乳酸菌发酵接骨木果汁降血糖与抗氧化活性机理

Preliminary Study on Hypoglycemic Antioxidant Activity and Mechanism of Elderberry Juice Fermented by Lactic Acid Bacteria

摘要:

为探究乳酸菌发酵对接骨木果汁抗氧化活性的影响，通过测定DPPH自由基、羟自由基和超氧阴离子自由基清除率和细胞抗氧化实验比较接骨木果汁发酵前后抗氧化活性的变化。实验结果显示，接骨木果汁发酵后对DPPH自由基、羟自由基和超氧阴离子自由基的清除能力提高，对α-葡萄糖苷酶和α-淀粉酶的抑制能力也增加，证明发酵果汁具有降血糖活性。HepG2细胞分别使用发酵前后酚类物质预处理24 h后再用H₂O₂刺激，发现HepG2细胞中总抗氧化能力（T-AOC）、过氧化氢酶（CAT）活力均高于对照组，乳酸脱氢酶（LDH）相对释放率高于空白组，但远远低于对照组，细胞中活性氧的积累降低，并且血红素加氧酶-1（HO-1）、醌氧化还原酶-1（NQO1）以及谷氨酸半胱氨酸连接酶催化亚基（GCLC）相关抗氧化酶的基因表达量在仅用H₂O₂处理后的HepG2细胞中降低，而在发酵前后分别经质量浓度为200 μg/mL和300 μg/mL酚类物质预处理的HepG2细胞中明显提高，表明接骨木果汁中的酚类化合物降低了H₂O₂对HepG2细胞的氧化损伤程度。由此可见，接骨木果汁发酵前后抗氧化能力发生变化的原因可能是在酚类化合物的作用下提高了HepG2细胞中HO-1、NQO1和GCLC的基因表达水平，因此说明果汁发酵后提高了对细胞的保护作用。

Abstract:

To investigate the effect of lactic acid bacteria fermentation on the antioxidant activity of elderberry juice, the changes of antioxidant activity of elderberry juice before and after fermentation were compared by measuring the scavenging rate of DPPH, hydroxyl and superoxide anion radicals and cellular antioxidant assay. The experimental results showed that the fermentation of elderberry juice improved the scavenging ability of DPPH, hydroxyl and superoxide anion radicals, and increased the inhibitory ability of α-glucosidase and α-amylase, which proved the hypoglycemic activity of fermented juice. HepG2 cells were pretreated with phenolic substances before and after fermentation for 24 h, respectively, and then stimulated with H₂O₂. It was found that the total antioxidant capacity (T-AOC) and catalase (CAT) activity in the cells were higher than those of the control group. The relative release rate of lactate dehydrogenase (LDH) was higher than that of the blank group but much lower than that of the control group. The accumulation of reactive oxygen species in the cells was reduced. Moreover, the gene expression levels of heme oxygenase 1 (HO-1), quinone oxidoreductase 1 (NQO1), and glutamate cysteine ligase catalytic subunit (GCLC)-related antioxidant enzymes was decreased in HepG2 cells treated with H2O2 only, however, they were significantly increased in HepG2 cells pretreated with phenolics before and after fermentation at mass concentrations of 200 μg/mL and 300 μg/mL, respectively, indicating that the phenolic compounds in elderberry juice reduced the degree of oxidative damage of HepG2 cells induced by H2O2. Therefore, the changes in antioxidant capacity of elderberry juice before and after fermentation might be due to the increased gene expression levels of HO-1, NQO1 and GCLC in HepG2 cells in the presence of phenolic compounds. Thus, it could be suggested that the juice fermentation could improve the protective effect on cells.