Judul: Potensi Antioksidan dan Toksisitas Ekstrak Daun Sansevieria cylindrica
Abstrak: One of the ornamental plants that have antioxidant activity is Sansevieria sp. These plant has many varieties, one of them is Sansevieria cylindrica that alleged to have antioxidant activity. Antioxidant properties of these plants is not known so we need to investigate it. This study aimed to test the antioxidant potency and toxicity of S. cylindrica leaf extract. S.cylindrica leaf was extracted using 80% methanol, ethanol, 80% acetone, and water. Extraction results was evaporated in vacuum to obtain powder rendements (extracted with methanol, ethanol, water) and clod rendement (extracted with acetone). Extract ability as an antioxidant was determined through neutralization of 1.1-diphenyl-2-picrilhidrazil radical (DPPH). The results from the DPPH test was a radical change color from purple to yellow and the absorbance was measured using a UV-Vis spectrophotometer at 514 nm wavelength. Extract that produced the best antioxidant activity was tested for toxicity using the Artemia salina (Brine Shrimp Test, BST). The antioxidant activity of methanol, ethanol, acetone, and water extract respectively is 65.64%, 67.02%, 70.95% and 71.93% at 800 ppm extract concentration. DPPH test of the four solvents did not produced significant differences (p> 0.05). Phytochemical test results showed the presence of flavonoids and tannins that estimated supports antioxidant activity. BST test result of S.cylindrica leaf extracts showed that the LC50 concentration of the extract occurred at 1223.6820 ppm.
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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: Estimating Parameter and the Convergence of Parameter Estimator of Poisson Hidden Markov Model
Abstrak: Model hidden Markov terdiri dari sepasang proses stokastik yaitu proses observasi dan proses yang memengaruhi observasi. Proses stokastik yang memengaruhi observasi ini diasumsikan membentuk rantai Markov dan tidak diamati. Model Poisson hidden Markov (MPHM) adalah salah satu model hidden Markov diskret dan proses observasinya jika diketahui proses yang memengaruhinya diasumsikan menyebar Poisson., A hidden Markov model (HMM) consists of a pair of stochastic processes, that is the observation process and process that affected observation. The stochastic process which causes this observation is assumed to form a Markov chain and is not observed. Poisson hidden Markov models (PHMM) is one of the discrete HMM and the observation process given the cause is assumed having a Poisson distribution.
Keyword: Poisson hidden Markov model, Forward-Backward algorithm, Expectation Maximization algorithm