Antileishmanial anthraquinones from the rhyzomes of Rumex abyssinicus Jacq (Polygonaceae)

Phytochemical investigation of the rhyzomes of Rumex abyssinicus (Polygonaceae) afforded six anthraquinones viz chrysophanol (1), physcion (2), emodin (3), mixture of physcion-8-O-β,D-glucopyranoside (4) and chrypsophanol-8-O-β,D-glucopyranoside (5), and emodin-8-O-β,D-glucopyranoside (6). All the compounds were characterised and identified by comparison of their MS and NMR data with available literature data. The isolated compounds were evaluated for their antileishmanial activity. Emodin (3) was the most active compounds with IC50 13.82 and 0.26 µg/mL against Leishmania donovani amastigotes and promastigotes, respectively. Emodin-8-O-β,D-glucopyranoside (6) also showed a moderate activity with IC50 27.53 and 37.08 µg/mL. This is the first report of antileishmanial compounds from R. abyssinicus and the antileishmanial activities of compounds 2, 4, 5 and 6 are here reported for the first time.