Two unusual 18,19-secoursane glycosides, bodiniosides A (1) and B (2), and two known triterpenoids, hypadienic acid (3) and 2,3,19-trihydroxyurs-12-en-28-oic acid (4), were isolated from the whole plants of Elsholtzia bodinieri. The structures of 1 and 2 were determined by intensive interpretation of spectral data. This is the first report of E-secoursane glycosides. In addition, the biogenetic relationships among these four triterpenoids are discussed.
Introduction. Β± Elsholtzia bodinieri (Labiatae), which is distributed in Yunnan and Guizhou Provinces in China, is a traditional Chinese medicine for the treatment of cough, headache, pharyngitis, fever, and hepatitis [1]. A previous study of this plant has resulted in the isolation of two new triterpene glycosides, hederagenin 3-O-b-dxylopyranoside and dodecandral 3-O-b-d-xylopyranoside [2]. In the present study, two new 18,19-secoursane glycosides, bodiniosides A (1) and B (2), along with two known triterpenoids, hypadienic acid (3) [3] and 2,3,19-trihydroxyurs-12-en-28-oic acid (4) [4], were isolated from the whole plant. The structure elucidation and a plausible biogenetic pathway of these four compounds are described here.
Results and Discussion. Β± Structure Elucidation. Bodinioside A (1), obtained as colorless flake crystals, gave rise to a quasi-molecular-ion peak at m/z 663.3727 ([M Γ H 2 O Γ H] ) in the HR-ESI-MS (negative-ion mode), which corresponded to the molecular formula C 36 H 58 O 12 . Thus, eight degrees of unsaturation were determined for 1. Inspection of the 1D and 2D NMR spectra (Table ) and comparison with those of 2,3,19-trihydroxyurs-12-en-28-oic acid (4), allowed us to identify the structure of bodinoside 1 (2a,3b,12b)-3- (b-d-glucopyranosyloxy)-2,12,21-trihydroxy-19-oxo-18,19secours-13(18)-en-28-oic acid, a new 18,19-secoursane glycoside.
The IR spectrum of 1 exhibited absorptions for COOH (3462 cm Γ1 ), OH (3385 cm Γ1 ), carbonyl (1741 and 1711 cm Γ1 ), and olefinic (1640 cm Γ1 ) groups. The UV spectrum showed end absorption indicating the absence of a conjugated system. In the 1 H-NMR spectrum, the signals of six tertiary Me (d 0.87, 1.00, 1.09, 1.24. 1.39, and 2.12) and one secondary Me group (d 0.92, d,