New coumarins from the n-butanol part of Prangos pabularia.

Chemical investigations of the n-butanol extract of the roots of Prangos pabularia were carried out using column chromatography, flash, semi-preparative HPLC, and chiral HPLC. Five unidentified compounds, including two prenylated coumarin glucosides, two prenylated furanocoumarin glucosides, and a benzofuran glucoside, together with twelve known compounds, were isolated from the n-butanol fraction of P. pabularia extract. The structures of these compounds were identified by HRMS, NMR, UV, ECD in combination with quantum chemical calculations, and comparison with the literature. The new compounds were named as yuganins C-G (1-5). Yuganin C (1) and yuganin D (2) are C-prenylated coumarin glucosides, yuganin E (3) is an 8-O-prenylated furanocoumarin glucoside, yuganin F (4) is a furanocoumarin 5-O-glucoside, and yuganin G (5) is a benzofuran glucoside. The isolated compounds were evaluated for their anti-vitiligo activity. All the individual isolated compounds showed anti-vitiligo effects. Compounds 10, 12, and 13 showed the highest melanin rate activation.