南瓜皮提取物的体外抑菌活性

In vitro antimicrobial activity of extracts from autumn squash rind

为了揭示南瓜较长贮存期与其皮部活性物质功能之间的关系,通过使用石油醚、乙酸乙酯、丙酮、甲醇、水5种不同极性强度的溶剂对南瓜皮进行连续梯度提取,采用孢子萌发抑制法、琼脂孔扩散法和对倍稀释法测定了不同提取物对5种真菌:扩展青霉(Penicillium expansum)、尖孢镰刀菌(Fusarium oxysporum)、黑根霉(Rhizopus stolonifer)、互格交链孢(Alternaria alternate)和粉红单端孢(Trichothecium roseum)和5种细菌:枯草芽孢杆菌(Bacillus subtilis)、大肠杆菌(Escherichia coli)、金黄葡萄球菌(Staphylicoccus aureus)、荧光假单孢杆菌(Pseudomonas fluorescence)和乳酸菌(Lactobacillus plantarum)的抑菌活性和最低抑菌浓度;并用扫描电镜观察了水提取物对菌体形态的影响。结果表明:除石油醚提取物外,四种提取物对供试菌有不同程度的抑制活性,其中水提取物的抑菌活性最强,水提取物处理使菌体外表形态发生明显的伤害性变化。初步说明南瓜皮中的预存抗菌物质是有助于南瓜较长贮存期的一个因素。

To explore the possible relevance between the long safe storage period of autumn squash and the contribution of its rind bioactive substances, petroleum ether, ethyl acetate, acetone, methanol and water were used to conduct a subsequent polarity gradient extraction on autumn squash rind.The activity of various extracts and their minimum inhibitory concentrations （MIC）against five fungi （Penicillium expansum, Fusarium oxysporum, Rhizopus stolonifer,Alternaria alternate and Trichothecium roseum ） and five bacteria（ Bacillus subtilis , Escherichia coli, Staphylicoccus aureus, Pseudomonas fluorescence and Lactobacillus plantarum ） were evaluated based on the methods of spore germination counting, agar well diffusion and double dilution. The modification on strain morphology ensuing the aqueous extract treatment at MIC was also investigated through electron scanning microscope.Results showed that all extracts but the one of petroleum ether displayed some inhibition capabilities on the growth of bioassay microbes and among them the strongest was the aqueous extract.Obvious detrimental alteration was observed on the cells or mycelium surface after aqueous extract treatment.Preliminary suggestion was that phytoalexin in the extracts from the rind was contributed to the long storage period of autumn squash.