Polyphenols, Vitamin C, in Vitro Antioxidant Capacity, α-Amylase and COX-2 Inhibitory Activities of Citrus Samples from Aceh, Indonesia.

Abstract

This study was conducted to analyse antioxidant potencies, vitamin C contents, polyphenol profiles, antidiabetic and anti-inflammatory potencies of citrus fruits from Indonesia. Total phenolics contents (TPC) of seven citrus fruits from northern Aceh, Indonesia, were measured using Folin-Ciocalteu (FC) and Fast Blue BB (FBBB) methods. Total flavonoid content (TFC) test showed for peel and pulp extracts of calung and jeruk takengon (local mandarin) the highest values. H-TEAC (hydrophilic trolox equivalent antioxidant capacity) and H-ORAC (hydrophilic oxygen reactive absorbance capacity) antioxidant capacity were highest for peel and pulp of jeruk takengon, calung and kruet mameh. Interestingly, peel extracts showed no α-amylase inhibition activity whilst pulp showed weak inhibitory activity. Polyphenol composition was dominated by flavanones, with hesperidin and neohesperidin as main flavanones (hesperidin: 131-5433mg/100g DW, neohesperidin: 431-4131mg/100g DW). Vitamin C contents were highly correlated with antioxidant capacities in pulp (R2=0.95 and R2=0.94at p<0.01 for H-TEAC and H-ORAC, respectively), and TPC and TFC were highly correlated with antioxidant capacities (R2=0.99 and R2=0.98 for TPC FC in pulp and R2=0.93 and R2=0.84 in peel for H-TEAC and H-ORAC, respectively; R2=0.88 and R2=0.80 in pulp, and R2=0.68 and R2=0.75 for TFC in peel for H-TEAC and H-ORAC at p<0.01). In-vitro COX-2 inhibitory activity tests resulted in higher activity for pulp compared to the corresponding peel extracts except for calung. Pulp extract of jeruk takengon showed the highest activity. In general, local citrus fruits from Aceh, Indonesia, are potential sources of polyphenols and vitamin C.