New Terpenoid Constituents of the Southwestern Caribbean Sea Whip Pseudopterogorgia elisabethae (Bayer), Including a Unique Pentanorditerpene

Abstract

Seven structurally diverse terpenoids, including four diterpenes, a norditerpene, a bisnorditerpene, and a biogenetically related pentanorditerpene, have been isolated from the hexane extract of the Caribbean gorgonian octocoral Pseudopterogorgia elisabethae, collected near the island of San Andrés, Colombia. The structures of all the new compounds were determined by detailed spectroscopic analysis and chemical derivatization. Many of the purified isolates were evaluated in vitro as potential agents to treat neuroinflammation and also as growth inhibitors against the pathogenic microbe Mycobacterium tuberculosis H37Rv.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The Natural Products Chemistry of the Gorgonian Genus Pseudopterogorgia (Octocorallia: Gorgoniidae)

“…84 Isoelisabethatriene (58) was originally obtained as a semisynthetic product upon treatment of 57 with SeO 2 in the presence of trimethylsilyl polyphosphate (PPSE), 84 but was later identified from an extract of P. elisabethae collected in the Florida Keys. 96,98 Follow-up biological screening of elisabethin D, whose structure was also confirmed by X-ray diffraction analysis, indicated no significant in vitro cancer cell cytotoxicity in the NCI's three-cell-line tumor panel, nor was it active in the NCI's test for agents active against the HIV. A chemical investigation of this gorgonian coral from San Andrés Island led to the isolation of the closely related bicyclic diterpene, elisabethatrienol (59).…”

“…Biological screening studies indicated that benzoxazoles 55 and 56 are strong growth inhibitors of M. tuberculosis H 37 Rv. 96 2.11.2.1.2(iii) Elisabethanes and related metabolites (compounds reported ¼ 11) In 1998, a routine inspection of the 1 H-and 13 C-NMR data of the hexane solubles of P. elisabethae collected near San Andrés Island revealed that the majority of the compounds present in that specimen possessed distinctively different carbon frameworks quite unlike those previously described for the aglycon portion of the Pss and seco-pseudopterosins. [80][81][82][83] 2.11.2.1.2(ii) Serrulatanes (compounds reported ¼ 16) Elisabethatriene (57), whose molecular structure was proposed based on spectroscopic data alone, was isolated and purified using a radioactivity-guided isolation protocol from a specimen of P. elisabethae collected in May 1999 at Sweetings Cay in the Bahamas.…”

“…66 Mosher's ester method was applied to determine the absolute configuration of this molecule as 1S, 4R, 7S, 9S, 11S. Subsequent chemical studies of the hexane solubles of the San Andrés species led to the isolation of elisabetholide (81), a novel -keto--lactone that is structurally reminiscent of elisabethin D (77) but has a distinct carbon skeleton, 99 a rare bisnor-diterpene named elisabethin G (82), 96 and a unique pentanor-diterpene, elisabethin H (83). The strongly antitubercular hydrocarbon 60 was reported in 2001, along with its hydroxylated congener 7-hydroxyerogorgiaene (61), by the Rodríguez group during a cursory chemical examination of the hexane extract of P. elisabethae from San Andrés Island.…”

“…Elisabethatriene, isoelisabethatriene, and elisabethatrienol are interesting, since these structures can be considered as biosynthetic intermediates leading to erogorgiaene (60), presumably via dehydrogenation and aromatization. 96 The structures of these metabolites were determined by interpretation of the 1D and 2D NMR, IR, UV, and HR-MS (highresolution mass spectrometry) spectra. 86 A number of laboratories have described studies on the total synthesis of erogorgiaene.…”

“…86 A number of laboratories have described studies on the total synthesis of erogorgiaene. 96 Albeit not without controversy, two research groups led by Mulzer and Rawal, have tackled the task of the total synthesis of the prototype elisabethane diterpene, elisabethin A (73). 91 Elisabethadione (63) and the structurally related diterpenoids 64 and 65 were isolated as yellow or orange materials of either gummy or oily consistency, from specimens collected in the Florida Keys, 56 the Bahamas, 74 and San Andrés Island, respectively.…”