Evaluation of anti-inflammatory, antibacterial and cytotoxic activities of Cordia africana leaf and stem bark extracts

Abstract

Cordia africana (Boraginaceae) is a tree used in traditional medicine to treat inflammation related conditions and infectious diseases. This study was undertaken with the objectives of establishing the scavenging effect of extracts and fractions of Codia africana on the mediator of inflammation Lipoxygenases (LOX), and some non-biological free radicals such as 2,2-diphenyl-1-picrylhydrazyl (DPPH), the [2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS) radicals and the Ferric ion reducing antioxidant power (FRAP). Antimicrobial activities, total phenolics/flavonoids and cytotoxicity of extracts of Codia africana were also evaluated. Extracts were obtained by maceration. Anti-inflammatory activity was determined using a LOX-inhibitor screening assay kit according to the manufacturer's instructions. A broth serial micro dilution method was used to determine the minimum inhibitory concentration (MIC) against, Gram-positive and Gram-negative bacteria and Mycobacterium species. The antioxidant activity was determined using free-radical-scavenging assays, and the 3-(4,5- dimethylthiazolyl-2)-2,5- diphenyltetrazolium bromide reduction assay was used for cytotoxicity. Both the extracts of C. africana inhibited LOX enzyme. The most active being the methanol extract of the bark with IC₅₀ value of 55 ± 0.9 μg/ml. Both the extracts of C. africana, had excellent to weak antimicrobial activites (MICs ranging from 32 to 1024 μg/ml) against bacteria. All the extracts had significant (P< 0.05) free-radical scavenging activity (IC₅₀ ranging from 6.79 ± 0.07 to 331.98 ± 0.07 μg/ml). There was a positive correlation between the antioxidant activity and the total flavonoid and total phenolic contents of Cordia africana. The cytotoxicity on Vero cells was low with LC₅₀ of 81.79 ± 13.31 and 99.67 ± 16.10 μg/ml. The results support the use of C. africana leaves in traditional medicine to treat inflammation related conditions and infectious diseases.

Keywords: Cordia Africana, Inflammation, antibacterial, antioxidant, total flavonoid.