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.

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.

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.

Synthesis and biological evaluation of a new series of N-ylides as protein farnesyltransferase inhibitors.

A new family of 30 benzoylated N-ylides 4 and 5 was synthesized and evaluated for the inhibitory activity on human protein farnesyltransferase. Most of these novel compounds possessed in vitro inhibition potencies in the micromolar range. The nature of the substituents on the pyridine and phenyl units proved to be important in determining inhibitory activity and generally, the replacement of the cyanoacrylonitrile function by a cyanoethylacrylate group decreased the biological potential on farnesyltransferase. These results completed our SAR study on this original class of N-ylides.

Synthesis and biological evaluation of a new series of phenothiazine-containing protein farnesyltransferase inhibitors.

Two new families of human farnesyltransferase inhibitors 13a-m and 14a-d, based on a phenothiazine scaffold, were synthesized. Compounds 14a and 14b were the most promising inhibitors of human farnesyltransferase with IC(50) values of 0.7 and 0.6 µM, respectively.

Synthesis and anticancer activity of analogues of phenstatin, with a phenothiazine A-ring, as a new class of microtubule-targeting agents.

A new family of microtubule-targeting agents with a phenothiazine A-ring was synthesized and evaluated for anti-proliferative activity and interaction with tubulin. These new derivatives showed significant activities against cellular proliferation and tubulin polymerization, rather similar to those of phenstatin. Phenothiazine derivative 21 proved to be the most potent compound synthesized with GI(50) values ranging from 29 to 93 nM on different cell lines. The same compound showed a better inhibition of COLO 205, A498, and MCF7 cell lines than the parent phenstatin.