Isolation and Identification of Novel Macrocyclic Lactones from Streptomyces avermitilis NEAU1069 with Acaricidal and Nematocidal Activity

Bioactivity-guided fractionation of Streptomyces avermitilis NEAU1069 fermentation broth was used to isolate and determine the chemical identity of bioactive constituents with acaricidal and nemotocidal activity. The structures of novel compounds 1 and 2 were determined on the basis of spectroscopic analysis, including 1D and 2D NMR as well as HRESI-MS, ESI-MS of spectrometry analysis, UV and IR spectroscopic analyses, and comparison with data from the literature. The acaricidal activities of the isolated compounds against adult mites and mite eggs were evaluated by mortality and unhatched eggs. The nematocidal activity of the isolated compounds against Caenorhabditis elegans was calculated according to the immobilized rates against the total number of tested nematodes. The results indicated that compounds 1 and 2 exhibited potent acaricidal activity against adult mites, with a mortality of >90% at a concentration of 30 μg/mL. However, compounds 1 and 2 showed only weak acaricidal activity against mite eggs, with unhatched mite egg rates of <60% at a concentration of 100 μg/mL. Compound 2, a hydroxylated derivative at C-23 of 1, possessed a high nematocidal activity against C. elegans, with an immobility of >90% at a concentration of 10 μg/mL. These results demonstrate that compounds 1 and 2, especially compound 2, have potential as pesticides with acaricidal and nematocidal activity.