Isolation and HPLC Quantitative Determination of 5α-Reductase Inhibitors from L.f. Leaf Extract.

Steroid 5α-reductase plays a crucial role in catalyzing the conversion of testosterone to dihydrotestosterone, which is involved in many androgen-dependent disorders. Leaf-hexane extract from L.f. has shown promise as a 5α-reductase inhibitor. The objectives of this current study were to isolate and identify 5α-reductase inhibitors from leaves and to use them as the bioactive markers for standardization of the extract. Three terpenoid compounds, (+)-eperua-8,13-dien-15-oic acid (), (+)-eperua-7,13-dien-15-oic acid (), and lupeol (), were isolated and evaluated for 5α-reductase inhibitory activity. Compounds and exhibited potent 5α-reductase inhibitory activity, while showed weak inhibitory activity. An HPLC method for the quantitative determination of the two potent inhibitors ( and ), applicable for quality control of leaf extracts, was also developed. The ethanolic extract showed a significantly higher content of and than found in the hexane extract, suggesting that ethanol is a preferable extraction solvent. This study is the first reported isolation of 5α-reductase inhibitors ( and ) from leaves. The extraction and quality control methods that are safe and useful for further development of leaf extract as an active ingredient for hair loss treatment products are also reported.