β-cyclopiazonic acid binds iron demonstrating siderophorelike activity and promotes growth in Pseudomonas aeruginosa

This chemical study reports a novel siderophore-like compound,β-cyclopiazonic acid(1,β-CPA)extracted from marine fungus Aspergillus flavus.The chemical structure ofβ-CPA was elucidated by a combination of extensive spectroscopic analyses and TDDFT-ECD calculations.The iron-binding ability and CAS assays demonstrate thatβ-CPA is a novel siderophore that features a different chemical structure from those of traditional siderophores.Theβ-CPA has no obvious influence on the growth of bacterium Pseudomonas aeruginosa PAO1.However,its iron chelator could promote the growth of P.aeruginosa PAO1,suggesting that P.aeruginosa employed siderophores to sequester iron,which is vital for their survival.The study provides the physiochemical evaluation ofβ-CPA,an unusual skeletonstructure siderophore,which for the first time,was proven to have the ability to bind iron and affect P.aeruginosa growth.This new discovery of siderophore provides an opportunity for developing novel anti-P.aeruginosa drugs.

Marine sponges of the genus Stelletta as promising drug sources: chemical and biological aspects

Marine sponges of the genus Stelletta are well known as rich sources of diverse and complex biologically relevant natural products, including alkaloids, terpenoids, peptides, lipids, and steroids. Some of these metabolites, with novel structures and promising biological activities, have attracted a lot of attention from chemists seeking to perform their total synthesis in parallel to intensive biological studies towards new drug leads. In this review, we summarized the distribution of the chemically investigated Stelletta sponges, the isolation, synthesis and biological activities of their secondary metabolites, covering the literature from 1982 to early 2018.

Uncommon Polycyclic Merosesquiterpenoids and Asteriscanoids from the Hainan Soft Coral Sinularia hurnesi

A rare highly fused racemic merosesquiterpenoid,9-epi-verrubenzospirolactone(1),six new asteriscane-type sesquiterpenoids,sinuhumesins A-F(4-9),and two related known ones(10 and 11)were isolated from Hainan soft coral Sinularia humesi.Compound 1 was further separated by chiral HPLC resolution to one pair of enantiomers[(+)-1 and(-)-1],respectively.The full structures of the new compounds were unambiguously determined by extensive spectroscopic analysis,chemical computation approaches,modified Mosher's method and/or X-ray diffract!on analysis,as well as comparison with previously reported data of related model compounds.

Polyoxygenated anti-inflammatory biscembranoids from the soft coral Sarcophyton tortuosum and their stereochemistry

Five novel biscembranoids,ximaolides H-L(1-5),along with four known related compounds(6-9) were isolated from the Hainan soft coral Sarcophyton tortuosum.The structures of the new compounds were determined by extensive spectroscopic analysis,quantum chemical calculations,and/or by comparing their CD spectra with those of the known compounds.Compounds 1 and 2 are the first examples of biscembranoids bearing a 1,35-bridged lactone moiety,4 is the first biscembranoid comprising an uncommon oxetane ring,and 5 represents the first 36-peroxyl biscembranoid.Ximaolides Ⅰ(2),K(4) and F(9) exhibited interesting anti-inflammatory activity by the inhibition of LPS-induced TNF-α protein release in RAW264.7 macrophages.

Marine alkaloids as the chemical marker for the prey–predator relationship of the sponge Xestospongia sp.and the nudibranch Jorunna funebris

The dietary relationship study between marine sponge Xestospongia sp.and its nudibranch predators Jorunna funebris based on the discovery of isoquinolinequinones has long been studied.In this study,chemical investigation of the sponge Xestospongia sp.and nudibranch J.funebris from the South China Sea yielded a new marine alkaloid neopetroside C(1),together with nine known alkaloids(2-10).The chemical structures of all the compounds were elucidated by extensive spectroscopic analysis.Neopetroside C(1)featured a riboside of nicotinic acid with a rareα-N glycosildic linkage and an acyl residue of(Z)-2-methylbut-2-enoic acid attached to C-5′.The plausible chemical ecology relationship between sponge Xestospongia sp.and its nudibranch predator J.funebris was proposed based on the biogenetic relationship of the common marine alkaloids.The observation of two structural fragments,(Z)-2-methylbut-2-enoyloxy and trigonelline groups in both sponge and nudibranch,indicated that nudibranch might uptake chemicals from sponge and then modify and transform them into chemical weapons to defend against predators.