Nadia, Airin2022-03-152022-03-152021-10wahyu sari yenihttps://repository.unri.ac.id/handle/123456789/10477Pyrazoline is a five ring heterocyclic compounds that cointaining two nitrogen atoms in a close position with one double bond in the ring which is known to have various bioactivities such as an anti-oxidant, anti-cancer, anti-microbial, and anti-bacterial. The pyrazoline derivative 5-(4- fluoropheny)-3-(1-hydroxynaphthalene-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (PF-NH1-4F) was synthesized by the cyclization reaction of chalcone 3-(4-fluorophenyl)-1-(1- hydroxynaphthalene-2-yl)-2-propen-1-one and phenyl hydrazine with NaOH (in methanol) as catalyst using monowave at 80°C for an hour. The chalcone was prepared by condensing 1- hydroxy-2-acetylnaphtalene and 4-fluorobenzaldehyde with NaOH as catalyst using microwave irradiation at 180 W about 17 minutes. The purity of the pyrazoline was analyzed using TLC, melting point, and HPLC. The yield of the synthesis of chalcone and pyrazoline compounds was 45% and 27,3%. The structure of the synthesized pyrazoline was comfirmed by UV, FTIR, and HRMS spectroscopy analysis. The toxicity of pyrazoline was evaluated by Brine Shrimp Lethality Test (BSLT) method. The result of the test showed that the pyrazoline PF-NH1-4F is highly toxic with LC50 value was 11,1 μg/mLenBSLTchalconepyrazolineArticle