Another group reported the fungicidal properties of 1,2,3-thiadiazole derivatives against
Alternaria solani (AS),
Botrytis cinerea (BC),
Cercospora arachidicola (CA),
Cercospora beticola (CB),
Colletotrichum lagenarium (CL),
Fusarium oxysporum (FO),
Gibberella zeae (GZ),
Macrophoma kuwatsukai (MK),
Phytophthora infestans(Mont) de Bary (PI),
Physalospora piricola (PP),
Pellicularia sasakii (Shirai) (PS),
Puccinia triticina Eriks (PT) and
Rhizoctonia solani Kuhn (RS)
[145]. The most active occurred to be structure
146 (
Figure 30) showed potent fungicidal inhibitory activity 84.8, 83.9, 83.3, 78.9, 75.0, 71.4, 70.7, 66.7, 64.7 and 63.6% against PS, PP, RS, PT, FO, CB, PI, AS, CL and CA, respectively. On the other hand, the propyl containing fused 1,2,4-triazolo[1,3,4]thiadiazole
147 (
Figure 30) exhibited the best fungicidal inhibition activity 93.0% for FO, 84.9% for BC, 77.8% for PS, 75.8% for PI, 75.0% for GZ, 62.1% for CA, 50.0% for CL, 40.5% for PP, 34.4% for AS and 33.3% for CB. The results of the antifungal study showed that fused 1,2,4-triazolo[1,3,4]thiadiazole led to the development of wide-spectrum antifungal agents
[145].
Figure 30. 1,2,3-thiadiazoles with broad antifungal activity.
Wang et al. reported a synthetic approach to new series of organotin 4-methyl-1,2,3-thiadiazole-5-carboxylates and benzo[1,2,3]thiadiazole-7-carboxylates
[146] and antifungal properties against
P. piricola and
Gibberella zeae. The triethyltin-based 1,2,3-thiadiazole carboxylate analogue
148 (
Figure 31) displayed antifungal efficacy EC
50 = 0.12 μg/mL and 0.16 μg/mL against
P. piricola, and
Gibberella zeae, respectively. The overall results of the present study indicated the antifungal effectiveness of organotin-based benzo-1,2,3-thiadiazole or 1,2,3-thiadiazoles analogues proved to be broad-spectrum fungicides
[146].
Figure 31. Antifungal benzo[1,2,3]thiadiazole-7-carboxylate derivative 148.
Antifungal properties have also been determined for carboxamide derivatives of thiadiazoles obtained by Zuo et al. utilized one-pot four-component Ugi reaction strategy under green synthetic conditions
[147]. All the synthesized analogues were investigated against eleven fungal strains to develop novel fungicidal candidates. The 1,2,3-thiadiazole containing carboxamide moiety
149 (Figure 32) displayed broad-spectrum fungicidal inhibition activities against CA 71%, AS 100%, GZ 62%, PP 85%, PG 14%, PS, 74%, CL 95%, PI 88% and RS 97%. Similarly good antifungal activity was observed for scaffold
150 that exhibited fungicidal inhibition against various fungal strains such as: CB (
Cercospora beticola) 67%, CA 79%, AS 44%, GZ 34%, PP 53%, PG 57%, PS 16%, CL 43%, RS 51% and PI 57%. The scaffold
149 displayed maximum fungicidal potential 100, 97 and 95% against fungal strains AS, RS and CL, respectively, while the zero percent antifungal activity was shown against CB and FO fungal strains, just as scaffold
150 displayed the best antifungal potential 67% against CB fungal strains and 0% against FO
[147].
Figure 32. The most active 4-methyl-1,2,3-thiadiazole-5-carboxamides.