摘要：
Flavonoids were extracted from Guanxi pomelo dropped fruits. The content of total flavonoids was up to 64.5％ after recrystallization. The antibacterial effects of flavonoids extracts on Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Candida albicans were studied by turbidimetric method using rutin as comparison. Meanwhile, the eliminating ability in vitro of flavonoids extract on hydroxyl radical (·OH), diphenyl bitter hydrazine free radical (DPPH·) and superoxide anion free radical (O2-·) were also studied.Results showed that flavonoids extracts had certain inhibition effect on Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Candida albicans, and the antibacterial rates were in the order of:Bacillus subtilis＞Candida albicans＞ Escherichia coli＞ Staphylococcus aureus. In addition, The antibacterial rate increased with the increase of flavonoids extracts concentration. The half inhibitory concentrations (IC50) of four kinds of the test bacterium were 2.18 mg/mL, 1.7 mg/mL, 4.6 mg/mL and 10.4 mg/mL, respectively, which were 100 times, 10 times, 10 times and 15 times that of rutin. Moreover, O2-·, DPPH·and·OH could be eliminated effectively by flavonoids extracts, the eliminating abilities were showed as follows:O2-·＞DPPH·>·OH. The half inhibitory concentrations were 1.23 mg/mL, 4.73 mg/mL and 11.46 mg/mL, respectively, which were 4 times, 400 times and 100 times that of rutin.%从琯溪蜜柚落果中提取黄酮,经重结晶获得总黄酮含量为64.5％的黄酮提取物.以芦丁为对照,采用比浊法研究黄酮提取物对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌和白色念珠菌的抑制作用,同时研究黄酮提取物对羟自由基(·OH)、二苯代苦味肼基自由基(DPPH·)和超氧阴离子自由基(O2-·)的体外清除能力,鉴定其抗氧化性能.结果表明,黄酮提取物对4种受试菌均具有一定抑制作用,抑菌率大小表现为:枯草芽孢杆菌＞大肠杆菌＞白色念珠菌＞金黄色葡萄球菌,并随提取物浓度的增大,抑菌率不断增加;黄酮提取物对4种受试菌的半数抑制浓度(IC50)分别为2.18 mg/mL、1.7 mg/mL、4.6 mg/mL、10.4 mg/mL,分别是芦丁IC50的100、10、10、15倍;黄酮提取物能有效地清除O2-·、DPPH·和·OH,清除能力大小表现为O2-·＞DPPH·>·OH,其IC50分别为1.23 mg/mL、4.73 mg/mL、11.46 mg/mL,分别是芦丁IC50的4、400、100倍.
