The anti-obesity effects of RL (a 3:1 mixture of Panax ginseng saponin fractions and Glycyrrhiza glabra L. extracts) on 3T3-L1 adipocytes and C57BL/6J obese mice were evaluated at different concentrations. We investigated the anti-obesity effects of RL through lipid accumulation inhibition rate, serum lipid composition analysis, adipose tissue size, adipogenic transcription factors and AMPK pathway. RL inhibited the lipid accumulation of 3T3-L1 adipocytes in a dose-dependent manner at concentrations of 50-200 μg/mL without cytotoxicity (50-400 μg/mL). Oral administration of RL at the highest concentration (400 mg/kg/day) did not cause significant liver toxicity in high-fat diet-induced obese mice. RL stimulated adiponectin secretion in a dose-dependent manner and primarily mediates the AMPK pathway to inhibit triglyceride synthesis and attenuate adipocyte hypertrophy. RL significantly reduced weight in obese mice, but none of the body weight, adipose tissue weight, serum triglyceride level, and AMPK pathway activation degree showed any difference between dosing concentrations of 200 and 400 mg/kg/day. Therefore, 200 mg/kg/day of RL is the optimal preclinical concentration, which can be a reference concentration for conversion into a human clinical trial dose.
Keywords: anti-obesity; dose-dependent; extract mixture; preclinical.