Effect of Extraction Solvents on Antioxidant and α-amylase Inhibition Activities of Spiced Green Chili Paste: An In Vitro Study

Abstract

Chili pepper (Capsicum frutescens L.) is widely produced and consumed as raw or processed products. Spiced green chili paste, locally known as Datta, is hot spicy paste consumed in South Ethiopia. Under this study, total phenolic contents (TPC), total flavonoid contents (TFC), in vitro antioxidant, and α-amylase inhibition activities of different extracts of green Datta paste were investigated. The TPC and TFC of the extracts were determined by the Folin ciocalteu and aluminum chloride methods, respectively. The antioxidant activities were determined by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging, ferric reducing power, and total antioxidant using phosphomolybdenum methods. In vitro porcine pancreatic α-amylase inhibition activity was evaluated using the dinitrosalicylic acid (DNSA) assay. The acetone extract contained the highest TPC (24.92 ± 2.88 milligram gallic acid equivalent/ gram of dried extract) and TFC (28.05 ± 8.36 milligram catechin equivalent/gram of dried extract). Similarly this extract showed stronger antioxidant capacity, 6.34 ± 1.21 milligram of ascorbic acid equivalent/gram of dried extract, 1.46 ± 0.22 milligram butylated hydroxytoluene equivalent/ gram of dried extract, and 46.99 ± 2.60 g/mL as determined by ferric reducing power, total antioxidant activity, and DPPH scavenging (IC50) activity, respectively. The same extract also exhibited the strongest α-amylase inhibition activity (IC50 = 0.45 mg/mL). TPC and TFC were strongly correlated with DPPH (R 2 = 0.99, R 2 = 0.91), reducing power (R 2 = 0.86, R 2 = 0.97), and total antioxidant activity (R 2 = 0.79, R 2 = 0.97), respectively. The α-amylase inhibition activity was strongly correlated with TPC (R 2 = 0.90) but weakly correlated with TFC (R 2 = 0.18). Thus the result indicated promising perspectives for the development and usage of acetone extract of Ethiopian spiced green chili pepper with considerable levels of natural antioxidants which can be used as functional food for preventing oxidative stress mediated human disorders.