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 β-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 μM, in comparison with Vc (IC50, 17.98 μM).