Judul: Aktivitas Antioksidan Fraksi Teraktif Buah dan Daun Asam
Abstrak: Tamarind plant (Tamarindus indica) contain tannins, flavonoids, and saponins which are usually have antioxidant activity. The purpose of this study was to determine antioxidant activity and total phenolic content of the most active fraction of tamarind fruits and leaves. Antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging method and total phenolic content by Folin-Ciocalteu method. The result showed that the most active fraction of tamarind fruits and leaves had IC50 value of 293.22 mg/L and 57.89 mg/L, respectively. These results were higher compared to ascorbic acid as positive control which was 2.12 mg/L. Total phenolic content of the most active fraction of tamarind fruits and leaves was 100.48 mg gallic acid equivalent/100 g dry fruits and 107.44 mg gallic acid equivalent/100 g dry leaves, respectively. The most active fraction of tamarind leaves had higher antioxidant activity compared to its fruit, however both fractions were lower compared to ascorbic acid.
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Judul: Aktivitas Antioksidan Ekstrak Buah dan Daun Mengkudu
Abstrak: Different parts of noni (Morinda citrifolia) plant including fruit and leaf exhibited antioxidant activity. This study was conducted to investigate the antioxidant activity, total phenol, and antioxidant compound group of Noni`s leaf and fruit extracts fractions. This fruit and leaf ethyl acetate extracts were fractionated by column chromatography, yielded 4 and 7 fractions based on the identical thin layer chromatography (TLC) profile. Antioxidant activities of extracts fractions were determined by radical scavenging assay using 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical and the total phenolic contents were measured using Folin-Ciocalteau method. Fraction 1 (IC50 38.18 ppm) of 4 fruit extract fractions and fraction 5 (IC50 85.86 ppm) of 7 leaf extract fractions revealed the highest antioxidant activity, though lower than vitamin C (IC50 3.85 ppm). The total phenolic contents varied from 0.40 mg of gallic acid equivalent/gram dry fruit and 1.15 mg of gallic acid equivalent/gram dry leaf. The result of phytochemical analysis confirmed the responsible antioxidant compounds present in fruit and leaf were considered as alkaloid and flavonoid. In addition, nonphenol compounds had a role as antioxidant acitivity in fruit.
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Judul: Zero-inflated negative binomial models in small area estimation.
Abstrak: The problem of over-dispersion in Poisson data is usually solved by introducing prior distributions which lead to negative binomial models. Poisson data sometime is also suffered by excess zero problems, a condition when data contains too many zero or exceeds the distribution's expectation. Zero Inflated Negative Binomial (ZINB) method can be utilized to solve such problems. This paper demonstrates the adaption of ZINB methods in Small Area Estimation with excess zero data. It is shown that the excess zero problem has substantially influenced the Empirical Bayes (EB) estimates, and the adaption of ZINB methods has improved the precision and reliability of the estimates. Key Words: Small Area Estimation, Zero-Inflation, Poisson-Gamma, Negative Binomial Regression, Empirical Bayes
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