Judul: Penambatan Molekuler dan Studi In Vitro Senyawa Bioaktif Ekstrak dan Fraksi Daun Sirih Merah (Piper crocatum) sebagai Inhibitor -Glukosidase.
Abstrak: Tren peningkatan DM tipe 2 ini telah menjadi masalah medis serius di seluruh dunia yang mendorong setiap upaya dalam mengeksplorasi agen terapi baru. DM tipe 2, penghambatan terapi α-glukosidase bermanfaat untuk menunda penyerapan glukosa setelah makan. Enzim α-glukosidase adalah enzim yang berperan dalam pemecahan karbohidrat menjadi glukosa dan dapat meningkatkan kadar glukosa darah, sehingga untuk mencegah naiknya gula darah maka dibutuhkan suatu inhibitor enzim α-glukosidase. Daun sirih merah digunakan secara turun menurun oleh masyarakat Indonesia dan dipercaya dapat menurunkan kadar glukosa darah. Penelitian sebelumnya berhasil mengisolasi senyawa bioaktif yang terkandung di dalam daun sirih merah, mengandung delapan senyawa aktif, selanjutnya senyawa tersebut dilihat interaksi molekuler dengan enzim α-glukosidase secara in silico kemudian dibuktikan secara in vitro. Penelitian ini bertujuan untuk mempelajari interaksi molekuler antara senyawa bioaktif daun sirih merah terhadap enzim α-glukosidase secara in silico serta menentukan tipe penghambatan ekstrak dan fraksi daun sirih merah terhadap enzim α-glukosidase secara in vitro. Ekstraksi dilakukan dengan metode maserasi menggunakan etanol 70%, kemudian ekstrak difraksinasi bertingkat menggunakan 3 jenis pelarut, yaitu n-heksana, etil asetat dan air. Penambatan molekuler senyawa bioaktif yang diisolasi dari daun sirih merah (Piper crocatum) dengan enzim α-glukosidase menggunakan autodock vina, diperoleh nilai binding affinity dan Ki. Hasil pengujian secara in silico kemudian dibuktikan secara in vitro untuk menentukan aktivitas penghambatan daun sirih merah terhadap enzim α-glukosidase dan menentukan tipe penghambatan dengan persamaan Dixon menggunakan dua konsentrasi substrat (10 mM dan 15 mM). Hasil uji in silico menunjukkan bahwa senyawa aktif yang berperan dalam menghambat enzim α-glukosidase adalah Columbin. Columbin berikatan di situs pengikatan dengan asam amino Ser240, Asp242, His280, Arg315, Glu411, Phe159, Arg442, Tyr158 dan Phe303. Hasil in vitro menunjukkan nilai IC50 terbaik diperoleh untuk fraksi etil asetat pada konsentrasi 743.80 μg/mL, dengan mekanisme penghambatan kompetitif. Berdasarkan hasil pengujian secara in silico maupun in vitro menunjukkan hasil yang serupa, dimana tipe penghambatan daun sirih merah kompetitif dengan senyawa yang diduga berperan sebagai inhibitor adalah columbin.
Keyword: Columbin, In Vitro, In Silico, Penghambatan α-Glukosidase

Judul: Total Phenolics, Flavonoids, and ɑ-Glucosidase Inhibitory Activity of n-Hexane, Ethyl Acetate and Methanol Extracts of Red Betel (Piper crocatum)
Abstrak: Sirih merah (Piper crocatum) mempunyai berbagai senyawa dengan kemampuan penghambatan enzim ɑ-glukosidase. Penelitian ini bertujuan menentukan ekstrak yang memiliki tingkat kandungan fenolik dan flavonoid yang optimal, serta penghambatan tertinggi pada enzim α-glukosidase. Metode maserasi bertingkat digunakan untuk mengekstraksi senyawa bioaktif sirih merah menggunakan pelarut-pelarut dengan peningkatan kepolaran (n-heksana, etil asetat, metanol). Pengujian dilakukan terhadap kadar fenolik total, flavonoid, serta kemampuan inhibisi ɑ-glukosidase. Hasil pengukuran total kadar fenolik, flavonoid, dan aktivitas penghambatan α-glukosidase menunjukkan nilai yang secara signifikan berbeda (p<0,05) pada semua ekstrak dengan total kadar fenolik dan flavonoid tertinggi pada ekstrak n-heksana berturut-turut sebesar 25,68 ± 0,29 mg GAE/g dan 65,84 ± 0,96 mg QE/g. Sementara itu, ekstrak metanol daun sirih merah memiliki daya hambat diantara semua ekstrak dengan nilai persen inhibisi α-glukosidase sebesar 43,87 ± 1,83%., Red betel leaf (Piper crocatum) had various compounds with the ability to inhibit α-glucosidase enzymes. The research aimed to determine the extract with optimal levels of phenolic and flavonoid content, as well as the highest inhibition of α-glucosidase enzyme. A multistage maceration method was used to extract bioactive compounds from red betel leaf using solvents with increasing polarity (n-hexane, ethyl acetate, methanol). Tests were conducted on the total phenolic content, flavonoids, and α-glucosidase inhibition ability. The measurement results of the total phenolic content, flavonoids, and α-glucosidase inhibition activity showed significantly different values (p<0,05) in all extracts with the highest total phenolic and flavonoid content in n-hexane extract, respectively, at 25,68 ± 0,29 mg GAE/g and 65,84 ± 0,96 mg QE/g. Meanwhile, the methanol extract of red betel leaf had inhibitory power among all extracts with a percentage inhibition of α-glucosidase at 43,87 ± 1,83%.
Keyword: ɑ-glukosidase/ɑ-glucosidase, antidiabetes/antidiabetic, fenolik/phenolic, flavonoid/flavonoid, sirih merah/red betel

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