芡种壳多酚超声辅助提取工艺优化及其对金黄色葡萄球菌的抑制效果

【目的】优化芡种壳多酚提取工艺，并分析其对金黄色葡萄球菌的抑制作用和抑菌稳定性，为芡种壳的资源化利用提供参考依据。【方法】采用超声辅助法提取芡种壳多酚，以多酚提取率（Y）为评价指标，对超声时间（X₁）、超声温度（X₂）和料液比（X₃）3个因素进行单因素和响应面试验，确定最佳提取工艺，初步纯化；采用琼脂扩散法研究芡种壳多酚对金黄色葡萄球菌的抑制活性，并测定最小抑菌浓度（MIC），同时考察温度、pH及金属离子浓度对芡种壳多酚稳定性的影响。【结果】3个因素对芡种壳多酚提取率影响的大小为:超声温度>料液比>超声时间，料液比及超声温度与料液比的交互作用对芡种壳多酚提取率有显著影响（P< 0.05），超声温度对多酚提取率有极显著影响（P< 0.01）。得到回归方程Y=14.57+0.064X₁+0.26X₂+0.11X₃+0.079X₁X₂-0.018X₁X₃-0.18X₂X₃-0.11X₁2-0.54X₂2-0.19X₃2；最佳提取工艺为:超声时间39 min、超声温度72 ℃、料液比1:41，在此条件下，芡种壳多酚提取率为14.479%，与预测值（14.630%）接近；芡种壳多酚对金黄色葡萄球菌具有明显抑制作用，MIC为0.1625 mg/mL；温度及Ca2+、Mg2+、K+、Na+4种金属离子对芡种壳多酚抑制金黄色葡萄球菌活性不具有显著影响（P> 0.05），而随着pH的增加，芡种壳多酚抑菌活性受到抑制。【结论】采用优化的超声辅助法可有效提取芡种壳中多酚物质，提取到的多酚对金黄色葡萄球菌的生长具有良好且较稳定的抑制效果。

Optimization of ultrasonic assisted extraction of polyphenol from Euryale ferox seed shells and its antimicrobial activity against Staphylococcus aureus

【Objective】The extraction technology of polyphenols from Euryale ferox seed shell was optimized, and its inhibition and stability to Staphylococcus aureus were analyzed to provide basis for resource utilization of E.ferox seed shell.【Method】The ultrasonic assisted extraction method was used to extract the polyphenols from E.ferox seed shell.The single factor experiment and response surface experiment with extraction yield of polyphenols(Y) as the evaluation index, and the ultrasound time(X₁), ultrasound temperature(X₂) and soild-liquid ratio(X₃) as three factors were carried out to determine the best extraction process, then the extract was preliminarily purified by macroporous resin.The inhibitory activity and the minimum inhibitory concentration(MIC) of E.ferox seed shell polyphenols on S.aureus was studied by agar diffusion method.The effects of temperature, pH and metal ion concentration on the stability of polyphenols were also investigated.【Result】The effects of three factors on yield of polyphenols from E.ferox seed shell were:ultrasound temperature> solid-liquid ratio> ultrasound time, the results showed that the solid-liquid ratio, and the interaction between ultrasound temperature and solid-liquid ratio had significant effects on yield of polyphenols(P< 0.05), while the ultrasound temperature had extremely significant effects(P< 0.01) on the extraction rate of polyphenols from E.ferox seed shell.The regression equation was obtained:Y=14.57+0.064X₁+0.26X₂+0.11X₃+0.079X₁X₂-0.018X₁X₃-0.18X₂X₃-0.11X₁2-0.54X₂2-0.19X₃2.The optimum extraction process was:ultrasound time was 39 min, ultrasound temperature was 72℃, solidliquid ratio was 1:41.Under these conditions, the extraction rate was 14.479%, which was close to the predicted value(14.630%). E.ferox seed shell polyphenol had certain inhibitory effect on S.aureus, the MIC was 0.1625 mg/mL.The temperature and Ca2+, Mg2+, K+ and Na+ metal ions had no significant effect on the inhibition of S.aureus reproductive activity by E.ferox seed shell polyphenols(P> 0.05), but with the increase of pH, the bacteriostatic activity of E.ferox seed shell polyphenols was inhibited.【Conclusion】The polyphenols in the shell of E.ferox can be effectively extracted by the optimized ultrasonic assisted method, and the polyphenols has a good and stable inhibitory effect on the growth of S.aureus.