Chiral Coumarin Enantiomers From Prangos pabularia Roots: Absolute Configuration, Tyrosinase Activation, and Anti-Vitiligo Potential in B16F10 Cells.

In order to isolate and characterize enantiomeric compounds from the roots of Prangos pabularia the dichloromethane extract was extensively fractionated by column chromatography, flash, semi-preparative high performance liquid chromatography (HPLC), and chiral HPLC. Six pairs of enantiomers were isolated from dichloromethane extracts using preparative chiral HPLC. The absolute configurations of the isolated isomers were identified using circular dichroism (CD). The anti-vitiligo activities of the corresponding (S)- and (R)-enantiomers were assessed by determining their tyrosinase activation rates. (S)-Pangelin 9 (PPE19-1) showed higher activity with 125.42% than (R)-pangelin 10 (PPE19-2) with 120.6%, while the positive control (8-methoxypsoralen) resulted in 122.3%. The percentage of activation rate of (S)-oxypeucidanin hydrate 1 (PPE4-1) was 119.74%, while it was 110.01% for (R) oxypeucidanin hydrate 2 (PPE4-2). We conclude that the (S, R) enantiomers of pangelin and oxypeucidanin hydrate (S, R) may be useful as pigmentation-promoting agents for the treatment of vitiligo.