Judul: Kinetika Inhibisi Ekstrak Sidaguri (Sida rhombifolia L) terhadap Xantina Oksidase secara Elektrokimia
Abstrak: Uric acid is final product of purine metabolism. Abnormal conditions of uric acid metabolism will cause precipitation of sodium urate crystals in joints, a condition termed gout. Xanthine oxidase (XO) is an enzyme that plays an important role in purine metabolism and functions to catalyze hypoxanthine oxidation into xanthine and, xanthine into uric acid. The well known xanthine oxidase inhibitors (XOIs) is allopurinol, which is one option out of the many synthetic drugs used in modern medicine for the treatment of gout. Nevertheless, the use of allopurinol can cause side effects such as allergies, fever, and gastrointestinal disorders. The side effects of synthetic drug use such as allopurinol have prompted people to turn to traditional medicine that utilizes herbs (medicinal herbs). Sida rhombifolia is one of the traditional medicinal plant with potential as anti-gout. The previous research showed that flavonoids crude extract from this plant could in vitro inhibit the activity of xanthine oxidase up to 71% and the kinetic study by spectrophotometric resulted that the type of flavonoids crude extract inhibition was a competitive inhibition. The purpose of research was to investigate the type of inhibition kinetics of S. Rhombifolia’s ethanol extract by electrochemical method and to compare the study of linearity and sensitivity between electrochemical and spectrophotometric methods. The determination of inhibition kinetics type which is formed can subsequently explain the inhibitory mechanism formed and describe the affinity formed between XO enzyme as a target with drug candidate compounds, whether it is temporary (competitive inhibition and uncompetitive inhibition) or permanent (non-competitive inhibition). The results showed that the yield of S. Rhombifolia’s ethanol extract was 9.82% with the inhibition activity of 13.64% to 82.69% (5.00-200 ppm) and the value of IC50 was 91.15±5.74 ppm. Allopurinol as a control showed the inhibition activity of 15.26-70.95% (0.10-4.00 ppm) and the value of IC50 was 2.45±2.21 ppm. Inibition kinetic of the ethanol extract caused a change of KM (0.187 mM or increase 68.73%) and unchange of Vmax. Based on the data, the type of inhibition kinetic was a competitive inhibition, that had the value of inhibitor affinity (α) of 3.18. The inhibitor affinity value (α) of the enzyme can be determined by calculating the ratio between the value of KM with inhibitors and KM values without inhibitor. Linearity of xanthine oxidase activity assay by electrochemical and spectrophotometric methods showed the range of 0.01-1.00 mM and 0.05-0.70 mM respectively. The sensitivity of electrochemical method was reported higher (0.95 μA mM-1) than the spectrophotometric method (0.007 min-1).
Keyword: electrochemistry, inhibition kinetics, Sida rhombifolia L, xanthine oxidase

Judul: Kinetika Inhibisi Flavonoid Sidaguri (Sida rhombi/alia L.) Terhadap Enzim Xantin Oksidase
Abstrak: Sidaguri is one of the traditional medicinal plants that has a potency as antigout. It has been reported that flavonoid from sidaguri could inhibit activity of x~hine oxidase enzyme (causes gout) up to 55,29% (Iswantini & Darusman, 200~ The aim of this research is to investigate the type of sidaguri's flavonoid crud~ extract kinetic inhibition and the effects of purification on inhibitory poterWY that have never been studied. The result of this research showed that sidagWi's extraction has yielded 11,85% flavonoid crude extract (LCso 501,23 ppm)~ith inhibitory effect from 47,71 % until 70,71% (100-800 ppm). Generally, the eSract has a good potential as gout medicine although it was tested in low conc~tration from the extract's toxicity rate. The kinetic inhibition of 200 ppm crudeDextract caused the increment ofKM (1,15 mM or increase 132%) from 0,87 roM i> 2,02 roM and without changed of V max. Based on that, the type of VI inhibinon is competitive inhibition (Webb 1963). Purification yielded 11 fracti~s and the highest activity came from fraction 4 (inhibitory effect of 79,09!'o). The purification has caused low increase of potent inhibitory effect. Fract~n 3 with 100 ppm has a bit higher inhibitory effect (51,58%) compare to the cI!oe extract at same concentration (47,71%) or increase 8,11%. In general the poten1l:linhibitory effect from purification result has lower strength compare to the 100 Ifm crude extract. GC-MS analysis from fraction 4 showed that there were 39 or..gruric compounds with BM estimation of 152-454 glmol. Based on FT-IR and GC-MS analysis, strengthened with phytochemical test we estimate that the potential compound with xanthine oxidase inhibitory activity is flavonoid compound.
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Judul: PEmetaan Kawasan Peka Bencana Tsunami di wilayah Pesisir propinsi Nusa Tenggara Timur
Abstrak: Kondisi geologi Indonesia yang merupakan pertemuan lempeng-lempeng tektonik menjadi kawasan Indonesia memiliki tingkat kerawanan yang tinggi terhadap bencana alam seperti gempa bumi, tsunami dan rawan letusan gunung api. Gempa bumi yang terjadi di dasar laut mengakibatkan pergolakan massa air yang dapat menghasilkan gelombang besar atau disebut tsunami.
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