绞股蓝抗氧化活性物质的分离鉴定

Isolation and Identification of Compounds with Antioxidant Activity from Gynostemma pentaphyllum Makino

研究绞股蓝抗氧化活性物质的成分以及其自由基消除和抗氧化活性。采用多种柱分离技术进行分离纯化,应用1H-NMR和13C-NMR光谱分析鉴定化合物的结构,HPLC分析其指纹图谱,采用DPPH、ABTS和FRAP三种体外检测体系进行抗氧化和自由基消除活性的研究。从绞股蓝正丁醇和乙酸乙酯萃取物中分离鉴定出2个抗氧化活性较强的化合物,分别为山奈酚-3-O-[2'-反式-肉桂酰基-3'-O-β-D-葡萄糖基-3'-O-β-D-葡萄糖基](化合物1)、3,4-二羟苯基-O-β-D-吡喃葡萄糖苷(化合物2)。HPLC证实正丁醇和乙酸乙酯部位分别含化合物1和2。DPPH自由基清除实验,化合物1和化合物2都显示了较好的自由基清除能力。在浓度为400~800μg/m L范围内,化合物2的抗氧化活性高于阳性对照Vc;ATBS实验,在12.5~100μg/m L浓度范围内,化合物1和化合物2的清除能力均高于Vc;FRAP实验结果为在较低浓度下,Vc的抗氧化活性高于化合物1和化合物2,但是在800μg/m L时,化合物1和化合物2的抗氧化活性接近Vc。

Compounds with radical-scavenging and antioxidant activities were isolated from Gynostemma pentaphyllum Makino, and their antioxidant properties were studied. The compounds were purified using various column chromatography techniques, the structures of the compounds were determined mainly by proton and carbon-13 nuclear magnetic resonance （1H-NMR and 13C-NMR） spectroscopy, and the fingerprints of the compounds were analyzed by high performance liquid chromatography （HPLC）. The radical-scavenging and antioxidant activities of the compounds were evaluated using the 2,2-diphenyl-l-picrylhydrazyl （DPPH）, 2,2＇-azino-bis（3-ethylbenzothiazoline-6-sulfonic acid） （ABTS）, and ferric reducing antioxidant power （FRAP） assays. Two compounds with strong antioxidant activity were obtained from the n-butanol and ethyl acetate fractions of G pentaphyllum and identified as kaempferol 3-O-[2G-（E）-coumaroyl-3G-O-β-o-glucosyl-（3R）-O-β-D- glucosylrutinoside] （compound 1） and 3,4-dihydroxyphenyl-O-β-D-glucopyranoside （compound 2）. The presence of compounds 1 and 2 in the n-butanol and ethyl acetate fractions, respectively, was verified by HPLC fingerprinting. DPPH assays revealed that both compound 1 and compound 2 have strong radical-scavenging activity against DPPH. In the concentration range of 400-800 μg/mL, the antioxidant activity of compound 1 was stronger than that of vitamin C （Vc）. ABTS assays showed that in the concentration range of 12.5-100 μg/mL, the radical-scavenging activities of compound 1 and compound 2 were stronger than that of Vc. Finally, FRAP assays indicated that the antioxidant activities of compounds 1 and 2 at low concentrations were weaker than that of Vc, but the activities of these compounds at a concentration of 800 μg/mL were comparable to that of Vc.