覆盆子不同多酚组成及抗氧化、抗糖尿病活性

为阐明覆盆子不同形态多酚抗氧化和抗糖尿病活性差异，采用不同溶剂和方法提取覆盆子中的水溶、醇溶、游离和结合多酚，比较不同提取物的总酚、总黄酮和可水解单宁含量差异，测定其自由基清除能力、α-葡萄糖苷酶抑制和抗糖基化能力，并采用质谱技术测定活性最佳样品的主要化学成分。结果表明：覆盆子醇溶性多酚提取物的总酚和可水解单宁含量最高，分别为414.95、182.47 μg/mg（以每毫克提取物中所含没食子酸当量表示），同时具有最高的1,1-二苯基-2-三硝基苯肼自由基清除能力、2,2’-联氮-双(3-乙基苯并噻唑啉-6-磺酸)阳离子自由基清除能力、α-葡萄糖苷酶活性抑制能力，半抑制浓度分别为40.68、23.90 μg/mL和1.65 μg/mL。结合多酚提取物的总黄酮含量和抗糖基化能力最强。共从醇溶性多酚中初步鉴定出31 个化合物，单宁类和黄酮类化合物为其主要活性成分。因此，提取游离多酚和水溶性成分后的覆盆子残渣具有进一步利用、开发高活性抗氧化和抗糖尿病活性成分的应用价值。

Composition and Antioxidant and Antidiabetic Activities of Different Polyphenol Fractions from the Fruits of Rubus chingii Hu

To elucidate the differences in the antioxidant and antidiabetic activities of different phenolic fractions from Rubus chingii Hu, aqueous-soluble, alcohol-soluble, free and bound polyphenols from the fruits of R. chingii Hu were extracted using different solvents and methods. The difference in the contents of total phenolic compounds, total flavonoids, and hydrolyzable tannins in the different extracts were compared, and the radical scavenging, α-glucosidase inhibitory and antiglycation activity of the extracts were determined. The major chemical components in the extract with the highest activity were determined using mass spectrometry (MS). The results indicated that the alcohol-soluble polyphenol-rich extract had the highest contents of total phenols and hydrolysable tannins (414.95 μg/mg and 182.47 μg/mg (expressed as gallic acid equivalent in per milligram of extract), respectively). Meanwhile, it also presented the strongest ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) cation radical and to inhibit α-glucosidase activity with half maximal inhibitory concentration (IC50) values of 40.68, 23.90 μg/mL and 1.65 μg/mL, respectively. But the highest total flavonoid content and antiglycation activity were observed in the bound polyphenol-rich extract. Totally, 31 compounds were tentatively identified from the bound polyphenol-rich extract, and tannins and flavonoids were the major bioactive constituents. Therefore, the R. chingii Hu residues left after the extraction of free polyphenols and aqueous-soluble constituents can be further utilized to develop bioactive constituents with high antioxidant and antidiabetic activities.