Role of Condensed Tannins in the Antioxidant Activity of Seeds of Cola nitida (Vent.) Schott & Endl. (Malvaceae)

Abstract

Background: Native to West Africa, Cola nitida is a tropical tree of about 8-12 in height that grows in lowland rainforest. This plant is best known in Africa for its seeds, used in phytotherapy but for their socio-cultural importance. Aims/Objective: This study investigated the antioxidant activity of condensed tannins of Cola nitida seeds by carrying out two antioxidant tests (DPPH and FRAP). Methods: From a hydro-ethanolic extract of Cola nitida seeds, two samples were made. One treated with casein (EC) and another one without treatment (EWC). The researsh of condensed tannins were carried out by precipitation with Stiasny reagent. The total polyphenol and tannin contents were evaluated by the Folin-Denis method and the antioxidant power by DPPH and FRAP tests. Results: Extract without treatment (EWC) showed more antioxidant activity than the extract treated with casein (EC). Thus, the IC50 of EWC which contains condensed tannins was 5.54±0.005 µg/ml, while that of EC (without condensed tannins) reached 61.92±0.165 µg/ml. Conclusion: Cola nitida seeds are rich in condensed tannins that play an important role in the antioxidant activity.