Design, synthesis and fungicidal activities of Thiasporine A analogues

Thiasporine A was a natural product containing phenylthiazole ring isolated from the marine-derived Actinomycetospora chlora SNC-032 and showed cytotoxicity against the lung cancer cell line H2122. Thiasporine A ( 4o ) and 29 Thiasporine A analogues ( 3a - 3o , 4a - 4n ) were synthesized using substituted benzonitriles as starting material, among which 24 analogues have not been reported in literature. Their structures were characterized by ¹H NMR, ¹³C NMR and HRMS spectra. The fungicidal activities of Thiasporine A and its analogues were tested. The results indicated that most of Thiasporine A analogues exhibited certain fungicidal activities. Compounds 3e and 3i were found to have the inhibition rates of 84.5% and 84.4% against Rhizoctonia solani at a concentration of 200 μmol/L, with the EC₅₀ values of 17.3 μmol/L and 21.9 μmol/L, respectively. Compounds 4b and 4j displayed the inhibition rate of 100% against Selerotium rolfsii at 200 μmol/L. compound 4b demonstrated an inhibition rate of 83.3% against Phytophthora parasitica at 200 μmol/L, which was better than the commercial thifluzamide. The inhibition rates of compound 3g against five fungi were all higher than 70% at 200 μmol/L.