The Effect of Harvesting Time on the Antioxidant and Antidiabetic Activity of Piper Crocatum (Sirih Merah) Extract

Abstract

Piper crocatum is traditionally used as a treatment against diabetes mellitus, minor wounds and inflammation. This study aimed to evaluate the effect of harvesting time on the antioxidant and antidiabetic activity of P. crocatum harvested at 2, 4, 6 and 8 months and identification of the compounds responsible for antidiabetic activity. The antioxidant activity of the extracts is evaluated by DPPH scavenging activity, total phenolic content (TPC) and total flavonoid content (TFC) tests while the antidiabetic activity is evaluated by alpha amylase and alpha glucosidase inhibition assays. The results show that extracts obtained from harvesting time at 8 months have the highest antioxidant activity with the DPPH scavenging activity, TPC and TFC being 74.90 ± 0.27%, 492.92 ± 1.40 mg GAE/g and 79.58 ± 1.17 mg QE/g respectively and the highest antidiabetic activity with the alpha amylase and alpha glucosidase inhibition activity being 87.05±0.64% and 88.70±0.42% respectively. Principal component analysis (PCA) was also carried out and it is found that principle component 1 and 2 are associated with the harvesting time (81.7%) and extract concentration (12.4%) respectively. Five compounds are identified to be responsible for antidiabetic activity: caffeic acid, p-coumaric acid, cyanidin-3-O-glucoside, tannin and gallic acid.