科研之友
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摘要
In our continued efforts to improve the potential utility of the alpha-methylene-gamma-lactone scaffold, 62 new and 59 known natural alpha-methylenelactam analogues including alpha-methylene-gamma- lactams, alpha-arylidene- gamma and delta-lactams, and 3-arylideneindolin-2-ones were synthesized as the bioisosteric analogues of the amethylenelactone scaffold. The results of antifungal and cytotoxic activity indicated that among these derivatives compound (E)-1-(2, 6-dichlorobenzyl)-3-(2-fluorobenzylidene) pyrrolidin-2-one (Py51) possessed good selectivity with the highest antifungal activity against Colletotrichum orbiculare with IC50 - 10.4 mu M but less cytotoxic activity with IC50 - 141.2 mu M (against HepG2 cell line) and 161.2 mu M ( against human hepatic L02 cell line). Ultrastructural change studies performed by transmission electron microscope showed that Py51 could cause important cell morphological changes in C. orbiculare, such as plasma membrane detached from cell wall, cell wall thickening, mitochondria disruption, a dramatic increase in vacuolation, and eventually a complete loss in the integrity of organelles. Significantly, mitochondria appeared one of the primary targets, as confirmed by their remarkably aberrant morphological changes. Analysis of structureeactivity relationships revealed that incorporation of the aryl group into the alpha-exo methylene and the N-benzyl substitution increased the activity. Meanwhile, the alpha-arylidene-gamma-lactams have superiority in selectivity over the 3-arylideneindolin-2-ones. Based on the results, the N- benzyl substituted a-(2-fluorophenyl)-gamma-lactam was identified as the most promising natural- based scaffold for further discovering and developing improved crop- protection agents.
