ISOLASI DAN IDENTIFIKASI SENYAWA PENANGKAP RADIKAL 2,2-DIFENIL-1-PIKRIHIDRAZIL DARI KULIT BATANG BIDARA (Zizyphus mauritiana Auct. non Lamk.)

PUTU OKA SAMIRANA, Dr. Ratna Asmah Susidarti, MS., Apt

2014 | Tesis | S2 Ilmu Farmasi

Keberadaan radikal bebas yang berlebihan sering memicu berbagai penyakit degeneratif. Penelitian ini bertujuan untuk mengisolasi dan mengidentifikasi senyawa antioksidan yang terdapat pada kulit batang bidara (Zizyphus mauritiana Auct. non Lamk.). Isolasi dilakukan secara bioassay-guided fractionation, sedang aktivitas antioksidan diuji dengan metode penangkapan radikal DPPH. Ekstrak metanol kulit batang bidara ditriturasi sehingga didapat fraksi n-heksan, etil asetat dan residu ekstrak methanol, yang selanjutnya diuji aktivitas antioksidan penangkapan radikal DPPH. Fraksi etilasetat yang aktif selanjutnya dipisahkan berulang-ulang menggunakan kromatografi cair vakum (KCV) dan pemurnian menggunakan KLT preparatif hingga didapatkan isolat aktif. Kemurnian isolat diuji secara KLT dan pemeriksaan titik lebur, dan strukturnya ditentukan secara kimiawi (pereaksi semprot) dan spektrometri UV-Vis, IR, LC-MS dan 1H-NMR. Ekstrak metanol, fraksi n-heksan, fraksi etilasetat, residu ekstrak metanol dan fraksi hasil pemisahan etil asetat ditentukan kandungan fenolik dan flavonoid totalnya. Hasil penelitian menunjukkan bahwa residu ekstrak metanol mengandung fenolik total paling tinggi (36,29 % b/b EAG) dan Fraksi E4 mengandung flavonoid total paling tinggi (21,31 % b/b EK). Isolat aktif memiliki aktivitas penangkap radikal DPPH dengan IC50 sebesar 7,58 μg/mL. Berdasarkan analisis spektroskopik, isolat aktif mengandung senyawa triterpen yang berkondensasi dengan gugus p-kumaroil dan memiliki konfigurasi trans.

The presence of excessive free radicals often leads to many degenerative diseases. This study aimed to isolate and identify the antioxidant compounds from the stem bark of Jujube tree (Zizyphus mauritiana Auct. non Lamk.). Isolation was conducted by bioassay guided fractionation, while antioxidant activity was assayed by DPPH radical scavenging method. The methanol extract of the stem bark was triturated into fraction n-hexane, ethyl acetate and methanol extract residue and all of them were examined for their DPPH radical scavenging antioxidant activity. The ethyl acetate fraction were then separated by repeated vacuum liquid chromatography (VLC) and purified using preparative TLC to obtain the active isolate. The purity of the isolate was evaluated by TLC method and melting point measurement. The structure of the isolate was identified chemically using various spray reagent and UV-Vis, IR, LC-MS and 1H-NMR spectroscopic method. The methanol extract, n-hexane fractions, ethyl acetate fraction, methanol extract residue and fractions derived from the separation of ethyl acetate fraction were determined for their total phenolic and flavonoid content. The results showed that the methanol extract residue containing the highest total phenolic (36.29 % w/w EGA), while E4 fraction containing the highest total flavonoids (21.31% w/w EQ). The active isolate having the DPPH radical scavenging activity with IC50 of 7.58 /mL. Based on spectroscopic analysis, active isolate contains triterpene compound which condense with p-coumaroyl group and their have trans configuration.

Kata Kunci : Zizyphus mauritiana, aktivitas penangkap radikal DPPH, triterpen, p-kumaroil, fenolik dan flavonoid total