Judul: Potensi Ekstrak Umbi dan Daun Ubi Jalar Ungu sebagai Inhibitor α-Glukosidase
Abstrak: Purple sweet potato has been reported as a component of daily diet for type 2 diabetes mellitus patient because of its low glycemic index. A mechanism for decreasing blood’s sugar content in diabetic patients is by inhibiting α- glucosidase enzyme. In this study, the potencies of alkaloid extract from leaves and anthocyanin extract from tuberous of purple sweet potato were investigated as an inhibitor of α-glucosidase. The sample used was purple sweet potato from Ciampea, Bogor. The 2000 ppm alkaloid extract could inhibit α-glucosidase activity (61.88%), whereas anthocyanin extract was inactive (only inhibited 0.25%). The alkaloid extract was then fractionated by column chromatography with silica gel stationary phase and chloroform as eluent. Fraction containing alkaloid with Dragendorf spraying was F10, which was further separated by preparative thin layers chromatography. F10.15 fraction contained alkaloid and had inhibition activity of 18.07% at 1250 ppm. Fourier transform infrared spectrum of this fraction showed –NH−, –OH, and –CH2– functional groups and was predicted as containing alicyclic polyhydroxy alkaloid with sugar-resembled skeleton.
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Judul: Isolasi Dan Pencirian Senyawa Aktif Dari Tumbuhan Anting-Anting (Acalypha indica L.) yang Berpotensi Menurunkan Kadar Glukosa Darah
Abstrak: Rebusan akar tumbuhan anling-anting telah digunakan secara tradisiod sebagai obat diabetes. Tetapi kandungan zat yang bcrpotensi sebagai antidiabetik dalam akar tumbuhan ini belum diketahui secara pasti, karena belum ads penelitian yang mengkaji khasiat antidiabetik tumbuhan tersebut. Oleh karena itu, penelitian ini benujuan menapis senyawa bioaktif pada tumbuhan anting-anting dan mengetahui bioaktivitasnya dalam menurunkan kadar glukosa darah. Untuk mengetahui ak~ivitash ipoglikemik tumbuhan ini dilakukan uji hayati dengan tikus putih jantan jenis Spraque dowley, yang dibuat menderita hiperglikemia dengan aloksan dosis 180 m$g BB. Pengukuran kadar glukosa darah dilakukan dengan metode o-toluidin. Sampel kering seluruh bagian tumbuhan difraksinasi dengan berbagai macam pelmt berdasarkan tingkat kepolaran. Selain itu juga dilakukan ekstraksi akar tumbuhan dengan akuades (refluks 2 jam). Seluruh ekstrak yang diperoleh diuji kandungan fitokimianya. Ekstrak yang memilii kandungan fitokimia sama dengan ekstrak akar selanjutnya diuji aktivitas hipoglikemiknya dan difraksinasi dengan kromatografi kolom. Hasil uji fitokimia rebusan akar anting-anting menunjukkan adanya senyawa golongan alkaloid, sehingga dapat diduga bahwa golongan senyawa yang berpotensi sebagai penurun kadar glukosa darah dalam akar tumbuhan ini adalah alkaloid. Ekstrak klorofom dari seluruh bagian tumbuhan mengandung triterpenoid, ekstrak kloroforrn-metanol mengandung alkaloid dan triterpenoid, ekstrak metanol mengandung alkaloid dan tanin. Ekstrak klorofom-metanol dan ekstrak metanol (ekstrak dengan kandungan fitokimia sama dengan ekstrak akar) selanjutnya diuji ahivitas hipoglikemiknya dan difraksinasi dengan kromatografi kolom. Hasil uji bayati menunjukkan bahwa rebusan akar tumbuhan anting-anting memiliki aktivitas bipoglikemik yang lebih besar dibandingkan dengin obat pembanding sampai dengan hari ke-7. Campuran ekstrak klorofom-metaool dan ekstrak metanol memiliki aktivitas bipoglikemik yang lebih rendah dibandingkan dengan obat pembanding. Fraksinasi terhadap ekstrak kloroform-metanol dan ekstrak metanol dengan kromatografi kolom menghasilkan 16 fraksi. Fraksi V, VI, XII. XIV, dan XV menunjukkan hasil positif terhadap uji alkaloid. Dari hasil analisis spekfrum ultraviolet dan inframerah diketahui bahwa Fraksi VI mengandung senyawa amina sekunder aromatik yang diduga mempakan senyawa golongan alkaloid. Fraksi XIV juga diduga mengandung senyawa golongan alkaloid.
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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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