Synthesis, in-vitro Antimicrobial and Antitubercular Screening of Some Schiff Base of 5-amino-4-(2-(4-phenyl-1,3-thiazol-2-yl)hydrazinylidene)-2,4-dihydro-3H-pyrazol-3-one

New series of some Schiff bases of 5-amino-4-(2-(4-phenyl-1,3-thiazol-2-yl)hydrazinylidene)-2,4-dihydro- 3H-pyrazol-3-one(TZP3a-l)has been synthesized. Title compounds were screened for their preliminary antimicrobial activity against Gram-positiveand Gram-negative bacteria as well as fungal strains. Antimycobacterialactivities of synthesized compounds werescreened against Mycobacterium tuberculosis andMycobacterium smegmatis. The synthesized Schiff bases (TZP3a,TZP3b,TZP3c,TZP3dand TZP3l)were found to havesignificantactivity against Gram-positive bacteria. CompoundsTZP3c, TZP3d and TZP3l showed appreciable antitubercular activity against Mycobacterium tuberculosis H37Rv strain (MIC = 15.28 x 10 -3 µM/mL) than the standard drug, Pyrazinamide (25.38 x 10 -3 µM/mL). Their invitro cytotoxicity (IC50) usingmouse embryonic fibroblasts cell line (NIH 3T3) was determined to establish selectivity index (SI). no new antitubercular drug has been registered during the last forty years.Further, the life-threatening infections caused by multidrug-resistant (MDR)Gram-positive bacteria's (Methicillin-Resistant Staphylococcus Aureus (MRSA), Penicillin-Resistant Streptococcus Pneumoniae (PRSP) and Vancomycin-Resistant Enterococci(VRE)); MDRGram-negative bacteria's(Klebsiellapneumoniae, Enterobacter cloacae and Escherichia coli)are resistant to atleast three of the antimicrobial groupsand the resistance of fungal strains increased to an alarming level. The MDR strains are resistant to atleast three of the antimicrobial groups. The three antimicrobial groups include third or fourth generation Cephalosporin's, Amino Glycosides, Fluoroquinolones, Piperacillin, and Ampicillin/Sulbactam 5-7 .