Novel 4,5-dihydropyrazole derivatives (3a-i), 3-(4-((3aR,4S,7R,7aS)-1,3-dioxo-3a,4,7,7a-tetrahydro-1H-4,7-methanoisoindol-2(3H)-yl)phenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbothio amide, were obtained by the addition of thiosemicarbazide (2) to the chalcones (1a-i). The addition-cyclization of 2,4-dibromoacetophenone (4) to pyrazole derivatives (3a-i) gave the new pyrazolyl-thiazole derivatives (5a-i), (3aR,4S,7R,7aS)-2-(4-(1-(4-(4-bromophenyl)thiazol-2-yl)-5-phenyl-4,5-dihydro-1H-pyrazol-3-yl)phenyl)-3a,4,7,7a-tetrahydro-1H-4,7-methanoisoindole-1,3(2H)-dione. Antibacterial and acetylcholinesterase (AChE) enzyme and human carbonic anhydrase (hCA) I, and II isoform inhibitory activities of the compounds 3a-i and 5a-i were investigated. Some of the compounds showed promising antibacterial activity. In addition, the hCA II and I were effectively inhibited by the lately synthesized derivatives, with K-i values in the range of 18.90 +/- 2.37 -58.25 +/- 13.62nM for hCA II and 5.72 +/- 0.98 -37.67 +/- 5.54nM for hCA I. Also, the K-i parameters of these compounds for AChE were obtained in the range of 25.47 +/- 11.11-255.74 +/- 82.20nM. Also, acetazolamide, clinical molecule, was used as a CA standard inhibitor that showed K-i value of 70.55 +/- 12.30nM against hCA II, and 67.17 +/- 9.1nM against hCA I, and tacrine inhibited AChE showed K-i value of 263.67 +/- 91.95.