Judul: Kinetika Inhibisi Enzim α-Glukosidase Secara In Vitro oleh Ekstrak Daun Aquilaria filaria sebagai Antihiperglikemik
Abstrak: Diabetes melitus atau hiperglikemik merupakan suatu gangguan metabolisme kronis akibat disfungsi insulin sehingga kadar gula dalam darah menjadi tinggi. Salah satu pengobatan antihiperglikemik ialah menggunakan inhibitor enzim α-glukosidase yang mampu menghambat absorpsi glukosa. Studi pendahuluan menunjukkan bahwa beberapa spesies Aquilaria berpotensi sebagai antihiperglikemik. Dalam penelitian ini, ekstrak etanol daun Aquilaria filaria (gaharu) diuji sebagai antihiperglikemik dan kinetika mekanisme antihiperglikemik melalui inhibisi enzim α-glukosidase berdasarkan pengujian secara in vitro diamati. Hasil penelitian menunjukkan bahwa ekstrak etanol daun gaharu memiliki potensi sebagai antihiperglikemik dengan nilai IC50 sebesar 26 ppm. Nilai inhibisi maksimum sebesar 49% dihasilkan pada pengujian dengan konsentrasi 25 ppm. Kajian atas kinetika inhibisi menunjukkan bahwa daun gaharu menginhibisi enzim α-glukosidase melalui mekanisme inhibisi campuran yang ditunjukkan oleh penurunan nilai Vmaks dari 2.18 menjadi 1.37 dan peningkatan nilai Km dari 0.30 menjadi 3.64.
Keyword: α-glukosidase, antihiperglikemik, Aquilaria filaria, inhibisi

Judul: Kinetika Inhibisi a-Glukosidase oleh Kulit Kayu Surian (Toona sinensis) sebagai Agen Antihiperglikemik
Abstrak: Surian (Toona sinensis) merupakan salah satu tanaman herbal yang umum dimanfaatkan sebagai obat, salah satunya obat antidiabetes. Penelitian ini bertujuan menentukan aktivitas inhibisi α-glukosidase dan IC50 ekstrak serta fraksi kulit kayu surian. Ekstrak diperoleh dengan cara refluk menggunakan air pada suhu 90oC dan maserasi menggunakan etanol 70% pada suhu ruang. Ekstrak etanol difraksionasi bertingkat menggunakan n-heksana, dietil eter, dan etil asetat. Hasil penapisan fitokimia menunjukkan bahwa sampel mengandung flavonoid, saponin, dan tanin. Inhibisi terbaik ditunjukkan oleh ekstrak etanol 70% yaitu 70.45 ppm diikuti oleh fraksi etil asetat, fraksi n-heksana, fraksi dietil eter, dan ekstrak air kulit kayu surian yang secara berturut-turut bernilai 81.96 μg/mL, 98.76 μg/mL, 140.25 μg/mL, dan 242.85 μg/mL. Studi kinetika menunjukkan bahwa ekstrak etanol 70% kulit kayu surian menghambat α-glukosidase melalui mekanisme inhibisi un-kompetitif, ditandai penurunan Vmaks dari 8.29x10-3 mM/min menjadi 1.65x10-3 mM/min dan penurunan Km dari 0.17 mM menjadi 0.03 mM.
Keyword: fitokimia, α-glukosidase, inhibisi, kinetika, surian

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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