Antiinflammatory activities of flavonoids and a triterpene caffeate isolated from Bauhinia variegata.

In the continuing search for novel antiinflammatory agents, six flavonoids, namely kaempferol (1), ombuin (2), kaempferol 7,4'-dimethyl ether 3-O-beta-D-glucopyranoside (3), kaempferol 3-O-beta-D-glucopyranoside (4), isorhamnetin 3-O-beta-D-glucopyranoside (5) and hesperidin (6), together with one triterpene caffeate, 3beta-trans-(3,4-dihydroxycinnamoyloxy)olean-12-en-28-oic acid (7) were isolated from the non-woody aerial parts of Bauhinia variegata. Compounds 1-7 were evaluated as inhibitors of some macrophage functions involved in the inflammatory process. These seven compounds significantly and dose dependently inhibited lipopolysaccharide (LPS) and interferon (IFN)-gamma induced nitric oxide (NO), and cytokines [tumor necrosis factor (TNF)-alpha and interleukin (IL)-12]. The concentration causing a 50% inhibition (IC50) of NO, TNF-alpha and IL-12 production by compounds 1, 2 and 7 was approximately 30, 50 and 10 microM, respectively, while at 50, 200 and 40 microM compounds 3, 4, and 5, 6 showed 15-30% inhibition, respectively. On the other hand, compounds 3 and 7 showed no inhibitory effect, while compounds 1, 4-6 reduced by around 10-30% the synthesis of NO by macrophages, when inducible NO synthase was already expressed with LPS/IFN-gamma for 24 h. These experimental findings lend pharmacological support to the suggested folkloric uses of the plant B. variegata in the management of inflammatory conditions.