New caffeoyl derivatives with potent DPPH radical scavenging activity from Elephantopus tomentosus

Eight new caffeoyl derivatives, elephantomentosides A-H (1 - 8), together with ten known ones (9 - 18), were isolated from the whole plant of Elephantopos tomentosus L. Their structures were elucidated using detailed spectroscopic analysis. Structurally, compounds 1 - 8 are composed of b-D-glucopyranose, and almost all of the substituent positions are at the C-1 ' and C-4 ' of glucopyranose. The anti-inflammatory and antioxidant activities of all isolated compounds were evaluated in vitro. Compounds 9-10, 13- 15, and 17-18 exhibited significant DPPH scavenging capacity with IC50 values in the range of 10.01-25.07 mu M, in comparison with Vc (IC50, 17.98 mu M). [GRAPHICS] .