Judul: Screening of Active Antibiofouling and Antibiocorrosion&#160;Compounds from Indonesian Marine Organisms Using NMR Spectroscopy&#160;Analysis
Abstrak: Industri maritim sebagai pendorong utama perdagangan global dan pertumbuhan ekonomi mengalami kerugian masif yang disebabkan oleh aktivitas biofouling dan biokorosi. Penelitian ini bertujuan menapis sejumlah 173 sampel lapisan EtOAc dan H2O organisme laut kategori toksisitas lemah hingga nontoksik terhadap serangkaian bioasai (antibakteri, antiquorum sensing, biosurfaktan, antibiofouling, dan antibiokorosi) dan analisis KLT serta NMR 1H. Sejumlah 15 dari total 173 sampel adalah aktif antibakteri terhadap Pseudomonas aeruginosa dan Staphylococcus aureus. Dari 15 sampel, 8 sampel berpotensi mengandung biosurfaktan. Di antara 8 sampel tersebut, 4 sampel adalah aktif sebagai inhibitor quorum sensing terhadap P. aeruginosa. Lapisan EtOAc tunikata (D1-I-0159-22E) memperlihatkan aktivitas terampuh terhadap asai antibiofouling (100 µg/mL, tidak ada kematian dan tidak ada pelekatan byssus) dan antibiokorosi (35 µg/mL, mpy 10,70±1,70). Analisis KLT dan NMR 1H menunjukkan keberadaan senyawa alkaloid dan terpenoid pada lapisan EtOAc tunikata, D1-I-0159-22E, As the primary driver of global trade and economic growth, the maritime industry is experiencing massive losses caused by biofouling and biocorrosion activities. This research aims to screen a total of 173 samples of EtOAc and H2O layers of marine organisms with weak to non-toxic categories against a series of bioassays (antibacterial, antiquorum sensing, biosurfactant, antibiofouling, and antibiocorrosion) and TLC as well as 1H NMR analyses. Among the 173 total samples evaluated, 15 showed antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus. Of the 15 samples, 8 potentially contained biosurfactant properties. Among these 8 samples, 4 were active as inhibitors of quorum sensing against P. aeruginosa. The EtOAc layer of tunicate (D1-I-0159-22E) exhibited the most potent activity in the antibiofouling (100 µg/mL, no death, and no byssus adhesion) and the antibiocorrosion (35 µg/mL, mpy 10.70±1.70) assays. TLC and 1H NMR analyses indicated the presence of alkaloid and terpenoid compounds in the EtOAc layer of tunicate, D1-I-0159-22E.
Keyword: NMR, antibiofouling, antibiokorosi, antiquorum sensing, biosurfaktan

Judul: Screening of Active Compounds based on Biological  Activities and NMR Spectroscopy of Tunicates and Soft Corals from Raja Ampat
Abstrak: Raja Ampat merupakan salah satu daerah di Indonesia yang terletak di pusat wilayah segitiga terumbu karang dan termasuk lokasi dengan biodiversitas laut terkaya di dunia. Penelitian ini bertujuan menapis lapisan etil asetat dari tunikata dan karang lunak asal Raja Ampat berdasarkan data aktivitas hayati dan spektrum NMR ¹H. Penapisan berdasarkan aktivitas dengan Artemia salina menunjukkan hasil baik sekali (faktor-Z = 0,88). Lapisan etil asetat tunikata Lissoclinum patella terpilih memiliki toksisitas terampuh (LC50 = 2,436 ± 0,345 µg/mL) terhadap A. salina dan menyebabkan malformasi mayor pada sumbu tubuh dan edema perikardial pada embrio ikan zebra (Danio rerio) pada konsentrasi 3 µg/mL. Tunikata Clavelina zobustra menunjukkan aktivitas selektif terhadap bakteri Gram negatif Klebsiella pneumoniae (1300 µg/mL atau 260 µg/disk) dengan zona hambat 8,75 ± 0,5 mm. Spektrum NMR ¹H sampel menunjukkan keberadaan beragam gugus fungsi dan substruktur berasal dari terpenoid, alkaloid, peptida, dan poliketida., Raja Ampat is one of the regions in Indonesia located in the center of the coral reef triangle and one of the locations with the richest marine biodiversity in the world. The aim of this study was to screen ethyl acetate layers from tunicates and soft corals from Raja Ampat based on biological activity data and ¹H NMR spectra. Biological activity screening using Artemia salina was proven as an excellent assay (Z-factor = 0,88). The selected ethyl acetate layer of tunicate Lissoclinum patella showed the most potent toxicity (LC50 = 2,436 ± 0,345 µg/mL) against A. salina and caused major malformations in the body axis and pericardial edema of zebrafish embryos (Danio rerio) at 3 µg/mL concentration. Tunicate Clavelina zobustra showed a selective antibacterial activity against Gram-negative bacteria Klebsiella pneumoniae (1300 µg/mL or 260 µg/disk) with an inhibition zone of 8,75 ± 0,5 mm. The ¹H NMR spectra of the sample showed the presence of various functional groups and substructures derived from terpenoids, alkaloids, peptides, and polyketides.
Keyword: antibacterial, Artemia salina, NMR, zebrafish embryos

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
Keyword: