扁茎黄芪植株中化学成分的分离鉴定及其抑菌活性

为综合开发利用药用植物扁茎黄芪Astragalus complanatus，对其非药用部位的化学成分及抑菌活性进行了初步研究。采用硅胶柱层析和LH-20凝胶层析技术从扁茎黄芪植株中分离鉴定了7个化合物，并测定了各化合物对8种细菌的抑菌活性。根据波谱分析结果，7个化合物分别被鉴定为β-谷甾醇 (1) 、β-sitostenone (2) 、lawsaritol A (3) 、3β-羟基-5α,8α-桥二氧麦角甾-6,22-二烯 (4) 、3′,7-二羟基-2′,4′-二甲氧基异黄烷 (5) 、D-1-O-甲基肌醇 (6) 和沙苑子苷 (7) ，所有化合物均为首次从扁茎黄芪植株中分离得到。抑菌活性测定结果表明:化合物 5 对蜡状芽孢杆菌Bacillus cereus、大肠杆菌Escherichia coli、金黄色葡萄球菌Staphylococcus aureus、枯草芽孢杆菌Bacillus subtilis、白菜软腐病菌Erwinia carotovora、猕猴桃溃疡病菌Pseudomonas syringaepv.actinidiae和烟草青枯病菌Ralstonia solanacearum均有不同程度的抑制作用，其中对猕猴桃溃疡病菌、烟草青枯病菌和白菜软腐病菌的最低抑制浓度(MIC)分别为37.5、18.8和75.0 μg/mL。3′,7-二羟基-2′,4′-二甲氧基异黄烷 (5) 的农用抑菌活性为首次报道。

Isolation and identification of chemical constituents of the aerial parts of Astragalus complanatus and their antibacterial activities

For the comprehensive utilization of medicinal plant Astragalus complanatus, the chemical constituents of its the non-meidcinal parts and their antibacterial activities were investigated preliminarily. Seven compounds were isolated by using silica gel and LH-20 gel chromatography, and their antibacterial activities against 8 species of bacteria were evaulated. After spectrometric analysis, the obtained compounds were identified as β-sitosterol (1) , β-sitostenone (2) , lawsaritol A (3) , 8-epidioxy-5α,8α-ergosta-6,22E-dien-3β-ol (4) , 3′,7-dihydroxy-2′,4′-dimethoxyisoflavan (5) , D-1-O-methyl inositol (6) and complanatuside (7) . All of the above compounds were isolated from the aerial parts of A. complanatus for the first time. Compound 5 showed inhibition effect on Bacillus cereus, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Erwinia carotovora, Pseudomonas syringae pv. actinidiae and Ralstonia solanacearum, and the MIC values of compound 5 against three species of plant pathogenic bacteria, including P. syringae, R. solanacearum and E. carotovora, were 37.5, 18.8 and 75 μg/mL, respectively. To our best knowledge, this is the first report about the inhibition effect of 5 on plant pathogenic bacteria.