Discovery of novel carbazole derivatives containing a 1,3,4-thiadiazole moiety as antifungal candidates

Abstract

Fifteen novel carbazole derivatives of 2-(9H-carbazol-9-yl)-N-(5-phenyl-1,3,4-thiadiazol-2-yl)acetamide were designed, synthesized and evaluated for their antifungal activities against Pellicularia sasakii (P. sasakii), Fusarium oxysporum (F. oxysporum), Gibberella zeae (G. zeae), Phytophthora infestans (P. infestans), Cytospora mandshurica (C. mandshurica) and Capsicum wilt (C. wilt). The results of antifungal activity tests indicated that the inhibitory rates of compounds 2-(2-chloro-9H-carbazol-9-yl)-N-(5-(4-fluorophenyl)-1,3,4-thiadiazol-2-yl)acetamide (3h) and 2-(2-chloro-9H-carbazol-9-yl)-N-(5-(thiophen-2-yl)-1,3,4-thiadiazol-2-yl)acetamide (3o) against P. sasakii were 72.89% and 74.29%, respectively, which displayed better bioactivity compared with commercial fungicides hymexazol (53.09%) and carbendazim (69.65%). Meanwhile, compounds 2-(9H-carbazol-9-yl)-N-(5-(thiophen-2-yl)-1,3,4-thiadiazol-2-yl)acetamide (3f) and 2-(3-iodo-9H-carbazol-9-yl)-N-(5-(p-tolyl)-1,3,4-thiadiazol-2-yl)acetamide (3 l) exhibited the inhibition rates of 72.40% and 67.65% against C. wilt, respectively, which were better than the commercial fungicides hymexazol (50.21%) and carbendazim (65.33%).

GRAPHICAL ABSTRACT

Keywords:

• Carbazole
• 1,3,4-thiadiazole
• synthesis
• antifungal

Disclosure statement

The authors declare no conflict of interest.

Figure 1. The design of the title compounds.

Additional information

Funding

The study was performed under financial support by the Qiandongnan Science and Technology Plan Project (Qiandongnan kehe J [2022]40), the Qiandongnan Science and Technology Plan Project (Qiandongnan kejichu [2021]17), 2022 Special Subject of Supporting the Quality Improvement Project of Municipal (Prefectural) Colleges and Universities in Qiandongnan (QDNCJ[2022]51klxy23), and the Youth Science and Technology Talent Growth Program of Guizhou Province’s Department of Education (Qian Jiaohe KY [2022]074).