Inhibition of inducible nitric oxide synthesis by the herbal preparation Padma 28 in macrophage cell line

Padma 28 is a mixture of herbs used in traditional Tibetan medicine with an ti-inflammatory activities. We investigated the effects of Padma 28 on nitr ic oxide (NO) production by the inducible nitric oxide synthase (iNOS) in l ipopolysaccharide stimulated mouse macrophages (RAW 264.7). Padma 28 (0-900 mug/mL) induced a concentration dependent inhibition of inducible nitric o xide synthesis. iNOS protein expression showed a concentration dependent re duction as revealed by immunoblotting when cells were incubated with increa sing amounts of Padma 28. Padma 28 decreased iNOS mRNA levels as shown by R T-PCR. Aqueous extracts from costi amari radix (costus root, the dried root of Saussurea lappa) and the outer cover of myrobalani fructus (the dried f ruit of Terminalia chebula), constituents of the complex herb preparation P adma 28, were found to inhibit inducible nitric oxide synthesis by decreasi ng iNOS protein and iNOS mRNA levels. The inhibition of inducible nitric ox ide synthesis might contribute to the anti-inflammatory activities of Padma 28.