Cyclic 3-alkyl pyridinium alkaloid monomers from a New Zealand Haliclona sp. marine sponge

New Alkylpyridinium Anthraquinone, Isocoumarin, C-Glucosyl Resorcinol Derivative and Prenylated Pyranoxanthones from the Culture of a Marine Sponge-Associated Fungus, Aspergillus stellatus KUFA 2017

An unreported isocoumarin, (3S,4R)-4-hydroxy-6-methoxymellein (2), an undescribed propylpyridinium anthraquinone (4), and an unreported C-glucosyl resorcinol derivative, acetyl carnemycin E (5c), were isolated, together with eight previously reported metabolites including p-hydroxybenzaldehyde (1), 1,3-dimethoxy-8-hydroxy-6-methylanthraquinone (3a), 1,3-dimethoxy-2,8-dihydroxy-6-methylanthraquinone (3b), emodin (3c), 5[(3E,5E)-nona-3,5-dien-1-yl]benzene (5a), carnemycin E (5b), tajixanthone hydrate (6a) and 15-acetyl tajixanthone hydrate (6b), from the ethyl acetate extract of the culture of a marine sponge-derived fungus, Aspergillus stellatus KUFA 2017. The structures of the undescribed compounds were elucidated by 1D and 2D NMR and high resolution mass spectral analyses. In the case of 2, the absolute configurations of the stereogenic carbons were determined by comparison of their calculated and experimental electronic circular dichroism (ECD) spectra. The absolute configurations of the stereogenic carbons in 6a and 6b were also determined, for the first time, by X-ray crystallographic analysis. Compounds 2, 3a, 3b, 4, 5a, 5b, 5c, 6a, and 6b were assayed for antibacterial activity against four reference strains, viz. two Gram-positive (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and two Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853), as well as three multidrug-resistant strains. However, only 5a exhibited significant antibacterial activity against both reference and multidrug-resistant strains. Compound 5a also showed antibiofilm activity against both reference strains of Gram-positive bacteria.

Neopetrosidines A-D, pyridine alkaloids isolated from the marine sponge Neopetrosia chaliniformis and their cell cycle elongation activity

Natural products that inhibit cell cycle progression show promise as anticancer agents and chemical probes. In our research on biologically active natural products that affect cell cycle progression of HeLa/fluorescent ubiquitination-based cell cycle indicator (Fucci)2 cells, the extract of the marine sponge Neopetrosia chaliniformis was revealed to inhibit cell proliferation. Purification of the extract afforded four new pyridine alkaloids, neopetrosidines A-D (1-4). Their structures were elucidated by the interpretation of spectroscopic data and chemical degradation. Compounds 1-4 were found to inhibit cell proliferation of HeLa/Fucci2 cells, and time-lapse imaging showed that 1 exerts its effect by increasing the duration of the cell cycle. Furthermore, we show that 1 perturbs bioenergetics to exhibit a cytostatic effect by reducing the mitochondrial membrane potential.

Bioactive Nitrogenous Secondary Metabolites from the Marine Sponge Genus Haliclona

Marine sponge genus Haliclona, one of the most prolific sources of natural products, contains over 600 species but only a small part of them had been classified and chemically investigated. On the basis of extensive literature search, this review firstly summarizes 112 nitrogenous secondary metabolites from classified and unclassified Haliclona sponges as well as from their symbiotic microorganisms. Most of these substances have only been found in Haliclona sponges, and display diverse bioactive properties with potential applications in new drug discovery.

Two New Compounds from Medicinal Insect Blaps japanensis and Their Biological Evaluation

Blaps japanensis is a medicinal insect used for the treatment of a variety of disorders in Yi-nationality of Yunnan province, China. In the present study, two new compounds, named pipajiains F and G (1 and 2), along with four known compounds, 3-indolealdehyde (3), L-tryptophan (4), ginsenine (5), and anoectochine (6) were isolated from B. japanensis. Their structures were identified on the basis of spectroscopic methods. Compound 1 is a phenolic compound bearing a pyridine-1-ium-1carboxylate motif in the structure which made 1 an unusual architecture. Compounds 2 is an indole alkaloid derivative. Biological activities of all these compounds towards COX-2, ROCK1/2, and JAK3 kinases were evaluated.

Enantioselective total synthesis of naturally occurring eushearilide and evaluation of its antifungal activity

The asymmetric total synthesis of a newly proposed structure of (3S,16E,20E,23S)-(+)-eushearilide was achieved primarily through an asymmetric Mukaiyama aldol reaction, Schlosser-modified Wittig reaction and 2-methyl-6-nitrobenzoic anhydride-mediated macrolactonization. Based on detailed spectroscopic analyses, the obtained synthetic compound was found to be identical to natural eushearilide. Therefore, we were able to determine the true structure of eushearilide. Moreover, the synthetic compound was found to exhibit significant in vitro antifungal activity against various fungi and bacteria.

Marine natural products

This review covers the literature published in 2013 for marine natural products (MNPs), with 982 citations (644 for the period January to December 2013) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1163 for 2013), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

Three new polyunsaturated lipids from a Guangxi marine sponge Haliclona sp

Three new polyunsaturated lipids, (6Z,9Z,12Z,15Z)-octadeca-6,9,12,15-tetraen-3-one (1), (6Z,9Z,12Z,15Z)-1-bromooctadeca-6,9,12,15-tetraen-3-one (2), and (Z)-ethyl docos-5-enoate (3), together with two known polyunsaturated lipids, 4(Z),7(Z),10(Z)-tridecatrienoic acid (4) and (6Z,9Z,12Z,15Z)-octadeca-1,6,9,12,15-pentaen-3-one (5), were isolated from the marine sponge Haliclona sp., which was collected from Guangxi, using HSCCC and HPLC methods. Chemical structures of the five compounds were elucidated by spectroscopic techniques.