| Summary: | 碩士 === 國立臺灣大學 === 藥學研究所 === 93 === Recent studies indicated that the seed of Asparagus officinalis (Liliaceae) contained cytotoxic steroidal glycosides. Hence, we wanted to explore whether a related and uninvestigated species, A. densiflorus, a common garden plant, contained similar bioactive constituents.
The water extract of the fresh fruits void of seeds was divided into fractions soluble in EtOAC, n-BuOH and H2O. The n-BuOH soluble part was further fractionated over centrifugal partition chromatography (CPC), and Sephadex LH-20 to give fractions rich in glycosides. Separation of these fractions via semipreparative RP-18 HPLC column (MeOH-H2O, ACN-H2O) led to the isolation of five glycosides. They are characterized as 26-O-β-D-glucopyranosyl-22α-methoxy-(25S)-furostan-3β,26-diol 3-O-α-L-rhamopyranosyl-(1→4)-β-D-glucopyranoside (1), 26-O-β-D-glucopyranosyl-22α-methoxy-(25R)-furostan-3β,26-diol 3-O-α-L-rhamopyranosyl-(1→4)- β-D-glucopyranoside (2), 26-O-β-D-glucopyranosyl-22α-hydroxy-(25R)-furostan-3β,26-diol 3-O-[α-L-rhamnopyranosyl-(1→2)- α-L-rhamopyranosyl-(1→4)]- β-D-glucopyranoside} (3), (25R,S)-5β-spirost-5-en-3β-ol 3-O-α-L-rhamnopyranosyl-(1→4)- β-D-glucopyranoside (4), (25S)-5β-spirostan-3-ol 3-O -α-L-rhamnopyranosyl-(1→2)- α-L-rhamnopyranosyl-(1→4)- β-D-glucopyranoside (5)Their structures were elucidated mainly by NMR spectral analysis. This study leads to the isolation and characterization of two new furostanoid glycosides(1, 3). In addition, compound 5 is demonstrated to possess cytotoxicity against breast cancer cell line (MCF-7) with IC50 value of 5.19 μg/ml。
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