Torilin from Torilis Japonica as a New Inhibitor of Testosterone 5α-Reductase

The study investigated the inhibitory effects of torilin, a compound isolated from the methanolic extract of Torilis japonica fruits, on 5α-reductase activity in vitro. Torilin demonstrated a stronger inhibition (IC50 = 31.7 ± 4.23 μM) compared to α-linolenic acid (IC50 = 160.3 ± 24.62 μM), but was less effective than finasteride (IC50 = 0.38 ± 0.06 μM). Other guaiane-type compounds like (-)-guaiol and guaiazulene showed weaker inhibitory effects, while azulene was inactive. The study suggested that the degree of unsaturation and the side-chain in the guaiane skeleton were crucial for 5α-reductase inhibition.