SINTESIS DAN UJI AKTIVITAS ANTIBAKTERI SECARA IN VITRO SENYAWA TURUNAN N-ASETIL-2-PIRAZOLINA TERSUBSTITUSI GUGUS HIDROKSI BERBAHAN DASAR VANILIN; SYNTHESIS AND IN VITRO ANTIBACTERIAL ACTIVITY OF HYDROXYL SUBSTITUTED N-ACETYL-2-PYRAZOLINE DERIVATIVES FROM VANILLIN

Okta Suryani, Tutik Dwi Wahyuningsih

2014 | Disertasi | PROGRAM STUDI S2 KIMIA

Synthesis of N-acetyl-2-pyrazoline derivatives and their antibacterial activity have been carried out. The synthesis of pyrazolines were performed via cycloaddition of 1-(2,4-dihydroxyphenyl)-3-(3,4- dimethoxyphenyl)-2-propen-1-on (chalcone 1) and 1-(2,4-dihydroxyphenyl)-3-(4-hydroxy-3-methoxyphenyl)-2-propen-1-on (chalcone 2) by reaction with hydrazine monohydrate in acidic condition. Chalcones were synthesized from vanillin and veratraldehyde by reaction with 2,4-dihydroxyacetophenone through Claisen Schmidt condensation. Chalcone 1 was synthesized from veratraldehyde using KOH 40% (w/w in aquadest) under stirring at room temperature for 24 h. Chalcone 2 was produced by stirring the mixture of vanillin with KOH 40% for 48 h and refluxing for 24 h, continually. Synthesis of 1-acetyl-3-(2,4-dihydroxyphenyl)-5-(3,4-dimethoxyphenyl)-2-pyrazoline (pyrazoline 1) and 1-acetyl- 3-(2,4-dihydroxyphenyl)-5-(4-hiydroxy-3-methoxyphenyl)-2-pyrazoline (pyrazoline 2) were performed by refluxing chalcone 1 and 2 by reaction with hydrazine monohydrate in glacial acetic acid for 4 h. All the synthesized compounds were characterized using FTIR, GC-MS 1H- and 13C-NMR spectrometers. Further, all the pyrazolines (1 and 2) were screened for their in-vitro antibacterial activities by agar well-diffusion against Gram positive (Staphylococcus aureus, Bacillus cereus, Bacillus subtilis) and negative (Eschericia coli, Shigella flexneri) bacterial, tetracycline (100 ppm) as positive control and dimethylsulfoxide (DMSO 99.9%) as negative control. The result showed that chalcones 1 and 2 have been succesfully synthesized in 80.91 and 68.90% yield, respectively. Furthermore, the cycloaddition reaction yielded the pyrazoline 1 and 2 in 55.56 and 66.10%, respectively. Pyrazoline 1 showed significant antibacterial activity against Gram-positive bacterial and found inactive against Gram negative bacterial. The highest activity showed by its zone of inhibitions(mm)/concentration(ppm) against Staphylococcus aureus (9.75/300). Good antibacterial activity for both Gram negative and positive bacterial was observed for Pyrazoline 2. Zone of inhibitions for gram positive showed by Bacillus subtilis (8.00/300) and Gram-negative Escherichia coli (4.50/500).

Kata Kunci : N-asetyl-2-pyrazoline, chalcone, vanillin, veratraldehida, antibacterial