Comparative in vitro antioxidant properties of water juice from selected African fruits consumed in Calabar, Cross River State (CRS), Nigeria

Abstract

This study is based on a comprehensive comparison among different African fruits relative to one another and to identify the ones with high antioxidant capacity as compared to the standard ascorbic acid. The antioxidant capacity was analyzed using ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical spectrophotometric assays. The results of the DPPH assay indicated the antioxidant capacity as follows (decreasing order): Soursop (Annona muricata) (81.81% at 400ug/ml), sweet orange (Citrus sinensis) (75.62% at 400ug/ml), cocoa (Theobroma cacao) (72.26% at 400ug/ml), watermelon (Citrulluslanatus) (70.50% at 50ug/ml), chivita (70.03% at 400ug/ml), garden egg (Solanummelongena) (65.58% at 100ug/ml), pawpaw (Carica papaya) (65.53% at 100ug/ml), surinam cherry (Eugenia uniflora) (65.00% at 400ug/ml), tomatoes (Solanumlycopersicum) (64.99% at 400ug/ml), malay apple (Syzygiummalaccense) (61.67% at 200ug/ml), tangerine (Citrus tangerina) (61.42% at 400ug/ml), monkey cola (Cola millenii K. Sckhum) (60.88% at 100ug/ml), lime (Citrus aurantifolia) (52.87% at 100ug/ml), cucumber (Cucumissativus) (51.71% at 400ug/ml). The antioxidant capacities of the fruit juices were however, less when compared to the standard ascorbic acid. The FRAP assay result revealed that only the juices from African star apple (Chrysophyllumafricanum) and cocoa (Theobroma cacao) were significantly (p<0.05) higher than the standard ascorbic acid at 400ug/ml. The fruit juices have been demonstrated as good sources of natural antioxidants, hence can be exploited in the production of functional foods.

Keywords: 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), antioxidants, fruits, water juice, Calabar