向日葵茎髓提取物的抑菌活性及机制

以向日葵茎髓为原料,制得3种不同极性向日葵茎髓提取物。采用琼脂扩散法测定3种不同极性向日葵茎髓提取物对4种受试菌的抑菌活性;并以其中的金黄色葡萄球菌和大肠杆菌为研究对象,探讨了乙酸乙酯萃取部位(EE)的抑菌机制。结果显示:不同极性萃取部位对4种受试菌均有一定抑制作用。其中,EE处理金黄色葡萄球菌和大肠杆菌的最低抑菌质量浓度(MIC)均为0.78 g/L,半数抑制质量浓度(IC50)分别为(1.11?0.01)和(1.59?0.03)g/L;抑菌作用与其总酚、总黄酮含量呈显著正相关性(P0.05)。通过SEM分析发现,EE处理引起菌体形态变化,破坏菌体的细胞膜结构;EE可增加金黄色葡萄球菌和大肠杆菌细胞膜结构的通透性,使菌体内的电解质、蛋白质、碱性磷酸酶向胞外泄露;应用4?,6-二脒基-2-苯基吲哚(DAPI)染色和荧光检测发现,EE能干扰细菌遗传物质(DNA)的复制,最终抑制受试菌增殖。

Antibacterial Activity and Mechanism of Sunflower Stalk Pith Extracts

Three different polarity extracts were prepared from sunflower stalk pith. The agar diffusion assay was used to investigate the antibacterial activities of the extracts, and the action mechanism of the ethyl acetate extract (EE) against Staphylococcus aureus and Escherichia coli was detected in this study. Results showed that all extracts have good bacteriostatic effects on the four tested bacteria. Both MIC values of Staphylococcus aureus group and Escherichia coli group which treated by EE were 0.78 g/L, and the IC50 valueswere1.11±0.01 and 1.59±0.03g/L, respectively. There was positive correlation between the antibacterial activities and the content of total phenols and total flavonoids (P<0.05).The damaged membrane structures induced by EE were observed by SEM. EE also increased the permeability of the cell wall and cell membrane of the tested bacterial strains with the release of the electrolytes, proteins and alkline phosphatase (AKP) in the cell. Finally, EE also could inhibit the replication of bacterial genetic material (DNA) and ultimately inhibited bacterial reproduction by 4'',6-diamidino-2-phenylindole (DAPI) method.