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Chemical investigation of ethyl acetate leaf-extract of Pterocarpus santalinoides led to isolation of a friedelane-terpenoid. Structure elucidation was done by comparison of the Nuclear Magnetic Resonance (NMR) spectral features with literature data and was consistent with reported values for friedelan-3-one. The following microorganisms (Clinical isolates): methicillin resistant Staphylococcus aureus (MRSA), S. aureus, Corynebacterium ulcerans, Streptococcus pneumoniae, Campylobacter jejuni, Helicobacter pylori, Escherichia coli, Shigella dysenteriae, Candida tropicalis and Candida krusei were used for the in vitro antimicrobial activity. The isolated compound had Minimum Inhibition Concentration (MIC) value of 10 µg/ml for MRSA, H. pylori, E. coli and Minimum Bactericidal/Fungicidal Concentration (MBC/MFC) of 40 µg/ml for E. coli; 20 µg/ml for MRSA, H. pylori and C. krusei; 10 µg/ml for S. aureus, S. pneumonia and C. tropicalis. It showed moderate antimicrobial activity against most of the pathogens tested. This is also the first report of the isolation of friedelan-3-one from this species.

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The antibacterial activity of compounds isolated from the stem bark and sawdust of Erythrophleum suaveolens were evaluated. Extraction of the pulverized plants materials was carried out using hexane, ethyl acetate and methanol. Extracts were fractionated using column chromatography and fractions were examined using Nuclear Magnetic Resonance spectroscopy. Antibacterial activities against Acidobacterium capsulatum, Actinobacterium sp., Agrobacterium tumefaciens, Bacillus subtili, Ralstonia solanacearum, Enterococcus faecium, Escherichia coli, Pseudomonas syringae, Pseudomonas aeruginosa and Proteus mirabilis were also carried out. A novel triterpene, 21-acetoxylupenone and betulin were identified in the fractions from the stem bark of E. suaveolens while cycloeucalenol and stigmasterol were obtained from the sawdust extract fractions. Pseudomonas aeruginosa was resistant to all control antibiotics but was inhibited by 21acetoxylupenone and cycloeucalenol with 23 mm and 24 mm diameter of Zones of Inhibition. Acidobacterium capsulatum, Actinobacterium sp., Agrobacterium tumefaciens, Ralstonia solanacearum, and Proteus mirabilis were completely inhibited at Minimum Bactericidal Concentration (MBC) of 50 µg/mL, while Bacillus subtilis, Enterococcus faecium, Escherichia coli, Pseudomonas syringae, and Pseudomonas aeruginosa were completely inhibited at MBC values of 100 µg/mL. Thus E. suaveolens stem bark and saw dust isolates can be used in the control of plants diseases where these pathogens are the causative agents.

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