Judul: Fraksi aktif ekstrak daun Sansevieria trifasciata Prain sebagai penghambat pertumbuhan sel lestari HeLa
Abstrak: Sansevieria trifasciata Prain is an ornamental plant which is also useful as a source of antibacterial and antioxidant agent. Studies of S. trifasciata Prain as anticancer have not been reported. Therefore, the objective of this study is to isolate bioactive compounds of S. trifasciata Prain leaves that shows in vitro proliferation inhibition of HeLa cell lines. The sample was macerated in 96% methanol and concentrated using a rotary evaporator. The crude extract was fractionated using chromatography column with silica gel as the stationary phase and gradient chloroform-ethyl acetate as the mobile phase. Qualitative phytochemical and inhibition activity using MTT assay (3- (4,5-dimethylthiazol- 2-yl)-diphenyltetrazolium-2,5-bromide) were performed on the crude extract and its fractions at concentrations between 200 and 1000 ppm. The crude extract contained flavonoids, alkaloids, and steroids, but the crude extract could not inhibit proliferation of HeLa cell lines. The chromatography resulted 10 fractions, however, there was only one fraction with the highest proliferation inhibition was 87.52% at concentration of 10000 ppm that. This fraction contained flavonoids and alkaloids.
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Judul: Aktivitas antibakteri fraksi aktif daun lidah mertua (Sansevieria trifasciata Prain)
Abstrak: Sansevieria trifasciata Prain is an indigenous plant of South Africa and indicated has an antibacterial activity. The purpose of this study is to evaluate the potential of this speciesas antibacterial to inhibit the activity of Staphylococcus aureus and Escherichia coli using disc diffusion method. Some leaves were extracted using maceration method. The result indicated that crude extract at concentration 1250, 2500, 5000, and 10000 ppm showed no activity against the test bacterial. Steroids, flavonoids, and alkaloids were found in the crude extract. The crude extract was fractionated using column chromatography. Ethyl acetate and chloroform were used as eluent with the best ratio (6:1). The fractionation yield 10 fractions. The fraction were test at concentration 10000, 20000, and 40000 ppm. The antibacterial assay showed there was only 1 fraction active against Gram-positive (S. aureus).
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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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