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 (IC₅₀ = 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 π electronic orbitals. Our results develop a quantitative framework for establishing structure–function relationships that will underpin the design of self-assembling peptide electronic materials