SINTESIS DAN UJI AKTIVITAS ANTIBAKTERI SENYAWA TURUNAN N-FORMIL-2-PIRAZOLINA TERSUBSTITUSI GUGUS HIDROKSI DARI p-ANISALDEHIDA

PRAMITA SIWI RAHMA A, Dra. Tutik Dwi Wahyuningsih, M.Si., Ph.D. ;Deni Pranowo, S.Si, M.Si

2015 | Skripsi | S1 KIMIA

Sintesis turunan senyawa N-formil-2-pirazolina dan uji aktivitas antibakterinya telah dilakukan. Sintesis senyawa pirazolina dilakukan melalui reaksi sikloadisi antara 1-(2,4-dihidroksifenil)-3-(4-metoksifenil)-2-propen-1-on (kalkon) dengan hidrazin monohidrat dalam suasana asam. Senyawa kalkon disintesis dari p-anisaldehida yang merupakan komponen utama minyak adas dengan 2,4-dihidroksiasetofenon melalui kondensasi Claisen Schmidt dalam suasana basa. Senyawa kalkon disintesis dari p-anisaldehida menggunakan KOH 40% (b/b) melalui pengadukan selama 48 jam pada temperatur kamar. Sintesis senyawa 1-formil-3-(2,4-dihidroksifenil)-5-(4-metoksifenil)-2-pirazolina dilakukan dengan metode refluks antara senyawa kalkon dan hidrazin monohidrat dengan penambahan asam format selama 6 jam. Produk hasil sintesis dikarakterisasi dengan spektrometer FTIR, GC-MS, 1H- dan 13C-NMR. Uji antibakteri dilakukan dengan metode difusi sumuran terhadap bakteri Gram positif (Staphylococcus aureus, Bacillus cereus, Bacillus subtilis) dan Gram negatif (Eschericia coli, Shigella flexneri) dengan kontrol positif tetrasiklin (100 ppm) dan kontrol negatif dimetilsulfoksida DMSO (99,9%). Hasil penelitian menunjukkan bahwa senyawa kalkon telah berhasil disintesis dengan rendemen sebesar 38%. Reaksi sikloadisi menghasilkan senyawa pirazolina dengan rendemen sebesar 88% dan menunjukkan aktivitas sebagai antibakteri terhadap bakteri Gram positif dan bakteri Gram negatif. Aktivitas tertinggi ditunjukkan dengan nilai DDH (mm)/konsentrasi (ppm) terhadap bakteri Gram positif yaitu B. subtillis (5,25/500) dan Gram negatif yaitu S. flexneri (3,25/100).

Synthesis of N-formyl-2-pyrazoline derivative and test of its antibacterial activity have been carried out. The synthesis of pyrazoline was performed via cycloaddition of 1-(2,4-dihydroxyphenyl)-3-(4-methoxyphenyl)-2-propen-1-on (chalcone) by reaction with hydrazine monohydrate in acidic condition. Chalcones was synthesized from Claisen Schmidt condensation of p-anisaldehyde with 2,4-dihydroxyacetophenone. Chalcone was synthesized from p-anisaldehyde using KOH 40% (w/w) at room temperature for 48 hours. Synthesis of 1-formyl-3-(2,4-dihydroxyphenyl)-5-(4-dimethoxyphenyl)-2-pyrazoline was performed by refluxing chalcone and hydrazine monohydrate in the presence of formic acid for 6 hours. All the synthesized compounds were characterized using FTIR, GC-MS, 1H- and 13C-NMR spectrometers. Further, pyrazolines was screened for their 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 chalcone has been succesfully synthesized in 38% yield. Furthermore, the cycloaddition reaction yielded the pyrazoline 88% and showed significant antibacterial activity against Gram-positive bacterial and Gram negative bacterial. The highest activity showed by its zone of inhibitions(mm)/concentration(ppm) against B. subtillis (5.25/500) and Gram-negative S. flexneri (3.25/100).

Kata Kunci : N-formil-2-pirazolina, kalkon, p-anisaldehida, antibakteri