Novel <i>N</i>-Substituted Amino Acid Hydrazone-Isatin Derivatives: Synthesis, Antioxidant Activity, and Anticancer Activity in 2D and 3D Models <i>In Vitro</i>

A series of novel mono and bishydrazones each bearing a 2-oxindole moiety along with substituted phenylaminopropanamide, pyrrolidin-2-one, benzimidazole, diphenylmethane, or diphenylamine fragments were synthesized, and their anticancer activities were tested by MTT assay against human melanoma A375 and colon adenocarcinoma HT-29 cell lines. In general, the synthesized compounds were more cytotoxic against HT-29 than A375. 3-((4-Methoxyphenyl)(3-oxo-3-(2-(2-oxoindolin-3-ylidene)hydrazinyl)propyl)amino)-N′-(2-oxoindolin-3-ylidene)propanehydrazide and (N′,N‴)-1,1′-(methylenebis(4,1-phenylene))bis(5-oxo-N′-(2-oxoindolin-3-ylidene)pyrrolidine-3-carbohydrazide) were identified as the most active compounds against HT-29 in 2D and 3D cell cultures. The same compounds showed the highest antioxidant activity among the synthesized compounds screened by ferric reducing antioxidant power assay (FRAP). Their antioxidant activity is on par with that of a well-known antioxidant ascorbic acid