N-Acyl Homoserine Lactone Derived Tetramic Acids Impair Photosynthesis in Phaeodactylum tricornutum.

Marine bacteria contribute substantially to nutrient cycling in the oceans and can engage in close interactions with microalgae. Many microalgae harbor characteristic satellite bacteria, many of which participate in N-acyl homoserine lactone (AHL) mediated quorum sensing. In the diffusion-controlled phycosphere, AHLs can reach high local concentrations, with some of them transforming into tetramic acids, compounds with a broad bioactivity.

Synthesis of 1,4-Oxazepane-2,5-diones via Cyclization of Rotationally Restricted Amino Acid Precursors and Structural Reassignment of Serratin.

Several natural products containing a 1,4-oxazepane-2,5-dione-core are known. One example is serratin, isolated from Serratia marcescens. Because of the presence of a carboxylic amide, which has a preference for a trans-conformation, and the presence of a labile lactone in this core, many synthetic methodologies commonly used for the cyclization toward medium-sized heterocycles cannot be applied.

Synthesis and biological evaluation of novel N-α-haloacylated homoserine lactones as quorum sensing modulators.

Novel N-α-haloacylated homoserine lactones, in which a halogen atom was introduced at the α-position of the carbonyl function of the N-acyl chain, have been studied as quorum sensing (QS) modulators and compared with a library of natural N-acylated homoserine lactones (AHLs). The series of novel analogues consists of α-chloro, α-bromo and α-iodo AHL analogues. Furthermore, the biological QS activity of the synthetic AHL analogues compared to the natural AHLs was evaluated.

Haloperoxidase mediated quorum quenching by Nitzschia cf pellucida: study of the metabolization of N-acyl homoserine lactones by a benthic diatom.

Diatoms are known to produce a variety of halogenated compounds, which were recently shown to have a role in allelopathic interactions between competing species. The production of these compounds is linked to haloperoxidase activity. This research, has shown that this system may also be involved in diatom-bacteria interactions via the H2O2 dependent inactivation of a type of quorum sensing (QS) molecule, i.