투고논문

Structure determination of two new compounds isolated from a marine sponge Haliclona(Gellius) sp.

 Kyung Lee¹, Yun Na Kim², Eun Ju Jeong^2,*

¹Department of Oceanography, Kunsan National University, Gunsan 54150, Korea

²Department of Plant & Biomaterials Science, Gyeongsang National University, Jinju 52725, Korea

Received June 9, 2021; Revised June 19, 2021; Accepted June 19, 2021

Abstract 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.

Keywords Sesterterpene, Haliclona sp., Spiroketal, DFT method, 1D and 2D NMR