Studies on the Constituents of Cimicifuga Species. XXVIII. Four New Cycloart-7-enol Glycosides from the Underground Parts of Cimicifuga simplex WORMSK

Cimicifuga (C.) species (Ranunculaceae) were reported by us and by other groups. In our continuing work, we have now isolated four new cycloart-7-ene triterpene arabinosides, named bugbanosides C—F (1—4), in low yields from the underground parts of C. simple. Their circular dichroism (CD) showed strong negative maxima at 214—217 nm (Fig 1). These CD maxima were also found to be characteristic to cycloart-7-ene triterpenic glycosides such as cimicifugoside, bugbanoside A, cimiaceroside A, shengm-7-enol glycosides, and cimig-7-enol glycoside (Fig. 2), and indicated basic skeletons, including absolute stereostructures of cycloart-7-ene triterpene glycosides. Therefore, structural elucidation of new compounds was undertaken on the bases of the CD data, along with the other spectral and chemical data. This paper deals with the isolation and structural elucidation of these minor glycosides. Compounds 1—4 were obtained as described in the experimental section by repeated chromatography on octadecylsilanized silicic acid (ODS) and silica-gel (SiO2) columns, and preparative (p) HPLC of the methanol extract of the underground parts of C. Simplex. The Hand C-NMR signals were attributed by using H–H correlated spectroscopy (H–H COSY), heteronuclear signal quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC), and nuclear Overhauser enhancement and exchange spectroscopy (NOESY). Compound 1 was obtained as a colorless powder, mp 157—158 °C, [a]D 257.5°, and named bugbanoside C. The molecular formula was determined to be C37H56O12 on the basis of positive high resolution secondary ion mass spectrometry (pos. HR-SI-MS) and the data of C-NMR. The IR spectrum showed strong hydroxyl bands at 3200—3600 cm, an ester carbonyl and a five membered ketone band at 1738 cm, and a ketone band at 1717 cm. The CD of 1 showed two negative maxima (De312: 23.43, De217: 29.25). The Hand C-NMR spectra (Tables 1, 2) showed the presence of a 3b-hydroxypropyl group (H-1, C-1, H-2, C-2, H-3, C-3), a tetrasubstituted cyclopropane group (H-19, C-19, C9, C-10), a secondary and six tertiary methyl groups (H-21, April 2001 Chem. Pharm. Bull. 49(4) 437—441 (2001) 437