New plant immunity elicitors from a sugar beet byproduct protect wheat against Zymoseptoria tritici.

The current worldwide context promoting agroecology and green agriculture require the discovery of new ecofriendly and sustainable plant protection tools. Plant resistance inducers, called also elicitors, are one of the most promising alternatives fitting with such requirements. We produced here a set of 30 molecules from pyroglutamic acid, bio-sourced from sugar beet byproducts, and examined for their biological activity on the major agro-economically pathosystem wheat-Zymoseptoria tritici. Foliar application of the molecules provided significant protection rates (up to 63% disease severity reduction) for 16 among them. Structure-activity relationship analysis highlighted the importance of all chemical groups of the pharmacophore in the bioactivity of the molecules. Further investigations using in vitro and in planta antifungal bioassays as well as plant molecular biomarkers revealed that the activity of the molecules did not rely on direct biocide activity towards the pathogen, but rather on the activation of plant defense mechanisms dependent on lipoxygenase, phenylalanine ammonia-lyase, peroxidase, and pathogenesis-related protein pathways. This study reports a new family of bio-sourced resistance inducers and provides new insights into the valorization of agro-resources to develop the sustainable agriculture of tomorrow.

Design, synthesis and evaluation of hydrazine and acyl hydrazone derivatives of 5-pyrrolidin-2-one as antifungal agents.

Twenty-eight 5-pyrrolidine-2-ones decorated by hydrazine or acyl hydrazones groups have been designed, synthesized and evaluated as antifungal agents on a panel of twelve fungal strains and three non albicans candida yeasts species which have demonstrated reduced susceptibility to commonly used antifungal drugs. Half of the target compounds exhibited good to high antifungal activities on at least one strain with MIC50 lower than the control antifungal agent - hymexazol or ketoconazole. 5-Arylhydrazino-pyrrolidin-2-ones were found active and the -NH-NH- linker proved to be essential to maintain the antifungal potential. Compound 2a is a broad-spectrum antifungal, active on 60% of the tested strains. Replacing the hydrazine linker by an acylhydrazone one narrowed the spectrum of activity but pyroglutamylaryl hydrazones, mainly aromatic ones, exhibited good activity, adequate "fungicide-like" properties and were devoted of cytotoxicity.

Design, synthesis and antifungal activity of pterolactam-inspired amide Mannich bases.

Pterolactam (5-methoxypyrrolidin-2-one) is a heterocycle naturally occurring in plants. In an attempt to identify antifungal agents, a series of novel Mannich bases of amide derivated from Pterolactam have been designed, synthesized and their antifungal activities were evaluated on a panel of nine fungal strains and three non albicans candida yeasts species which have demonstrated reduced susceptibility to commonly used antifungal drugs. A third of the target compounds exhibited good to high antifungal activities on at least one strain with EC50 lower than the control antifungal agent. N,N'-aminals derivated from Pterolactam proved to be good candidates for the development of biosourced fungicides, with compound 3o being the most broader-spectrum agent, active against five strains and devoted of any cytotoxicity.

Enhanced antitumor potential induced by chloroacetate-loaded benzophenones acting as fused tubulin-pyruvate dehydrogenase kinase 1 (PDHK1) ligands.

The majority of cancers detected every year are treated with anti-cancer compounds. Unfortunately, many tumors become resistant to antineoplastic drugs. One option is to use cocktails of compounds acting on different targets to try to overcome the resistant cells. This type of approach can produce good results, but is often accompanied by a sharp increase of associated side effects. The strategy presented herein focuses on the use of a single compound acting on two different biological targets enhancing potency and lowering the toxicity of the chemotherapy. In this light, the approach presented in the current study involves the dual inhibition of human pyruvate dehydrogenase kinase-1 (PDHK1) and tubulin polymerization using mono-, di- and tri-chloroacetate-loaded benzophenones and benzothiophenones. Synthesized molecules were evaluated in vitro on tubulin polymerization and on pyruvate dehydrogenase kinase 1. The cell cycle distribution after treatment of DA1-3b leukemic cells with active compounds was tested. Twenty-two benzo(thio)phenones have been selected by the National Cancer Institute (USA) for evaluation of their anti-proliferative potential against NCI-60 cancer cell lines including multidrug-resistant tumor cell lines. Seventeen molecules proved to be very effective in combating the growth of tumor cells exhibiting inhibitory activities up to nanomolar range. The molecular docking of best antitumor molecules in the study was realized with GOLD in the tubulin and PDHK1 binding sites, and allowed to understand the positioning of active molecules. Chloroacetate-loaded benzo(thio)phenones are dual targeted tubulin- and pyruvate dehydrogenase kinase 1 (PDHK1)-binding antitumor agents and exhibited superior antitumor activity compared to non-chlorinated congeners particularly on leukemia, colon, melanoma and breast cancer cell lines.

Pyroglutamide-Based P2X7 Receptor Antagonists Targeting Inflammatory Bowel Disease.

This report deals with the design, the synthesis, and the pharmacological evaluation of pyroglutamide-based P2X7 antagonists. A dozen were shown to possess improved properties, among which inhibition of YO-PRO-1/TO-PRO-3 uptake and IL1ß release upon BzATP activation of the receptor and dampening signs of DSS-induced colitis on mice, in comparison with reference antagonist GSK1370319A. Docking study and biological evaluation of synthesized compounds has highlighted new SAR, and low toxicity profiles of pyroglutamides herein described are clues for the finding of a usable h-P2X7 antagonist drug. Such a drug would raise the hope for a cure to many P2X7-dependent pathologies, including inflammatory, neurological, and immune diseases.

Exploring isoxazoles and pyrrolidinones decorated with the 4,6-dimethoxy-1,3,5-triazine unit as human farnesyltransferase inhibitors.

Unprecedented triazinyl-isoxazoles were afforded via an effective cycloaddition reaction between nitrile oxides and the scarcely described 2-ethynyl-4,6-dimethoxy-1,3,5-triazine as dipolarophile. The biological evaluation of the newly synthesized compounds showed that the inhibition of human farnesyltransferase by zinc complexation could be improved with triazine-isoxazole moieties. The replacement of the isoxazole unit by a pyrrolidin-2-one was detrimental to the inhibitory activity while the pyrrolidin-2-thione derivatives conserved the biological potential. The potential of selected compounds to disrupt protein farnesylation in Chinese hamster ovary (CHO) cells transfected with pEGFP-CAAX was also evaluated.

Phenyliodine(III) Diacetate/I2 -Mediated Domino Approach for Pyrrolo[1,4]Thiazines and 1,4-Thiazines by a One-Pot Morin Rearrangement of N,S-Acetals.

An efficient domino transformation using a phenyliodine(III) diacetate (PIDA)/I2 combination towards Morin 1,4-thiazine compounds has been developed starting from N,S-acetals. The latter leads to "one-step" regioselective methylene insertion without the need for traditional sulfoxide intermediates in good yields. The reaction involves easily accessible N,S-acetals obtained from cost-effective basic ketones and cysteamine as starting materials. This process ultimately leads to 1,4-thiazines related to natural product and fused derivatives necessary for further QSAR study.

New salicylic acid and pyroglutamic acid conjugated derivatives confer protection to bread wheat against Zymoseptoria tritici.

BACKGROUND: To promote sustainable agriculture and healthy food, research that contributes towards a new generation of eco-friendly phytosanitary compounds is increasingly encouraged. The plant hormone salicylic acid (SA) is known for its ability to induce resistance in plants against a wide range of pathogens, whereas pyroglutamic acid (PGA), a constrained analogue of γ-aminobutyric acid, has never been studied in the context of plant protection. RESULTS: The present study investigated for the first time the protection efficacy of SA and PGA and five new conjugated derivatives against Zymoseptoria tritici, the main pathogen in wheat crops. SA and four derivatives showed significant disease severity reductions in planta (up to 49%). In vitro assays revealed that some molecules, including SA, displayed a small direct antifungal activity, whereas others, such as PGA, showed no effect. This finding suggests that, especially for molecules without any direct activity, the mode of action relies mainly on the induction of plant resistance. CONCLUSION: Further investigations are needed to identify the defence pathways involved in plant resistance mechanisms elicited or primed by the molecules. The manufacture of these products was easily achieved on a scale of tens of grams of raw materials, and is easily scalable. The synthetic pathway is simple, short and inexpensive. For all of these reasons, the production of the target molecules is attractive for producers, whereas the prospect of a generation of non-polluting compounds with lasting efficiency against Z. tritici in wheat comes at a key moment for the sustainability of agriculture. © 2018 Society of Chemical Industry.

From Conventional Lewis Acids to Heterogeneous Montmorillonite K10: Eco-Friendly Plant-Based Catalysts Used as Green Lewis Acids.

The concept of green chemistry began in the USA in the 1990s. Since the publication of the 12 principles of this concept, many reactions in organic chemistry have been developed, and chemical products have been synthesized under environmentally friendly conditions. Lewis acid mediated synthetic transformations are by far the most numerous and best studied. However, the use of certain Lewis acids may cause risks to environmental and human health. This Review discusses the evolution of Lewis acid catalyzed reactions from a homogeneous liquid phase to the solid phase to yield the expected organic molecules under green, safe conditions. In particular, recent developments and applications of biosourced catalysts from plants are highlighted.

On the discovery of new potent human farnesyltransferase inhibitors: emerging pyroglutamic derivatives.

In the current context of lack of emergence of innovative human farnesyltransferase inhibitors families, and given all new therapeutic perspectives that open up for such molecules in rare diseases (e.g. Hutchinson-Gilford progeria syndrome), and in delta hepatitis, cardiovascular or neuroinflammatory diseases, we have just discovered a new series of powerful inhibitors. These molecules are pyroglutamic acid derivatives, and were evaluated on human farnesyltransferase in vitro then modeled in silico on the active site of the protein. Three main points of the pyroglutamic acid cycle have undergone chemical modulations pyroglutamides in position 5 (compounds 7a-h), constrained bicyclic analogues of pyrroloimidazoledione type (compounds 1a-h), modulation of the position 3 (compounds 2-5 and 8), and allowed the first SAR in the field. Five derivatives in the current work have IC50 values in the small nanomolar range (2-5 nM). These new lead compounds open the way for the next generation of farnesyltransferase inhibitors.

Methylene versus carbonyl bridge in the structure of new tubulin polymerization inhibitors with tricyclic A-rings.

The phenothiazine group has been identified as a suitable A ring in the structure of tubulin polymerization inhibitors. In our search to identify more potent inhibitors, a study of different isosteric tricyclic groups as new potential A rings was first realized and permitted to identify 1-azaphenothiazine and iminodibenzyl as favorable modulations providing compounds with improved activity against tubulin. An investigation of the methylene group as the connector between the A and B rings revealed that the "CH2" bridge was tolerated, improving the biological potency when the A unit was of phenothiazine, 1-azaphenothiazine or iminodibenzyl type. Molecules 6-8 and 12 showed increased biological activity in comparison to parent phenstatin 2 on COLO 205 colon cancer cell line. The most antineoplastic agent in the current study was phenothiazine 5 displaying a GI50 of 25nM against the melanoma MDA-MB-435 cell line.

Studies on phenothiazines: New microtubule-interacting compounds with phenothiazine A-ring as potent antineoplastic agents.

New phenothiazine derivatives 6-20 have been designed, synthesized and evaluated in vitro for their ability to inhibit tubulin polymerization and antiproliferative activity against 60 cancer cell lines, including several multi-drug resistant (MDR) tumor cell lines. The phenothiazine unit may successfully replace the classical 3,4,5-trimethoxyphenyle A ring of parent combretastatin A-4 or phenstatin, confirming previous studies. The most promising structural modulations have been realized on the B ring, the 2'-fluoro-4'-methoxy substitution in compound 6 and the 2'-trifluoromethyl-4'-methoxy substitution in compound 7 providing the best antitubulin and antitumor activity in the current study. Compounds 6-8 and 16 exhibited more important cell growth inhibition than parent phenstatin 2 on human colon Duke's type D, colorectal adenocarcinoma COLO 205 and on human kidney adenocarcinoma A498 cell lines. 10-Methylphenothiazine derivatives 19 and 20 did not show biological activity but exerted bright fluorescence and solvatochromism effects. These molecules deserve further chemical efforts in order to provide valuable tools for biophysical studies.

Phenothiazine-based CaaX competitive inhibitors of human farnesyltransferase bearing a cysteine, methionine, serine or valine moiety as a new family of antitumoral compounds.

A new family of CaaX competitive inhibitors of human farnesyltransferase based on phenothiazine and carbazole skeleton bearing a l-cysteine, l-methionine, l-serine or l-valine moiety was designed, synthesized and biologically evaluated. Phenothiazine derivatives proved to be more active than carbazole-based compounds. Phenothiazine 1b with cysteine residue was the most promising inhibitor of human farnesyltransferase in the current study.

Discovery of indolizines containing triazine moiety as new leads for the development of antitumoral agents targeting mitotic events.

A new family of 3-aroylindolizines bearing a dimethoxytriazine unit in their position 1 was designed, synthesized and evaluated for their ability to inhibit tubulin polymerization and cellular growth in vitro. Compound 39 was the best candidate in the current study with a GI50 value of 870 nM on SNB-75 CNS cancer cells and of 920 nM on MDA-MB-231/ATCC breast cancer cells. The standard NCI Compare results indicated that indolizine 39 may target PLK1 (polo-like kinase 1).

Evaluation and comparison of three different separation techniques for analysis of retroamide enantiomers and their biological evaluation against h-P2X7 receptor.

The P2X receptors are seven-transmembrane domain G protein-coupled receptors and the 7 subtypes of P2X receptors identified in humans, and named P2X1 to P2X7, are channel receptors whose endogenous ligand is ATP. New antagonists of the P2X7 receptor were developed, since this purinergic receptor was highlighted to be involved in many diseases such as different types of pain, cancer, ischemia, neurodegenerative diseases (including Parkinson's and Alzheimer's diseases) characterized by inflammatory processes. With the aim of evaluate the impact of chirality on the pharmacological activity of a new P2X7R antagonist, a semi-preparative method was developed in supercritical fluid chromatography (SFC). Among four polysaccharide based chiral stationary phases: Chiralcel OD-H and OJ-H and Chiralpak AS-H and AD-H, the last one namely amylose tris (3,5-dimethylphenylcarbamate) with a mobile phase consisted of carbon dioxide-ethanol (80:20, v/v), led to the successful separation of the enantiomers in short run time and with good resolution. Limits of detection and quantification were calculated and were found equal for compound 1, to 1.37 µM and 4.57 µM respectively, for peak 1 and were equal to 1.60 µM and 5.30 µM respectively, for peak 2 at λ=210 nm. Before carrying out the pharmacological evaluation of each enantiomer, two complementary methodologies, e.g. liquid chromatography and capillary electrophoresis were performed in parallel to improve the limits of detection and quantification to assess the enantiomeric purity. HPLC using a Chiralpak AD stationary phase led to four times lower limits of detection and quantification with regard to SFC. In the same time, capillary electrophoresis involving dual cyclodextrins system constituted of a SBE-ß-CD and a MM-ß-CD mixture enhanced the signal-to-noise ratio and led to similar limits of detection and quantification with regard to SFC. No trace of the other enantiomer was found in the isolated one. Biological activities of individual enantiomers were then evaluated and revealed no cytotoxicity against cell lines and a significant difference in terms of their IC50 values with respect to the investigated racemate (6.43 µM): 3.49 µM for the (R)-enantiomer and >10(-4)µM for the (S)-enantiomer, for compound 1, showing that, this antagonist activity is stereospecific.

Studies on indolizines. Evaluation of their biological properties as microtubule-interacting agents and as melanoma targeting compounds.

With the aim of investigating new analogues of phenstatin with an indolizin-3-yl unit, in particular as the B-ring, three new series of compounds (6-8, 9-34 and 54) were synthesized and tested for interactions with tubulin polymerization and evaluated for cytotoxicity on an NCI-60 human cancer cell lines panel. The replacement of the 3'-hydroxy-4'-methoxyphenyl B-ring of phenstatin with substituted indolizine unit results in the conservation of both antitubulin and cytotoxic effect. Indolizines 9 and 17 were the most effective in the present study and showed the highest antiproliferative effect on melanoma cell lines MDA-MB-435 (GI50 = 30 nM) and could serve as new lead compounds for the development of anti-cancer therapeutics.

Eaton's reagent-mediated domino π-cationic arylations of aromatic carboxylic acids to Iasi-red polymethoxylated polycyclic aromatic hydrocarbons: products with unprecedented biological activities as tubulin polymerization inhibitors.

A rapid domino π-cationic arylation of aromatic carboxylic acids, mediated by Eaton's reagent, has been developed for the synthesis of Iasi-red polymethoxylated polycyclic aromatic hydrocarbons (PAHs). This route is currently the easiest method to obtain such popular PAH compounds, which bear in addition numerous methoxy groups. The domino process was generalized, the structure of the obtained red products and the mechanism of their formations were elucidated, and some of their photophysical properties were determined. Newly synthesized polymethoxylated-PAHs were tested for their interaction with tubulin polymerization as well as for their cytotoxicity on a panel of NCI-60 human cancer cell lines. Interestingly, one of these rubicene derivatives exhibited remarkable cytotoxicity in vitro, including inhibition of leukemia, colon, melanoma, CNS, and ovarian cancer cell lines with GI50 values in the low nanomolar range (GI50 < 10 nM).

Enantioseparation of pyroglutamide derivatives on polysaccharide based chiral stationary phases by high-performance liquid chromatography and supercritical fluid chromatography: a comparative study.

Analytical enantioseparation of three pyroglutamide derivatives with pharmacological activity against the purinergic receptor P2X7, was run in both high-performance liquid chromatography and supercritical fluid chromatography. Four polysaccharide based chiral stationary phases, namely amylose and cellulose tris (3,5-dimethylphenylcarbamate), amylose tris ((S)-α-methylbenzylcarbamate) and cellulose tris (4-methylbenzoate) with various mobile phases consisted of either heptane/alcohol (ethanol and 2-propanol) or carbon dioxide/alcohol (methanol or ethanol) mixtures, were investigated. After analytical screenings, the best conditions were transposed, for compound 1, to semi-preparative scale. Each approach was fully validated to meet the International Conference on Harmonisation requirements and compared. Whereas the limits of detection and quantification were near six-fold better in HPLC than in SFC (respectively 0.20 and 0.66 µM versus 1.11 and 3.53 µM for one of the enantiomers), in terms of low solvent consumption (7.2 mL of EtOH versus 3.2 mL of EtOH plus 28.8 mL of toxic and inflammable heptane per injection in SFC and HPLC, respectively), time effective cost (9 min versus 40 min per injection in SFC and HPLC, respectively) and yields (98% versus 71% in SFC and HPLC, respectively), the latter method proved its ecological superiority.

Antagonists of the P2X7 receptor: mechanism of enantioselective recognition using highly sulfated and sulfobutylether cyclodextrins by capillary electrokinetic chromatography.

This work concerns the successful enantiomeric separation of pyroglutamic acid derivatives, known to be P2X7 receptor antagonists, achieved by electrokinetic chromatography. After a broad screening, two negatively charged cyclodextrins, sulfobutylether-ß-cyclodextrin (SBE-ß-CD), and highly sulfated-γ-cyclodextrin (HS-γ-CD) were chosen as stereoselective agents to cooperate with the BGE for complexation. A fused silica capillary coated with polyethylene oxide, filled with a phosphate buffer (25 mM, pH 2.5) containing various concentrations of CD, was used. Assuming a 1:1 stoichiometry, calculations of the binding constants, employing the three different linearization plots, were performed from the corrected electrophoretic mobilities values of the enantiomers, at different concentrations of SBE-ß-CD and HS-γ-CD in the BGE. The highest complexation was found with the SBE-ß-CD. Among the three equations, results showed better linearity (R(2) > 0.99) using the y-reciprocal fit. This plotting method was then performed to determine the binding constants of each enantiomer at different temperature for compounds 1 and 2 with SBE-ß-CD and HS-γ-CD in order to access to the thermodynamic parameters of the eight complexes. The linearity of the Van't Hoff plot, in the range of 288-303 K leading to negative enthalpy values, showed that the complexation phenomenon is enthalpically controlled and thermodynamically favored.