Cyclooxygenase inhibition and antimycobacterial effects of extracts from Sudanese medicinal plants

Fifty one dichloromethane, ethyl acetate and ethanol extracts obtained from seven tree species used in Sudanese traditional medicine were screened for in vitro anti-inflammatory activity using COX-1 and COX-2 assays and for antimycobacterial activity using the broth micro-dilution methods against Mycobacterium aurum A+. In the cyclooxygenase assays, all ethyl acetate (leaf, bark, root) and ethanol root extracts of Acacia seyal, ethyl acetate twig extracts of Capparis decidua, dichloromethane bark extracts of Combretum hartmannianum and ethanol bark extracts of Ziziphus spina-christi showed inhibitory effect against prostaglandin synthesis by COX-2 ranging from 58 to 97% and weak (< 50%) or no activity against COX-1 induced prostaglandin production. In the antimycobacterial assays, ethanol extracts of A. seyal (bark), C. hartmannianum (leaf, bark), Kigelia africana (bark) and Z. spina-christi (bark) inhibited growth of M. aurum A+ with MIC values ranging between 0.19 and 1.56 mg/ml. The in vitro anti-inflammatory activity observed in this study support the utilization of these plants in Sudanese traditional medicine as crude anti-inflammatory agents. The inhibition of COX-1 and COX-2 and the antimycobacterial effects of these plants have not been reported previously. Isolation of bioactive compounds from A. seyal and Erythrina latissima are in progress in our laboratory.