Pumilanol, an antiprotozoal isoflavanol from Tephrosia pumila

A novel isoflavan-4-ol (pumilanol), (rel)-3β-(2′-hydroxy-4′,5′-methylenedioxyphenyl)-6-methoxy-4α,7-dihydroxybenzo-3,4-dihydropyran (1) and two known flavonoids, tephrinone (2) and rotenone (3) together with lupeol and stigmasterol were isolated from the roots of Tephrosia pumila (Fabaceae) from a collection made in Andhra Pradesh, India. The structures of the compounds were determined by MS, 1D and 2D-NMR spectral analysis. Pumilanol (1) exhibited significant antiprotozoal activity against T. b. rhodensiense, T. cruzi and L. donovani with IC50 of 3.7, 3.35 and 17.2 μg/mL, respectively, but displayed high toxicity towards L-6 (IC50 of 17.12 μg/mL) rat skeletal myoblasts.

Graphical abstractA novel isoflavan-4-ol (pumilanol), (rel)-3β-(2′-hydroxy-4′,5′-methylene dioxyphenyl)-6-methoxy-4α,7-dihydroxybenzo-3,4-dihydropyran (1) and two known flavonoids, tephrinone (2) and rotenone (3) together with lupeol and stigmasterol were isolated from the roots of Tephrosia pumila (Fabaceae). Pumilanol (1) exhibited significant antiprotozoal activity against T. b. rhodensiense, T. cruzi and L. donovani with IC50 of 3.7, 3.35 and 17.2 μg/mL, respectively, but displayed high toxicity towards L-6 cells (IC50 of 17.12 μg/mL).