A novel-type luciferin from Siberian luminous earthworm Fridericia heliota : structure elucidation by spectral studies and total synthesis

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Wiley-VCH Verlag GmbH & Co for personal use, not for redistribution. The definitive version was published in Angewandte Chemie International Edition 53 (2014): 5566–5568, doi:10.1002/anie.201400529.We report structure elucidation and synthesis of the luciferin from the recently discovered luminous earthworm Fridericia heliota. This luciferin represents a key component of a novel ATP-dependent bioluminescence system. The UV, fluorescence, NMR and HRMS spectral studies were performed on 5 mkg of the isolated substance, and gave four isomeric structures, conforming with spectral data. These isomers were chemically synthesized and one of them was found to produce light in the reaction with a protein extract from Fridericia. The novel luciferin was found to have an unusual deeply modified peptidic nature, implying an unprecedented mechanism of action.We acknowledge support from the Program of the Government of the Russian Federation “Measures to attract leading scientists to Russian educational institutions” (grant no. 11. G34.31.0058), the programs MCB RAS, President of the Russian Federation “Leading science school” (grant 3951.2012.4) and the Russian Foundation for Basic Research (grant 14-03-01015). B.M.S. was supported by a stipend from the Program of the President of the Russian Federation.2015-04-1

Investigating the action of the microalgal pigment marennine on Vibrio splendidus by in vivo 2H and 31P solid-state NMR

This work investigates the potential probiotic effect of marennine - a natural pigment produced by the diatom Haslea ostrearia - on Vibrio splendidus. These marine bacteria are often considered a threat for aquaculture; therefore, chemical antibiotics can be required to reduce bacterial outbreaks. In vivo 2H solid-state NMR was used to probe the effects of marennine on the bacterial membrane in the exponential and stationary phases. Comparisons were made with polymyxin B (PxB) - an antibiotic used in aquaculture and known to interact with Gram(−) bacteria membranes. We also investigated the effect of marennine using 31P solid-state NMR on model membranes. Our results show that marennine has little effect on phospholipid headgroups dynamics, but reduces the acyl chain fluidity. Our data suggest that the two antimicrobial agents perturb V. splendidus membranes through different mechanisms. While PxB would alter the bacterial outer and inner membranes, marennine would act through a membrane stiffening mechanism, without affecting the bilayer integrity. Our study proposes this microalgal pigment, which is harmless for humans, as a potential treatment against vibriosis. -- Keywords : Antimicrobial pigment ; Polymyxin B ; Membrane fluidity ; Model membranes ; 31P and 2H NMR ; In-cell NMR

The total synthesis of sevanol, a novel lignan isolated from the thyme plant (Thymus armeniacus)

Recently, a novel lignan sevanol was isolated from the thyme plant Thymus armeniacus. During structure-functional elucidation it showed significant biological activity on ASIC3 acid sensing channels. Herein we describe the first synthesis of sevanol with a 3% overall yield. The construction of a dihydronaphthalene ring by oxidative dimerization of a protected dihydroxycinnamic acid ester in the presence of ferric chloride (III) is a key step in this first total synthesis of sevanol. © 2018 Elsevier Lt

The total synthesis of sevanol, a novel lignan isolated from the thyme plant (Thymus armeniacus)

Recently, a novel lignan sevanol was isolated from the thyme plant Thymus armeniacus. During structure-functional elucidation it showed significant biological activity on ASIC3 acid sensing channels. Herein we describe the first synthesis of sevanol with a 3% overall yield. The construction of a dihydronaphthalene ring by oxidative dimerization of a protected dihydroxycinnamic acid ester in the presence of ferric chloride (III) is a key step in this first total synthesis of sevanol. © 2018 Elsevier Lt

Novel side reaction accompanying cyclization of Glu(R1)-Glu(R2) dipeptides via lactamization of the Glu(R1) residue

A series of linear peptides with the general formula H-Glu(R1)-Glu(R2)-OH was subjected to cyclization under standard conditions. Formation of respective 2,5-diketopiperazines was accompanied by transformation of the N-terminal Glu(R1) to pyroglutamic acid residue. Even in the case R1 is an amino acid residue attached to the N-terminal γ-carboxyl group, lactamization leads to its elimination. The observed reaction has not been reported so far in the literature. Correspondingly, an alternative route to Glu(R1)-Glu(R2)-containing 2,5-diketopiperazines was applied to improve the overall yields. Copyright © 2018 European Peptide Society and John Wiley & Sons, Ltd

Novel side reaction accompanying cyclization of Glu(R1)-Glu(R2) dipeptides via lactamization of the Glu(R1) residue

A series of linear peptides with the general formula H-Glu(R1)-Glu(R2)-OH was subjected to cyclization under standard conditions. Formation of respective 2,5-diketopiperazines was accompanied by transformation of the N-terminal Glu(R1) to pyroglutamic acid residue. Even in the case R1 is an amino acid residue attached to the N-terminal γ-carboxyl group, lactamization leads to its elimination. The observed reaction has not been reported so far in the literature. Correspondingly, an alternative route to Glu(R1)-Glu(R2)-containing 2,5-diketopiperazines was applied to improve the overall yields. Copyright © 2018 European Peptide Society and John Wiley & Sons, Ltd

The Light Emitter of the 2-Coumar­anone Chemiluminescence: Theoretical and Experimental Elucidation of a Possible Model for Bioluminescent Systems

International audienceThe bioluminescence reaction of many biological subspecies, most notably fireflies, forms dioxetanone derivatives as high-energy intermediates. The thermal instability of dioxetanones complicates understanding of the transition from the ground state to the first excited state that leads to light emission. Herein, we report the reaction mechanism of 2-coumaranones, synthetically accessible strongly chemiluminescent materials that mimic the bioluminescence reaction. The pathways of chemiexcitation and photorelaxation are clarified on the basis of synthetic evidence and spectrochemical as well as computational mechanistic analysis