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 3-0-p-D-glueopyranoside (4), isorhamnetin 3-O-beta-D-glucopyranoside (5) and hesperidin (6), together with one triterpene caffeate, 3Atrans(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 gm, respectively, while at 50, 200 and 40 gm 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. Copyright (c) 2008 John Wiley & Sons, Ltd.