Inhibitory effect of different fennel (Foeniculum vulgare) samples and their phenolic compounds on formation of advanced glycation products and comparison of antimicrobial and antioxidant activities

In this study, antioxidant, antibacterial and antiglycation properties of methanolic extracts of 23 fennel samples were evaluated and their major compounds were determined using HPLC analysis. The anti-glycative activity of extracts was evaluated in the bovine serum albumin (BSA)/glucose system. The level of glycation, conformational alterations and protein binding to RAGE receptors were assessed by Congo red binding assay and a brown staining method. Among samples, Kh1 from Iran possessed the highest TFC (14.8 mgQUE g−1), TPC (262 mg/g DW) and antioxidant activity (IC50 = 76 μg/ml). The HPLC results revealed high variation in 23 fennel samples according to their major flavonoid (quercetin, apigenin and rutin) and phenolic (chlorogenic, caffeic and 1,5-dicaffeoylquinic acid) compounds. The antibacterial activity of methanolic extracts against four food-borne pathogens was also assessed. The seed extracts of Kh1 and En samples showed moderate to good inhibitory activities (MICs = 62.5-125 μg/ml) against three bacteria, as well as high anti-glycative activity.