Flavanones biotransformation of citrus by-products improves antioxidant and ACE inhibitory activities in vitro

Abstract

The enzymatic biotransformation effects of tannase/β-glucosidase on phenolic profile, antioxidant capacity, and angiotensin-converting enzyme (ACE) inhibitory activity of extracts from two citrus industry wastes were studied. Hesperidin and hesperetin ACE inhibitory activity were also measured. The major phenolic in crude extracts was hesperidin, whereas it was hesperetin after being biotransformed. Antioxidant capacity and ACE inhibitory activity of enzyme-treated extracts were significantly higher. Citrus pectin residue extracts treated with enzymes (CPRTB) had the highest antioxidant and anti-ACE activities (FRAP = 298±3 μmolTE mg−1, DPPH = 230 ± 10 μmolTE mg−1, IC50 = 0.21 mg mL−1, IE = 100%), and the highest hesperetin content (42.7 mg g−1). Hesperetin standard solution showed higher anti-ACE activity than hesperidin (IE = 82.8–100% and 62–76%, respectively). Despite the lower flavanone concentration in CPRTB compared to the 1000μMhesperetin solution, both had the same anti-ACE activity, suggesting that the bioactivity of citrus extracts is due to the synergism of different phenolic compounds. Enzymatic biotransformation resulted in the production of extracts with increased anti-hypertension activities and might potentially be used to develop value-added products.