Judul: Pengoptimuman Metode Isolasi Asiatikosida Dari Pegagan (Centella Asiatica).
Abstrak: Asiatikosida merupakan senyawa penciri pada pegagan (Centella asiatica) yang memiliki aktivitas antiinflamasi, antioksidan, dapat menginduksi perubahan ekspresi gen, penyembuh luka, mereduksi pembentukan bekas luka, neuroprotektif, dan meningkatkan biosintesis kolagen. Dalam penelitian ini telah dikembangkan metode isolasi senyawa asiatikosida dari pegagan. Ekstraksi asiatikosida dilakukan secara maserasi dengan menggunakan metanol sebagai pelarut. Pemurnian selanjutnya menggunakan kromatografi kolom dan kromatografi lapis tipis preparatif (KLTP). Asiatikosida hasil isolasi dicirikan berdasarkan kromatogram cair-spektrum massa serta ditentukan kemurniannya dengan kromatografi cair kinerja tinggi. Sampel 1 (fraksi KLTP ke-2 dari fraksi kolom ke-4 ekstrak metanol) memiliki rendemen akhir dugaan asiatikosida sebesar 0.063% dengan tingkat kemurnian 89.7%, sedangkan sampel 2 (fraksi KLTP ke-2 dari ekstrak kasar pegagan) memiliki rendemen akhir 0.092% dengan tingkat kemurnian 40.4%. Metode isolasi asiatikosida yang telah dioptimumkan pada penelitian ini sudah lebih baik dibandingkan metode sebelumnya.
Keyword: asiatikosida, Centella asiatica, ekstraksi, isolasi

Judul: Pengoptimuman Ekstraksi dan Pemurnian Asiatikosida dari Pegagan (Centella asiatica)
Abstrak: Extraction of asiaticoside from Centella asiatica has already reported but the effective extraction method should be continuously developed. This study was developed to find an effective extraction and purification method of asiaticoside from this species. Extraction parameter such as temperature, time, and solvent were varied and extraction was conducted using ultrasonic. Asiaticoside content from crude extract was determined using ultraviolet-visible spectrophotometer. Asiaticoside from the extract was further isolated by column chromatography with chloroform: methanol as using step gradient elution. The concentration and purity of asiaticoside fraction from preparative TLC was determined using high performance liquid chromatography analysis. The optimum extraction conditions was that using ethanol as solvent at 30 °C for 15 min. The result showed that the best eluent to separate asiaticoside fraction was chloroform: methanol in 6:4, 5:5, and 4:6 ratios. The asiaticoside contents of fraction 1 and 2 was 23:14 mg/g preparative TLC fraction and 193.75 mg/g preparative TLC fraction with purity less than 50%.
Keyword: extraction, Centella asiatica, asiaticoside

Judul: The Effects of Variance of Interest rate to Variance of Annuity Future Values
Abstrak: Time value of money is a concept that refers to the difference of the value of money due to time difference. The value of money for present time would not be the same as the value of money in the future. The value of money for present time is called as Present Value (PV) of the money and the value of money for future time is called Future Value (FV) of the money. Determination the value of money, for present and future time, depends on the time and rate of return. The value of money is determined by several factors such as inflation, fluctuation of interest rates, and government policy in securities and taxation. Due to fluctuation of the value of money we need a FV formulation, it is useful for knowing whether an investment can be profitable or not, and this information is useful also in budget analysis. Annuity is defined as a series of payments made for a specific period. The payment, fixed or varied, can be made at the beginning or at the end of the period. Annuity paid at the beginning of the period is called annuity-due and annuity paid at the end of the period is called immediate annuity-certain. The accumulated value of the annuity after few years later is called as a final value or a future value. Burnecki et al. (2003) have discussed about the FV of a fixed-rate annuity in which payments are made according to the arithmetic or geometric series. They have also examined FV for annuities in which payments are made according to arithmetic or geometric series with random rates of interest. This paper examines FV for annuity-due in which payments are made according to arithmetic or geometric series with interest rates as a random variable, which is normal distribution ,  . Future value formula is expressed in recursive form. FV for annuity-due which payments are made according to the arithmetic or geometric series with random rates of interest is calculated by theoretical way and simulation way. The random rates of interest is denoted as k k i  i  , where k i an independent random variable; i is a constant and k  is a random variable which has normal distribution ,  . By using the determined parameters, a sequence of random rates of interest are generated for theoretical calculation. Meanwhile for the simulation, the random rates of interest is generated 1000 times for the simulation. The generated data give mean value, variance, and standard deviation. Moreover, error of mean value, variance, and standard deviation from the theoretical and simulation results are calculated. Error calculation uses Symmetric Mean Absolute Percentage Error (SMAPE). The smaller the value of SMAPE is the more accurate the simulation. The interest rate variances are varied from 0.000036 to 0.0001 to study the relationship between variance of rates of interest and variance of future value. The theoretical and simulation results show that when the variance of random rates of interest increases, then the variance of FV increases linearly. FV of the annuity-due in
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