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Five new furanoid diterpene glycosides, named borapetoside C (l), D (2), E (3), F (4), and G (5), were isolated from the stems of Tinospora t uberculata Beum6e (Menispermaceae).The structures of 1-5 were elucidated by chemical and spectroscopic methods.In preceding papers[',2], we reported on two new diterpenoids and their glucosides, isolated from the stems of Tinospora tuberculata Beumee (Menispermaceae). This paper deals with the isolation and structure elucidation of five new diterpene glycosides which we named borapetoside C The compounds 1-5 were isolated from the stems of T tuberculata and their molecular formulas determined as (4) and C27H34012 (5) by elemental analyses. In their EI mass spectra these compounds exhibit fragment peaks at mlz = 81,94, and 121 which are due to the furan ring conjunction. The fragment at mlz = 121 reveals that these compounds are furanoid diterpenes possessing an oxygen function at C-12 and an angular methyl group at C-9r31. The fragment peak at mlz = 60 (EI-MS)L31 indicates that they contain sugar moieties. The 'H-and I3C-NMR spectral data of these products and of their related derivatives are compiled in Tables 1 and 2, these data are compared with those of borapetoside A (6), borapetoside B (7), borapetol A (8), and borapetol B (9)['321.Compound 1 contains a 6-lactone unit, and a methoxy- These results show that 8-H and C-20 of 1 are located on the same side. This is confirmed by the epimerization reaction of the acetate 10 of 1, thus 10 was refluxed with Ac20 and anhydrous sodium acetate to afford the epi-

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Four new furanoid diterpenes, named tinotufolin C (1), D (2), E (3), and F (4), were isolated from the fresh leaves of Tinospora tuberculata Beumée (Menispermaceae). The structures of 1–5 were elucidated by chemical and spectroscopic methods.