Abstract:
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 intermediates
C and compounds
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 activity. Compound
C5 exhibited an EC
50 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 (EC
50 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.