以意大利青霉菌(Penicillium italicum)为供试菌，研究桂枝主要抑菌活性成分肉桂醛、肉桂酸的抑菌机制。通过测定肉桂醛、肉桂酸对供试菌的孢子萌发、菌丝生长形态、细胞膜通透性、可溶性糖和蛋白质含量以及代谢关键酶活性的影响, 以阐明二者的作用机理。研究发现，肉桂醛溶液对供试菌的最小抑菌浓度(MIC)、最小杀菌浓度(MFC)分别为0.025 mg/mL和0.1 mg/mL，肉桂酸溶液分别为0.1 mg/mL和0.4 mg/mL；与对照组相比，经处理的菌体，其孢子萌发率降低，菌丝扭曲膨大或断裂，细胞膜渗透率增强，菌体内可溶性糖及蛋白质含量减少，琥珀酸脱氢酶（Succinate dehydrogenase，SDH）和苹果酸脱氢酶（Malate dehydrogenase，MDH）活性降低。试验结果表明，肉桂醛和肉桂酸能有效抑制意大利青霉菌的孢子萌发，阻碍菌体生长，破坏细胞膜致使通透性增加，内含物外渗，且能有效破坏三羧酸循环（Tricarboxylic acid cycle，TCA）过程，菌体能量代谢途径受阻，从而抑制其正常的生长发育。

Penicillium italicum was used as the test fungal species in this study to investigate the antifungal mechanism of the main active ingredients of Ramulus cinnamomi, namely cinnamaldehyde and cinnamic acid. The mechanisms of the action of cinnamaldehyde and cinnamic acid were identified by evaluating their effects on spore germination, cell membrane permeability, mycelial morphology, soluble sugar content, and the activities of key metabolic enzymes. Results showed that the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of cinnamaldehyde were 0.025 mg/mL and 0.1 mg/mL, respectively, and the MIC and MFC of cinnamic acid were 0.1 mg/mL and 0.4 mg/mL, respectively. Compared to the control group, the treated fungi had a low spore germination rate, distorted, swollen, and broken mycelia, elevated cell membrane permeability, reduced soluble sugar and protein content, and reduced activities of succinate dehydrogenase (SDH) and malate dehydrogenase (MDH). The experimental results indicated that cinnamaldehyde and cinnamic acid could inhibit spore germination and mycelial growth in Penicillium italicum, damage the cell membrane to increase permeability, facilitate leakage of intracellular contents, interrupt the tricarboxylic acid cycle (TCA) process, and block the energy-generating metabolic pathways, thus inhibiting the growth and development of mycelia．

国家自然科学基金项目(31460533)；江西省教育厅科技落地计划项目(111)；江西省教育厅科技项目(GJJ-14287)；江西省博士后科研择优资助项目(2013KY31)；留学人员科技活动项目(人社厅函[2013]277号)；中国博士后科学基金第54批面上项目（2013M541870）资助