PEMANFAATAN METABOLIT SEKUNDER DAUN PAITAN (Tithonia diversifolia) SEBAGAI INHIBITOR ENZIM ALFA-GLUKOSIDASE

MADE GENDIS PUTRI PERTIWI, Dr. Endang Astuti, M.Si. ; Dr. Deni Pranowo, M.Si.

2016 | Skripsi | S1 KIMIA

Penelitian pemanfaatan metabolit sekunder daun Tithonia diversifolia untuk menghambat aktivitas enzim alfa-glukosidase dan penentuan tipe inhibitor telah dilakukan. Penelitian diawali dengan ekstraksi metabolit sekunder dengan metode maserasi selama 24 jam menggunakan pelarut n-heksana dan etanol 70%. Kandungan metabolit sekunder yang terdapat pada ekstrak n-heksana (EH) dan ekstrak etanol 70% (EE) dianalisis secara kualitatif melalui uji fitokimia menggunakan metode uji warna. Enzim alfa-glukosidase diperoleh melalui isolasi dan pemurnian parsial dari beras lapuk. Pemurnian parsial ekstrak kasar enzim alfa-glukosidase dilakukan dengan pengendapan menggunakan ammonium sulfat dan dialisis. Enzim alfa-glukosidase hasil pemurnian diuji aktivitas dan ditentukan kinetika reaksi enzimatisnya. Metabolit sekunder yang bersifat polar dan non polar diuji aktivitas penghambatannya terhadap enzim alfa-glukosidase dengan menentukan persentase inhibisi serta tipe inhibitornya. Hasil penelitian menunjukan bahwa EH dengan rendemen 0,70% mengandung senyawa golongan terpenoid sedangkan EE dengan rendemen 2,57% mengandung senyawa golongan flavonoid dan tanin. Pemurnian parsial ekstrak kasar enzim mampu meningkatkan aktivitas enzim alfa-glukosidase sebesar 0,044 U/mL. Enzim alfa-glukosidase dapat menghidrolisis substrat p-nitrofenil-alfa-D-glukopiranosida (pNPG) dengan nilai KM sebesar 9,915 mM dan Vmaks sebesar 0,706 µmol/menit. Aktivitas penghambatan tertinggi terhadap alfa-glukosidase oleh metabolit sekunder polar sebesar 48,68% pada konsentrasi 6,25 mg/L. Metabolit sekunder nonpolar sebesar 6,21% pada konsentrasi 12,50 mg/L sedangkan aktivitas penghambatan quersetin sebagai kontrol positif sebesar 35,39% pada konsentrasi 50 mg/L. Hasil tersebut menyatakan bahwa metabolit sekunder polar berpotensi menghambat aktivitas enzim alfa-glukosidase dengan tipe inhibitor unkompetitif.

Research of alpha-glucosidase inhibiting activity and inhibition type of secondary metabolites from Tithonia diversifolia have been done. The alpha-glucosidase was extracted from the partial purification of rotting-rice. Firtsly, T. diversifolia leaves were macerated using n-hexane and 70% ethanol for 24 hours. Phytochemical analysis revealed the presence of secondary metabolites in n-hexane extract (EH) and ethanol 70% extract (EE) qualitatively by varying color. The alpha-glucosidase was obtained by isolation and partial purification of rotting-rice. Crude extract enzyme was partial purified by ammonium sulfate precipitation and dialysis method. Then, activity of alpha-glucosidase and reaction kinetic were determined. The percent of inhibition from both polar and non-polar secondary metabolites was determined through inhibitory assay. Inhibition type of secondary metabolites was investigated. The results showed that 0.70% of n-hexane extract contains the terpenoids while 2.57% of etanol extract contains the flavonoid and tannin. Increasing of alpha-glucosidase activity (0.044 U/mL) is caused by partial purified of crude extract enzyme. The pNPG substrate is hydrolyzed by alpha-glucosidase with KM value is 9.915 mM and Vmax is 0.706 µmol/min. The inhibitory activity results showed the polar secondary metabolites has the highest inhibitory activity is 48.68% at concentration of 6.25 mg/L. Non-polar secondary metabolites is 6.21% at concentration of 12.50 mg/L and quercetin as positive control is 35.39% at concentration of 50.00 mg/L. Therefore, polar secondary metabolites might be potential as un-competitive inhibitors in inhibiting activity of alpha-glucosidase.

Kata Kunci : aktivitas, enzim alfa-glukosidase, inhibitor, dan metabolit sekunder