Abstract:
The isolation and structure elucidation of 12 new compounds from four different genera
of marine sponge is described. Continued work with the marine sponge Raspailia
topsenti resulted in the isolation of two clerodane diterpenes, raspailodanes F (40) and G
(41). Raspailodane F contains a novel tricyclo[5.4.0.0]undecane scaffold including a
cyclopropyl ring. A nonadecanoic acid derivative, petrosianoic acid (122), was isolated
from an unknown species of the genus Petrosia. It is believed that 122 is only the third
nonadecanoic acid derivative reported from the marine environment. The marine sponge
Dendrilla rosea was examined for the presence of new spongian diterpenes. While no new
diterpenes were discovered, the acetylenic nitrile dendronitrile (158) was isolated along
with two known diterpenes and a known steroid. Dendronitrile is the first acetylenic
nitrile discovered from the marine environment and only the third ever reported. Seven
new lamellarins and one new dictyodendrin were isolated from Dictyodendrilla dendyi
alongside one known lamellarin and two known dictyodendrins. Lamellarins Θ (187)
and κ (188) are related to known lamellarins. The remaining five lamellarins are
sulfated derivatives, lamellarin Θ 4'',4'''-disulfate (190), lamellarin O 4'''-sulfate (191),
lamellarin O 4'',4'''-disulfate (192), lamellarin κ 4'''-sulfate (193), and lamellarin κ 4'',4'''-
disulfate (194). Dictyodendrin F (195) is a new natural product previously only reported
as a semi-synthetic derivative of known dictyodendrins. Lamellarin shows moderate
cytotoxic activity. The biological activity of the remaining compounds, particularly the
sulfated derivatives, is under investigation.
The screening protocol used to analyse crude sponge extracts was refined and a number of
advances were made towards the automated analysis of the spectra generated. A method
was devised to extract peak data from screen HSQC spectra and by combining these data,
to produce a software-based mask of known correlations. The application of this mask
was demonstrated in three different ways to three different screen HSQC spectra. To
aid in the identification of interesting correlations identified by the mask, a database of
HSQC correlations was compiled from literature and in-house sources. A new method of
describing the chemical environment of a given position was developed to suit the needs of the database. At present, the database contains 91 compounds and represents over 2500
individual HSQC correlations. Development of both the software screening technique and
the HSQC correlation database is ongoing.
