Synthesis and bacteriostatic activity of ten-,twelve-and sixteen-membered azalactone compounds containing phenoxymethyl and chloromethyl group
Macrolides have been extensively utilized in drug discovery to identify new and highly potent fungistatic compounds.A series of novel ten-,twelve-,and sixteen-membered azolides containing phenoxymethyl and chloromethyl compounds C and E were designed and synthesized based on the macrolide compounds WLD and D16-19,which had previously been investigated by the research group as lead compounds.Their fungistatic activities were evaluated in vitro.The results demonstrated that the majority of the compounds C and E exhibited inhibitory activities against the five pathogenic fungi tested at a concentration of 50 mg/L.Among these,C5 and C6 showed inhibition rates of 88%and 90%against Alternaria solani,respectively,while C6 exhibited a 94%inhibition rate against Fusarium graminearum.Notably,the addition of structural fragments carbamate and urea did not significantly enhance the compound activity.Furthermore,hexadecyl azalactones C5 and C6 displayed higher inhibitory activity compared to ten-and twelve-membered azalactone C1-C4,indicating that the azalactone ring,as the main structural element of the compounds,had a greater impact on their activities.Compound C5 exhibited an EC50 value of 2.95 mg/L against A.solani,similar to the activity of the control drug pyraclostrobin and superior to the lead compound D16-19 against A.solani(EC50 value of 4.76 mg/L).This suggests that adding phenoxymethyl to hexadecyl azoguanide can enhance the compounds'activity against A.solani.Further investigation is warranted to determine the potential of compound C5 as a novel bacteriostatic lead compound.