ISOLASI DAN KARAKTERISASI SENYAWA ANTIBAKTERI DARI KULIT BATANG Xylocarpus granatum J. Koenig

EVELIN AGUSTI, Dr. Ir. Alim Isnansetyo, M. Sc.; Prof. Dr. apt. Ratna Asmah Susidarti, M.S.

2021 | Tesis | MAGISTER BIOTEKNOLOGI

Xylocarpus granatum merupakan tanaman mangrove sejati yang memiliki bioaktivitas sebagai antibakteri. Bioaktivitas antibakteri yang dimiliki berasal dari senyawa kimia (terpenoid, saponin, flavonoid, alkaloid, dan tanin) yang dihasilkan karena lingkungan hidup mangrove yang ekstrim. Tujuan dari penelitian ini adalah melakukan isolasi dan penentuan struktur senyawa yang berperan sebagai antibakteri dari ekstrak kulit batang X. granatum menggunakan metode bioassay guided fractionation, serta menguji aktivitas antibakteri tersebut kepada bakteri Gram positif maupun Gram negatif. Sampel diambil dari Pulau Setoko, Kota Batam, Kepulauan Riau. Sampel diekstraksi dengan metode maserasi bertingkat (n-heksan, etil asetat, kemudian etanol). Masing-masing ekstrak diuji akitivitas antibakteri terhadap bakteri Gram positif dan Gram negatif dengan metode difusi agar lapis ganda. Ekstrak yang paling aktif selanjutnya difraksinasi dengan metode kromatografi kolom dan diperoleh isolat aktif. Isolat aktif dikarakterisasi dengan Gas Chromatography-Mass Spectrometry (GC-MS) untuk mengetahui senyawa yang terkandung dan aktivitas antibakterinya diuji Minimum Inhibitory Concentration (MIC) dan Minimum Bactericidal Concentration (MBC) menggunakan metode mikrodilusi. Hasil ekstraksi yang memiliki aktivitas antibakteri terbaik adalah ekstrak etanol kulit batang X. granatum. Senyawa-senyawa yang terbaca pada basis data WILEY 09 Library, dengan similarity index dan persen area dominan adalah 1,2-Benzenediol (Catechol) dan 1,3,5-Benzenetriol (Phloroglucinol). Isolat aktif diujikan pada bakteri Gram positif (Mycobacterium sp. dan Staphylococcus aureus) dan bakteri Gram negatif (Aeromonas hydrophila dan Vibrio sp.). Aktivitas antibakteri X. granatum terhadap bakteri Mycobacterium sp., S. aureus, Aeromonas hydrophila dan Vibrio sp. menunjukkan nilai MIC berturut-turut sebesar 25 mikrogram/ml, 50 mikrogram/ml, 200 mikrogram/ml, dan >400 mikrogram/ml. Nilai MBC terhadap Mycobacterium sp., S. aureus, A. hydrophila dan Vibrio sp. yaitu sebesar 50 mikrogram/ml, 200 mikrogram/ml, >400 mikrogramg/ml, dan >400 mikrogram/ml. Aktivitas antibakteri isolat aktif kulit batang X. granatum terhadap bakteri Gram negatif lebih rendah dibandingkan dengan bakteri Gram positif. Penelitian ini menambah informasi mengenai potensi kulit batang X. granatum dari Kepulauan Setoko, Kota Batam, Kepulauan Riau sebagai agen antibakteri Mycobacterium sp. yang selama ini belum pernah dilaporkan.

Xylocarpus granatum is a true mangrove plant that shows bioactivity as antibacterial. Its antibacterial bioactivity derived from chemical compounds (terpenoids, saponins, flavonoids, alkaloids, and tannins) which are produced due to the extreme environment of mangroves. The aims of this study were to isolate and determine the structure of the compounds that act as antibacterial from the X. granatum stem bark extract using the bioassay guided fractionation method, and to test the antibacterial activity on Gram-positive and negative bacteria. Sample was taken from Setoko Island, Batam City, Riau Islands. Sample was extracted by multilevel maceration extraction method (n-hexane, ethyl acetate, then ethanol). Each extract was then tested for its antibacterial activity against Gram-positive and negative bacteria by using the double layer agar diffusion method. The most potent extract was then fractionated by column chromatography method and the active isolate was obtained. Active isolate was further isolated and purified by column chromatography method. The result of purification was characterized by Gas Chromatography-Mass Spectrometry (GC-MS) to determine the compounds present in the extract of X. granatum stem bark and their antibacterial activity were assayed for Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) using the microdilution method. The result of extraction which showed antibacterial activity was ethanol extract. The compounds read in the WILEY 09 Library database, with a similarity index and percent of the dominant area, were identified as 1,2-Benzenediol (Catechol) and 1,3,5-Benzenetriol (Phloroglucinol). Active isolates were tested against Gram-positive bacteria (Mycobacterium sp. and Staphylococcus aureus) and Gram-negative bacteria (Aeromonas hydrophila and Vibrio sp.). Antibacterial activity of X. granatum against Mycobacterium sp., S. aureus, Aeromonas hydrophila and Vibrio sp. exhibited MIC values of 25 microgram/ml, 50 microgram/ml, 200 microgram/ml, and >400 microgram/ml, respectively. MBC values against Mycobacterium sp., S. aureus, A. hydrophila and Vibrio sp. were 50 microgram/ml, 200 microgram/ml, >400 microgram/ml, and >400 microgram/ml, respectively. The antibacterial activity of the active isolate of X. granatum stem bark against Gram-negative bacteria was lower than that of Gram-positive bacteria. This study provides information about the potential of X. granatum stem bark from the Setoko Islands, Batam City, Riau Islands as an antibacterial agent for Mycobacterium sp. which has never been reported to date.

Kata Kunci : antibakteri, ekstrak etanol, fraksinasi, isolat aktif, Xylocarpus granatum