巨尾桉单宁的纯化工艺及其抗氧化抑菌性能

利用NKA-9大孔树脂纯化了巨尾桉树皮和树叶中的单宁,并采用二苯基苦基肼自由基(DPPH·)和羟基自由基(·OH)的清除作用评价了其抗氧化性,采用滤纸片扩散法测定了其对5种常见食源性致病菌的抑菌作用。结果表明,在上样质量浓度0.8 g/L、上样量10 mL、体积分数80%乙醇解吸液用量为3倍柱体积(BV)的动态纯化条件下,树皮单宁纯化物中单宁的质量分数为47.82%;在上样质量浓度0.5g/L、上样量10mL、体积分数80%解吸液用量3BV的动态纯化条件下,树叶单宁纯化物中单宁的质量分数为37.00%。树皮和树叶中单宁纯化物对DPPH·的半抑制浓度(IC50)分别为0.0121和0.0168g/L;当单宁质量浓度为0.6 g/L时,对·OH的清除作用相当于V_C的2.55和2.19倍。树皮和树叶中单宁纯化物对大肠杆菌、金黄色葡萄球菌、痢疾杆菌、沙门氏菌、蜡状芽孢杆菌的抑制作用均强于粗提物,且对痢疾杆菌的抑菌圈直径分别达13.25、12.50 mm。

Purification, antioxidant activity and antibacterial effect of tannins from Eucalyptus Grandis x E. Urophylla

The tannins from bark and leaf of Eucalyptus Grandis x E.Urophylla were purified by NKA-9 macroporous resin, the antioxidant activities were evaluated from the scavenging activities of 1,1-diphenyl-2 -picrylhydrazyl radical (DPPH•) and hydroxy radical (•OH), and the antimicrobial activities against 5 food-borne pathogenic bacterium were tested by the disk diffusion method. When the conditions for dynamic purification were loading of 0.8 g/L sample solution with 10 mL, and complete desorption with 3 BV of 80% ethanol, the mass fraction of bark tannins purified products was 47.82%. When the conditions for dynamic purification were loading of 0.5 g/L sample solution with 10 mL, and complete desorption with 3 BV of 80% ethanol, the mass fraction of tannins purified products from leaf was 37.00%. IC50 values of the purified tannins of bark and leaf on DPPH· scavenging effect were 0.0119 and 0.0121g/L, respectively. When the concentration was 0.5g/L, the scavenging rates on ·OH of the purified tannins of bark and leaf were equivalent to 2.55 and 2.19 times of VC, that of VC was 24.20%. The antimicrobial activities of purified tannins against Escherichia coli, Staphyloccocus aureus, Shigella, Salmonella, Bacillus cereus were better than the crude extracts, and the diameter of antibacterial zone of purified tannins of bark and leaf against Shigella were 13.25 and 12.50mm.