Determination of the Chemical Composition of Eucalyptus spp. for Cellulosic Pulp Production

The chemical composition of wood is important to assess the quality of this raw material for the industry of cellulosic pulp production. The purpose of this work was to determine the chemical composition of Eucalyptus spp. grown for cellulosic pulp production. Ten Eucalyptus spp. clones with six years of age, located in the municipality of Itamarandiba, Minas Gerais, Brazil, were used. Quantification was obtained for extractives, monosaccharides, uronic acids, acetates, lignin, ash and the phenolic composition of the extracts. In average, clones showed around 2.7% extractives, with a predominance of polar compounds soluble in ethanol and water; 27.7% lignin and 0.3% ash. Glucose was the main sugar detected (64.2%), followed by xylose (19.3%). The main components of the extractives were steroids, fatty acids and aromatic acids, followed by smaller amounts of substituted alkanoic acids, fatty alcohols, glycerol derivatives and triterpenes. The ethanol–water extracts presented total phenol contents ranging from 321.4 to 586.6 mg EAG/g of extract, tannins from 28.1 to 65.1 mg catechin/g of extract and flavonoids from 73.6 to 256.9 mg catechin/g of extract. Clones with a higher holocellulose amount and a lower lignin content showed a higher potential for cellulosic pulp production. These findings are important for the development of high-quality wood based on important traits for the pulp and paper sector.

Targeting Bacterial Sortases in Search of Anti-Virulence Therapies with Low Risk of Resistance Development

Increasingly ineffective antibiotics and rapid spread of multi- and pan-resistant bacteria represent a global health threat; hence, the need of developing new antimicrobial medicines. A first step in this direction is identifying new molecular targets, such as virulence factors. Sortase A represents a virulence factor essential for the pathogenesis of Gram-positive pathogens, some of which have a high risk for human health. We present here an exhaustive collection of sortases inhibitors grouped by relevant chemical features: vinyl sulfones, 3-aryl acrylic acids and derivatives, flavonoids, naphtoquinones, anthraquinones, indoles, pyrrolomycins, isoquinoline derivatives, aryl β-aminoethyl ketones, pyrazolethiones, pyridazinones, benzisothiazolinones, 2-phenyl-benzoxazole and 2-phenyl-benzofuran derivatives, thiadiazoles, triazolothiadiazoles, 2-(2-phenylhydrazinylidene)alkanoic acids, and 1,2,4-thiadiazolidine-3,5-dione. This review focuses on highlighting their structure–activity relationships, using the half maximal inhibitory concentration (IC50), when available, as an indicator of each compound effect on a specific sortase. The information herein is useful for acquiring knowledge on diverse natural and synthetic sortases inhibitors scaffolds and for understanding the way their structural variations impact IC50. It will hopefully be the inspiration for designing novel effective and safe sortase inhibitors in order to create new anti-infective compounds and to help overcoming the current worldwide antibiotic shortage.

Honey-collecting in prehistoric West Africa from 3500 years ago

Honey and other bee products were likely a sought-after foodstuff for much of human history, with direct chemical evidence for beeswax identified in prehistoric ceramic vessels from Europe, the Near East and Mediterranean North Africa, from the 7th millennium BC. Historical and ethnographic literature from across Africa suggests bee products, honey and larvae, had considerable importance both as a food source and in the making of honey-based drinks. Here, to investigate this, we carry out lipid residue analysis of 458 prehistoric pottery vessels from the Nok culture, Nigeria, West Africa, an area where early farmers and foragers co-existed. We report complex lipid distributions, comprising n-alkanes, n-alkanoic acids and fatty acyl wax esters, which provide direct chemical evidence of bee product exploitation and processing, likely including honey-collecting, in over one third of lipid-yielding Nok ceramic vessels. These findings highlight the probable importance of honey collecting in an early farming context, around 3500 years ago, in West Africa.

Composition and antioxidant properties of extracts from Douglas fir bark

This study aimed to investigate the antioxidant ability and the chemical composition of apolar and polar extractives from Douglas-fir bark, cork and phloem, establishing a possible correlation with the structural variation along the tree stem and geographic location. Douglas-fir bark extractives’ composition were analyzed at three stem heights in trees from two locations. Cork and phloem extracts’ composition were analyzed in samples collected at stem base. Extractives content in Douglas-fir bark varied between 14 and 31% and polar extractives (11–29%) were dominant over non-polar. Lipophilic extracts were mainly composed of terpenoids, representing 27–77% of all compounds, highlighted by callitrisic acid (11–34%). Sterols were also abundant (6–45%), with β-sitosterol representing 7–33% of all compounds. Alkanoic acids were present in smaller amounts. Ethanol–water extracts showed high phenolic (562–762 mg GAE/g extract), flavonoid and condensed tannins contents (399–683 mg CE/g extract and 120–262 mg CE/g of extract), high scavenging (IC50 2.8 µg extract/mL) and reducing (12 mM Fe2+/g extract) abilities. Cork had high phenolic (819 mg GAE/g extract) and flavonoid contents (524 mg CE/g extract) and high antioxidant capacity (1080 mg TEAC/g extract). Detailed knowledge of Douglas-fir extracts demonstrates their potential as a source of fine chemicals towards different applications.

Synthesis and evaluation of new thiazole-containing rhodanine-3-alkanoic acids as inhibitors of protein tyrosine phosphatases and glutathione S-transferases

Thiazole-containing derivatives of rhodanine-3-alkanoic acids with propanoic or undecanoic acid groups were synthesized and evaluated as inhibitors of some protein tyrosine phosphatases and glutathione S-transferases. The rhodanines bearing longer carboxylated N-alkyl chain were found to inhibit PTP1B, MEG1, MEG2, and VE-PTP as well as GST from equine liver and GSTA1-1 with IC50 values in the low micromolar range. The inhibitory effect on protein tyrosine phosphatase activity depends on substituent at position 2 of the thiazole ring. The best compound showed a competitive type of VE-PTP inhibition. In case of GST from equine liver, the inhibition was of mixed or non-competitive type with respect to glutathione or CDNB substrate, respectively. Possible binding modes of the inhibitors were discussed based on molecular docking calculations.