Isatin is an endogenous compound identified in humans that possesses wide range of biological activities. Isatin has anxiogenic, sedative, anticonvulsant activity and acts as a potent antagonist on atrial natriuretic peptide receptors in vitro. A series of p-substituted isatin semicarbazones have shown anticonvulsant activity in MES, scPTZ and scSTY tests. Various isatin N-Mannich bases of isatin-3-thiosemicarbazones have shown antiviral and tuberculostatic activity. Methisazone is an effective compound against variola and vaccinia viruses. The N-dimethyl and morpholino derivative of 5-methyl isatin and trimethoprim exhibited an EC50 of more than 4.3 and 17.7 microgram mL-1 and 17.7 microgram mL-1, respectively. Isatin (3-o-nitrophenyl)hydrazone has shown activity against Walker carcinoma-256. Various substituted indolinones showed antitubercular activity against M. tuberculosis H37Rv with MIC ranging from 10-20 microgram mL-1. Isatin derivatives of Mannich bases had fibrinolytic, muscle relaxant, antiallergic, immunosuppressant, and antithrombotic activity. Isatin showed cardioinhibitory effect on frog heart, and hypotensive, respiratory depression and antidiuretic effects.Izatin je endogeni spoj prisutan u organizmu čovjeka koji posjeduje niz farmakoloških učinaka. Izatin djeluje kao antioksidans, sedativ i antikonvulziv. In vitro je snažni antagonist na receptorima za natrijeve ione u atriju. Serija p-supstituiranih semikarbazona izatina pokazala je antikonvulzivno djelovanje u MES, scPTZ i scSTY testovima, a N-Mannichove baze izatina i izatin-3-tiosemikarbazona virustatsko i tuberkulostatsko djelovanje. Metisazon je učinkovit protiv infekcija variola i vakcinia virusima. EC50 N-dimetil i morfolino derivata 5-metilizatina i trimetoprima veći je od 4,3, odnosno 17,7 g mL-1. Izatin (3-o-nitrofenilhidrazon) inhibira rast tumorskih stanica Walker-256, a supstituirani indolinoni su aktivni protiv M. tuberculosis H37Rv (MIC vrijednosti 1020 g mL-1. Mannichove baze izatina djeluju kao fibrinolitici, miorelaksansi, antihistaminici, imunosupresivi i antitrombotici. Izatin ima kardioinhibitorni učinak na srce žabe, a djeluje i kao hipotenziv, depresor respiracije i antidiuretik
