Polyphenol-Rich Extracts of Xylopia and Aframomum Species Show Metabolic Benefits by Lowering Hepatic Lipid Accumulation in Diet-Induced Obese Mice

Metabolic syndrome is a complex condition associated with a series of pathologies featuring glucose intolerance, diabetes, high blood pressure, dyslipidemia, microalbuminuria, overweight, and obesity. It is also related to nonalcoholic fatty liver disease (NAFLD), recognized as the most familiar cause of chronic liver disease worldwide. The overall prevalence of metabolic syndrome and, consequently, the one of NAFLD is constantly increasing worldwide. The initial management of these diseases involves lifestyle modifications, including changes in diet and physical exercise. In addition to conventional drugs like orlistat, botanicals are traditionally used to counteract these disorders, and some of them are currently under evaluation. The present work evaluated the in vivo beneficial effects of hydroalcoholic extracts of two Cameroonian spices, focusing on obesity-related hepatic lipid injury in high-fat-fed C57BL/6 mice. Hydroethanolic extracts were prepared and characterized by reverse phase-high-performance liquid chromatography (HPLC)-photodiode array detection and ultra performance liquid chromatography-triple time-of-flight electrospray ionization tandem mass spectroscopy (TOF-ESI-MS/MS) analysis. Plant extracts were orally administered for 30 days at different dose levels (100 and 200 mg kg(-1) body weight (BW)) to obese C57BL/6 mice. Food intake (FI) and BW were recorded daily. Plasma biochemical parameters and lipid content were estimated at the beginning and at the end of the experiment. Liver tissues were subjected to histological examinations, lipid content, as well as oxidative stress markers, and FAME (fatty acid methyl esters) were estimated. Oral administration of extracts at 200 mg kg(-1) BW significantly reduced FI and prevented BW gain. A decrease in the weight of the liver and a decrease in the hepatic and plasma lipid content were observed. Plasma enzyme (serum glutamic-oxaloacetic transaminase, SGOT; serum glutamic pyruvic transaminase, SGPT; alkaline phosphatase, ALP) activities were not indicative of any organ damage. Chemical analysis suggested that phenolic acids (4-caffeoylquinic acid, p-coumaric acid 4-O-glucoside, 5-caffeoylshikimic acid, caffeic acid hexose, and 4-O-methyl gallic acid) and flavonoids (morusin derivatives, naringenin-7-O-glucoside, and homoisoflavanone) identified in the extracts could potentially justify the biological properties observed. The main findings of this study showed that Xylopia parviflora (A. Rich.) Benth and Aframomum citratum (Pereira ex Oliv. et Hanb.) K. Shum decreased hepatic lipid accumulation in high-fat-diet (HFD)-induced obese C57BL/6 mice and confirmed, at least in part, our previous in vitro and ex vivo studies. The molecular mechanisms underlying these effects are still unclear and will be explored in the future.