Judul: Profil Kimiawi Ekstrak Ramuan Kunyit, Temulawak, dan Meniran Berdasarkan Aktivitas Antioksidan
Abstrak: Research of the antioxidants and chemical profile that generated a lot of herbs have been carried out. The aim of this research is to analyze chemical profile of extracts concoction turmeric, curcuma, and meniran based of the best antioxidant activity. Samples were made formula and prepared by maceration with 96% ethanol. Formula used based on the comparison meniran:turmeric:curcuma, that is 1:1:1, 1:1:0, 1:0:1, 0:1:1, 1:0:0, 0:1:0, and 0:0:1. Antioxidant activity was determined by 1,1-diphenyl-2-picrylhidrazyl (DPPH) method. The extracts concoction chemical profiles was determined by spectrophotometry fourier transform infrared (FTIR) and thin layer chromatography (TLC). The extracts concoction turmeric, curcuma, meniran showed high antioxidant activity because they had IC50 less than 200 ppm, except formula 0:0:1. Three extracts having highest antioxidant activity are formula 1:0:0, 1:0:1, and 0:1:0 were 19.9135 ppm, 69.5428 ppm, and 103.3161 ppm respectively. The chemical profiles from those extracts showed different pattern because they have different functional groups (based of FTIR profiles) and different number of separate compounds (based of TLC profiles).
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Judul: Profil Kimiawi dari Formulasi Ekstrak Meniran, Kunyit, dan Temulawak Berdasarkan Aktivitas Antioksidan Terbaik
Abstrak: Indonesia is known as a megabiodiversity countries with the title because it has such biodiversity of flora and fauna. Flora or plant widely used as medicine by traditional means, namely phyllanthin, curcuma, and turmeric. Phyllanthin, curcuma, and turmeric extracts are the plant extracts which contains antioxidant activity. This study aimed to evaluate the antioxidant activity of the formulation phyllanthin, turmeric, and curcuma. Phyllanthin, curcuma, and turmeric is extracted using 96% ethanol and extract formulation carried M:K:T ratio of 1:1:1, 1:1:0, 1:0:1, 0:1:1, 1:0 : 0, 0:1:0, and 0:0:1. Extract formulation phyllanthin: curcuma: turmeric (M:K:T) tested the antioxidant activity with DPPH method. Extracts formulation of which have the highest antioxidant activity of the chemical profile was analyzed by TLC and FTIR. Antioxidant activity which have the highest to explained from extract formulation M:K:T = 1:0:0, 1:1:0, dan 1:0:1 by IC50 percentage antioxidant activity are 33.42 ppm, 45.52 ppm, dan 57.65 ppm. TLC chromatogram profiles obtained from formulations M:K:T = 1:1:0, 1:0:1, and 1:0:0 showed the number of spots as much as 10, 8, and 7 spots. FTIR spectrum results showed functional groups of O-H stretching, C-H stretching, C=C stretching and C=C bending in each formulation which have the highest antioxidant activity.
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Judul: Bifurkasi Hopf pada siklus bisnis IS-LM tanpa dan dengan waktu tunda
Abstrak: One of business cycle models in dynamical economics is the IS-LM business cycle model with time delay, where the time delay lies in stock capital variables. It is a time delay between the existence of stock capital and the time to get ready to invest. In a model without time delay, changing the parameter of investment rate on income could affect the system stability. On the other hand, in a model with time delay, there exists critical time delay changing the system stability. This shows limit cycle, which can be concluded that Hopf bifurcation occurs
Keyword: Bogor Agricultural University (IPB), time delay, Hopf bifurcation, business cycle model