Luo Jianjun, Li Zhibin, Wang Jingjing, Weng Qunfang, Chen Shaohua, Hu Meiying
Key Laboratory of Natural Pesticide and Chemical Biology, College of Agriculture, South China Agricultural University, Guangzhou 510642, China.
Molecules. 2016 Feb 19;21(2):237. doi: 10.3390/molecules21020237.
This study investigated the antifungal activity and potential antifungal mechanism(s) of isoliquiritin against P. litchi Chen, one of the main litchi pathogens. The antifungal activity of isoliquiritin against P. litchi Chen had been proven in a dose-dependent manner through in vitro (mycelial growth and sporangia germination) and in vivo (detached leaf) tests. Results revealed that isoliquiritin exhibited significant antifungal activity against the tested pathogens, especially, P. litchi Chen, with a minimum inhibitory concentration of 27.33 mg/L. The morphology of P. litchi Chen was apparently changed by isoliquiritin through cytoplasm leakage and distortion of mycelia. The cell membrane permeability of the P. litchi Chen increased with the increasing concentration of isoliquiritin, as evidenced by a rise in relative electric conductivity and a decrease in reducing sugar contents. These results indicated that the antifungal effects of isoliquiritin could be explained by a membrane lesion mechanism causing damage to the cell membrane integrity leading to the death of mycelial cells. Taken together, isoliquiritin may be used as a natural alternative to commercial fungicides or a lead compound to develop new fungicides for the control of litchi downy blight.
本研究调查了异甘草素对荔枝霜霉病主要病原菌之一的荔枝霜霉病菌（Peronophythora litchi Chen）的抗真菌活性及潜在抗真菌机制。通过体外（菌丝生长和孢子囊萌发）和体内（离体叶片）试验，已证实异甘草素对荔枝霜霉病菌的抗真菌活性呈剂量依赖性。结果表明，异甘草素对受试病原菌，尤其是荔枝霜霉病菌表现出显著的抗真菌活性，最低抑菌浓度为27.33 mg/L。异甘草素通过细胞质泄漏和菌丝变形，使荔枝霜霉病菌的形态明显改变。随着异甘草素浓度的增加，荔枝霜霉病菌的细胞膜通透性增加，相对电导率升高和还原糖含量降低证明了这一点。这些结果表明，异甘草素的抗真菌作用可通过膜损伤机制来解释，该机制导致细胞膜完整性受损，从而导致菌丝体细胞死亡。综上所述，异甘草素可作为商业杀菌剂的天然替代品或开发新型杀菌剂防治荔枝霜霉病的先导化合物。
