细叶小檗总生物碱的抑菌活性及热降解动力学

以半仿生法提取细叶小檗果实中的总生物碱,通过考察自然光照、紫外光照、温度和p H等因素的影响,以细叶小檗总生物碱残留量和抑菌圈内外差值(D-d)为考察指标记录变化,探究总生物碱与抑菌活性的稳定性及其热降解动力学。结果显示,细叶小檗果中提取的总生物碱对革兰氏阳性和阴性细菌均有抑制效果,其稳定性与抑菌活性易受温度和p H值的影响,自然光照30 d与紫外照射3 h对总生物碱稳定性与抑菌活性均无影响。总生物碱的热降解速率随着温度升高而加快,抑菌活性随着处理温度的升高而减弱,在90℃处理20 h,100℃处理4 h后的时候完全失活。总生物碱在酸碱处理后抑菌活性明显增强,再经80℃热处理48 h,酸碱组抑菌活性仍会保留。研究表明,总生物碱稳定性与抑菌活性易受温度和p H值的影响,酸化可将(D-d)提高13~18 mm,碱化提高3~5mm;均可增强其热稳定性,酸处理组(D-d)为20~22mm,碱处理组(D-d)为5~9mm;总生物碱的热降解反应符合一级动力学模型,活化能Ea为58.8 kJ/mol,半衰期t1/2随着温度的升高而缩短。该研究初步揭示了总生物碱在不同条件下的抑菌活性和热降解动力学,为小檗碱等生物碱的提取加工提供了理论依据和参考。

Antimicrobial Activity and Thermal Degradation Kinetics of Total Alkaloids from Berberis poireti

Total alkaloids from Berberis poireti were extracted by the semi-bionic method. The stability of total alkaloids, antimicrobial activity and the thermal degradation kinetics were investigated through examining the effects of natural light, ultraviolet light, temperature, and p H, and tracking the changes in the content of total alkaloids in Berberis poireti and difference between the inside and outside inhibitory zone(Dd). The results showed that the total alkaloids extracted from Berberis poiretii exhibited inhibitory effects on Gram-positive and Gram-negative bacteria. The stability and antimicrobial activity were significantly influenced by temperature and pH, whilst natural lighting for 30 days and ultraviolet lighting for 3 hours did not exhibit such effects. The rate of thermal degradation for total alkaloids increased with increasing temperature. The antimicrobial activity decreased with an increase of temperature, and was completely lost at 90 ℃ for 20 hours or 100 ℃ for 4 hours. The antimicrobial activity of the total alkaloids was largely enhanced after the acidic-alkaline treatment, and, was retained after the treatment at 80 ℃ for 48 h. The research showed that the stability of total alkaloids, antimicrobial activity were greatly affected by temperature and p H, with acidification increasing the(D-d) by 13~18 mm, alkalization increasing by 3~5 mm after the acidification and, respectively. The acidification and alkalization could also enhance the thermal stability and led to D-d as 20~22 mm and 5~9 mm. The thermal degradation of total alkaloids conformed to the first order dynamic process with the activation energy(Ea) is 58.8 KJ/mol. The half-life(t1/2) was shortened with an increase of temperature. This study preliminarily revealed the antibacterial activity and thermal degradation kinetics of total alkaloids under different conditions, and provided a theoretical basis and reference for the extraction and processing of alkaloids such as berberine.