The methanolic extract of the leaves of Cassia roxburghii DC., was investigated for its anthraquinone glycosides and antioxidant activity. Two new anthraquinone glycosides named emodin 1-O-β-D-glucopyranosyl-(1 → 2)-glucopyranoside (1) and aloemodin 8-O-β-D-glucopyranosyl-(1 → 6)-glucopyranoside (2) along with aloemodin 8-O-β-D-glucopyranoside (3), emodin (4), aloemodin (5) and one flavonoid, quercetin-3-O-α-L-rhamnopyranoside, were isolated from the leaves of C. roxburghii. Structures of the isolated compounds were established by UV, HRESI-MS, and 1D/2D (1)H/(13)C NMR spectroscopy. The total extract and some isolated compounds were determined against DPPH (2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazinyl radical, for their free radical scavenging activity, the total alcoholic extract showed strong antioxidant activity while the two new compounds showed weak antioxidant activity.
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