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Procyanidins and catechins were found in high amounts in the methanol extract of the bark of the mangrove tree Xylocarpus granatum. The procyanidins showed a consistent structural pattern with catechin as the starter and epicatechin as the extender units. Four limonoids with a tetranortriterpenoid structure, previously identified in X. granatum, were isolated as well. Catechins, procyanidins, limonoids and plant extracts were evaluated for DPPH radical scavenging and 15-lipoxygenase (15-LO) inhibiting effects. Catechins and procyanidins demonstrated high activity, and the procyanidin of the pentamer type was found to be most potent (IC 50 ; DPPH: 3.3 ± 0.3 μM, 15-LO: 9 ± 1 μM). Extracts were also found to have antibacterial activity.

Antimicrobial effect of the crude organic extract of Xylocarpus granatum stem barks was studied in the Department of Pharmacology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh, during the period from October to December 2003. Disc diffusion method has been adopted in this study and petri dishes (120 mm in diameter) containing nutrient agar medium seeded with the test organism was used for antimicrobial screening. Test materials diffuse from the discs to the surrounding medium of the plate. The plates are then kept in an incubator (37º) for 18 hours to allow the growth of the microorganisms. The antibacterial activity of the test agent is determined by measuring the diameter of the zone of inhibition in term of millimeter. Antimicrobial screening showed that the crude ethanol extract and other partially extracted fraction of the barks of Xylocarpus granatum possess antimicrobial activity against most of the test organisms depending upon the nature of their active ingredients in the extract and capacity of diffusion into the agar medium. Among the test organisms, the extract showed significant antimicrobial activity against Staphylococcus epidermis, Staphylococcus aureus, Shigella boydii, and Proteus spp. and moderate activity against Escherichia coli, Streptococcus pyogenes, and no activity against Shigella dysentery, Enterococci, Salmonella typhi.

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The methanol extract of Mimosa pudica was studied for its antibacterial activity against twelve pathogenic bacteria. The extract was also studied for its effect on acetic acid induced writhing model in mice. The extract showed good activity against two gram-positive and six gram-negative bacteria but failed to show any activity against Staphylococcus pyogenes, Salmonella typhi, Shigella boydii and Vibrio cholera. The extract exhibited no antinociceptive activity in acetic acid induced writhing test; rather it increased the abdominal constriction or writhing as compared to the control group which is a sign of pain sensation.