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Three new flavonol 3-O-glycosides, rhamnetin 3-O-[(S)-3-hydroxy-3-methyl-glutaroyl(1→6)]-β-D-glucopyranoside (1), rhamnocitrin 3-O-[(S)-3-hydroxy-3-methylglutaroyl(1→6)]-β-D-glucopyranoside (2), and isorhamnetin 3-O-[(S)-3-hydroxy-3-methylglutaroyl(1→6)]-α-L-rhamnopyranosyl(1→2)-β-D-glucopyranoside (3), along with 13 known compounds, were isolated from Oxytropis racemosa TURCZ. Their structures were deduced by means of spectroscopic methods and chemical evidence. 2 and 6 showed cytotoxic activities against HCT-8 (IC₅₀ 6.38 µM) and A549 (IC₅₀ 5.20 µM), respectively.
Introduction: <i>Oxytropis racemosa</i> Turcz is an important minority medicine that is used mainly to improve children's indigestion, especially in inner Mongolia and Tibet. Previous studies indicated that the characteristic constituents of this plant are acylated flavonoids.<br>Objective: Rapidly identify the characteristic chemical constituents of <i>O. racemosa</i> by high-performance liquid chromatography-diode array detection-electrospray ionisation/multi-stage mass spectrometry (HPLC-DAD-ESI/MS<i><sup>n</sup></i>) and suggest a useful method to control the quality of this medicinal plant.<br>Methods: In the HPLC fingerprint, 32 flavonoids were tentatively identified by a detailed analysis of their mass spectra, UV spectra and retention times. Furthermore, 13 flavonoids were confirmed by comparison with previously isolated compounds obtained from <i>O. racemosa</i>.<br>Results: In total, 32 flavonoids, including 13 flavonoids with 3-hydroxy-3-methylglutaric acid (HMG) moieties and four flavonoids with 3-malonyl moieties, were identified in the extract of <i>O. racemosa</i>. Among the compounds identified, 10 were characterised as new compounds for their particular acylated sugar moieties.<br>Conclusions: The method described is effective for obtaining a comprehensive phytochemical profile of plants containing unstable acylated flavonoids. The method is also useful for constructing the chromatographic fingerprint of the minority medicine -<i>O. racemosa</i> Turcz for quality control. Copyright © 2012 John Wiley & Sons, Ltd.