산철쭉 꽃을 MeOH로 추출하고, 이를 EtOAc, n-BuOH과 H_2O로 분배 추출하였다. EtOAc추출물과 n-BuOH 추출물에 대하여 sillica gel과 ODS column을 이용하여 chromatography하거나, 아세틸화 한 후 sillica gel column chromatography를 수행하여 2종의 triterpenoid와 3종의 diterpenoid를 분리하였다. 각 화합물은 ^1H-^1H COSY, HMQC, HMBC와 같은 2D-NMR가법을 포함한 스펙트럼 데이터를 해석하여 2α, 3β-dihydroxylolean-12-ene(1), ursolic acid(2), grayanotoxin Ⅳ(3), graynotoxin Ⅰ(4), graynotoxin Ⅲ(5)등으로 동정하였다.

Extracts were obtained from the flower of Rhododendron 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 2α,3β-dihydroxylolean-12-ene (1), ursolic acid (2), grayanotoxin IV (3), grayanotoxin Ⅰ(4) and grayanotoxin Ⅱ (5) based on the interpretation of several spectral data including 2D-NMR such as ^1H-^1H COSY, HMQC and HMBC.