Determination of oenothein B as the active 5-alpha-reductase-inhibiting principle of the folk medicine Epilobium parviflorum - Lesuisse, D; Berjonneau, J; Ciot, C; Devaux, P; Doucet, B; Gourvest, J F; Khemis, B; Lang, C; Legrand, R; Lowinski, M; Maquin, P; Parent, A; Schoot, B; Teutsch, G; Chodounska, H; Kasal, A (J Nat Prod, 1996)