SINTESIS DAN UJI AKTIVITAS ANTIBAKTERI SENYAWA PIRAZOLINA BERBAHAN DASAR 3-METOKSI-4-HIDROKSIBENZALDEHIDA (VANILIN) DAN 4-METOKSIBENZALDEHIDA (p-ANISALDEHIDA)

HARYADI NUGRAHA PUTRA, Dr. Chairil Anwar; Dr. Tutik Dwi Wahyuningsih, M.Si

2015 | Skripsi | S1 KIMIA

Telah dilakukan sintesis turunan senyawa pirazolina serta uji aktivitasnya sebagai antibakteri. Senyawa pirazolina pada penelitian ini terdiri dari N-fenil-3-(4-klorofenil)-5-(4-hidroksi-3-metoksi-5-nitrofenil)-2-pirazolina (pirazolina 1), N-fenil-3-(4-hidroksifenil)-5-(4-hidroksi-3-metoksi-5-nitrofenil)-2-pirazolina (pirazolina 2), dan N-fenil-3-(2,4-dihidroksifenil)-5-(4-metoksifenil)-2-pirazolina (pirazolina 3). Pirazolina 1, 2, dan 3 disintesis menggunakan metode refluks dengan asam asetat glasial sebagai katalis. Pirazolina 1 dan 2 masing-masing disintesis melalui reaksi siklokondensasi 1-(4-klorofenil)-3-(4-hidroksi-3-metoksi-5-nitrofenil)-2-propen-1-on (kalkon 1) dan 1-(4-hidroksifenil)-3-(4-hidroksi-3-metoksi-5-nitrofenil)-2-propen-1-on (kalkon 2) dengan fenilhidrazin sedangkan pirazolina 3 disintesis dengan metode siklokondensasi antara 1-(2,4-dihidroksifenil)-3-(4-metoksifenil)-2-propen-1-on (kalkon 3) dan hidrazin monohidrat. Senyawa kalkon 1 dan 2 masing-masing diperoleh dari reaksi kondensasi Claisen Schmidt antara 4-hidroksi-3-metoksi-5-nitrobenzaldehida (nitrovanilin) dengan 4-kloroasetofenon dan 4-hidroksiasetofenon menggunakan katalis NaOH 40% (b/v) sedangkan kalkon 3 merupakan hasil dari reaksi 4-metoksibenzaldehida (p-anisaldehida) dengan 2,4-dihidroksiasetofenon menggunakan katalis KOH 60% (b/v). Senyawa nitrovanilin diperoleh dari reaksi nitrasi vanillin menggunakan kalsium nitrat (Ca(NO3)2). Produk hasil sintesis dianalisis menggunakan spektrometer FTIR, GC-MS, 1H- dan13C-NMR. Uji aktivitas antibakteri hanya dilakukan pada pirazolina 3 karena pirazolina 3 mempunyai kemurnian yang paling tinggi daripada pirazolina 1 dan 2. Uji aktivitas antibakteri menggunakan metode "difusi sumuran" menggunakan bakteri Gram positif (S. aureus, B. cereus, dan B. subtillis) dan Gram negatif (E. coli dan S. flexneri) serta DMSO 99% sebagai control negatif dan tetrasiklin (100 ppm) sebagai control positif. Hasil reaksi nitrasi terhadap vanilin yaitu senyawa nitrovanilin dengan rendemen 95,95%. Hasil reaksi kondensasi Claisen-Schmidt berupa senyawa kalkon 1, 2, dan 3 dengan rendemen masing-masing 94,60%; 47,17%; dan 30,34%. Senyawa target berupa pirazolina 2 dan 3 berhasil disintesis dengan rendemen masing-masing 42,86% dan 71,43%. Senyawa pirazolina 3 menunjukkan adanya aktivitas antibakteri baik pada bakteri Gram positif maupun Gram negatif. Aktivitas tertinggi terjadi pada konsentrasi 500 ppm pada bakteri S. aureus dan B. cereus dan 1000 ppm pada bakteri B. subtillis, E. coli dan S. flexneri.

Syntheses of pyrazoline derivatives and their antibacterial activities have been done. The pyrazolines that have been synthesized were N-phenyl-3-(4-chlorophenyl)-5-(4-hydroxy-3-methoxy-5-nitrophenyl)-2-pyrazoline (pyrazoline 1), N-phenyl-3-(4-hydroxyphenyl)-5-(4-hydroxy-3-methoxy-5-nitrophenyl)-2-pyrazoline (pyrazoline 2), and N-phenyl-3-(2,4-dihydroxyphenyl)-5-(4-methoxyphenyl)-2-pyrazoline (pyrazoline 3). Pyrazolines 1, 2, and 3 were synthesized by reflux method with glacial acetic acid as a catalyst. Both pyrazoline 1 or 2 were synthesized through cyclocondensation reaction between 1-(4-chlorophenyl)-3-(4-hydroxy-3-methoxy-5-nitrophenyl)-2-propen-1-on (chalcone 1) and 1-(4-hydroxyphenyl)-3-(4-hydroxy-3-methoxy-5-nitrophenyl)-2-propen-1-on (chalcone 2) with phenyl hydrazine, whereas pyrazoline 3 was synthesized through the cyclocondensation method, between 1-(2,4-dihydroxyphenil)-3-(4-methoxyphenyl)-2-propen-1-on (chalcone 3) and hydrazine monohydrate. Chalcones 1 and 2 were synthesized through Claisen Schmidt condensation method of 4-hydroxy-3-methoxy-5-nitrobenzaldehyde (nitrovanillin) with 4-chloroacetophenone and with 4-hydroxyacetophenone using catalyst of NaOH 40% (w/v), whereas chalcone 3 was synthesized from 4-methoxybenzaldehyde (p-anisaldehyde) and 2,4-dihydroxyacetophenone using catalyst of KOH 60% (w/v). Nitrovanillin was obtained by nitration of vanillin using calcium nitrate (Ca(NO3)2). The products of syntheses were analyzed by FTIR, GC-MS, 1H- and 13C-NMR. The antibacterial activity test was only performed on pyrazoline 3 because pyrazoline 3 has the highest purity than pyrazolines 1 and 2. The antibacterial activities test has been done with "wells diffusion" method using Gram positive bacteria (S. aureus, B. cereus, and B. subtillis) and Gram negative bacteria (E. coli and S. flexneri), also DMSO 99% as a negative control and tetracycline (100 ppm) as a positive control. The result from nitration of vanillin showed that nitrovanillin was obtained at 95.95% yield. On the other hand, Claisen Schmidt condensation has produced chalcones 1, 2, and 3 with the yield of 94.60%; 47.17%; and 30.34%, whereas products of pyrazolines 2 and 3 were 42.86% and 71.43%. Pyrazoline 3 showed good antibacterial activity both in Gram positive and Gram negative bacteria. The highest activity showed at 500 ppm for S. aureus and B. cereus, also 1000 ppm for B. subtillis, E. coli and S. flexneri.

Kata Kunci : Kata kunci : pirazolina, kalkon, vanilin, p-anisaldehida, aktivitas antibakteri.