冰城链霉菌HU176中两个米尔贝霉素D异构体的分离鉴定及其杀线虫活性OA

To discover novel milbemycin-type compounds with insecticidal activity,two isomers(1 and 2)of milbemycin D with nematicidal activity were isolated and purified from the secondary metabolites of Streptomyces bingchenggensis HU176.Purification was achieved using gel column chromatography and high-performance liquid chromatography(HPLC).Based on comprehensive spectroscopic analyses(1H NMR,13C NMR,HRESI-MS)and comparison with literature data,their structures were identified as 12-desmethyl-12-ethyl milbemycin A4 and 24-desmethyl-24-ethyl milbemycin A4,respectively.Bioassay results showed that compounds 1 and 2 exhibited moderate nematicidal activity against Bursaphelenchus xylophilus,with LC50 values of 14.53 and 16.89 μg/mL,respectively.These values were comparable to that of the positive control avermectin B1a(LC50=12.42 μg/mL).Notably,compound 1 is a new milbemycin analog,and compound 2,a known compound,is reported as a natural product for the first time.These findings provide a valuable reference for the further development and utilization of milbemycin-type compounds.