Judul: In Vitro Inhibition of Xanthine Oxidase by Roselle (Hibiscus sabdariffa) and Ciplukan (Physalis angulata) Extracts.
Abstrak: The enzyme xanthine oxidase catalyses xanthine oxidation into uric acid, which plays a crucial role in gout. Roselle and ciplukan as common medicine herbs used in many traditional treatment because it contains secondary metabolite compounds potentially as xanthine oxidase inhibitory. In this research, to water and ethanol extracts from roselle and ciplukan was conducted phytochemical assay, toxicity to Artemia salina , herbs, extract assay, and inhibition assay to xanthine oxidase activity by in vitro, and than to compared allopurinol as positive control. Uric acid crystal growth rate from saturated solution with turbidimetry method was also observed. Ciplukan phytochemical assay showed that flavonoid, tannin, saponin, alkaloid, and steroid compounds but alkaloid and steroid were not detected in roselle extract. Probit analysis to water and ethanol extracts from roselle calyxes and ciplukan herbs showed lethal concentration 50 value (LC50) of 96.95, 40.03, 252.79, and 63.83 ppm, respectively. Ethanol and water extracts from ciplukan (70.08% and 43.66%) showed higher inhibition activity than ethanol and water roselle extracts (35.53% and 20.42%) but still lower than alloprinol (98.63%) in concentration 100 ppm. Among 4 extracts, only ciplukan ethanol extract had the lowest Inhibition concentration 50 value as 74.49 ppm indicated that it is potential to be developed as medicine. Turbidimetry method was not successful for observing uric acid crystal growth.
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Judul: Analisis Fitokimia, Sitotoksik, dan Aktivitas Inhibisi Xantin Oksidase Ekstrak Air dan Etanol Suruhan (Peperomia pellucida (L.) Kunth)
Abstrak: Penyakit gout merupakan kelainan metabolik yang ditandai oleh meningkatnya konsentrasi asam urat. Enzim yang memiliki peranan penting dalam pembentukan asam urat adalah xantin oksidase, yang mengkatalisis oksidasi hipoxantin dan xantin menjadi asam urat. Suruhan (Peperomia pellucida (L.) Kunth) merupakan tanaman obat yang biasa digunakan untuk berbagai pengobatan tradisional. Penelitian ini bertujuan menguji fitokimia, toksisitas terhadap A. salina L, dan aktivitas inhibisi xantin oksidase secara in vitro ekstrak air dan etanol dari suruhan yang dibandingkan dengan alopurinol sebagai kontrol positif. Senyawa metabolit sekunder yang terdapat pada ekstrak air dan etanol suruhan meliputi alkaloid, steroid, tanin, saponin, dan flavonoid. Berdasarkan analisis sitotoksik, ekstrak air dan ekstrak etanol menunjukkan nilai LC50 masing-masing 473.80 ppm dan 276.96 ppm. Ekstrak etanol memiliki daya inhibisi sebesar 32.22%, lebih baik bila dibandingkan ekstrak air sebesar 27.21% pada konsentrasi 150 ppm. Alopurinol memiliki daya inhibisi yang paling besar (32.84%) dibandingkan ekstrak air maupun etanol pada konsentrasi yang sama. Namun dengan nilai persen inhibisi tersebut, ekstrak etanol suruhan dapat dikatakan berpotensi sebagai herba untuk alternatif pengobatan asam urat. Kata kunci : xantin oksidase, asam urat, suruhan, inhibisi
Keyword: Xanthine Oxidase, Gout, Suruhan, Inhibition

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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