Unrevealing Molecular Mechanism of Action of Gallic Acid Isolated from Fruit Juice of Emblica Officinalis for its Anti-Diabetic and Anti-Hyperlipidemic Potential

Abstract

Obesity and metabolic syndrome related type 2 diabetes mellitus account for a relatively high proportion of unavoidable morbidity and premature mortality globally. Taking a glance at the various hypotheses responsible for the risk and outcome of diabetes, lies its association with a 3-fold increase in mortality from cardiovascular disease. In spite of having better therapeutic potential for treatments of obesity and related metabolic disorders, PPARs dual agonists display numerous side effects including heart failure, edema, anemia, leucocytopenia etc. Many Ayurvedic medicines containing Emblica officinalis (family Euphorbeaceae) demonstrated better efficacy without any significant toxicity. Therefore, we have investigated pharmacological importance of E. officinalis in diabetes and related cardio-metabolic disorders. We have isolated gallic acid from fruit juice of E. officinalis using microwaveassisted extraction which was quantified by validated HPTLC method and content of gallic acid identified was 4.32%w/v. In vitro study on 3T3-L1 cell line showed that gallic acid induced Glut-4 and PPAR-γ protein expression and activate C/EBPs and ap2. Various animal models of hypertriglyceridemia were utilized to assess anti-hyperlipidemic potential E. officinalis and its active principle i.e. gallic acid; and it was observed that treatment depicted good anti-hyperlipidemic potential. Gallic acid and E. officinalis showed promising antidiabetic action in db/db mice by restoring insulin sensitivity. E. officinalis and gallic acid showed significant protection against increase in weight in db/db mice as well as in highfructose- fed rats. In depth of molecular mechanism of action, gallic acid increased protein expression of LDL-R on hepatocytes with increased Glut-4 and PPAR-γ. PCSK9 and leptin mRNA expression was found to be declined with the help of E. officinalis. Gallic acid has showed declined level of fatty infiltration in high-fat-fed rats with decreased lipid accumulation in intima of aortic arc. Gallic acid showed protection against raise MABP, PRA and TNF-α level in high-fructose-fed animals. Moreover, gallic acid treatment increased insulin sensitivity through activation of Akt rather than AMPK signaling while fruit juice of E. officinalis showed dual activation, Akt and AMPK as well. LC-MS method was developed and validated for quantification of gallic acid from biological matrices and it was observed that gallic acid has 22-23% bioavailability with 1.15 ± 0.30 h half-life at a dose of 50 mg/kg of body weight in rats. Acute dose toxicity showed LD50 is greater than 2000 g in mice and no sign of toxicity was observed in 28 days repeated dose toxicity. 28 days repeated dose data showed no significant toxicity pertaining to the various biochemical and histopathological evaluations. Hence, we could conclude that gallic acid possess potent anti-diabetic and antihyperlipidemic potential due to action of PPAR-α and PPAR-γ without any significant toxicity.