Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Science , Haikou 571010, People's Republic of China.
J Agric Food Chem. 2014 May 28;62(21):4905-10. doi: 10.1021/jf500968b. Epub 2014 May 19.
Cortex Pseudolaricis is the root bark of Pseudolarix amabilis Rehder, found only in China, and has been widely used in folk antifungal remedies in traditional Chinese medicine. In order to find the natural antifungal agents against mango anthracnose, eight compounds, namely pseudolaric acid A (1), ethyl pseudolaric acid B (2), pseudolaric acid B (3), pseudolaric acid B-O-β-d-glucoside (4), piperonylic acid (5), propionic acid (6), 3-hydroxy-4-methoxybenzoic acid (7), and 4-(3-formyl-5-methoxyphenyl) butanoic acid (8) were isolated from the ethanol extracts of Cortex Pseudolaricis by bioassay-guided fractionation and evaluated for in vitro antifungal activity against Colletotrichum gloeosporioides Penz. Results demonstrated that all of the eight compounds inhibited the mycelial growth of C. gloeosporioides at 5 μg/mL. Among them, pseudolaric acid B and pseudolaric acid A showed the strongest inhibition with the EC50 values of 1.07 and 1.62 μg/mL, respectively. Accordingly, both Pseudolaric acid B and Pseudolaric acid A highly inhibited spore germination and germ tube elongation of C. gloeosporioides. Dipping 100 μg/mL pseudolaric acid B treatment exhibited more effective suppression on postharvest anthracnose in mango fruit when compared to the same concentration of carbendazim. Scanning electron microscopy observations revealed that pseudolaric acid B caused alterations in the hyphal morphology of C. gloeosporioides, including distortion, swelling, and collapse. Pseudolaric acid B caused the mycelial apexes to show an abnormal growth in dimensions with multiple ramifications in subapical expanded areas with irregular shape. These findings warrant further investigation into optimization of pseudolaric acid B to explore a potential antifungal agent for crop protection.
土荆皮为松科植物金钱松(Pseudolarix kaempferi Gord.)或近缘植物的干燥根皮，仅在中国发现，在中国民间抗真菌疗法中被广泛应用于传统中药。为了寻找防治芒果炭疽病的天然抗真菌剂，从土荆皮的乙醇提取物中通过生物测定指导的分离，分离得到了 8 种化合物，分别为土槿皮酸 A(1)、乙基土槿皮酸 B(2)、土槿皮酸 B(3)、土槿皮酸 B-O-β-D-葡萄糖苷(4)、胡椒酸(5)、丙酸(6)、3-羟基-4-甲氧基苯甲酸(7)和 4-(3-甲酰基-5-甲氧基苯基)丁酸(8)，并评估了它们对 Colletotrichum gloeosporioides Penz 的体外抗真菌活性。结果表明，这 8 种化合物在 5μg/mL 时均能抑制 C. gloeosporioides 的菌丝生长。其中，土槿皮酸 B 和土槿皮酸 A 的抑制作用最强，EC50 值分别为 1.07 和 1.62μg/mL。因此，土槿皮酸 B 和土槿皮酸 A 均能强烈抑制 C. gloeosporioides 的孢子萌发和芽管伸长。与相同浓度的多菌灵相比，100μg/mL 的土槿皮酸 B 处理对芒果果实采后炭疽病的抑制作用更为明显。扫描电子显微镜观察发现，土槿皮酸 B 导致 C. gloeosporioides 的菌丝形态发生改变，包括扭曲、肿胀和崩溃。土槿皮酸 B 导致菌丝顶端呈异常生长，在亚顶端扩展区域出现多个分支，形状不规则。这些发现值得进一步研究优化土槿皮酸 B，以探索一种潜在的作物保护用抗真菌剂。
