Evaluation of antioxidant and antibacterial properties of six Sapindaceae members

Abstract

Free radical scavenging and antibacterial activities were determined for six Sapindaceae members namely: Allophylus africanus, Cardiospermum grandiflorum, Blighia sapida, Blighia unijugata, Deinbollia pinnata and Zanha golungensis used for the treatment of wounds, inflammation and infectious diseases in South Western Nigeria. The antioxidant activities were determined by 2,2′-azinobis-3- ethylbenzothiazoline-6-sulfonic acid (ABTS), 1,1-Diphenyl-2-picrylhydrazyl (DPPH), and FRAP assays. Five of the plant species produced above 70% inhibition of ABTS radicals at 0.02 mg/ml. A concentration dependent inhibition of DPPH radicals ranging between 33.8 and 99.2% at 0.1 mg/ml was observed. The ferric reducing capacity was comparable with that of butylated hydroxytoluene (BHT) and ascorbic acid. Positive correlation (R2 = 0.9359) was found between total phenolics content and DPPH antioxidant activity of the plant extracts. In the antibacterial study, the plant extracts were more active against Gram-positive than Gram-negative bacteria. The most susceptible bacterium was B. cereus. Extracts from B. sapida and B. unijugata did not show any activity on the tested organisms even at 2.0 mg/ml. None of the extracts exhibited activity againstSerratia marcescens, Pseudomonas aeruginosa and Klebsiella pneumonae. The strongest antibacterial activity was found in A. africanus and C. grandiflorum extracts. Among the six Sapindaceae species, A. africanus had the best antioxidant and antibacterial activities. Key words: Antioxidant, antibacterial, Sapindaceae, polyphenolic contents.