Testosterone 5α-reductase inhibitory constituents from the fruits of Rosa multiflora THUNB.

Abstract

An excess of dihydrotestosterone (DHT) is considered to be an important factor causing acne, while testosterone 5α-reductase is responsible for converting testosterone into DHT. In the course of a search for plant resources used for treatment of acne from natural medicines, the 50% of ethanolic extract of "Eijitsu (dried fruits of Rosa multiflora)" showed the strongest inhibitory activity against testosterone 5α-reductase in the previous screening test.
Examination of the constituents of the extract resulted in the isolation and/or identification of multiflorin A (1), multinoside A (2), multinoside A monoacetate (3), isoquercitrin (4), ursolic acid (5), 3-acetyl ursolic acid (6), betulinic acid (7), 3β, 6α, 19α-trihydroxyurs-12-en-28-oic acid (8), lauric acid (9), myristic acid (10), palmitic acid (11), oleic acid (12), linoleic acid (13) and γ-linolenic acid (14).
Among them, three fatty acids (12-14) showed inhibitory activities with IC₅₀ values of 52.2, 36.5 and 7.3 μg/ml, respectively. The chemical compositions of fatty acids in fractions were then examined by HPLC, as a result, the fraction with a stronger inhibitory activity showed higher contents of 12-14. These results suggest that unsaturated fatty acids (12-14) could be ascribed as active principles of the 50% ethanolic extract from R. multiflora. In addition, 5, 6, 8-10 and 12 were isolated from R. multiflora for the first time.