Antioxidant and cyclooxygenase inhibitory phenolic compounds from Ocimum sanctum Linn

Anti-oxidant bioassay-directed extraction of the fresh leaves and stems of Ocimum sanctum and purification of the extract yielded the following compounds; cirsilineol [1], cirsimaritin [2], isothymusin [3], isothymonin [4], apigenin [5], rosmarinic acid [6], and appreciable quantities of eugenol. The structures of compounds 1-6 were established using spectroscopic methods. Compounds 1 and 5 were isolated previously from O. sanctum whereas compounds 2 and 3 are here identified for the first time from O. sanctum. Eugenol, a major component of the volatile oil, and compounds 1, 3, 4, and 6 demonstrated good antioxidant activity at 10-microM concentrations. Anti-inflammatory activity or cyclooxygenase inhibitory activity of these compounds were observed. Eugenol demonstrated 97% cyclooxygenase-1 inhibitory activity when assayed at 1000-microM concentrations. Compounds 1, 2, and 4-6 displayed 37, 50, 37, 65, and 58% cyclooxygenase-1 inhibitory activity, respectively, when assayed at 1000-microM concentrations. Eugenol and compounds 1, 2, 5, and 6 demonstrated cyclooxygenase-2 inhibitory activity at slightly higher levels when assayed at 1000-microM concentrations. The activities of compounds 1-6 were comparable to ibuprofen, naproxen, and aspirin at 10-, 10-, and 1000-microM concentrations, respectively. These results support traditional uses of O. sanctum and identify the compounds responsible.