红花夹竹桃萃取物对植物病原真菌的抑菌活性

Antimicrobial Activities of Nerium indicum Mill Extracts on Fungal Pathogens

以红花夹竹桃Nerium indicum Mill枝叶为试验材料,分别用石油醚、乙酸乙酯、正丁醇对夹竹桃枝叶提取物进行萃取,采用生长速率法测定不同萃取物对5种病原真菌(小麦雪腐病菌、小麦全蚀病菌、梨黑星病菌、辣椒炭疽病菌、稻瘟病菌)的抑菌活性,计算3种萃取物对5种病原真菌的毒力回归方程和半抑制率(EC50)。结果显示:3种萃取物对5种病原真菌的菌丝体生长均有一定的抑制作用,且抑制率随着萃取物浓度的上升而增大。乙酸乙酯萃取物对供试病原菌的抑制效果最好,质量浓度为10.0mg·mL^(-1)时,乙酸乙酯萃取物对5种病原真菌的抑制率均大于65.0%,尤其对小麦雪腐病原真菌的抑制效果最为显著,最大抑制率达85.7%,半抑制浓度(EC50)为2.03mg·mL^(-1);石油醚萃取物其次,正丁醇萃取物抑制效果最差。3种萃取物对小麦雪腐病原菌的抑制作用均较强,半抑制浓度(EC50)均小于6.28mg·mL^(-1),与其余4种植物病原菌的EC50值相比,抑制效果显著。说明红花夹竹桃乙酸乙酯萃取物能够抑制5种病原菌的正常生长,其中对小麦雪腐病原菌的抑制效果最好。

The branches and leaves of Nerium indicum Mill plants were extracted using petroleum ether,ethyl acetate or nbutanol in this study.The antimicrobial activities of the extracts against 5 pathogenic fungi on plants(i.e.,Gerlachia nivalis,Gaeumannomyces graminis,Venturia nashicola,Colletotrichum capsici,and Magnaporthe oryzae)were determined based on the fungal growth rates under the treatments.From the data,regression equations were obtained,and EC 50 calculated.It was found that the extracts exhibited varying inhibitory rates,which increased with increasing concentration of the extract.The ethyl acetate extract showed the greatest inhibitory effects on the pathogens.At a concentration of 10 mg·mL-1,the extract demonstrated an inhibition rate exceeded 65.0%against all 5 fungi,especially G.nivalis,which reached 85.7%with an EC 50 of 2.04 mg·mL-1.The petroleum ether extract and the nbutanol extract followed in that order on the inhibition effect.All 3 extracts retarded the growths of G.nivalis with an EC 50 below 6.28 mg·mL-1,which was significantly lower than the EC 50 on other fungi tested.