• Ocean and Polar Research
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• v.42 no.1
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• pp.15-20
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• 2020

The marine sponge Hyrtios sp. collected in the Philippines was extracted and partitioned. The resulting organic layer was purified by C₁₈ reversed-phase column chromatography and HPLC to achieve the separation of nine scalarane-type sesterterpenes, including one new compound with eight known scalarane analogs. The chemical structures of the isolated compounds 1-9 were elucidated by 1D and 2D NMR and MS data analysis. All nine compounds were evaluated for their antibacterial activities against three Gram-positive and three Gram-negative bacteria. The compound 3 exhibited potent antibacterial activities against Bacillus subtilis and Micrococcus luteus. The compounds 7 and 9 displayed considerable activities against Bacillus subtilis and the others had moderate results.

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.254.3-255
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• 2001

• 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.

• Animal cells and systems
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• v.9 no.1
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• pp.9-11
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• 2005

A new species of the genus Smenospongia (Dictyoceratida, Thorectidae), S. coreana n. sp., is described from Gageodo Island, Korea. This new species is readily distinguished from the other species of Smenospongia by the un-lobated growth forms and un-crowded primary fibres. S. aurea and S. lamellata are no distinction between primary and secondary elements, but this species is easily distinguished from them. The matrix easily derived from the fibres. This species has five sesterterpenes, three scalaranetypes and two linear furanosesterterpenes, in chemical compounds.

• Journal of the Korean Magnetic Resonance Society
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• v.16 no.1
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• pp.1-10
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• 2012

A new scalaran class sesterterpenoid with five known ones was isolated from a marine sponge Smenospongia species collected from the Gageo island, Korea. Chemical structure of all of compounds was determined on the basis of a combination of extensive 1D and 2D NMR experiments and MS data. The new compound exhibited a new functional group on a common scalaran sesterterpene skeleton, identified as 12-deacetoxy-23-deacetoxyscalarin. The compound 1 moderately showed the effect of the activation of AMP-activated protein kinase (AMPK) in L6 myoblast cell.

• The Plant Pathology Journal
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• v.15 no.1
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• pp.14-20
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• 1999

Twenty isolates of Helminthosporium species were obtained from various grass plants and tested for controlling efficacy on the development of plant diseases. An isolate of Helminthosporium sp. TP-4 was chosen and six antibiotic substances were purified from cultures of the fungus by repeated silica gel column chromatography and preparative thin-layer chromatography. They were identified as ophiobolin a, 6-epiophiobolin A, 3-anhydroophiobolin A, 3-anhydro-6-epiophiobolin A, iphiobolin B, and iphiobolin I mainly by mass spectrometry and nuclear magnetic resonance spectrometry. Ophiobolins inhibited the growth of a grampositive bacterium Streptomyces griseus, but were not active against gram-negative bacteria. They also showed an antifungal activity. In in vivo tests, iphiobolin B exhibited potent controlling activities against rice blast, tomato late blight, and wheat leaf rust with control values more than 90% and 70% at concentration of $500\mu\textrm{m}$/ml and 100 ${\mu}{\textrm}{m}$/ml. Ophiobolin A and 6-epiophiobolin A controlled the development of wheat leaf rust more than 80% at concentrations of 100 /ml and $500\mu\textrm{m}$/ml respectively. 3-Anhydro-6-epiophiobolin A was not active against any plant disease. On the other hand, the A-series ophiobolins other than 3-anhydroophiobolin A showed stronger phytotoxic activity in a leaf-wounding assay using 8 plant species than those of 3-anhydroophiobolin A, ophiobolin B, and ophiobolin I. The results indicate that there is little correlation between antifungal activity and phytotoxicity of ophiobolins.