Judul: Fraksi Aktif Antioksidan dari Ekstrak Kulit Kayu Sungkai (Peronema canescens Jack.)
Abstrak: Sungkai (Peronema canescens Jack.) bark extract is potentially containing extractive materials with antioxidant properties. The objective of this research was to fractionate 70% of ethanol extract of sungkai bark, hydrolize the n-hexane residue, determine fraction content and antioxidant activity using in vitro testing, and analyze chemical compounds found in three of the most active fraction. Fractionation was conducted using solvent-solvent extraction with n-hexane and ethyl acetate. Antioxidant activity was examined using 1,1-difenil-2-pikrilhidrazil (DPPH) method. The chemical components of three most active fraction were analyzed by gas chromatography mass spectrometry (GC-MS). Extract value of n-hexane fraction was the highest levels.. The three most active fractions with antioxidant properties are non-hydrolized etil acetate, n-hexane, and hydrolized ethyl acetate (IC50 43.67, 44.55, and 53.34 μg/mL). Phenolic compound identification shows several dominant compounds: quinic acid, guaiacol, hydroquinone, isovanillic acid, genkwanin, catechol, and benzoic acid. Those compounds are categorized as phenol and own strong antioxidant activity
Keyword: phenol, sungkai, antioxidant

Judul: Total Fenolik dan Flavonoid serta Aktivitas Antioksidan Ekstrak Kulit Kayu Sengon (Paraserianthes falctaria (L.))
Abstrak: (Paraserianthes falcataria (L)) is widely used in wood industry and resulted many wastes. The leaf was found to have antioxidant activity, but the bark is still reused. The researches about (Paraserianthes falcataria (L)) bark that have been conducted was not studied to show potency of natural antioxidant. This research was performed to determine the antioxidant activity of (Paraserianthes falcataria (L)) bark extract. Phytochemical scavenging showed that aqueous, ethanol 70%, and 96% bark extracts were positively reacted to saponin, flavonoid, tanin, steroid, and triterpenoid test, while the only negative result was happened to alkaloid test. The highest ammount of total phenolic and flavonoid was found in ethanol 70% extract, those were 161.57 ± 3.93 GAE (mg/g) and 64.46 ± 2.94 CE (mg/g) respectively. The highest IC50 value was found in ethanol 96% extract with value of 40.17 ± 0.65 mg/L.
Keyword: antioxidant, flavonoid, phenolic, Paraserianthes falcataria (L) bark

Judul: Dynamics Model for Rural and Urban Economic Growth
Abstrak: Lewis theory of structural change has focused on mechanisms that allow countries to transform their domestic economic structure to a more modern economy. The proposed model deals with the mechanism of interaction between rural and urban Economic. This model is concerned with the process of labor transfer from rural to urban areas. This study aims to model the dynamics of economic growth in rural and urban areas, including determining the equilibrium solution and to carry out simulation of the model. The simulation results show that the transfer of labor from rural to urban areas will increase the rate of change of capital so that structural changes can be realized. In addition, increased propensity to save in rural areas will also accelerate structural change
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