Antioxidant capacity and amylase inhibitory potentials of bioactive compounds extracted from fresh centella asiatica and ITS soluble product

Abstract

The objective of this study is to investigate the effect of sample-water ratio (m/v), extraction time (min) and extraction temperature (oC) on total phenolic content (TPC) of Centella asiatica. The optimized mode (1: 100 (m/v), 90 min, 25oC) of the extraction condition was established to obtain the maximum total phenolic content (23.2 ± 0.5 mg FAE/g DW). Moreover, total flavonoid content (TFC) (11.2 ± 0.1 mg RE/g DW) and tannin content (13.8 ± 1.0 mg/g DW) were determined. The ability to scavenging DPPH free radicals was also investigated with IC50 (224.8 ± 9.2 μg FAE /ml concentration of TPC). Moreover, TPC, TFC and tannin were considered as contributors to inhibit alpha-amylase and alpha-glucosidase activities at a certain concentration of TPC in the extracts. At 417.9 μg FAE/mL of TPC in extract, the amylase inhibition made up 23.0 ± 1.2% while 65.2 ± 2.4% was the percentage of alpha-glucosidase inhibition. Spray drying using maltodextrin and gum arabic as carriers resulted in significant loss of TPC, TFC and tannins of Centella asiatica’s extracts. Keywords: Centella asiatica, total phenolic content (TPC), total flavonoid content (TFC), tannin, antioxidants, alpha-amylase inhibiton, alpha-glucosidase inhibition, spray drying.