ANTIBACTERIAL ACTIVITY OF EXTRACTS AND CONSTITUENTS OF PELARGONIUM SIDOIDES AND PELARGONIUM RENIFORME

The antibacterial activity of extracts and isolated constituents (scop oletin, umckalin, 5,6,7-trimethoxycoumarin, 6,8-dihydroxy-5,7-dimethox ycoumarin, (+)-catechin, gallic acid and its methyl ester) of Pelargon ium sidoides and Pelargonium reniforme (Geraniaceae), plant species us ed in folk medicine by the Southern African native population, was eva luated against 8 microorganisms, including 3 Gram-positive (Staphyloco ccus aureus, Streptococcus pneumoniae, and beta-hemolytic Streptococcu s 1451) and 5 Gram-negative bacteria (Escherichia coli, Klebsiella pne umoniae, Proteus mirabilis, Pseudomonas aeruginosa, Haemophilus influe nzae). Minimum inhibitory concentrations (MICs) varied with the prepar ation of the extracts and microorganisms tested, from about 0.6 mg/ml for aqueous phases to over 10 mg/ml for crude Pelargonium extracts. Wi th the exception of the ineffective (+)-catechin, all the potentially active compounds exhibited antibacterial activities with MICs of 200-1 000 mu g/ml. The results provide for a rational basis of the tradition al use of the titled Pelargonium species.