Apigenin 7-O-B-glucoside from the leaves of Acanthus integrifolius T. Anders., Acanthaceae

The first investigation on chemical constituents of Acanthus integrifolius resulted in the isolation of apigenin-7-O- -glucoside from the leaves of this plant. Its chemical structure was determined by ESIMS, 1 H NMR, 13 C NMR, DEPT, HMBC and HMQC.
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Apigenin 7-O-B-glucoside from the leaves of Acanthus integrifolius T. Anders., Acanthaceae Journal of Chemistry, Vol. 42 (4), P. 496 - 498, 2004 Apigenin 7-O- -glucoside from the leaves of Acanthus integrifolius T. Anders., Acanthaceae Received 18th-Sept.-2003 Phan Minh Giang, Phan Tong Son Faculty of Chemistry, College of Natural Science, Vietnam National University, Hanoi Summary The first investigation on chemical constituents of Acanthus integrifolius resulted in the isolation of apigenin-7-O- -glucoside from the leaves of this plant. Its chemical structure was determined by ESIMS, 1H NMR, 13C NMR, DEPT, HMBC and HMQC. Acanthus integrifolius T. Anders., 3 Acanthaceae (local name: ¾c ã) is a shrub OH HOCH2 2 4 growing to the height of 1 - 2 m and possessing HO O 8 1 O O 5 white flowers [1]. The leaves of A. integrifolius HO 7 9 2 6 (Folium Acanthi) are used in the treatment of OH 3 6 10 pain and rheumatism [2]. Our first phyto- 5 4 chemical investigation on A. integrifolius was OH O prompted by the need to identify the compounds responsible for anti-inflammatory Figure 1: Chemical structure of apigenin therapeutic effects of this plant. 7-O- -glucoside (1) Successive liquid-liquid fractionation of the nucleus protons; the 13C NMR chemical shifts aqueous MeOH extract of the leaves of A. of this moiety were consistent with the integrifolius by solvents with increasing identification of 1 as a derivative of apigenin polarity gave n-hexane-, CH2Cl2-, ethyl acetate- and n-BuOH-soluble fractions. The n-hexane [3]. The second group, appearing between 3.1 and 5.06, comprised the resonances of a soluble fraction contained mainly phytosterols glucosidic moiety. The anomeric proton as indicated in a TLC analysis and was not further investigated. Two-time column resonance observed at 5.06 (1H, d, J = 7 Hz) chromatography of the ethyl acetate soluble indicated the -glucose. The proton signals at fraction on lipophilic Sephadex LH-20 gave 12.96 (1H, s) (downfield-shifted due to the hydrogen bonding with 4-oxo group) and 10.41 apigenin-7-O- -glucoside (1) with 95% purity. (1H, s) were indicative for the hydroxyl groups We reported herein the structure elucidation of located at C-5 and C-4’. The molecular formula this flavone glucoside. C21H20O10 (from ESIMS quasimolecular ion The 1H-NMR spectrum of 1 in DMSO-d6 peaks at m/z 433.4 ([M+H]+), 455.4 ([M+Na]+) contained two distinctive groups of resonances. and 431.4 ([M-H]+)) provided the identity of 1 Those at 7.96 (2H) and 6.95 (2H) (both as d, J as apigenin 7-O- -glucoside, the 1H and 13C = 9 Hz), 6.87 (1H, s), 6.84 (1H) and 6.45 (1H) NMR resonance signals of which are in good (both as d, J = 2.2 Hz), represented the flavone accordance with those reported for the apigenin 496 7-O-diglycosides [4]. This structure was firmly radical) and cumene hydroperoxide (peroxyl confirmed by the correlation between the sugar radical) [6]. The in vitro superoxide anion proton Glc-1 ( 5.06) and C-7 ( 163.0) in the radical and peroxyl radical scavenging HMBC spectrum (Fig. 1). The HPLC-UV properties of apigenin 7-glucoside may spectrum of apigenin 7-O- -glucoside taken on contribute to its anti-inflammatory effect. There line was shown in the Fig. 2. is accumulating evidence that natural antioxidants inhibit the expression of inducible Peak A2 12.7 ...