Judul: Uji Potensi Inhibitor Αlfa-Glukosidase dan Hipoglikemik Ekstrak Biji Mahoni (Swietenia mahagoni Jacq.) sebagai Kandidat Obat Antidiabetes.
Abstrak: Swietenia mahagoni Jacq. dikenal dengan nama mahoni adalah tanaman obat yang banyak digunakan untuk mengobati berbagai penyakit, termasuk diabetes. Tujuan penelitian ini adalah menguji potensi inhibitor alfa-glukosidase dan hipoglikemik ekstrak biji mahoni sebagai kandidat obat antidiabetes. Biji mahoni diekstraksi dengan metode maserasi dan refluks menggunakan pelarut etanol dan air sehingga diperoleh empat jenis ekstrak yaitu ekstrak maserasi air, ekstrak maserasi etanol, ekstrak refluks air dan ekstrak refluks etanol. Pengujian aktivitas inhibisi alfa-glukosidase dilakukan secara in vitro dengan metode ELISA reader. Pada konsentrasi 100 ppm, ekstrak dengan pelarut etanol memiliki persen inhibisi yang lebih tinggi dan berbeda nyata dengan ekstrak dengan pelarut air (P<0.05). Dari ke empat jenis eksktrak, dipilih ekstrak maserasi etanol karena memiliki aktivitas inhibisi terbaik yaitu 18.147 % dan selanjutnya diuji daya hipoglikemiknya secara in vivo menggunakan tikus Sprague Dawley jantan. Kondisi hiperglikemik pada tikus didapatkan dengan pemberian sukrosa 90% sebanyak 1 ml/ekor. Dosis ekstrak biji mahoni yang digunakan yaitu 100, 200, 300, 400 dan 500 mg/kg BB. Hasil uji hipoglikemik menunjukkan bahwa semua dosis dapat menurunkan kadar glukosa darah tikus percobaan pada level normal. Dosis 100 mg/kg BB ekstrak telah mempunyai efek hipoglikemik.
Keyword: alfa-glukosidase, biji mahoni, diabetes mellitus, hipoglikemik

Judul: Aktivitas Antioksidan Ekstrak Biji Mahoni (Swietenia mahagoni Jacq.) sebagai Kandidat Obat Antidiabetes
Abstrak: Diabetes mellitus (DM) is a progressive chronic degenerative disease with glucose, protein, and lipid metabolic dysfunction. DM is one of oxidative stress conditions that requiring additional exogenous antioxidants. Mahagony is potential for antioxidant which can be used as an antidiabetic medicine. The objective of this research is to compare antioxidant activity of several Swietenia mahagony seed extracts from different methods of extraction (reflux and maceration) and type of solvents (ethanol and water). Antioxidant activity of all extract were evaluated by DPPH method and quantified the IC50 values. The IC50 values of all extracts are 1.03 mg/ml, 1.87 mg/ml, 4.09 mg/ml, and 1.15 mg/ml, respectively to ethanol maceration extract (ME), water maceration extract (MA), ethanol reflux extract (RE), and water reflux extract (RA). The result showed that extract resulted from maceration method using ethanol has the highest antioxidant activity, compare to the others (MA, RE, and RA).
Keyword: Swietenia mahagoni Jacq, reflux, maceration, DPPH, antioxidant, Bogor Agricultural University (IPB)

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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