In preceding papers, we reported the isolation and structural elucidation of 22 steroids, two sesquiterpenoid glycosides, one phenylpropanoid, one flavonoid glycoside, and three phenylpropanoid sucrose esters from the MeOH extract of the underground parts of Trillium kamtschaticum PALL. (Liliaceae) and, further, that four phenolic compounds among these compounds had a stronger antioxidative activity than L-cysteine.1,2) In a further investigation of this extract, we now report the isolation and structural elucidation of three new steroid glycosides along with two known 18-norspirostanol glycosides.The MeOH extract of the underground parts of T. kamtschaticum was successively subjected to Diaion HP20 and silica gel column chromatography as well as HPLC on ODS to afford five compounds (1-5) (Fig. 1).Compounds 4 and 5 were identified as trillenosides A and B, respectively, based on their physical and spectral data. 1)Compound 1, named trikamsteroside C, was obtained as an amorphous powder. The IR spectrum of 1 showed absorptions due to hydroxyl groups (3404 cm Ϫ1) and an a,b-unsaturated ketone group (1693 cm Ϫ1 ). In the positive FAB-MS, 1 exhibited an [MϩNa] ϩ ion peak at m/z 1041; the high-resolution ( H correlation spectroscopy (COSY), heteronuclear multiple-quantum coherence (HMQC), and heteronuclear multiple-bond correlation (HMBC) techniques, and 1 was characterized as a tetraglycoside of 18-norspirostanol. Further, the 13 C-NMR data of the aglycone moiety and the sugar moiety were superimposable on those of epitrillenoside C (6) 3) and 4, 1) respectively. The structure of 1 was therefore defined as epitrillenogenin 1-O-Compound 2, named trikamsteroside D, was obtained as an amorphous powder and the molecular formula of 2 was analyzed as C 48 H 74 O 24 by HR-positive FAB-MS. Its IR spectrum revealed absorptions at 3386 and 1741 cm Ϫ1 due to hydroxyl groups and a five-membered ketone group, respectively. The 1 H-NMR spectrum of 2 was analogous to that of 4, with an additional signal due to one methyl group. The 13 C-NMR spectrum of 2 was also similar to that of 4 except for the appearance of signals due to one each of methyl carbon, methine carbon, and quaternary carbon and the lack of signals due to two olefinic carbons. These 1 H-and 13 C-NMR signals were assigned in detail by 2D-NMR techniques similar to those of 1. In the HMBC spectrum of 2, key correlations were observed between H-1 of the arabinopyranosyl group and C-1, between H-17 and C-15, between H-14 and C-15, between H 2 -26 and C-22, between H 3 -27 and C-24, between H-24 and C-23, and between H-23 and C-24, and the planar structure of 2 was determined as illustrated in Fig. 2. Further, the 13 C-NMR assignments of the sugar moiety and A-ring of the aglycone moiety were quite similar to those of 4, indicating the same sugar chain as 4 was attached to C-1 of aglycone. The configurations of the aglycone moiety were confirmed by the following evidence. On acidic hydrolysis, 2 afforded an aglycone (2a) Sciences, Sojo University; 4-22-2 Ikeda, Kumamo...