摘要
核桃青皮是核桃(Juglans regia L.)加工的副产物,因含有多种活性成分,可能是一种潜在的天然抗氧化剂和抑菌剂来源。本研究旨在研究核桃青皮提取物的抗氧化能力和抑菌活性,为开发新的饲用抗生素替代品提供参考。以蒸馏水及25%、50%、75%和100%的甲醇、乙醇,丙酮为溶剂分别提取8和12h获得核桃青皮提取物。通过测定提取物中的总酚和总黄酮含量,根据还原能力和2,2-二苯基-1-苦肼基(DPPH)自由基清除率评价其抗氧化能力;以大肠杆菌、枯草芽孢杆菌和金黄色葡萄球菌为受试菌,分别测定抑菌圈直径、最小抑菌浓度(MIC)及抑菌率评价其抑菌活性。结果表明,有机溶剂浓度显著影响提取物中的总酚和黄酮含量(P<0.01);除丙酮外,提取时间对提取物中总酚和黄酮含量均有显著的影响(P<0.05);在所有提取溶剂中,以25%乙醇提取8h获得的总酚和黄酮最高,分别达到25.35和12.63mg·g-1。有机溶剂浓度对提取物的还原能力具有显著的影响(P<0.01),而提取时间仅对丙酮提取物的还原能力具有显著影响(P<0.05),其中25%乙醇提取物的还原能力在各处理中最高,为0.366。有机溶剂浓度对提取物的DPPH自由基清除率具有显著的影响(P<0.01),而提取时间仅对甲醇提取物的自由基清除率有显著影响(P<0.01),其中75%丙酮提取物可清除88.81%的自由基,在各处理中最高。有机溶剂浓度对大肠杆菌、枯草芽孢杆菌和金黄色葡萄球菌的抑菌圈直径和最小抑菌浓度(MIC)均有显著的影响(P<0.01);从提取时间来看,除甲醇提取物对大肠杆菌以及丙酮提取物对枯草芽孢杆菌的抑菌圈直径无显著影响外(P>0.05),其他均有显著的差异(P<0.01);此外,提取时间显著影响对大肠杆菌的MIC(P<0.05),乙醇和丙酮提取物的金黄色葡萄球菌MIC以及丙酮提取物的枯草芽孢杆菌MIC有显著差异(P<0.05),其他提取物的MIC均不受提取时间的影响(P>0.05)。抑菌率测试结果表明核桃青皮25%乙醇提取物对枯草芽孢杆菌的抑菌活性强于对大肠杆菌和金黄色葡萄球菌的抑制。由此可见,所有核桃青皮提取物均具有一定的抗氧化及抑菌活性,尤其以25%乙醇8h提取物的作用最好。
Walnut green husk is a by-product generated in the walnut （Juglans regia L. ） process- ing that could be valued as a source of natural compounds with antioxidant and antimierobial properties. In this work, antioxidant capacity and antimicrobial activity of the extract of walnut green husk were analyzed to provide references for developing the new feed antibiotic alterna- tives. Several solvents （methanol, ethanol and acetone） with the concentration of 25%, 50%,75% and 100% （v/v aqueous solutions） and distilled water were used to extract the active ingre- dients of walnut green husks for 8 or 12 hours. Total phenols and flavonoids contents of the ex- tracts were determined. Antioxidant capacity of the extracts was evaluated according to the re- ducing power and 2, 2-diphenyl-l-picrylhydrazyl （DPPH） free radical scavenging rate. Antibacte- rial activity on Escherichia colt, Bacillus subtilis and Staphylococcus aureus was also evaluated according to the inhibition zones, minimum inhibitory concentration （MIC）, and growth inhibito- ry rate. The results were as follows% contents of total phenols and {lavonoids were significantly affected by solvent concentration （P〈0.01）, and by extraction time （P%0.05） except acetone extracts. The highest total phenols and flavonoids yield （25. 35 and 12. 63 mg · g^-l） were achieved with 25% ethanol solution. The reducing power and DPPH free radical scavenging rate were significantly affected by solvent concentration （P〈0.01）, however, extraction time only showed significant effect on reducing power of acetone extracts （P〈0.05） and DPPH free radical scavenging rate of methanol extracts （P〈0.01）. The greatest reducing power （0. 366） and DP- PH free radical scavenging rate （88.81%） were found in 25% ethanol and 75% acetone extracts. The inhibition zones and MIC against E. colt, B. subtilis and S. aureus were significantly affect- ed by the concentration of solvents （P〈0.01）. The inhibition zones of acetone extracts against B. subtilis and ethanol extracts against E. colt were not significantly affected by the extraction time （P〈0.05）, and the remaining showed significant differences （P%0.01）. There were signif- icant effects of extraction time on MIC of all extracts against E. colt （P〈O. 05）, however, only MIC against S. aureus of ethanol and acetone extracts and MIC against B. subtilis were signifi- cantly different （P〈0. 05）. Further analyses indicated that extracts with 25% ethanol for 8 hours showed the highest antibacterial activity against E. colt, S. aureus and B. subtilis. The results of growth inhibitory rate showed that antibacterial activity of the extracts against B. sub- tills was higher than E. colt and S. aureus. In summary, all extracts show a reasonably good an- tioxidant and antibacterial activity, the best one is extracts with 25% ethanol for 8 hours.
出处
《畜牧兽医学报》
CAS
CSCD
北大核心
2017年第6期1118-1127,共10页
ACTA VETERINARIA ET ZOOTECHNICA SINICA
基金
国家自然科学基金(31560653)
关键词
核桃青皮
提取物
抗氧化活性
抑菌活性
walnut （Juglans regia L. ） green husks
extracts
antimicrobial activity
antioxidantactivity
