Novel thiosemicarbazone chitosan derivatives: Preparation, characterization, and antifungal activity

► Three novel thiosemicarbazone chitosan derivatives were obtained via condensation reaction of thiosemicarbazide chitosan with phenylaldehyde, o-hydroxyphenylaldehyde, and p-methoxyphenylaldehyde, respectively. ► The derivatives had broad-spectrum antifungal activity that was greatly enhanced in comparison with chitosan. ► Antifungal activity of o-HPHTCNCS against Stemphylium solani and Rhizoctonia solani was comparable to that of polyoxin. ► At 0.05 mg/mL, the o-hydroxyphenylaldehyde thiosemicarbazone chitosan inhibited growth of R. solani at 52.6%, and was stronger than polyoxin whose antifungal index was found to be 31.5%.