산철쭉 끝을 MeOH로 추출하고, 이를 EtOAc, n-BuOH과 $H_2O$로 분배 추출하였다. EtOAc추출물과 n-BuOH 추출물에 대하여 silica gel과 ODS column을 이용하여 chromatography하거나, 아세틸화 한 후 sillica gel column chromatography를 수행하여 2종의 triterfenoid와 3종의 diterpenoio를 분리하였다. 각 화합물은 $^1H-^lH;COSY$, HMQC, HMBC와 같은 2D-NMR기법을 포함한 스펙트럼 데이터를 해석하여 $2{alpha};3{beta}-dihydroxylolean-12-ene (1), ursolic acid (2), grayanotoxin IV (3), grayanotoxin I (4) 및 grayanotoxin III (5) 등으로 동정하였다.
Extracts were obtained from the flower of Rhododendro yedoense var. poukhanense. (7 kg) in 80% aqueous MeOH and successively fractionated with solvent of EtOAc, n-BuOH and $H_2O$, successively. Silica gel and ODS column chromatographies of the EtOAc and n-BuOH fractions were repeatedly carried out by using the various solvent systems to give five terpenoids. Chemical structures of the isolated terpenoids were determined as $2{alpha},3{eta}-dihydroxylolean-12-ene$ (1), ursolic acid (2), grayanotoxin IV (3), grayanotoxin I (4) and grayanotoxin III (5) based on the interpretation of several spectral data including 2D-NMR such as $^1H-^1H;COSY$, HMQC and HMBC.
