Judul: Antioxidant, HMG-CoA Reductase Ihibition activity, and Chemical Compound Identification of Surian (Toona sinensis) Leaves Extract.
Abstrak: Surian (Toona sinensis) is forest plant that are widespread in Asia. This plant only used and known as a comodity for carpentry in Indonesia but in other nation surian is known as spices and traditional medicine because of its natural antioxidant potential. The objective of this study was assayed total phenolic content, total flavonoids content, antioxidant activity, HMG-CoA reductase inhibition activity and to analyze chemical compound from Surian leaves extract. Surian leaves were extracted by water and ethanol solvent. Water extraction was conducted by reflux in 90 oC then ethanol extraction was conducted by maceration, which is through various concentration 70%, 80%, 90%, and 96% of ethanol. Total Phenolic content was determined according to the Folin–Ciocalteu method using miligram of gallic acid equivalent and total flavonoid content was evaluated using aluminium chloride by compared with quercetin standard. Antioxidant activity of the water and ethanol extracts was evaluated using DPPH radical scavenging method. Inhibition of HMG-CoA reductase was assayed in vitro using single concentration inhibition with atorvastatin as comparison. Total phenolic and flavonoid content of ethanol 90% extract and ethanol 96% extract had higher amount than the other. The ethanol 96% extract had the strongest DPPH inhibition conccentration 50% (IC50), which is 3.38 μg /mL while ascorbic acid is 3.90 μg /mL as a comparison. The ethanol 96% extract also had highest inhibition HMG-CoA reductase activity which is 79.13% and this activity strongest in water fraction from this extract with inhibition 91.49% while atorvastatin as a comparsion is 92.45%. Antioxidant and inhibition ezyme activity had strong corelaltion with total flavonoid content. Chemical compound by LC-MS assay mostly are counted in the flavonoids group.
Keyword: Antioxidant, Flavonoids, HMG-CoA reductase, Toona sinensis

Judul: Antioxidant Activity and Total Flavonoids Content of Water and Ethanol Extract of Surian Leaves (Toona sinensis) on Various Tree Ages
Abstrak: Ekstrak daun tanaman surian diketahui memiliki kandungan senyawa flavonoid yang berfungsi sebagai antioksidan. Penelitian ini bertujuan menguji aktivitas antioksidan dan menghitung kadar total flavonod dari ekstrak air dan etanol daun surian pada berbagai umur pohon surian. Penelitian ini menggunakan pelarut air, etanol 30%, 70% dan 96% pada umur tanaman 16, 27 dan 34 tahun. Kadar total flavonoid diukur menggunakan metode Alumunium Klorida (AlCl3) dan aktivitas antioksidan menggunakan metode FRAP. Hasil penelitian menunjukan ekstrak etanol 96% daun surian menghasilkan kadar total flavonoid dan aktivitas antioksidan FRAP tertinggi pada umur tanaman 34 tahun dan ekstrak air daun surian menghasilkan kadar total flavonoid dan aktivitas antioksidan FRAP terendah pada umur tanaman 16 tahun. Kadar total flavonoid tertinggi sebesar 84.4559 mg QE/g DW dan kadar total flavonoid terendah sebesar 5.1069 mg QE/g DW. Aktivitas antioksidan FRAP tertinggi sebesar 330.061 μmol TE/g DW dan aktivitas antioksidan FRAP terendah sebesar 837.939 μmol TE/g DW. Simpulan dari penelitian adalah semakin tinggi kadar total flavonoid pada ekstrak daun surian maka semakin berpotensi sebagai sumber antioksidan alami., Surian leaves extract is known to contain flavonoid compounds that function as antioxidants. This study aimed to examine the antioxidant activity and calculate the levels of flavonoid from the aqueous and ethanol extracts of surian leaves from various ages of surian trees. This study used water, 30%, 70%, and 96% ethanol as a solvent for the surian plants ages 16, 27, and 34 years. Total flavonoid levels are measured using the Aluminum Chloride (AlCl3) method and antioxidant activity using the FRAP method. The results showed that the 96% ethanol extract of surian leaves produced the highest levels of total flavonoids and FRAP antioxidant activity at the age of 34 years and the aqueous extract of surian leaves produced the lowest levels of total flavonoids and antioxidant activity of FRAP at the age of 16 years. The highest total flavonoid content is 84.4559 mg QE/g DW and the lowest total flavonoid content is 5.1069 mg QE/g DW. The highest FRAP antioxidant activity is 330.061 μmol TE/g DW and the lowest FRAP antioxidant activity is 837.939 μmol TE/g DW. The conclusion from the research is that the higher the total flavonoid content in surian leaves extract, the more potential it is as a source of natural antioxidants.
Keyword: antioxidant, FRAP, surian leaves, flavonoids

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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