Medicinal plants from nepal: evaluation as inhibitors of leukotriene biosynthesis.

The methanolic extracts of 25 different Nepalese medicinal plants were tested for their activity to inhibit the biosynthesis of leukotriene B(4) in bovine polymorphonuclear leukocytes. The selected indigenous plants are used in traditional herb remedies to treat inflammatory diseases such as asthma, bronchitis, rheumatism, and skin disorders presumed to be mediated by leukotrienes. The leaves of Zanthoxylum nepalensis were shown to be the most potent inhibitor with an IC(50) value of 11 microgram/ml. The extracts obtained from Astercantha longifolia and Hedychium ellipticum also exhibited potent inhibitory action with IC(50) values of 20 and 22 microgram/ml, respectively.