Synthesis of 4-(Phenylamino)quinazoline-2(1H)-thiones Using Green Solvents.

Given the importance of quinazolines and quinazolinethiones in therapeutic and Food and Drug Administration (FDA)-approved molecules, we thought interesting to consider their synthesis in green solvents. We have shown that obtain 4-(arylamino)quinazoline-2-(1H)-thiones and 4-(arylamino)pteridine-2-(1H)-thiones analogues was efficient in green solvents derived from biomass, especially eucalyptol. Although reaction times are somewhat long to achieve good yields, the products were obtained by simple filtration. This considerably limited the loss of atoms due to the use of large quantities of solvents for purification on silica gel columns, and makes our route a sustainable one.

Synthetic Modifications of Andrographolide Targeting New Potential Anticancer Drug Candidates: A Comprehensive Overview.

This review collects the synthetic modifications performed on andrographolide, a natural molecule derived from Andrographis paniculata, for oncology applications. Various pharmacomodulations were carried out, and the products were tested on different cancer cell lines. The impact of these modifications was analyzed with the aim of mapping the positions essential for activity to facilitate future research in this field. However, this study makes it clear that, in addition to structural modifications of the molecule, which can result in varying degrees of effectiveness in targeting interactions, the lipophilic capacity of the structures obtained through hemisynthesis is of significant importance.

Protecting-group free synthesis of glycoconjugates displaying dual fungicidal and plant defense-eliciting activities.

A straightforward synthesis of carbohydrate templated isoxazolidines is described, by reaction of unprotected glycosylhydroxylamines (operating as 1,3-dipoles) with methyl acrylate using microwave activation. Rhamno- and erythro-isoxazolidines are recognized by plant cells, resulting in a strong ROS-production as a plant immune response, and exert a high antifungal activity against Botrytis cinerea.

Sabinene: A New Green Solvent Used in the Synthesis of Thiazolo[5,4-b]pyridines by Thermal or Microwave Activation.

Following the work already carried out in our laboratory on eucalyptol, a new green solvent derived from biomass, we are now looking at sabinene as another new green solvent. Sabinene is also derived from biomass, has no known toxicity and can be recycled by distillation. We have shown that it can be used as it is or distilled to synthesize thiazolo[5,4-b]pyridine heterocycles by thermal activation or microwave irradiation. This new solvent was compared with various conventional and green solvents. The conditions were optimised to enable us to carry out the syntheses in satisfactory yields, and we were able to show that sabinene, a natural bicyclic monoterpene, could be used effectively as a solvent.

Broadening the reaction scope of unprotected aldoses via their corresponding nitrones: 1,3-dipolar cycloadditions with alkenes.

Condensation reactions of unprotected tetroses and pentoses with hydroxylamines afforded nitrones, which were easily converted to densely functionalized isoxazolidines in the presence of electron-poor alkenes. The 1,3-dipolar cycloaddition occurred with good facial discrimination of the chiral nitrone but under rather low endo/exo control. Stereochemistry of isomers was ascertained by chemical correlation with known derivatives from the literature. Microwave activation appeared as the most efficient reaction mode, affording the expected adducts within several minutes whereas hours were needed under standard heating. Alternatively, the transformation proved also possible under high pressure conditions by using a hand pump system, avoiding any energy source. Although water could not be used as the solvent, leading to hydrolysis of the nitrone substrate, a large variety of organic solvents proved efficient. The method has potential use in the preparation of non-ionic carbohydrate-based amphiphiles.

Regiospecific formation of sugar-derived ketonitrone towards unconventional C-branched pyrrolizidines and indolizidines.

The synthesis of unprecedented branched pyrrolizidines and indolizidines was accomplished via nitrone chemistry. The required ketonitrone, a known intermediate usually obtained as a mixture of regioisomers, was prepared in a pure form from d-arabinose by a sequence of oximation/reduction/oxidation steps. Nucleophilic vinylation or allylation followed by ring-closing metathesis of the corresponding N-allylpyrrolidines furnished the targeted iminosugars, which proved potent and selective inhibitors of alpha-glucosidase from rice (GH31 family).

Antioxidant Effects of Catechins (EGCG), Andrographolide, and Curcuminoids Compounds for Skin Protection, Cosmetics, and Dermatological Uses: An Update.

Here we have chosen to highlight the main natural molecules extracted from Camellia sinensis, Andrographis paniculata, and Curcuma longa that may possess antioxidant activities of interest for skin protection. The molecules involved in the antioxidant process are, respectively, catechins derivatives, in particular, EGCG, andrographolide, and its derivatives, as well as various curcuminoids. These plants are generally used as beverages for Camellia sinensis (tea tree), as dietary supplements, or as spices. The molecules they contain are known for their diverse therapeutic activities, including anti-inflammatory, antimicrobial, anti-cancer, antidiabetic, and dermatological treatment. Their common antioxidant activities and therapeutic applications are widely documented, but their use in cosmetics is more recent. We will see that the use of pharmacomodulated derivatives, the addition of co-antioxidants, and the use of various formulations enable better skin penetration and greater ingredient stability. In this review, we will endeavor to compile the cosmetic uses of these natural molecules of interest and the various structural modulations reported with the aim of improving their bioavailability as well as establishing their different mechanisms of action.