Phenolic composition and in vitro bioactive and enzyme inhibitory properties of bell pepper (Capsicum annuum L.) plant extracts

The phenolic composition and bioactive properties of Holland and Italian bell pepper plant (Capsicum annuum L.) hydroethanolic extracts were investigated by HPLC-DAD-ESI/MS and in vitro cell- and enzyme-based assays, respectively. O-Glycosylated luteolin derivatives were identified as the major compounds, representing ∼60% of the phenolic fraction. Both extracts displayed remarkable antioxidant activity and ability to inhibit α-glucosidase and the formation of advanced glycation end products (AGEs) compared to the positive controls, which yielded statistically higher or equal IC50 values. Notably, the extracts were up to 57 times more effective than aminoguanidine in inhibiting AGEs. The lipase enzyme involved in fat metabolism and the pro-inflammatory mediator nitric oxide were also inhibited in some extent, with orlistat and dexamethasone being 10–13.4-fold and ∼17-fold more effective than the extracts, respectively. A notable cytotoxicity occurred on the tested human tumor cell lines, mainly on Caco-2 with GI50 values ranging from 18 to 65 μg/mL. Furthermore, activity greater than that of food preservatives was observed against some foodborne fungi and bacteria. These results highlight bell pepper plant by-products as a renewable source of functional ingredients that could be utilized in food, nutraceutical, and medicinal formulations to manage type 2 diabetes, obesity, and other oxidative stress-mediated conditions.