6 research outputs found
Cyclic 3‑Alkyl Pyridinium Alkaloid Monomers from a New Zealand <i>Haliclona</i> sp. Marine Sponge
Bioassay and NMR approaches have
been used to guide the isolation
of one known and two new cyclic 3-alkyl pyridinium alkaloid (3-APA)
monomers from the New Zealand marine sponge <i>Haliclona</i> sp. The new compounds, dehydrohaliclocyclins C (<b>3</b>)
and F (<b>4</b>), are the first reported examples of cyclic
3-APA monomers with unsaturation in the alkyl chain. The known compound
haliclocyclin C (<b>2</b>) was also isolated from a mixture
with <b>4</b>. The structures of compounds <b>2</b>–<b>4</b> were elucidated using NMR spectroscopy, mass spectrometry,
and chemical degradation
Sorbicillamines A–E, Nitrogen-Containing Sorbicillinoids from the Deep-Sea-Derived Fungus <i>Penicillium</i> sp. F23–2
Five new nitrogen-containing sorbicillinoids
named sorbicillamines
A–E (<b>1</b>–<b>5</b>) were isolated from
an agitated culture of the deep-sea-derived fungus Penicillium sp. F23–2, which has previously
produced indole alkaloids and terpenoids when cultured under static
conditions. The structures of <b>1</b> to <b>5</b>, including
absolute configurations, were determined based on MS, NMR, and circular
dichroism (CD) data. The cytotoxicities of the five new sorbicillin
alkaloids against the HeLa, BEL-7402, HEK-293, HCT-116, and P388 cell
lines were evaluated
Identification and Bioactivity of 3-<i>epi</i>-Xestoaminol C Isolated from the New Zealand Brown Alga <i>Xiphophora chondrophylla</i>
We report here the bioassay-guided
isolation of a new 1-deoxysphingoid,
3-<i>epi</i>-xestoaminol C (<b>1</b>), isolated from
the New Zealand brown alga <i>Xiphophora chondrophylla</i>. This is the first report of a 1-deoxysphingoid from a brown alga.
We describe the isolation and full structure elucidation of this compound,
including its absolute configuration, along with its bioactivity against
mycobacteria and mammalian cell lines and preliminary mechanism of
action studies using yeast chemical genomics
Bioactivity-Guided Metabolite Profiling of Feijoa (<i>Acca sellowiana</i>) Cultivars Identifies 4‑Cyclopentene-1,3-dione as a Potent Antifungal Inhibitor of Chitin Synthesis
Pathogenic fungi continue to develop
resistance against current
antifungal drugs. To explore the potential of agricultural waste products
as a source of novel antifungal compounds, we obtained an unbiased
GC-MS profile of 151 compounds from 16 commercial and experimental
cultivars of feijoa peels. Multivariate analysis correlated 93% of
the compound profiles with antifungal bioactivities. Of the 18 compounds
that significantly correlated with antifungal activity, 5 had not
previously been described from feijoa. Two novel cultivars were the
most bioactive, and the compound 4-cyclopentene-1,3-dione, detected
in these cultivars, was potently antifungal (IC<sub>50</sub> = 1–2
μM) against human-pathogenic <i>Candida</i> species.
Haploinsufficiency and fluorescence microscopy analyses determined
that the synthesis of chitin, a fungal-cell-wall polysaccharide, was
the target of 4-cyclopentene-1,3-dione. This fungal-specific mechanism
was consistent with a 22–70-fold reduction in antibacterial
activity. Overall, we identified the agricultural waste product of
specific cultivars of feijoa peels as a source of potential high-value
antifungal compounds
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
Thermodynamic Factors Impacting the Peptide-Driven Self-Assembly of Perylene Diimide Nanofibers
Synthetic peptides offer enormous
potential to encode the assembly
of molecular electronic components, provided that the complex range
of interactions is distilled into simple design rules. Here, we report
a spectroscopic investigation of aggregation in an extensive series
of peptide-perylene diiimide conjugates designed to interrogate the
effect of structural variations. By fitting different contributions
to temperature dependent optical absorption spectra, we quantify both
the thermodynamics and the nature of aggregation for peptides by incrementally
varying hydrophobicity, charge density, length, as well as asymmetric
substitution with a hexyl chain, and stereocenter inversion. We find
that coarse effects like hydrophobicity and hexyl substitution have
the greatest impact on aggregation thermodynamics, which are separated
into enthalpic and entropic contributions. Moreover, significant peptide
packing effects are resolved via stereocenter inversion studies, particularly
when examining the nature of aggregates formed and the coupling between
Ï€ electronic orbitals. Our results develop a quantitative framework
for establishing structure–function relationships that will
underpin the design of self-assembling peptide electronic materials