Judul: Molecular Docking of Flavonoid Compounds Against  Streptococcus mutans Glucosyltransferase Inhibition as Antibiofilm
Abstrak: Penyebab terjadinya karies gigi yaitu plak yang berada pada permukaan gigi dalam bentuk biofilm. Bakteri Streptococcus mutans berperan dalam pembentukan biofilm dan menghasilkan enzim glukosiltransferase yang dapat mengkatalisis pembentukan ekstra polisakarida. Beberapa senyawa flavonoid diketahui dapat menghambat sintesis biofilm. Oleh karena itu, senyawa flavonoid berpotensi untuk dikembangkan sebagai antibiofilm untuk pencegahan karies gigi. Penelitian ini bertujuan menentukan senyawa flavonoid dari penapisan virtual terhadap inhibisi glukosiltransferase pada S. mutans sebagai antibiofilm melalui penambatan molekuler dengan mempertimbangkan nilai energi bebas ikat, jenis pengikatan dan residu katalitik. Metode yang digunakan adalah preparasi ligan dan reseptor, penapisan virtual dan penambatan molekuler. Hasil penapisan virtual dari 87 senyawa flavonoid, diperoleh 36 senyawa yang dapat menginhibisi glukosiltansferase. Hasil penambatan molekuler menunjukkan 9 ligan yang dapat menghambat glukosiltransferase dengan nilai energi bebas ikat lebih negatif dari ligan alami (maltosa). Likuiritigenin memiliki ΔG paling negatif yaitu -7,0 kkal/mol dan nilai Ki 7,39 µM. 9 ligan memiliki jenis pengikatan terbaik pada enzim glukosiltransferase. Senyawa yang berikatan pada 3 residu katalitik enzim glukosiltransferase yaitu taksifolin, gallokatekin, sakuranetin sedangkan 6 senyawa lain berikatan pada 2 residu katalitik., The cause of dental caries is plaque that is on the dental surface in the form of a biofilm. Streptococcus mutans bacteria play role in the formation of biofilms and produce glucosyltransferase enzyme that can catalyze the formation of extra polysaccharides. Several flavonoid compounds are known to inhibit biofilm synthesis. Therfore, flavonoid compounds have the potential to be developed as antibiofims for the prevention of dental caries. This research aims to determine polyphenolic compounds from virtual screening against glucosyltransferase inhibition in S. mutans as an antibiofilm through molecular docking by considering the value of binding free energy, type of binding and catalytic residue. The methods used are ligand and receptor preparation, virtual screening and molecular docking. The results of virtual screening of 87 polyphenolic compounds, obtained 36 compounds that could inhibit glucosyltransferase. Molecular docking results showed 9 ligans that could inhibit glucosyltransferase with binding free energy value more negative than the native ligand (maltose). Liquiritigenin has the most negative ΔG which is -7,0 kkal/mol and Ki value of 7,39 µM. Compounds that bind to 3 catalytic residues of glucosyltransferase enzyme are taxifolin, gallocatechin, sakuranetin while 6 other compounds bind to 2 catalytic residues.
Keyword: biofilm, glucosyltransferase, molecular docking, S. mutans

Judul: Dental Antibiofilm Potential of Ruku-Ruku Plant by In Silico Study of Glucosyltransferase Enzyme Inhibition
Abstrak: Biofilm gigi terbentuk akibat infeksi Streptococcus mutans yang memfermentasi karbohidrat menjadi asam. Bakteri tersebut memproduksi glukosiltransferase yang berperan dalam sintesis glukan enamel. Tanaman ruku-ruku memiliki senyawa aktif yang berpotensi sebagai antibiofilm. Penelitian ini bertujuan menguji potensi inhibisi senyawa aktif tanaman ruku-ruku terhadap glukosiltransferase serta menganalisis interaksinya. Penelitian dilakukan dengan metode penapisan virtual dan penambatan molekuler menggunakan perangkat lunak YASARA Structure. Hasil penelitian menunjukkan dari 40 senyawa aktif tanaman ruku-ruku, terdapat enam senyawa terbaik yang mampu menginhibisi glukosiltransferase serta memiliki interaksi dengan tiga residu penting pada enzim, yaitu Asn481, Glu515, dan Trp517. Senyawa tersebut adalah asam ursolat, asam olenolat, apigenin-7-glukuronida, orientin, isoorientin, dan isoviteksin yang memiliki konstanta disosiasi lebih rendah dibandingkan ligan alami dengan rentang 0.048 hingga 0.398 µM dan memiliki nilai energi bebas ikatan lebih negatif dari ligan alami dengan rentang -9979 hingga -8730 kal/mol., Dental biofilm is formed due to infection of Streptococcus mutans, which is able to ferment carbohydrates into acid. These bacteria produce glucosyltransferase which plays role in synthesizing glucan enamel. Ruku-ruku plant have active compounds that have potential as antibiofilm. This study aimed to examine the inhibition potential of active compounds from ruku-ruku plant against the glucosyltransferase and to analyze its interaction. The research was conducted using virtual screening molecular and docking methods with YASARA Structure software. The results showed that of 40 active compounds from ruku-ruku plant, there were six best compounds that could inhibit glucosyltransferase and interact with three important residues, namely Asn481, Glu515, and Trp517. These compounds are ursolic acid, oleanolic acid, apigenin-7-glucuronide, orientin, isoorientin, and isovitexin which have lower dissociation constants than natural ligands in range of 0.048 to 0.398 µM and have more negative free energy of binding values with range of -9979 to -8730 cal/mol.
Keyword: biofilm, glucosyltransferase, molecular docking, ruku-ruku, S. mutans

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