4 research outputs found
The Oxeatamides: Nitrogenous Spongian Diterpenes from the New Zealand Marine Sponge <i>Darwinella oxeata</i>
As part of our ongoing search for
novel and bioactive compounds
from New Zealand marine organisms, we investigated the extracts of
the sponge <i>Darwinella oxeata</i>. NMR-guided fractionation
led to the isolation of nine new nitrogenous spongian diterpenes,
oxeatamide A (<b>1</b>), iso-oxeatamide A (<b>2</b>),
oxeatamides B–G (<b>3</b>–<b>8</b>), and
oxeatamide A 23-methyl ester (<b>9</b>), as well as two known
compounds, membranolides C and D (<b>10</b>, <b>11</b>)
The Nitrogenous Hamigerans: Unusual Amino Acid-Derivatized Aromatic Diterpenoid Metabolites from the New Zealand Marine Sponge Hamigera tarangaensis
The
NMR-directed isolation and structure elucidation of nine new
nitrogenous hamigeran diterpenoids from the New Zealand marine sponge Hamigera tarangaensis are described. Featured in
this set are the oxazole-containing hamigeran M (<b>4</b>) and
eight compounds (<b>5a</b>–<b>6a</b> and <b>7a</b>–<b>8c</b>) related to the constitutional structure
of hamigeran D (<b>1</b>). Moderate cytotoxicity in the low-micromolar
range against the HL-60 promyeloid leukemic cell line is reported
for seven of the new compounds. The structural nature of these compounds
suggests that their adducts are derived from an amino acid source
and has allowed for revision of the configuration about C-18 of the
archetypal compound, hamigeran D, from <b>1a</b> to <b>1b</b>. The existence of three constitutionally identical forms of hamigeran
Q (<b>8a</b>–<b>8c</b>) requires the involvement
of an <i>allo</i>-isoleucine stereoisomer and suggests the
intriguing possibility of partial prokaryotic biogenesis of these
unusual secondary metabolites
Hamigerans R and S: Nitrogenous Diterpenoids from the New Zealand Marine Sponge <i>Hamigera</i> tarangaensis
Seven new members of the hamigeran
family of diterpenoids have
been isolated from the New Zealand marine sponge <i>Hamigera
tarangaensis</i>. Among the new additions are hamigeran R (<b>1</b>), considered to be the first benzonitrile-based marine natural
product, and hamigeran S (<b>2</b>), the first dimeric structure
in the series. The formation of <b>1</b> and <b>2</b> is
thought to occur via the reaction of hamigeran G with a nitrogen source,
where the nitrile carbon of <b>1</b> is derived from the terpenoid
skeleton
Polyhalogenated Indoles from the Red Alga <i>Rhodophyllis membranacea</i>: The First Isolation of Bromo-Chloro-Iodo Secondary Metabolites
An unusual tetrahalogenated indole
with the exceptionally rare inclusion of the three halogens bromine,
chlorine, and iodine was found using mass spectrometry within a fraction
of a semipurified extract obtained from the red alga <i>Rhodophyllis
membranacea.</i> We report herein the isolation and structure
elucidation, using a combination of NMR spectroscopy and mass spectrometry,
of 11 new tetrahalogenated indoles (<b>1</b>–<b>11</b>), including four bromochloroiodoindoles (<b>5</b>–<b>7</b>, <b>10</b>). Several were evaluated for cytotoxic
and antifungal activities against the HL-60 promyelocytic cell line
and <i>Saccharomyces cerevisiae</i>, respectively