Phorbasin A:  A Novel Diterpene from a Southern Australian Marine Sponge, Phorbas Species

Abstract

A southern Australian Phorbas species has yielded a novel diterpene, phorbasin A (1), possessing an unprecedented carbon skeleton. The structure for phorbasin A was determined by detailed spectroscopic analysis.

Polyoxygenated Diterpenes from the Sponge Phorbas sp.

“…An aliquot (1.73 g) of the fraction eluted with 10% MeOH(aq) was dried and separated by reversed-phase HPLC (YMC-ODS-A column, 20% MeOH(aq)) to afford, in the order of elution, compounds 13, 11,6,3,8,5,4,15,9,7,12,14,2, and 1 as white solids. An aliquot (1.75 g) of the fraction eluted with 100% MeOH was dried and separated by reversed-phase HPLC (YMC-ODS-A column, 15% MeOH(aq)) to afford, in the order of elution, compounds 4, 12, 2, 1, 16, 10, and 17 as white solids.…”

“…Ten new polyoxygenated diterpenes (7)(8)(9)(10)(11)(12)(13)(14)(15)(16) along with six known gagunin compounds (1)(2)(3)(4)(5)(6) were isolated from the sponge Phorbas sp. collected in the Korean Sea.…”

“…[3][4][5][6] Other chemical species isolated from Phorbas include the phorbasins, which are essentially diterpenoids with skeletal rearrangements, the phorbasides, which are 14-membered lactone metabolites, and the phorbasterones and amaranzole A, which are steroids bearing unique functional groups. [7][8][9][10][11] Sponges of the genus Phorbas are common in the waters off the southwestern coast of Korea. Our previous studies of these animals yielded gagunins, cytotoxic diterpenoids with highly oxygenated functionalities on a 10,13-epi-homoverrucosane skeleton.…”

Metallacycle-mediated cross-coupling in natural product synthesis

“…72–76 Members of this class have been reported to possess a range of antibiotic and cytotoxic properties, with phorbasin C attracting the attention of the Micalizio laboratory (Figure 23A). While the structure of the target was not clear from the reported isolation, the Micalizio laboratory began a synthesis campaign that targeted the development of a regio- and stereoselective allylic alcohol–alkyne coupling process for establishment of the C6–C7 bond.…”

A new derivative of phorbaketals isolated from a Marine Sponge Phorbas species

“…This organism has been known to produce various potent bioactive compounds with unique structures since the first isolation of phorbazoles in 1994. [3][4][5][6] These structurally diverse natural products also showed a wide range of biological activities such as:…”