Polybrominated diphenyl ether (PBDE) compounds, derived from marine organisms, originate from symbiosis between marine sponges and cyanobacteria or bacteria. PBDEs have broad biological spectra; therefore, we analyzed structure and activity relationships of PBDEs to determine their potential as anticancer or antibacterial lead structures, through reactions and computational studies. Six known PBDEs (1–6) were isolated from the sponge, Lamellodysdiea herbacea; ¹³C NMR data for compound 6 are reported for the first time and their assignments are confirmed by their theoretical ¹³C NMR chemical shifts (RMSE < 4.0 ppm). Methylation and acetylation of 1 (2, 3, 4, 5-tetrabromo-6-(3′, 5′-dibromo-2′-hydroxyphenoxy) phenol) at the phenol functional group gave seven molecules (7–13), of which 10, 12, and 13 were new. New crystal structures for 8 and 9 are also reported. Debromination carried out on 1 produced nine compounds (1, 2, 14, 16–18, 20, 23, and 26) of which 18 was new. Debromination product 16 showed a significant IC₅₀ 8.65 ± 1.11; 8.11 ± 1.43 µM against human embryonic kidney (HEK293T) cells. Compounds 1 and 16 exhibited antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae with MID 0.078 µg/disk. The number of four bromine atoms and two phenol functional groups are important for antibacterial activity (S. aureus and K. pneumoniae) and cytotoxicity (HEK293T). The result was supported by analysis of frontier molecular orbitals (FMOs). We also propose possible products of acetylation and debromination using analysis of FMOs and electrostatic charges and we confirm the experimental result.

Two new steroid sulfates 1 and 2 were obtained from a lipophilic extract of an undescribed bryozoan species in the genus Calyptotheca. The structures of compounds 1 and 2 were elucidated by spectroscopic methods and chemical modifications. Steroids 1 and 2 exhibited moderate cytotoxicity at IC₅₀ 54 and 30 µM, respectively, against NBT-T2 cells.

Research of Manzamine C, Indole Alkaloids as cancer cell inhibitors in nutrient starvation, from the Indonesian Marine Sponge Xestospongia muta was done on May 2018. The goal of this study is to determine the cytotoxic activity of metabolite compounds of Xetospongia muta under glucose starvation. The active metabolite isolated using bioassay-guided separation with several steps of chromatography. Interpretation of IR data indicates that the active metabolites have the functional group of secondary NH₂ at 3435.56 cm¹, CH methyl at 2853.39 cm¹, CH methylene at 2769.64 cm¹ and CN imine at 1637.27 cm¹. The LCMS-ESI analysis showed that the active metabolite has a molecular weight [M+H]⁺ 347.445 m/z which indicates the active metabolite has a molecular formula C23H29N3. The activity of metabolite compounds against PANC-1 cells showed cytotoxic activity under glucose starvation conditions with values IC₅₀=10 μM, whereas no growth inhibition was observed up to 100 μM under the general culture conditions.

The investigation of the trophic status based on the nitrate-phosphate correlation and chlorophyll-a abundance in Deudap beach and Lhok Reudup beach, Pulau Nasi, Aceh were carried out in November 2018. Determination of sampling location based on purposive sampling method. The total nitrate, total phosphate concentration, and chlorophyll-a abundance determined by Ultra Violet-Visible (UV-Vis) spectrophotometre which was confirmed from the real-time NOAA database. The results of the chlorophyll-a abundance analysis showed that the abundance of chlorophyll-a in the surface layer ranges 0.7 - 0.11 μg / L. Total nitrate and total phosphate concentrations at deudap beach and lhok reudup in the surface layer ranges 260 - 183 μg / L and 9.4 - 6.8 μg / L. Furthermore, the results indicate that the phenomenon of the chlorophyll-a abundance is closely related to the availability of the macronutrient of nitrate and phosphate. Based on the correlation between total nitrate-phosphate and chlorophyll-a abundance in deudap beach and lhok reudup, Nasi Island are included in the category of oligotrophic waters.