Judul: Aktivitas Antidiabetes Fraksi Hasil Fraksinasi Ekstrak Etanol Kulit Kina Ledger (Cinchona ledgeriana Moens).
Abstrak: Ekstrak etanol kulit kina ledger (Cinchona ledgeriana Moens) memiliki aktivitas antidiabetes karena mampu menghambat aktivitas enzim -glukosidase dengan nilai IC50 13.86 μg/mL. Tujuan penelitian ini adalah menentukan rendemen fraksi yang dihasilkan dari fraksinasi ekstrak etanol kulit kina ledger dan aktivitas antidiabetes fraksi-fraksi tersebut, menganalisis komponen kimia fraksi yang memiliki aktivitas antidiabetes tertinggi. Fraksi teraktif dianalisis dengan Gas chromatografi-mass spectrometry (GC-MS). Fraksinasi ekstrak etanol dilakukan dengan metode solvent-solvent extraction dengan pelarut nheksana dan etil asetat. Aktivitas antidiabetes diukur menggunakan uji penghambatan enzim -glukosidase berdasarkan reaksi enzimatik secara in vitro. Hasil penelitian menunjukkan rendemen fraksi n-heksana, etil asetat, dan residu berdasarkan nisbah bobot kering fraksi terhadap bobot kering ekstrak etanol berturut-turut adalah 3.36, 9.23, dan 87.41%. Fraksi residu tergolong aktif menghambat aktivitas -glukosidase (IC50 38 μg/mL), sedangkan fraksi nheksana dan fraksi etil asetat tidak memiliki aktivitas antidiabetes (IC50>100 μg/mL). Hasil identifikasi komponen kimia menunjukkan bahwa fraksi residu mengandung senyawa dari kelompok alkaloid dan fenolik yang bersifat menghambat aktivitas enzim -glukosidase yaitu dimetilamin, hidrokuinon, dan katekol.
Keyword: antidibetes, -glukosidase, ekstrak etanol, Kina ledger

Judul: Aktivitas antidiabetes fraksi hasil fraksinasi ekstrak etanol daun kina ledger (Cinchona ledgeriana Moens).
Abstrak: Diabetes melitus (DM) merupakan salah satu masalah kesehatan yang besar. DM adalah suatu penyakit yang tubuh penderitanya tidak dapat secara otomatis mengendalikan tingkat gula glukosa dalam darahnya. Tanaman kina mengandung senyawa alkaloid yang terbentuk secara alami. Kelompok senyawa fenolik dan alkaloid diketahui berpotensi sebagai antidiabetes. Tujuan dari penelitian ini untuk menetapkan rendemen dan aktivitas daun kina sebagai agen antidiabetes secara in vitro serta menentukan fraksi teraktif. Tujuan lain untuk mengetahui komponen kimia yang ada di dalam fraksi teraktifnya. Fraksinasi menggunakan metode solvent-solvent extraction, pengujian antidiabetes melalui uji penghambatan enzim α-glukosidase secara in vitro dan analisis komponen kimia menggunakan gas chromatography mass spectrometry (GC-MS). Rendemen fraksi n-heksana, fraksi etil asetat, dan residu sebesar 0.20%, 1.96%, dan 10.10%. Fraksi etil asetat dan residu tergolong aktif antidiabetes (IC50 etil asetat= 15.80 μg/mL, residu= 35.13 μg/mL) dan fraksi n-heksana tidak aktif (IC50>100 μg/mL). Analisis komponen kimia menunjukkan fraksi etil asetat mengandung senyawa dominan levoglukosan.
Keyword: -glukosidase, antidiabetes, fraksinasi, kina, levoglukosan

Judul: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite