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Diterpenoids from Taiwanese Soft Corals Xenia umbellata,Junceella juncea, and Junceella fragilis

by Chen, Yu-hui

Abstract (Summary)
This research focuses on diterpenoids from Taiwanese soft corals Xenia umbellata Lamarck, Junceella juncea Pallas and Junceella fragilis Ridley. Twelve diterpenoids in addition to one sesequiterpenoid were isolated. Our investigation of the soft coral X. umbellata Lamarck afforded five natural products, including two new xenicane diterpenes, xenibelatols A-B (1-2), together with two known xenicane diterpenes, 7,8-oxido- isoxeniolide (3), 9-hydroxyxeniolide-F (4), and a cadinene sesequiterpene, xenitorin A (5). Chemical investigation of the gorgonian J. juncea Pallas, has resulted in isolation of a new briarane diterpene, juncenolide H (6). Continuing our investigation of the gorgonian J. fragilis Ridley, we isolated seven briarane diterpenes, including four new briaranes, flajunolides A-D (7-10), along with three known briaranes, junceellolide E (11), umbraculolide A (12), 11This research focuses on diterpenoids from Taiwanese soft corals Xenia umbellata Lamarck, Junceella juncea Pallas and Junceella fragilis Ridley. Twelve diterpenoids in addition to one sesequiterpenoid were isolated. Our investigation of the soft coral X. umbellata Lamarck afforded five natural products, including two new xenicane diterpenes, xenibelatols A-B (1-2), together with two known xenicane diterpenes, 7,8-oxido- isoxeniolide (3), 9-hydroxyxeniolide-F (4), and a cadinene sesequiterpene, xenitorin A (5). Chemical investigation of the gorgonian J. juncea Pallas, has resulted in isolation of a new briarane diterpene, juncenolide H (6). Continuing our investigation of the gorgonian J. fragilis Ridley, we isolated seven briarane diterpenes, including four new briaranes, flajunolides A-D (7-10), along with three known briaranes, junceellolide E (11), umbraculolide A (12),11£\, 20£\-epoxy-4-deacetoxy junceellolide D (13). The new compounds 1,2 and 6-10 possess xenicane-type and briarane-type skeletons respectively. The structures of new compounds were determined by 1D-, 2D-NMR spectroscopic analysis and physical methods such as optical rotation, UV, IR, mass spectrum, as well as comparison with the spectroscopic data reported for related compounds. Compounds 1 and 2 are geometric isomers of compounds 3 and 4. The only difference between them resides in the side chain. The geometry of the side chain influenced the relative spatial proximity of H-12, H-13, H-14 to the carbonyl at C-3, and consequently the extent to which these protons are subjected to the anisotropic effects of the carbonyl. Compounds 6-10 have acetyl groups at C-2, C-9, C-12, C-14 positions. Because of structural difference appears in briarane skeleton, they showed different chemical shifts in specific positions. Biological activity test¡Arevealed that compound 5 exhibited moderate cytotoxic activity against KB and WiDr cancer cell lines with ED50 values at 5.9 and 9.9 £gg/ml respectively.
Bibliographical Information:

Advisor:Ya-ching Shen; Meng-hsien Chen; none; none

School:National Sun Yat-Sen University

School Location:China - Taiwan

Source Type:Master's Thesis

Keywords:xenicane xenibelatol acetyl group anisotropic effect flajunolide juncenolide briarane diterpenoid soft coral widr kb gorgonian

ISBN:

Date of Publication:02/02/2007

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