Precursor-Directed Biosynthesis of Antialgal Fluorinated Bacillamide Derivatives in .

The bacillamides are a class of indole alkaloids produced by the genus that possess significant antialgal activity. Incorporation of fluorine into the bacillamides was carried out using a precursor-directed biosynthesis approach, with 4-, 5-, and 6-fluorotryptophan added to growing cultures of IMG-11. This yielded the corresponding fluorinated analogues of bacillamides A and C, in addition to new derivatives of the related metabolite -acetyltryptamine, thus demonstrating a degree of plasticity in the bacillamide biosynthetic pathway.

Antibacterial and Anti-Biofilm Activity of Pyrones from a Strain.

The emergence of drug resistant microbes over recent decades represents one of the greatest threats to human health; the resilience of many of these organisms can be attributed to their ability to produce biofilms. Natural products have played a crucial role in drug discovery, with microbial natural products in particular proving a rich and diverse source of antimicrobial agents. During antimicrobial activity screening, the strain P33 was found to inhibit the growth of multiple pathogens.

Bioactive α,β-conjugated 3-keto-steroids from the Australian brown alga Cystophora xiphocarpa.

As part of our ongoing study of the specialised metabolites present in brown algae belonging to the Cystophora genus, eight new steroids including three pairs of diastereoisomers were isolated from Cystophora xiphocarpa (Harvey) (Sargassacea, Fucales). The metabolites identified by standard spectrometric methods are (16S,22S)-16,22-dihydroxyergosta-4,24(28)-dien-3-one and (16S,22R)-16,22-dihydroxyergosta-4,24(28)-dien-3-one, (16S,22S,24R)-16,22,24-trihydroxyporifera-4,28-dien-3-one and (16S,22S,24S)-16,22,24-trihydroxystigma-4,28-dien-3-one along with (16S,22S,24E)-16,22-dihydroxystigma-4,24(28)-dien-3-one and (16S,20S)-16,20-dihydroxyergosta-4,24(28)-dien-3-one. (16S,22S,24E)-16,22-Dihydroxystigma-4,24(28)-dien-3-one possessed the most potent cytotoxicity of the steroids in this series with cell growth inhibitions of GI 8.

Isolation of 2-Alkyl-4-quinolones with Unusual Side Chains from a Chinese Isolate.

Chemical investigation of a strain isolated from Hebei, China, led to the isolation of a suite of quinolones, quinolone--oxides, and phenazines, the structures of which were elucidated by detailed spectroscopic analysis. Most notable among the secondary metabolites isolated was an unprecedented 4-quinolone containing an -methyl group in the side chain and a new derivative including a phenyl ring in the side chain, which expand significantly the variety of structural motifs found in the quinolones and raise interesting questions about their biosynthesis.

Isolation, Identification, and Decomposition of Antibacterial Dialkylresorcinols from a Chinese Strain.

A chemical investigation of a Chinese strain has yielded a new benzoquinone () and furanone (), in addition to the known dialkylresorcinols and . Extensive decomposition studies on the major metabolite produced an additional furanone derivative (), a hydroxyquinone (), and two unusual resorcinol and hydroxyquinone dimers ( and ). Structures were elucidated by nuclear magnetic resonance spectroscopy in combination with tandem mass spectrometry analysis.

Bioactive Compounds Isolated from Marine-Derived Microbes in China: 2009-2018.

This review outlines the research that was carried out regarding the isolation of bioactive compounds from marine-derived bacteria and fungi by China-based research groups from 2009-2018, with 897 publications being surveyed. Endophytic organisms featured heavily, with endophytes from mangroves, marine invertebrates, and marine algae making up more than 60% of the microbial strains investigated. There was also a strong focus on fungi as a source of active compounds, with 80% of publications focusing on this area.

Cytotoxic compounds from Laurencia pacifica.

Background: The current investigation sought to explore the nature of the secondary metabolites in the algae, Laurencia pacifica.

Results: This report details the first isolation of the sesquiterpenes isoaplysin (1), isolaurenisol (2), debromoisolaurinterol (3), debromoaplysinol (4), laur-11-en-10-ol (5), 10α-hydroxyldebromoepiaplysin (6), and the previously unknown 10-bromo-3,7,11,11-tetramethylspiro[5.5]undeca-1,7-dien-3-ol (7) from the algae, Laurencia pacifica.