In vitro effects of peanut skin polyphenolic extract on oxidative stress, adipogenesis, and lipid accumulation

The in vitro bioactivity of peanut skin was evaluated on its ability to protect RAW264.7 macrophages against the formation of reactive oxygen species (ROS), the occurrence of inflammatory responses, and the ability to prevent differentiation in 3T3-L1 preadipocytes and the lipid accumulation in HepG2 hepatocytes. Here, high-performance liquid chromatography coupled with ion-trap tandem mass spectrometry identified 18 flavonoids in peanut skin extract (PSE) including condensed tannins and flavones. The PSE showed strong antioxidant potential against 2-diphenyl-1-picrylhydrazyl, peroxyl radicals, and antioxidant activity by inhibiting the ROS formation by 60%–80% in RAW264.7 macrophages. The effects of PSE flavonoids against inflammation induced by lipopolysaccharide resulted in the reduced expression of biomarkers IL-6 and TNF-α and the decreased production of nitric oxide. The administration of PSE decreased the differentiation of 3T3-L1 adipocytes by approximately 60%–72% and ameliorated the hepatic steatosis in HepG2 cells by decreasing the lipid concentration by up to 85%. Novelty impact statement: Phenolic compounds are widely studied because of their ability to prevent and treat the risk factors related to the onset of several diseases including cancer, diabetes, and obesity. Peanut skin is an agroindustry waste from which phenolic compounds can be processed and reused as a low-cost raw material to formulate new products. Peanut skin extract contained 18 flavonoids that justified the high total phenolic content and antioxidant capacity, the in vitro potential to prevent oxidative stress via reactive oxygen species scavenging, to suppress adipogenesis in 3T3-L1 preadipocytes and the hepatic steatosis in the HepG2 cell model.