O-Acetylserine sulfhydrylase (isoform A, OASS-A) is a pyridoxal-5′-phosphate-dependent enzyme responsible for cysteine biosynthesis in many pathological microorganisms. It is proposed that inhibition of OASS-A could represent a novel strategy to overcome bacterial resistance to antibiotics. A class of 2-substituted-cyclopropane-1-carboxylic acids was synthesized, based on structural determinants grasped by analyzing a group of synthetic pentapeptides known to efficiently bind OASS-A from Haemophilus influenzae (HiOASS-A). The cyclopropane derivatives were submitted to a binding affinity assay with HiOASS-A and three of them, with K_diss in the low micromolar range, showed higher affinity than the most active synthetic pentapeptide. Thus, in this communication we report the first example of potent non-natural small molecule inhibitors of HiOASS-A. In addition, a molecular modelling study suggested a possible inhibition mechanism, through which the new cyclopropane ligands block HiOASS-A. Noteworthily, the novel, small-sized, non-peptidic inhibitors retain the structural motifs of the bulky peptides, which are relevant for the enzyme inhibition.

The recent elucidation of the X-ray structure of several class A GPCRs clearly indicates that the amphipathic helix 8 (H8) is a conserved structural domain in most crystallized GPCRs. Very little is known about the presence and the possible role of an analogous H8 domain in the distantly related class C GPCRs. In this study, we investigated the structural properties for the H8 domain of the mGluR2 receptor, a class C GPCR, by applying extended molecular dynamics simulations. Our study indicates that the amphipathic H8 adopts membrane-sensitive conformational states, which depend on the membrane composition. Cholesterol-rich membranes stabilize the helical structure of H8 whereas cholesterol-depleted membranes induce a disruption of H8. The observed link between membrane cholesterol levels and H8 conformational states suggests that H8 behaves as a sensor of cholesterol concentration.

Azelaic Acid (AzA) is a 9-carbon atom dicarboxylic acid, with numerous pharmacological uses in dermatology. Its effectiveness in papulopustular rosacea and acne vulgaris, among other dermatological disorders such as keratinization and hyper-pigmentation, is thought to be related to its anti-inflammatory and antimicrobial properties. It is a by-product of Pityrosporum fungal mycelia metabolism but also it is found in different cereals such as barley, wheat, and rye. Diverse topical formulations of AzA exist in commerce, and it is mainly produced via chemical synthesis. In this study we describe the extraction of AzA from whole grains and whole-grain flour (Triticum durum Desf.) through green methods. Seventeen different extracts were prepared and analyzed for their AzA content by HPLC-MS methods and then screened for their antioxidant activity using spectrophotometric assays (ABTS, DPPH, and Folin–Ciocalteu). Minimum-inhibitory-concentration (MIC) assays against several bacterial and fungal pathogens were performed, to validate their antimicrobial activity. The obtained results indicate that whole grain extracts provide a wider spectrum of activity than the flour matrix; in particular, the Naviglio^® extract showed higher AzA content, while the hydroalcoholic ultrasound-assisted extract provided better antimicrobial and antioxidant activity. The data analysis was performed using principal component analysis (PCA), as an unsupervised-pattern-recognition technique, to extract useful analytical and biological information.