Antibacterial activity of two triterpenes from stem bark of Protorhus longifolia

Antibiotic resistance of pathogenic strains has hugely contributed to the wide spread of new and re-emerging infectious diseases. There is thus the need for the discovery of new (non-penicillin based) antibiotics. The triterpenes [3β-hydroxylanosta-9,24-dien-21-oic acid (1) and methyl-3β-hydroxylanosta-9,24-dienoate (2)] isolated from stem bark of Protorhus longifolia (Benrh.) Engl. were evaluated for their antibacterial activity against a panel of selected general and antibiotic resistant Gram positive and Gram negative bacteria. The antibacterial activity of the compounds was determined using disc diffusion method. The compounds exhibited antibacterial activity against most of the tested bacteria with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranging from 0.16 to 5.00 mg/ml and 0.63 to 5.00 mg/ml, respectively. The triterpenes did not exhibit any bacterial DNA damaging effects, but apparently affected the microbial cell membrane integrity. The triterpenes could be a potentially effective antimicrobial agent to combat infectious diseases. Key words: Triterpenes, antibacterial activity, antibiotic resistance, DNA damage.