Comparative Study on Polyphenols Content and Antioxid ant Activity of Three Sweet Peppers Varieties (Capsicum annuum L.)

Abstract

The genus Capsicum contains various sweet and hot pepper varieties, including Capsicum annum L. The various species in this genus are used as herbs, vegetables, or medicines, and recent studies have shown that they are a rich source of bioactive compounds as well. In this study, our objective was to evaluate the antioxidant activity as well as the content of phenols (TPC), the content of flavonoids (TFC) and total condensed tannins (TCT) of ethanolic extracts of the fresh and dried sweet pepper Capsicum annuum L. The antioxidant activities of the extracts were examined using different biochemical assays, namely diphenylpicrylhydrazyl (DPPH), total antioxidant capacity (TAC) and ferric reducing power (FRAP). The total phenolic contents (TPC) were determined spectrophotometrically according to the Folin-Ciocalteu colorimetric method. Total flavonoid content was measured by the aluminum chloride colorimetric assay. High-performance liquid chromatography (HPLC) has been used to identify the phenolic compounds in ethanolic extracts. The obtained results showed the presence of considerable amounts of total phenolic (757.3±3.5 mgGAE/100g), flavonoid (482.66±1.5 mgQE/100g) and Condensed Tannins (15.97±0.5 mg GAE/100g) content in dry red pepper extract. The use of HPLC has allowed the identification of Gallic Acid, Ascorbic Acid, Chlorogenic Acid, Caffeic Acid, Quercetin, Vanillin, and Rutin in pepper ethanolic extracts. Green and yellow dry peppers contain significant amounts of gallic acid exceeding (134.0 μg /mg). The fresh yellow and red peppers also contained significant amounts of Quercetin exceeding (109.3 μg/mg), the dry red pepper has the strongest antioxidant activity. In conclusion, these findings can be regarded as very promising and justify further study, including the identification of antioxidant components in pepper extracts. Our work constitutes a first step in the study of fresh and dry sweet pepper as a promising source of natural antioxidants.