• Journal of the Korean Magnetic Resonance Society
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• v.25 no.2
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• pp.24-32
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• 2021

Two new sesterterpenes, including a known sesterterpene, were isolated from the marine sponge Haliclona sp. collected in the Gageo island, Korea. One of the new sesterterpenes (1) was an unusual compound possessing a spiroketal moiety and the other (2) represented a four ring-fused skeleton. The planar structure of compound 1 was identical to gombaspiroketals A and B isolated from the marine sponge Clathria gombawuiensis, but the configuration for the two chiral centers was different each other. On the other hand, the skeletal structure of compound 2 was similar to that of phorone A isolated from Phorbas sp. and a compound from C. gombawuiensis, except for one configuration at C-8. However, in comparing the ¹H and ¹³C NMR spectral data, the proton and carbon chemical shifts for the three compounds were almost consistent. The NOESY spectrum revealed that the C-8 configuration of 2 was reversed to that of the two reported compounds. The configuration for compound 2 was supported by quantum mechanical calculation for the carbon chemical shifts and DP4+ probability for the protons and carbons of 2.

• Journal of the Korean Magnetic Resonance Society
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• v.27 no.4
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• pp.35-41
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• 2023

From a marine sponge Dysidea species, four new furanosesquiterterpenoids were isolated and characterized. Their structural elucidation was achieved through an extensive analysis employing NMR, MS data, and DFT method. Notably, all compounds shared as identical molecular formula. Compound 2 was identified as a derivative of compound 1, while compounds 3 and 4 exhibited an identical planar structure. Determination of the configurations of chiral centers in compounds 1 and 2 involved a comparative analysis between measured and calculated ECD spectra, along with the application of DP4+ probability analysis. Distinctly, the configurations of isomers 3 and 4 were established by scrutinizing proton chemical shifts based on the NOE correlation.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.1
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• pp.15-17
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• 2017

In carbon-11 labeling, $[^{11}C]$methyltriflate (methyltrifluoromethanesulfonate, MeOTf) is the most widely used through mild reaction condition with high yield. Strong inorganic bases, KOH, NaH and so on, were chosen to activate precursors that have phenolic alcohol as a nucleophilic moiety, because of its poor nucleophilicity. However, these catalyst can also react with radioactive intermediate, $[^{11}C]$MeOTf to afford side products. We will briefly discuss the history of the effort to increase the yield of $[^{11}C]$raclopride and suggest the alternate method for better radiochemical yield and consistency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.516-522
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• 1998

An Actinomycetes strain, MSA-1, containing antimicrobial component was isolated from the black sponge, Halichondzia okadai, and was identified to a genus level by morphological and chemotaxonornic methods. The gray colored spores were oval type with smooth surface and formed flexibilis spore chains. The cell wall of this strain was type I containing D-aminopimellic acid (D-DAP) and no specific sugar was detected. Phospholipid of the cell membrane was PII type including phophoethanolamine and the major fatty acids of total lipid were branched anteiso-15 : 0, iso-16 : 0, 16 : 0 and iso-17 ; 0. From these results and other characteristics described in the Bergey's Manual, this strain was identificated as a Streptomyces sp. Meanwhile, 10mg of pale yellow colored antimicreobial component was isolated by HPLC method from the cultured Streptomyces sp. (70g of cryophillized mycellis). By crystallographyc analysis, HIRESMS and NMR assignment, the antimicrobial component produced from the strain MSA-1 was elucidated as the staurosporine (indolo[2,3-a]carbazole alkaloid).

• Membrane and Water Treatment
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• v.15 no.2
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• pp.79-88
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• 2024

Modification of Polyvinylidene fluoride (PVDF) hollow fiber membranes (HFMs) characteristics and performance were investigated via post treatment using different oxidants. sodium hypochlorite (NaOCl), hydrogen peroxide (H₂O₂) and potassium persulfate (KPS). Fourier transform infrared (FTIR) and Proton nuclear magnetic resonance (¹H-NMR) results revealed no structural differences after post treatment. Cross-sectional micrographs show finger-like structures at the outer and inner walls of the HFMs and sponge-like structures in middle, where NaOCl and KPS post treated fibers exhibited a decrease in finger-like structures in addition to aggregates appearing on the surface, consequently leading to an increase in the surface roughness (Ra) from 48 nm to 52.8nm and 56 nm, respectively. Hydrogen peroxide post treatment only was observed to decrease the water contact angle from 98° to 81.4°. It was also observed that the elongation at break and the modulus deceased after NaOCl post treatment from 34.5 to 28.5% and from 19.3 Mpa to 16.6 Mpa, respectively. Moreover, pure water flux after H₂O₂ post treatment increased from 87.8 LMH/bar to 113 LMH/bar at 0.45 bar, while no changes were detected for the methylene blue dye rejection (74%) between raw and hydrogen peroxide post treated fibers at the same pressure. According to the findings hydrogen peroxide post treated PVDF HFMs have the most uniform surfaces, with almost no alterations in structural and mechanical properties or porosities with enhanced hydrophilicity and pure water flux maintaining appropriate rejection. Therefore, it is considered an efficient surface modifying agent for UF/NF membranes or low-pressure separators.