Biological activities of limonoids, catechins, procyanidins and extracts from Xylocarpus granatum

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 (IC50; DPPH: 3.3 +/- 0.3 mu M, 15-LO: 9 +/- 1 mu M). Extracts were also found to have antibacterial activity.