[Chemical constituents of Helleborus thibetanus]

The chemical constituents of Helleborus thibetanus were isolated and purified by silica gel column chromatography, Sephadex LH-20 gel column chromatography, and semi-preparative RP-HPLC, and the structures of all compounds were identified by modern spectrographic technology(MS, NMR). The MTT method was used to measure the cytotoxicity of compounds 1-8. Twelve compounds were isolated from the roots and rhizomes of H. thibetanus and were identified as(25R)-22β,25-expoxy-26-[(O-β-D-glucopyranosyl)oxy]-1β,3β-dihydroxyfurosta-5-en(1), β-sitosterol myristate(2), β-sitosterol lactate(3), β-sitosterol 3-O-β-D-glucopyrannoside(4), 4,6,8-trihydroxy-3,4-dihydronaphthalen-1(2H)-one(5), 1,3,5-trimethoxybenzene(6), 7,8-dimethylbenzo pteridine-2,4(1H,3H)-dione(7), 1H-indole-3-carboxylic acid(8), p-hydroxy cinnamic acid(9), lauric acid(10), n-butyl α-L-arabinofuranoside(11) and methyl-α-D-fructofuranoside(12), respectively. Among them, compound 1 is a new compound and named thibetanoside L; compounds 2, 5-8, 11 are first isolated from the family Ranunculaceae; compound 12 is isolated from the genus Helleborus for the first time. The results of MTT assay showed that the IC_(50) values of compounds 1-8 against HepG2 and HCT116 cells were greater than 100 μmol·L~(-1).

Steroidal constituents from Helleborus thibetanus and their cytotoxicities

Thibetanosides E-H (1-4), four new steroidal constituents including three rare sulfonates (2-4), were isolated from the roots and rhizomes of Helleborus thibetanus, together with nine known steroidal compounds (5-13). Their structures were elucidated by detailed spectroscopic analysis, including 1D and 2D NMR techniques and chemical evidence. In this study, compounds 2-13 were evaluated for their cytotoxic activities against HCT116, A549 and HepG2 tumor cell lines in vitro. Among them, compound 8 (thibetanoside C) showed cytotoxicities against A549 cells(IC₅₀ 39.6 ± 1.9 μmol·L^-1) and HepG2 cells(IC₅₀ 41.5 ± 1.1 μmol·L^-1), respectively. Compound 9 (23S, 24S)-24-[(O-β-D-fucopyranosyl)oxy]-3β, 23-dihydroxy-spirosta-5, 25(27)-diene-1β-ylO-(4-O-acetyl- α-L-rhamnopyranosyl)-(1→2)-O-[β-D-xylopyranosyl-(1→3)]-α-L-arabinopyranoside) showed cytotoxicity against HCT116 cells(IC₅₀ 33.6 ± 2.1 μmol·L^-1).