In prehistoric hunter-gatherer-fisher communities, demographic growth and a more sedentary life-style are usually associated with locally concentrated food resources. Technologies believed to have ...been employed for preserving excess food resources include, among many others, salting, smoking, and/or sun-drying of fish and meat. However, direct proof of salting is often lacking, as salt is highly soluble. We present here the first robust evidence of the earliest known examples of fish salting from Middle Mesolithic structures at an archaeological site in Central Sudan (7th millennium BC). A multidisciplinary approach was applied, including a contextual geoarchaeological study (field analysis; micromorphological and scanning electron microscopy), a mineralogical-microstructural analysis of salt crystallization (X-ray diffraction, scanning electron microscopy), and a chemical analysis of salt concentration (ionic chromatography) in the soil in which salted fish bones have been found. The results indicate that salting fish with the aim of preserving it was common at the site of Al Khiday since the Middle Mesolithic and this habit cannot be related to post-depositional precipitation due to aridification of the area. A clear-cut emphasis on fishing characterized the economy of the human population of the time. This foraging system, together with salting and storing fish seems to be closely connected with its nearly sedentary status.
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•The earliest use of salt for fish conservation is here proved in the Nile valley.•Mineralogical and chemical analysis indicate the use of halite.•This food conservation practice favoured sedentism in hunter-gatherer-fisher society.
β-Lactamases (BLs) able to hydrolyze β-lactam antibiotics and more importantly the last resort carbapenems, represent a major mechanism of resistance in Gram-negative bacteria showing multi-drug or ...extensively drug resistant phenotypes. The early detection of BLs responsible of resistant infections is challenging: approaches aiming at the identification of new BLs inhibitors (BLI) can thus serve as the basis for the development of highly needed diagnostic tools. Starting from benzo-b-thiophene-2-boronic acid (BZB), a nanomolar inhibitor of AmpC β-lactamase (K
= 27 nM), we have identified and characterized a set of BZB analogues able to inhibit clinically-relevant β-lactamases, including AmpC, Extended-Spectrum BLs (ESBL), KPC- and OXA-type carbapenemases and metallo-β-lactamases (MBL). A multiligand set of boronic acid (BA) β-lactamase inhibitors was obtained using covalent molecular modeling, synthetic chemistry, enzyme kinetics and antibacterial susceptibility testing. Data confirmed the possibility to discriminate between clinically-relevant β-lactamases on the basis of their inhibition profile. Interestingly, this work also allowed the identification of potent KPC-2 and NDM-1 inhibitors able to potentiate the activity of cefotaxime (CTX) and ceftazidime (CAZ) against resistant clinical isolates (MIC reduction, 32-fold). Our results open the way to the potential use of our set of compounds as a diagnostic tool for the sensitive detection of clinically-relevant β-lactamases.
Production of β-lactamases (BLs) is the most widespread resistance mechanism adopted by bacteria to fight β-lactam antibiotics. The substrate spectrum of BLs has become increasingly broad, posing a ...serious health problem. Thus, there is an urgent need for novel BL inhibitors. Boronic acid transition-state analogues are able to reverse the resistance conferred by class A and C BLs. We describe a boronic acid analogue possessing interesting and potent broad-spectrum activity vs class A and C serine-based BLs. Starting from benzo(b)thiophene-2-boronic acid (BZBTH2B), a nanomolar non-β-lactam inhibitor of AmpC that can potentiate the activity of a third-generation cephalosporin against AmpC-producing resistant bacteria, we designed a novel broad-spectrum nanomolar inhibitor of class A and C BLs. Structure-based drug design (SBDD), synthesis, enzymology data, and X-ray crystallography results are discussed. We clarified the inhibitor binding geometry responsible for broad-spectrum activity vs serine-active BLs using double mutant thermodynamic cycle studies.
Recent decades have witnessed a dramatic increase of multidrug resistant (MDR) bacteria, compromising the efficacy of available antibiotics, and a continual decline in the discovery of novel ...antibacterials. We recently reported the first library of benzobthiophen-2-ylboronic acid inhibitors sharing broad spectrum activity against β-lactamases (BLs). The ability of these compounds to inhibit structurally and mechanistically different types of β-lactamases has been here structurally investigated. An extensive X-ray crystallographic analysis of boronic acids (BAs) binding to proteins representative of serine BLs (SBLs) and metallo β-lactamases (MBLs) have been conducted to depict the role played by the boronic group in driving molecular recognition, especially in the interaction with MBLs. Our derivatives are the first case of noncyclic boronic acids active against MBLs and represent a productive route toward potent broad-spectrum inhibitors.
Women with deleterious mutations in BRCA1/2 have a high lifetime penetrance of developing breast cancer and/or ovarian cancer. Genetic and/or environmental factors may influence BRCA penetrance, and ...identifying modifiable exposures might be valuable for prevention.
We implemented a multicenter prospective 2-arm (1:1) randomized controlled trial to investigate whether a Mediterranean dietary intervention with moderate protein restriction would reduce potential modulators of BRCA penetrance such as insulin-like growth factor 1 (IGF-1), body weight, and metabolic risk factors. We studied the baseline characteristics of women with BRCA-positive disease who joined the trial cohort, focusing on the relationships between selected lifestyle exposures, metabolic/anthropometric parameters, and BRCA-related cancer.
A total of 502 women (304 with a previous diagnosis of breast cancer and/or ovarian cancer and 198 unaffected) with deleterious BRCA mutations, with or without a previous cancer, aged 18 to 70 years and without metastases were included. Late age at menarche and pregnancy were negatively associated with BRCA-related cancer, especially in women with BRCA1-positive disease. Higher fat mass and the presence of 4 or 5 metabolic risk factors were significantly associated with BRCA-related cancer (hazard ratio, 1.87, 95% confidence interval, 1.21-2.88; and hazard ratio, 1.87, 95% confidence interval, 1.11-3.19, respectively), with greater effect in BRCA2-positive women.
Our findings confirm previous observations about reproductive factors in women with BRCA disease and suggest a potential impact of metabolic factors in BRCA-related cancer. The prospective follow-up of the trial cohort will enable us to study the environmental modulators of BRCA penetrance and their impact in relation to the history of BRCA-related cancer. ClinicalTrials.gov NCT03066856
Identifying modifiable exposures is important in BRCA1/2 mutation carriers. We studied the relationships between selected lifestyle/metabolic exposures and BRCA-related cancer in the patients who joined our Mediterranean dietary intervention trial. Late age at menarche and pregnancy were negatively associated with BRCA-related cancer. Higher fat mass and dysmetabolism were significantly associated with BRCA-related cancer, with greater effect in BRCA2-positive women.
Benzobthiophene-2-ylboronic acid, 1, is a 27 nM inhibitor of the class C β-lactamase AmpC and potentiates the activity of β-lactam antibiotics in bacteria that express this and related enzymes. As is ...often true, the potency of compound 1 against the enzymes is much attenuated in cell culture against Gram negative bacteria, where the minimum inhibitor concentration of compound 1 is in the mid-micromolar range. Here, we modulated the properties of this lead to enhance its ability to cross the membrane, using a combination of X-ray crystallography, structure-based design, and application of physical models of outer membrane crossing. This strategy led us to derivatives with substantially improved permeability. Also, the greater solubility of these compounds allowed us to measure their efficacy at higher concentrations than with the lead 1, leading to higher maximum potentiation of the antibiotic effect of ceftazidime on resistant bacteria.
The elucidation of the structural/functional specificities of highly conserved enzymes remains a challenging area of investigation, and enzymes involved in cellular replication are important targets ...for functional studies and drug discovery. Thymidylate synthase (TS, ThyA) governs the synthesis of thymidylate for use in DNA synthesis. The present study focused on Lactobacillus casei TS (LcTS) and Escherichia coli TS (EcTS), which exhibit 50 % sequence identity and strong folding similarity. We have successfully designed and validated a chemical model in which linear, but not constrained, dansyl derivatives specifically complement the LcTS active site. Conversely, chemically constrained dansyl derivatives showed up to 1000-fold improved affinity for EcTS relative to the inhibitory activity of linear derivatives. This study demonstrates that the accurate design of small ligands can uncover functional features of highly conserved enzymes.
N,O-Didansyl-l-tyrosine (DDT) represented the starting lead for further development of novel non-substrate-like inhibitors of bacterial thymidylate synthase. The N-dansyl structure modulation led to ...a submicromolar inhibitor of Lactobacillus casei TS (LcTS), which is highly specific with respect to human TS (hTS). Using molecular dynamics simulation, a binding mode for DDT vs LcTS was predicted, explaining activity and species-specificity along the series.
Thymidylate synthase (TS) is a well-recognized target for anticancer chemotherapy. Due to its key role in the sole de novo pathway for thymidylate synthesis and, hence, DNA synthesis, it is an ...essential enzyme in all life forms. As such, it has been recently recognized as a valuable new target against infectious diseases. There is also a pressing need for new antimicrobial agents that are able to target strains that are drug resistant toward currently used drugs. In this context, species specificity is of crucial importance to distinguish between the invading microorganism and the human host, yet thymidylate synthase is among the most highly conserved enzymes. We combine structure-based drug design with rapid synthetic techniques and mutagenesis, in an iterative fashion, to develop novel antifolates that are not derived from the substrate and cofactor, and to understand the molecular basis for the observed species specificity. The role of structural and computational studies in the discovery of nonanalog antifolate inhibitors of bacterial TS, naphthalein and dansyl derivatives, and in the understanding of their biological activity profile, are discussed.
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