In vitro antioxidant and α-amylase inhibition activities of spiced red chili paste (datta) from South Ethiopia

Abstract

Spiced chili paste (green or red), locally known as Datta, is a traditional popular spicy paste consumed in Ethiopia. This study investigated the total phenolic contents (TPC), total flavonoid contents (TFC), in vitro antioxidant, and α-amylase inhibition activities of water, acetone, petroleum ether, methanol, and 80% methanol extracts of red Datta paste. TPC and TFC of the extracts were determined by the Folin–Ciocalteu and aluminum chloride method, respectively. DPPH scavenging, reducing power, and total antioxidant activities were taken as parameters for the evaluation of antioxidant activity. It was found that acetone extract contained the highest TPC (14.98 ± 0.76 mg of gallic acid equivalent/g of dried extract) and TFC (22.05 ± 0.87 mg of quercetin equivalent/g of dried extract). The acetone extract showed the highest, 2- diphenyl-1 picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀ = 87.30 ± 3.17 g/ml), iron reducing power (11.06 ± 2.10 mg of ascorbic acid equivalent/g dried extract), and total antioxidant activity (0.62 ± 0.13 mg butylated hydroxytoluene equivalent/g of dried extract) than the other four extracts tested. The acetone extract also exhibited the highest percentage of α-amylase inhibition activity (54.31 ± 4.70%). TPC and TFC were strongly correlated with DPPH (r = 0.93, 0.94. p < 0.01), ferric reducing power (r = 0.89, 0.83, p < 0.05), and total antioxidant activity (r = 0.88, 0.85, p < 0.05), respectively. The α-amylase inhibition activity was well correlated with TPC (r = 0.78, p > 0.05) and TFC (r = 0.81, p > 0.05). This indicated that phenolic compounds are the main contributors of antioxidant and α-amylase inhibiting activities in red Datta paste. The study revealed that crude extract of red Datta paste can be used as natural antioxidants as well as for preventing oxidative stress mediated human disorders such as suppressing hyperglycaemia.

Keywords: chili pepper, Datta paste, antioxidant, α-amylase, phenolic content