DNA‐Templated [2 2] Photocycloaddition: A Straightforward Entry into the Aplysinopsin Family of Natural Products

Biosynthetic considerations inspired us to harness the template properties offered by DNA to promote a [2+2] photo‐induced cycloaddition. The method was developed based on the dimerization of (E)‐aplysinopsin, which was previously shown to be unproductive in solution. In sharp contrast, exposure of this tryptophan‐derived olefin to light in the presence of salmon testes DNA (st‐DNA) reproducibly afforded the corresponding homo‐dimerized spiro‐fused cyclobutane in excellent yields. DNA provides unique templating interactions enabling a singular mimic of the solid‐state aggregation necessary for the [2+2] photo‐cycloaddition to occur. This method was ultimately used to promote the prerequisite dimerizations leading to both dictazole B and tubastrindole B, thus constituting the first example of a DNA‐mediated transformation to be applied to the total synthesis of a natural product.Agence Nationale de la Recherche for financial support (D-CYSIV project; ANR-2015-CE29-0021-01)

Anti-AGEs and antiparasitic activity of an original prenylated isoflavonoid and flavanones isolated from Derris ferruginea

A new isoflavonoid, 5-hydroxy-3-(4-hydroxyphenyl)-8-isopropenyl-8,9-dihydro-4H-furo-[2,3-h]-chromen-4-one named derrisisoflavone G (1), four known prenylated flavanones (2–5), four known isoflavonoids (6–9) and two phenolic derivatives (10, 11) have been isolated from crude extracts of Derris ferruginea stems and leaves. Compounds 1–11 were identified using spectroscopic methods whereas an unambiguous structural assignment of 1 was accomplished through hemi-synthesis. Compounds 2–5 exhibited strong in vitro antiparasitic activity against Plasmodium falciparum and Leishmania major but with poor selectivity, whereas 1–5 significantly inhibited the formation of advanced glycation endproducts (AGEs)

CANPA: Computer-Assisted Natural Products Anticipation

International audienc

Constitution of a Lichen Metabolite Data Base (LDB) through HRLC-MS/MS analysis of 250 lichen compounds

International audienc

Computational Metabolomics Tools Reveal Subarmigerides, Unprecedented Linear Peptides from the Marine Sponge Holobiont Callyspongia subarmigera

: A detailed examination of a unique molecular family, restricted to the Callyspongia genus, in a molecular network obtained from an in-house Haplosclerida marine sponge collection (including Haliclona, Callyspongia, Xestospongia, and Petrosia species) led to the discovery of subarmigerides, a series of rare linear peptides from Callyspongia subarmigera, a genus mainly known for polyacetylenes and lipids. The structure of the sole isolated peptide, subarmigeride A (1) was elucidated through extensive 1D and 2D NMR spectroscopy, HRMS/MS, and Marfey's method to assign its absolute configuration. The putative structures of seven additional linear peptides were proposed by an analysis of their respective MS/MS spectra and a comparison of their fragmentation patterns with the heptapeptide 1. Surprisingly, several structurally related analogues of subarmigeride A (1) occurred in one distinct cluster from the molecular network of the cyanobacteria strains of the Guadeloupe mangroves, suggesting that the true producer of this peptide family might be the microbial sponge-associated community, i.e., the sponge-associated cyanobacteria

Potential of fascaplysin and palauolide from Fascaplysinopsis cf reticulata to reduce the risk of bacterial infection in fish farming

Marine natural products isolated from the sponge Fascaplysinopsis cf reticulata, in French Polynesia, were investigated as an alternative to antibiotics to control pathogens in aquaculture. The overuse of antibiotics in aquaculture is largely considered to be an environmental pollution, because it supports the transfer of antibiotic resistance genes within the aquatic environment. One environmentally friendly alternative to antibiotics is the use of quorum sensing inhibitors (QSIs). Quorum sensing (QS) is a regulatory mechanism in bacteria which control virulence factors through the secretion of autoinducers (AIs), such as acyl-homoserine lactone (AHL) in gram-negative bacteria. Vibrio harveyi QS is controlled through three parallel pathways: HAI-1, AI-2, and CAI-1. Bioassay-guided purification of F. cf reticulata extract was conducted on two bacterial species, i.e., Tenacibaculum maritimum and V. harveyi for antibiotic and QS inhibition bioactivities. Toxicity bioassay of fractions was also evaluated on the freshwater fish Poecilia reticulata and the marine fish Acanthurus triostegus. Cyclohexanic and dichloromethane fractions of F. cf reticulata exhibited QS inhibition on V. harveyi and antibiotic bioactivities on V. harveyi and T. maritimum, respectively. Palauolide (1) and fascaplysin (2) were purified as major molecules from the cyclohexanic and dichloromethane fractions, respectively. Palauolide inhibited QS of V. harveyi through HAI-1 QS pathway at 50 μg ml-1 (26 μM), while fascaplysin affected the bacterial growth of V. harveyi (50 μg ml-1) and T. maritimum (0.25 μg). The toxicity of fascaplysin-enriched fraction (FEF) was evaluated and exhibited a toxic effect against fish at 50 μg ml-1. This study demonstrated for the first time the QSI potential of palauolide (1). Future research may assess the toxicity of both the cyclohexanic fraction of the sponge and palauolide (1) on fish, to confirm their potential as alternative to antibiotics in fish farming

Tsavoenones A-C Unprecedented polyketides with a 1,7-dioxadispiro[4.0.4.4]tetradecane core from the lichen Parmotrema tsavoense

International audienceNew racemic dispiranic polyketides, tsavoenones A (1), B (2) and C (3), having a novel 1,7-dioxadispiro[4.0.4.4]tetradecane scaffold were isolated from the foliose lichen Parmotrema tsavoense. These compounds were structurally elucidated by extensive NMR analyses, comparison between experimental and theoretical 13C NMR data and X-ray crystallography. A putative biosynthetic scenario for the formation of 1-3 from parmosidone D, a meta-depsidone previously isolated from the same lichen material, was proposed. Tested for its cytotoxicity, 1 displayed a moderate activity against human myelogenous leukemia K562 cell line with an IC50 value of 66 μg mL-1. © 2018 The Royal Society of Chemistry