Judul: Penapisan Senyawa Aktif Bunga dan Daun Temulawak (Curcuma xanthorrhiza) sebagai Antioksidan
Abstrak: This study aimed to screen antioxidant compounds on leaves and flower of C. xanthorrhiza using DPPH (2,2-diphenyl-1-picrylhydrazil) method. The flower and leaves were extracted with n-hexane, ethyl acetate, and methanol. Essential oil of the leaves was obtained through water distillation. Each extract and essential oil were determined for theirs antioxidant activities. The ethyl acetate extract of leaves had the best radical scavenging activity with IC50 41.50±7.80 μg/mL but not as good as ascorbic acid as the positive control with IC50 3.36±0.29 μg/mL. Fractionation performed on ethyl aceate leaves extract using silica gel column chromatography by step gradient elution with n-hexane, ethyl acetate, and methanol. Fractionation resulted 13 fractions (F1-F13) and the most active fraction was the F11 fraction (IC50 24.05±2.38 μg/mL). Fraction F11 was separated further by preparative thin layer chromatography and gave 8 fractions (F11.1-F11.8). Fractions F11.1 had the highest antioxidant activity with IC50 of 28.22±7.35 μg/mL. Phytochemical assay and infrared spectroscopy on F11.1 showed that the active compound as the antioxidant was flavonol. Keywords: C. xanthorrhiza, leaves, antioxidant, flavonol
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Judul: Potensi Pelepah Temulawak (Curcuma xanthorriza) sebagai Antikanker dan Antioksidan
Abstrak: The study aimed to evaluate the potency of temulawak (Curcuma xanthorrhiza) stem as anticancer by brine shrimp lethality test (BSLT) and antioxidant by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. The stem of temulawak midrib obtained from Bogor, was extracted by n-hexane, chloroform, ethyl acetate, methanol, and water, and the volatile oil was obtained by water distillation. The chloroform extract and volatile oil showed anticancer potency towards Artemia salina (LC50: 370.69 ± 22.69 μg mL-1 ; 123.05 ± 3.49 μg mL-1, respectively). Ethyl acetate and chloroform extracts had antioxidant activities (IC50: 46.41 ± 15.49 μg mL-1 and 52.72 ± 3.46 μg mL-1) but the activity did not as strong as ascorbic acid (control positive, IC50 1.80 ± 0.33 μg mL-1). The chloroform extract was further fractionated by column chromatography with Silica Gel G60F254-Merck as stationary phase and gradient of n-hexane, chloroform, and methanol as mobile phase. Antioxidant and anticancer potency of fraction which had antioxidant activity qualitatively were tested. The most antioxidant active fraction (F9) had anticancer potency (LC50: 522.95 ± 43.35 μg mL-1) and antioxidant activity (IC50: 79.57 ± 8.96 μg mL-1). In conclusion, F9 is potencial as an anticancer and antioxidant.
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Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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