.

MATERIALS AND METHODS

All relevant papers in the English language were collected up to June 2018. The keywords of gallic acid, antioxidant, anticancer, antimicrobial, gastrointestinal-, cardiovascular-, metabolic-, neuropsychological-, and miscellaneous- diseases were searched in Google Scholar, PubMed, and Scopus.

RESULTS

Several beneficial effects are reported for gallic acid, including antioxidant, anti-inflammatory, and antineoplastic properties. This compound has been reported to have therapeutic activities in gastrointestinal, neuropsychological, metabolic, and cardiovascular disorders.

CONCLUSION

Current evidence confirms the pharmacological and therapeutic interventions of gallic acid in multiple health complications; however, available data are limited to just cellular and animal studies. Future investigations are essential to further define the safety and therapeutic efficacy of gallic acid in humans.

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.

Gallic acid, a common dietary phenolic protects against high fat diet induced DNA damage

Purpose

Aim of the study was to find out if gallic acid (GA), a common phenolic in plant foods, prevents obesity induced DNA damage which plays a key role in the induction of overweight associated cancer.

Methods

Male and female C57BL6/J mice were fed with a low fat or a high fat diet (HFD). The HFD group received different doses GA (0, 2.6–20 mg/kg b.w./day) in the drinking water for 1 week. Subsequently, alterations of the genetic stability in blood and inner organs were monitored in single cell gel electrophoresis assays. To elucidate the underlying molecular mechanisms: oxidized DNA bases, alterations of the redox status, lipid and glucose metabolism, cytokine levels and hepatic NF-κB activity were monitored.

Results

HFD fed animals had higher body weights; increased DNA damage and oxidation of DNA bases damage were detected in colon, liver and brain but not in blood and white adipose tissue. Furthermore, elevated concentrations of insulin, glucose, triglycerides, MCP-1, TNF-α and NF-κB activity were observed in this group. Small amounts of GA, in the range of human consumption, caused DNA protection and reduced oxidation of DNA bases, as well as biochemical and inflammatory parameters.

Conclusions

Obese animals have increased DNA damage due to oxidation of DNA bases. This effect is probably caused by increased levels of glucose and insulin. The effects of GA can be explained by its hypoglycaemic properties and indicate that the consumption of GA-rich foods prevents adverse health effects in obese individuals.

Electronic supplementary material

The online version of this article (10.1007/s00394-018-1782-2) contains supplementary material, which is available to authorized users.

Dietary supplementation of defatted kenaf (Hibiscus cannabinus L.) seed meal and its phenolics-saponins rich extract effectively attenuates diet-induced hypercholesterolemia in rats

Kenaf is one of the important commercial fiber crops worldwide and defatted kenaf seed meal (DKSM) is a secondary by-product from the kenaf industry. Thus, efforts to turn this low-cost agricultural waste into value-added functional food ingredients will definitely bring advantageous impacts to the community health, environment and economy. The present study was aimed to investigate the cardioprotective properties of DKSM and its phenolics-saponins rich extract (PSRE) in diet-induced hypercholesterolemic rat model. Hypercholesterolemia was induced in Sprague-Dawley rats via atherogenic diet feeding and dietary interventions were conducted by incorporating DKSM (15% and 30%) and equivalent levels of PSRE (2.3% and 4.6%, respectively, equivalent to the total content of phenolics and saponins in DKSM groups) into the atherogenic diets. After 10 weeks of DKSM and PSRE supplementation, the hepatosomatic index, hepatosteatosis, serum lipid profile, Castelli risk indexes as well as hepatic and renal functions of hypercholesterolemic rats were significantly improved (p < 0.05). Besides, the levels of hepatic Hmgcr and serum Pcsk9 were lowered, along with transcriptional upregulations of hepatic Cyp7a1, Abca1, Lcat, ApoA2 and ApoE (p < 0.05). The gene expression of hepatic Ldlr was marginally enhanced by DKSM supplementation (p > 0.05), but superiorly upregulated by PSRE (p < 0.05). The combined results showed that hypercholesterolemia and the atherogenic risk in rats were effectively attenuated by DKSM and PSRE supplementation, possibly via modulations of multiple vital processes in hepatic cholesterol metabolism. Furthermore, phenolics and saponins may be the bioactives conferring DKSM and PSRE with their anti-hypercholesterolemic properties. In conclusion, DKSM and PSRE are prospective cardioprotective functional food ingredients for hypercholesterolemic individuals.

Anthocyanins inhibit high glucose-induced renal tubular cell apoptosis caused by oxidative stress in db/db mice

Oxidative stress is an important contributory factor resulting the development of kidney injury in patients with diabetes. Numerous in vitro and in vivo studies have suggested that anthocyanins, natural phenols commonly existing in numerous fruits and vegetables, exhibit important antioxidative, anti‑inflammatory and antihyperlipidemic effects; however, their effects and underlying mechanisms on diabetic nephropathy (DN) have not yet been fully determined. In the present study, the regulation of apoptosis metabolism and antioxidative effects exhibited by anthocyanins [grape seed procyanidin (GSPE) and cyanidin‑3‑O‑β‑glucoside chloride (C3G)] were investigated, and the molecular mechanism underlying this process was investigated in vivo and in vitro. GSPE administration was revealed to suppress renal cell apoptosis, as well as suppress the expression of Bcl‑2 in diabetic mouse kidneys. Furthermore, GSPE administration was demonstrated to suppress the expression of thioredoxin interacting protein (TXNIP), in addition to enhancing p38 mitogen‑activation protein kinase (MAPK) and extracellular signal‑regulated kinase 1/2 (ERK1/2) oxidase activity in diabetic mouse kidneys. In vitro experiments using HK‑2 cells revealed that C3G suppressed the generation of HG‑mediated reactive oxygen species, cellular apoptosis, the expression of cleaved caspase‑3 and the Bax/Bcl‑2 ratio; and enhanced the expression of cytochrome c released from mitochondria. Furthermore, treatment with C3G was revealed to suppress the expression of TXNIP, in addition to the phosphorylation of p38 MAPK and ERK1/2 oxidase activity in HK‑2 cells under HG conditions. In addition, treatment with C3G was revealed to attenuate the HG‑induced suppression of the biological activity of thioredoxin, and to enhance the expression of thioredoxin 2 in HK‑2 cells under HG conditions. In conclusion, the present study demonstrated that anthocyanins may exhibit protective effects against HG‑induced renal injury in DN via antioxidant activity.

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.

Vescalagin from Pink Wax Apple [Syzygium samarangense (Blume) Merrill and Perry] Alleviates Hepatic Insulin Resistance and Ameliorates Glycemic Metabolism Abnormality in Rats Fed a High-Fructose Diet

This study investigates the ameliorative effect of vescalagin (VES) isolated from Pink wax apple fruit on hepatic insulin resistance and abnormal carbohydrate metabolism in high-fructose diet (HFD)-induced hyperglycemic rats. The results show that in HFD rats, VES significantly reduced the values of the area under the curve for glucose in an oral glucose tolerance test and the homeostasis model assessment of insulin resistance index. VES significantly enhanced the activity of hepatic antioxidant enzymes while reducing thiobarbituric acid-reactive substances in HFD rats. Western blot assay revealed that VES reduced hepatic protein expression involved in inflammation pathways while up-regulating expression of hepatic insulin signaling-related proteins. Moreover, VES up-regulated the expression of hepatic glycogen synthase and hepatic glycolysis-related proteins while down-regulating hepatic gluconeogenesis-related proteins in HFD rats. This study suggests some therapeutic potential of VES in preventing the progression of diabetes mellitus.

IMPROVEMENT IN OXIDATIVE STRESS AFTER DUODENOJEJUNOSTOMY IN AN EXPERIMENTAL MODEL OF TYPE 2 DIABETES MELLITUS

Background:

Type 2 Diabetes Mellitus is a multifactorial syndrome with severe complications. Oxidative stress is accepted as a causal factor of chronic complications

Aim:

To demonstrate alterations in oxidative stress after metabolic surgery.

Methods:

Twenty-four 2-day-old Wistar rats were used. In 16, Type 2 Diabetes Mellitus was induced by 100 mg/kg streptozotocin injection. The development of diabetes was confirmed after 10 weeks using an oral glucose tolerance test. Eight diabetic rats composed the diabetic surgical group; the remaining eight composed the diabetic group. Eight animals in which diabetes was not induced formed the clinical control group. The Marchesini technique was used in the diabetic surgical group. After 90 days, the rats were sacrificed, and the oxidative stress markers were measured.

Results:

Thiobarbituric acid reactive substances, superoxide dismutase and catalase were significantly reduced in the diabetic surgical group compared to the diabetic group.

Conclusion:

The duodenojejunostomy was effective in controlling the exacerbated oxidative stress present in diabetic rats.

Beneficial protective effects of 2-allyl amino 4-methyl sulfanyl butyric acid on glucose metabolism and glycoprotein components in streptozotocin induced diabetic rats with molecular modeling

In the present study, the potential effects of 2-allyl amino 4-methyl sulfanyl butyric acid (AMSB) on the glucose metabolism and glycoprotein components in streptozotocin (STZ) induced experimental diabetic rats were determined. Further, molecular modeling was performed to investigate the modes of AMSB interaction with insulin receptor active sites. The blood glucose and plasma insulin levels were measured in the STZ induced diabetic rats, whereas the glucose metabolism and glycoprotein components were analyzed from the plasma and tissues. After oral treatment of AMSB there was a significant reduction in blood glucose, glucose-6-phosphatase, fructose-1,6-bisphosphatase and glycogen phosphorylase. On the other hand, the activity of the glycoprotein levels, such as hexose, hexosamine, fucose and sialic acid, were significantly reduced. In addition, a significant elevation in plasma insulin, hexokinase, glycogen and glycogen synthase were also observed in the AMSB treated rats. The molecular modeling study revealed that AMSB has a stable binding pattern to the active site of insulin, with a Gscore value of -7.34 Kcal mol^-1. From this study we conclude that AMSB has a potent antidiabetic activity in addition to its protective effect on glycoprotein metabolism.

Anthocyanins inhibit high-glucose-induced cholesterol accumulation and inflammation by activating LXRα pathway in HK-2 cells

The dysregulation of cholesterol metabolism and inflammation plays a significant role in the progression of diabetic nephropathy (DN). Anthocyanins are polyphenols widely distributed in food and exert various biological effects including antioxidative, anti-inflammatory, and antihyperlipidemic effects. However, it remains unclear whether anthocyanins are associated with DN, and the mechanisms involved in the reciprocal regulation of inflammation and cholesterol efflux are yet to be elucidated. In this study, we evaluated the regulation of cholesterol metabolism and the anti-inflammatory effects exerted by anthocyanins (cyanidin-3-O-β-glucoside chloride [C3G] or cyanidin chloride [Cy]) and investigated the underlying molecular mechanism of action using high-glucose (HG)-stimulated HK-2 cells. We found that anthocyanins enhanced cholesterol efflux and ABCA1 expression markedly in HK-2 cells. In addition, they increased peroxisome proliferator-activated receptor alpha (PPARα) and liver X receptor alpha (LXRα) expression and decreased the HG-induced expression of the proinflammatory cytokines intercellular adhesion molecule-1 (ICAM1), monocyte chemoattractant protein-1 (MCP1), and transforming growth factor-β1 (TGFβ1), as well as NFκB activation. Incubation with the PPARα-specific inhibitor GW6471 and LXRα shRNA attenuated the anthocyanin-mediated promotion of ABCA1 expression and cholesterol efflux, suggesting that anthocyanins activated PPARα-LXRα-ABCA1-dependent cholesterol efflux in HK-2 cells. Moreover, the knockout of LXRα abrogated the anti-inflammatory effect of anthocyanins, whereas the PPARα antagonist GW6471 does not have this effect. Further investigations revealed that LXRα might interfere with anthocyanin-induced decreased ICAM1, MCP1, and TGFβ1 expression by reducing the nuclear translocation of NFκB. Collectively, these findings suggest that blocking cholesterol deposition and inhibiting the LXRα pathway-induced inflammatory response might be one of the main mechanisms by which anthocyanins exert their protective effects in DN.

Gallic acid ameliorates renal functions by inhibiting the activation of p38 MAPK in experimentally induced type 2 diabetic rats and cultured rat proximal tubular epithelial cells

Diabetic nephropathy (DN) is one of the leading causes of morbidity and mortality in diabetic patients that accounts for about 40% of deaths in type 2 diabetes. p38 mitogen activated protein kinase (p38 MAPK), a serine-threonine kinase, plays an important role in tissue inflammation and is known to be activated under conditions of oxidative stress and hyperglycemia. The role of p38 MAPK has been demonstrated in DN, and its inhibition has been suggested as an alternative approach in the treatment of DN. In the present study, we investigated the nephroprotective effects of an anti-inflammatory phenolic compound, gallic acid (GA, 3,4,5-trihydroxybenzoic acid), in high fat diet/streptozotocin (HFD/STZ) induce type 2 diabetic wistar albino rats. GA (25 mg/kgbw and 50 mg/kgbw, p.o.) treatment for 16 weeks post induction of diabetes led to a significant reduction in the levels of blood glucose, HbA1c, serum creatinine, blood urea nitrogen and proteinuria as well as a significant reduction in the levels of creatinine clearance. GA significantly inhibited the renal p38 MAPK and nuclear factor kappa B (N-κB) activation as well as significantly reduced the levels of renal transforming growth factor beta (TGF-β) and fibronectin. Treatment with GA resulted in a significant reduction in the serum levels of proinflammatory cytokines viz. interleukin 1 beta (IL-1β), IL-6 and tumor necrosis factor alpha (TNF-α). Moreover, GA significantly lowered renal pathology and attenuated renal oxidative stress. In cultured rat NRK 52E proximal tubular epithelial cells, GA treatment inhibited high glucose induced activation of p38 MAPK and NF-κB as well as suppressed proinflammatory cytokine synthesis. The results of the present study provide in vivo and in vitro evidences that the p38 MAPK pathway plays an important role in the pathogenesis of DN, and GA attenuates the p38 MAPK-mediated renal dysfunction in HFD/STZ induced type 2 diabetic rats.

Gallic Acid Decreases Inflammatory Cytokine Secretion Through Histone Acetyltransferase/Histone Deacetylase Regulation in High Glucose-Induced Human Monocytes

Hyperglycemia contributes to diabetes and several diabetes-related complications. Gallic acid is a polyhydroxy phenolic compound found in various natural products. In this study, we investigated the effects and mechanism of gallic acid on proinflammatory cytokine secretion in high glucose-induced human monocytes (THP-1 cells). THP-1 cells were cultured under normoglycemic or hyperglycemic conditions, in the absence or presence of gallic acid. Hyperglycemic conditions significantly induced histone acetylation, nuclear factor-κB (NF-κB) activation, and proinflammatory cytokine release from THP-1 cells, whereas gallic acid suppressed NF-κB activity and cytokine release. It also significantly reduced CREB-binding protein/p300 (CBP/p300, a NF-κB coactivator) gene expression, acetylation levels, and CBP/p300 histone acetyltransferase (HAT) activity. In addition, histone deacetylase 2 (HDAC2) expression was significantly induced. These results suggest that gallic acid inhibits hyperglycemic-induced cytokine production in monocytes through epigenetic changes involving NF-κB. Therefore, gallic acid may have potential for the treatment and prevention of diabetes and its complications.

Pu-erh tea down-regulates sterol regulatory element-binding protein and stearyol-CoA desaturase to reduce fat storage in Caenorhaditis elegans

Consumption of Pu-erh has been reported to result in numerous health benefits, but the mechanisms underlying purported weight-loss and lowering of lipid are poorly understood. Here, we used the nematode Caenorhaditis elegans to explore the water extract of Pu-erh tea (PTE) functions to reduce fat storage. We found that PTE down-regulates the expression of the master fat regulator SBP-1, a homologue of sterol regulatory element binding protein (SREBP) and its target stearoyl-CoA desaturase (SCD), a key enzyme in fat biosynthesis, leading to an increased ratio of stearic acid (C18:0) to oleic acid (C18:1n-9), and subsequently decreased fat storage. We also found that both the pharyngeal pumping rate and food uptake of C. elegans decreased with exposure to PTE. Collectively, these results provide an experimental basis for explaining the ability of Pu-erh tea in promoting inhibition of food uptake and the biosynthesis of fat via SBP-1 and SCD, thereby reducing fat storage.

Phenolic content and antioxidant capacity in algal food products

The study objective was to investigate total phenolic content using Folin-Ciocalteu's method, to assess nine phenols by HPLC, to determine antioxidant capacity of the water soluble compounds (ACW) by a photochemiluminescence method, and to calculate the correlation coefficients in commercial algal food products from brown (Laminaria japonica, Eisenia bicyclis, Hizikia fusiformis, Undaria pinnatifida) and red (Porphyra tenera, Palmaria palmata) seaweed, green freshwater algae (Chlorella pyrenoidosa), and cyanobacteria (Spirulina platensis). HPLC analysis showed that the most abundant phenolic compound was epicatechin. From spectrophotometry and ACW determination it was evident that brown seaweed Eisenia bicyclis was the sample with the highest phenolic and ACW values (193 mg·g-1 GAE; 7.53 µmol AA·g-1, respectively). A linear relationship existed between ACW and phenolic contents (r = 0.99). Some algal products seem to be promising functional foods rich in polyphenols.

Interactions of the active components of Punica granatum (pomegranate) with the essential renal and hepatic human Solute Carrier transporters

Abstract Context: Solute carrier transporters (SLCs) are membrane proteins responsible for cellular influx of various substances including many pharmaceutical agents; therefore, they largely impact on drug disposition and elimination in body. Punica granatum Linnaeus (Lythraceae), pomegranate, is a fruit with antidiabetic potential. Oleanolic acid (OA), ursolic acid (UA), and gallic acid (GA) are the major bioactive components of pomegranate. Co-administration of these compounds with other drugs could result in altered drug pharmacokinetics, possibly due to competing for transporter proteins.

OBJECTIVE

We investigated the interactions of these three compounds with the essential hepatic and renal SLC transporters.

MATERIALS AND METHODS

Uptake of radiolabeled transporter model substrates was assessed in HEK293 cells over-expressing SLC transporters including the organic anion transporters (OATs), organic anion transporting polypeptides (OATPs) and organic cation transporters (OCTs), in the presence or absence of 10.0 µM UA, OA, or GA. Their IC50 values on specific SLC transporters were also evaluated using varying concentrations of the particular compound (ranging from 0.10 nM to 80.0 µM).

RESULTS

Our results demonstrated UA could significantly inhibit OAT3 and OATP2B1 uptake (IC50: 18.9 ± 8.20 µM and 11.0 ± 5.00 µM, respectively) and GA has a pronounced inhibitory effect on OATP1B3 uptake (IC50: 1.60 ± 0.60 μM).

DISCUSSION AND CONCLUSION

Our study reports the interactions of OA, UA, and GA with the essential SLC transporters. This information may contribute to elucidating the drug-drug/herb interactions involved with these three compounds and form the basis of therapeutic optimization when drugs are co-administered.

Finding needles in a haystack: application of network analysis and target enrichment studies for the identification of potential anti-diabetic phytochemicals

Diabetes mellitus is a debilitating metabolic disorder and remains a significant threat to public health. Herbal medicines have been proven to be effective anti-diabetic agents compared to synthetic drugs in terms of side effects. However, the complexity in their chemical constituents and mechanism of action, hinder the effort to discover novel anti-diabetic drugs. Hence, understanding the biological and chemical basis of pharmacological action of phytochemicals is essential for the discovery of potential anti-diabetic drugs. Identifying important active compounds, their protein targets and the pathways involved in diabetes would serve this purpose. In this context, the present study was aimed at exploring the mechanism of action of anti-diabetic plants phytochemicals through network and chemical-based approaches. This study also involves a focused and constructive strategy for preparing new effective anti-diabetic formulations. Further, a protocol for target enrichment was proposed, to identify novel protein targets for important active compounds. Therefore, the successive use of network analysis combined with target enrichment studies would accelerate the discovery of potential anti-diabetic phytochemicals.

Experimental and theoretical studies on Gallic acid assisted EDC/NHS initiated crosslinked collagen scaffolds

The effect of Gallic acid (GA) in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-hydroxysuccinimide (NHS) on collagen scaffold is investigated. The thermal mechanical analyzer (TMA), differential scanning calorimetric (DSC), and thermogravimetric analysis (TGA) including tensile strength (TS, 180 ± 3 MPa), denaturation temperature (Td, 80.03°C), % elongation (% E, 180 ± 9) and weight loss (31.76%), indicate that the modification improves the structural integrity and stability of the collagen scaffold. The GA-EDC/NHS treatment inhibits the action of collagenase against collagen degradation compared to GA and EDC/NHS. It is concluded from docking studies that GA binds with collagen like peptide (CLP) and collagenase through multiple H-bonds and hydrophobic interactions leading to low binding energy -5.1 and -5.3 Kcal/mol, respectively. The hydrophobic core of the GA molecules, probably incorporates itself into the hydrophobic areas of the collagen groups, whereas OH and COOH moieties of GA establish multiple H-bonds with neighboring collagen molecules and carboxamide bond, thereby improving the swelling and water uptake properties, biocompatibility and cell adhesion properties. This results in improving stability of the scaffold, which prevents the free access of the collagenase to reactive sites in the triple helical collagen chains.

Gallic acid ameliorated impaired glucose and lipid homeostasis in high fat diet-induced NAFLD mice

Gallic acid (GA), a naturally abundant plant phenolic compound in vegetables and fruits, has been shown to have potent anti-oxidative and anti-obesity activity. However, the effects of GA on nonalcoholic fatty liver disease (NAFLD) are poorly understood. In this study, we investigated the beneficial effects of GA administration on nutritional hepatosteatosis model by a more “holistic view” approach, namely ¹H NMR-based metabolomics, in order to prove efficacy and to obtain information that might lead to a better understanding of the mode of action of GA. Male C57BL/6 mice were placed for 16 weeks on either a normal chow diet, a high fat diet (HFD, 60%), or a high fat diet supplemented with GA (50 and 100 mg/kg/day, orally). Liver histopathology and serum biochemical examinations indicated that the daily administration of GA protects against hepatic steatosis, obesity, hypercholesterolemia, and insulin resistance among the HFD-induced NAFLD mice. In addition, partial least squares discriminant analysis scores plots demonstrated that the cluster of HFD fed mice is clearly separated from the normal group mice plots, indicating that the metabolic characteristics of these two groups are distinctively different. Specifically, the GA-treated mice are located closer to the normal group of mice, indicating that the HFD-induced disturbances to the metabolic profile were partially reversed by GA treatment. Our results show that the hepatoprotective effect of GA occurs in part through a reversing of the HFD caused disturbances to a range of metabolic pathways, including lipid metabolism, glucose metabolism (glycolysis and gluconeogenesis), amino acids metabolism, choline metabolism and gut-microbiota-associated metabolism. Taken together, this study suggested that a ¹H NMR-based metabolomics approach is a useful platform for natural product functional evaluation. The selected metabolites are potentially useful as preventive action biomarkers and could also be used to help our further understanding of the effect of GA in hepatosteatosis mice.

Protective effect of gallic acid on alloxan-induced oxidative stress and osmotic fragility in rats

In the present study, we investigated the antioxidant effect of gallic acid (GA) on membrane lipid peroxidation and osmotic fragility in alloxan-induced diabetic Wistar rats. GA was administered orally at doses of 5, 10, and 20 mg/kg body weight for 45 days, after which liver and kidney tissues were analyzed for the degree of lipid peroxidation, reduced glutathione, and the activities of antioxidants such as catalase, superoxide dismutase, and glutathione peroxidase. Administration of GA to alloxan-induced diabetic rats reduced the blood glucose level with an increase in the level of insulin. Liver and kidney tissues from diabetic animals exhibited disturbances in antioxidant defense compared with normal rats. GA at a dose of 20 mg/kg b.w. showed a significant effect than that of the other doses. In addition, the results revealed that GA protected the integrity of erythrocyte membrane in diabetic rats as demonstrated by lower percentage of hemolysis and resistance to hydrogen peroxide-induced peroxidation. The anti-hyperglycemic activity of GA in alloxan-induced diabetic rats was also comparable with glibenclamide, a reference drug. These results suggest that GA could provide a beneficial effect on diabetes by decreasing oxidative stress-related diabetic complications.

Resting blood flow in the skin: does it exist, and what is the influence of temperature, aging, and diabetes?

Measurement of resting blood flow to the skin and other organs is an important indicator of health and disease and a way to assess the reaction to various stimuli and pharmaceutical interventions. However, unlike plasma ions such as sodium or potassium, it is difficult to determine what the proper value for resting blood flow really is. Part of the problem is in the measurement of blood flow; various techniques yield very different measures of skin blood flow even in the same area. Even if there were common techniques, resting blood flow to tissue, such as the skin, is determined by the interaction of a plurality of factors, including the sympathetic nervous system, temperature, pressure, shear forces on blood vessels, tissue osmolality, and a variety of other stimuli. Compounding this variability, the blood flow response to any stressor is reduced by free radicals in the blood and diminished by aging and diabetes. Race also has an effect on resting blood flow to the skin. All these factors interact to make the exact resting blood flow difficult to determine in any one individual and at any one time. This review examines the main techniques to assess blood flow, the factors that alter blood flow in the skin, and how aging and diabetes affect blood flow. Recommendations for the measurement of resting blood flow are presented.