Cytotoxic Biscembranes from the Soft Coral Sarcophyton glaucum

Abstract

Seven new tetracyclic biscembranes (1-7) have been isolated from the soft coral Sarcophyton glaucum. Four (1-4) may be formed biogenetically by a Diels-Alder reaction of Delta(4(5)) and Delta(8(9)) geometrical isomers of methyl sarcoate and Delta(21(34), 35(36)) dienes, including two with a tetrahydrofuran ring between C-27 and C-30 (3, 4), and three biscembranes (5-7) are probably derived from methyl sarcoate isomers with Delta(1(14), 4(5), 8(9)) and a cembrane diene. Their structures were established on the basis of spectroscopic methods. Six of them (1-5, 7) exhibited weak cytotoxic activity against proliferation of human promyelocytic leukemia cells (HL-60).

Lobophytones H-N, Biscembranoids from the Chinese Soft Coral Lobophytum pauciflorum

“…However, comparison of NMR data revealed downfield shifted C-26 (d C 83.2) and upfield shifted C-27 (d C 68.6) and C-30 (d C 71.2) of 3 to replace those (d C 73.8, 83.6, 88.9, respectively) of ximaolide F. These findings suggested ximaolides F (also G 18) ) containing an ether bridge across C-27 and C-30 as in the case of bisglaucumlides G and H 8) rather than the ether bridge between C-26/C-30 as reported in literature.…”

“…The plausible biogenetic pathway of biscembrane analogues was assumed to be derived by a Diels-Alder cycloaddition of two "mono" cembranoids, representing cembranoid-diene and cembranoid-dienophile. [1][2][3][4][5][6][7][8] This depiction was late on supported by the natural occurring monomeric cembranoids, such as dienophiles methyl sarcoate 3) and methyl tetrahydrosarcoate 7) (methyl tortuosoate), 6) which were regarded to be the precursors to form left part of biscembranoids. Biscembranoids were mainly obtained from the coral genus of Sarcophyton (S. tortuosum, S. glaucum, S. latum, and S. elegans), with the exception of isobiscembranoids 9) recently to be isolated from a soft coral Lobophytum pauciflorum which was previously reported to contain steroids 10,11) and diterpenoids.…”

Lobophytones U – Z1, Biscembranoids from the Chinese Soft Coral Lobophytum pauciflorum

“…Methyl sartortuoate (8) [4] and nyalolide (9) [7] were identified on the basis of spectroscopic analysis and comparison with the reported data in literature.…”

Cembrane Diterpenes Chemistry and Biological Properties

“…resulted in the isolation and characterization of 15 new cembranoid diterpenes, namely, dendronpholides C-F, I-P, R (171)(172)(173)(174)(175)(176)(177)(178)(179)(180)(181)(182)(183), sinulaflexiolides E, and F(184, 185). Dendronpholides C (171), and J (176) showed a selective and significant inhibition against BGC-823 (IC 50 = 0.05, 0.20 μg/mL, respectively) [65,66].…”

“…Biscembranoid diterpenoids were discovered in two species of the genus Lobophytum pauciflorum yielded lobophytones A-S (566-584) [166][167][168], while Sarcophyton producted other analogs, ximaolides A-G (585-591) [169,170], methyl neosartortuate acetate (592) [58], methyl tortuoate A (593), methyl tortuoate B (594) [7], nyalolide (595) [8], bisglaucumlides A-K (596-606) [171,172]. in vitro cytotoxicity against the human nasophyringeal carcinoma CNE-2 cell line, with IC 50 values of 22.7 and 24.7 μg/mL, and the murine P-388 tumor cell line, with IC 50 values of 3.5 and 5.0 μg/mL, respectively [7].…”