Resolution of P-Sterogenic 1-Phenylphosphin-2-en-4-one 1-Oxide into Two Enantiomers by (R,R)-TADDOL and Conformational Diversity of the Phosphinenone Ring and TADDOL in the Crystal State

The resolution of racemic 1-phenylphosphin-2-en-4-one 1-oxide (2), was achieved through the fractional crystallization of its diastereomeric complexes with (4R,5R)-(−)-2,2-dimethyl -α,α,α′,α′-tetraphenyl-dioxolan-4,5-dimethanol (R,R-TADDOL) followed by the liberation of the individual enantiomers of 2 by flash chromatography on silica gel columns. The resolution process furnished the two enantiomers of 2 of 99.1 and 99.9% e.e. at isolated yields of 62 and 59% (counted for the single enantiomer), respectively. The absolute configurations of the two enantiomers were established by means of X-ray crystallography of their diastereomerically pure complexes, i.e., (R)-2•R,R)-TADDOL and (S)-2•(R,R)-TADDOL. The structural analysis revealed that in the (R)-2•(R,R)-TADDOL complex, the P-phenyl substituent occupied a pseudoequatorial position, whereas in (S)-2•(R,R)-TADDOL, it appeared in both the pseudoequatorial and the pseudoaxial positions in four symmetrically independent molecules. Concurrent conformational changes of the TADDOL molecules were best described by the observed changes of a pseudo-torsional CO...OC angle that could be considered as a possible measure of TADDOL conformation in its receptor–ligand complexes. The structural analysis of the (R,R)-TADDOL molecule revealed that efficiency of this compound for use as an effective resolving factor comes from its ability to flexibly fit its structure to both enantiomers of a ligand molecule, producing a rare case of resolution for both pure enantiomers with one chiral separating agent. The resolved (R)-2 was used to assign the absolute configuration of a recently described (−)-1-phenylphosphin-2-en-4-one 1-sulfide by chemical correlation. In addition, an attempted stereoretentive reduction of (R)-2 by PhSiH3 at 60 °C revealed an unexpectedly low barrier for P-inversion in 1-phenylphosphin-2-en-4-one.

Essential Oil Composition From Cryptomeria japonica D.Don Grown in Azores: Biomass Valorization From Forest Management

Cryptomeria japonica biomass was obtained monthly from forest lumbering operations at São Miguel, Terceira and Pico (Azores), between May 2018 and June 2020. C japonica stands with different ages (2 to ±50 years), grown in different soil types (lithosol and andosol) and at different altitudes (200 to >800 m) were used. The chemical composition of 118 C japonica essential oil (EO) samples, plus 1 sample from an EO solid deposit, were analyzed by gas chromatography and gas chromatography–mass spectrometry. Chemical composition cluster analysis showed 2 clusters, cluster I and II, with no chemical correlation. Cluster I grouped all 117 EO samples that resulted from extraction of branches and foliage with, or without, strobili, from strobili, and from the solid deposit sample. Cluster II grouped the 2 samples of EO isolated from wood, with a markedly different composition. Cluster I showed 5 subclusters (Ia-Ie). The degree of chemical correlation between the samples in these subclusters varied between moderate (subclusters Id and Ie), high (subclusters Ib and Ic), and very high (subcluster Ia). Of the 119 samples, 94 (79% of the total) were included in subcluster Ia, with 66 samples from São Miguel, 2 from Terceira, and 26 from Pico, showing a yield range from 0.1% to 0.4% (v/w). All these samples, with a high chemical correlation, were obtained by steam distillation from branches and foliage with, or without, female or male strobili, or both. This subcluster did not show any grouping pattern regarding the collection month, the altitude (200 to >800 m), the soil type (lithosol, andosol, or its subtypes), or the wood age (±30 to ±50 years). Subcluster Ia was characterized by the dominance of α-pinene (13%-43%), sabinene (5%-25%), phyllocladene (2%-22%), limonene (2%-16%), kaurene (traces-13%), elemol (1%-11%), and terpinen-4-ol (1%-7%). The determination of the concentration limits of the EOs representative components confirmed the homogeneity of C japonica EO, obtained from plant material collected in the 3 Azores islands, despite the variability in the range of some diterpenes that deserves further study. This study allowed for the determination of the concentration limits of the EOs representative components, with the purpose of adding value to C japonica EO, obtained from forest lumbering.

Sesquiterpene Lactones with the 12,8-Guaianolide Skeleton from Algerian Centaurea omphalotricha

In continuing our investigation on the chemical diversity of Algerian plants, we examined Centaurea omphalotricha, whose chemical composition has been poorly studied. The present work was aimed at characterizing the secondary metabolite pattern of the CHCl3 extract of the aerial parts of this plant that displayed antiproliferative properties in a preliminary screening on HeLa cell line. The chemical analysis led us to characterize the bioactive oxygenated terpenoid fraction which includes, within major known metabolites, two new minor sesquiterpene lactones, centaurolide-A (1) and centaurolide-B (2). The structures of two compounds exhibiting the 12,8-guaianolide skeleton were determined by spectroscopic methods as well as by chemical correlation with inuviscolide (3), a well-known bioactive guaianolide isolated from Dittrichia (=Inula) viscosa. Centaurolides A and B represent the first report of 8,12-guaianolide skeleton in Centaurea genus. The effect of new compounds 1 and 2 and inuviscolide (3) on HeLa cell has also been evaluated.

Identification and Quantification of a Phytotoxic Metabolite from Alternaria dauci

Alternaria dauci is the causal agent of Alternaria leaf blight (ALB) in carrot (Daucus carota) crops around the world. However, to date, A. dauci has received limited attention in its production of phytotoxic metabolites. In this investigation, the bioassay-guided isolation of the extract from liquid cultures of A. dauci resulted in the isolation of two metabolites identified as α-acetylorcinol (1) and p-hydroxybenzoic acid (2), based on their spectroscopic data and results from chemical correlation reactions. Testing of both metabolites in different assays showed an important phytotoxic activity for p-hydroxybenzoic acid (2) when tested in the leaf-spot assay on parsley (Petroselinum crispum), in the leaf infiltration assay on tobacco (Nicotiana alata) and marigold (Tagetes erecta), and in the immersion assay on parsley and parsnip (Pastinaca sativa) leaves. Quantification of the two metabolites in the crude extract of A. dauci kept at different times showed that p-hydroxybenzoic acid (2) is one of the first metabolites to be synthesized by the pathogen, suggesting that this salicylic acid derivative could play an important role in the pathogenicity of the fungus.

Taxonomic Implication of Integrated Chemical, Morphological, and Anatomical Attributes of Leaves of Eight Apocynaceae Taxa

Up to now, the taxonomic conflict of the Apocynaceae family has attracted the attention of scientists and researchers worldwide. Recently, this family was divided into five subfamilies. The present study aims to investigate the implication of interlacing macro-, micro-morphological, anatomical, and chemical characteristics of the leaves of eight Apocynaceae plants (Adenium obesum, Dipladenia boliviensis, Carissacarandas, Nerium oleander, Asclepias curassavica, Calotropisprocera, Acokanthera oblongifolia, and Thevetia neriifolia), and to provide valuable taxonomic differentiation of these species. The macro-morphological investigation includes shape, apex, base, and venation of leaves, while the micro-morphological study includes leaf epidermal cells, stomata, and trichomes. The anatomical features of the leaf blade were studied by scanning electron microscope (SEM). Additionally, the chemical composition of the silylated methanolic extract was analyzed by Gas chromatography–mass spectroscopy (GC-MS). Sixty-three compounds were characterized from the silylated extracts of the eight plants, where quinic acid, sucrose, D-pinitol, and D-(−)-fructopyranose were determined as major compounds. The Principal Component Analysis (PCA) based on the chemical composition revealed a significant chemical correlation among all species with the presence of sugars and amino acids, as well as phenolic acids and iridoid glycosides. The cluster analysis, based on all merged characters, showed that the eight species can be categorized into three clusters. The first cluster comprises A.obesum, A. curassavica, and T. neriifolia, while the second cluster contains D. boliviensis, N. oleander, A. oblongifolia, and C. carandas, and the third cluster consists of C. procera alone. This cluster revealed some similarities to the recent classification of Apocynaceae, while it showed inconsistency regarding A.obesum, C. procera, and N. oleander. Due to the obtained inconsistent data and observed variation among the studied species, further study is recommended for more characterization of these species, based on additional parameters, including molecular characteristics, particularly A.obesum, C. procera, and N. oleander.

Mineralization mechanisms of groundwater in a semi-arid area in Algeria: statistical and hydrogeochemical approaches

The study area of Ain Oussera (3,790 km2) is located in the semi-arid high plains of the Saharian Atlas (200 km south of Algiers). Groundwater investigated in the present study is from the Albian formations which are considered as a major source for drinking and irrigation water. The objective of this study is to identify the different hydrochemical processes controlling the groundwater mineralization. For this purpose, chemical analyses were performed on 31 wells sampled during May 2014. The chemical study (total dissolved solids (TDS), Piper, chemical correlation) allowed the origins of groundwater mineralization to be identified. The dissolution of evaporate minerals, precipitation of carbonate minerals, and ion exchange reactions have been identified as major sources of mineralization processes. Anthropogenic processes due to human activities (sewage effluents and agricultural fertilizers) also contribute to the mineralization of the water. The results of principal component analysis also confirm that both natural and anthropogenic processes contribute to the chemical composition of groundwater in the study area.

Application of Magnetic Nanoparticles with Structure of Core-shell, as Bactericidal

Initially, magnetic nanoparticles (MNP) Fe3O4 are synthesized by a chemical correlation method and its core / shell structure is detected using SEM, FT-IR analysis. The purpose of this production was to use the nanoparticle performance level in the absorption of antibiotics, namely, ampicillin (amp). Absorption sampling was analyzed by UV-Vis spectrophotometer and the results indicate that the absorbance of the ampere increases to 85%. The bond between these two is electrostatic bonding, which was confirmed by EDX analysis. Ultimately, this compound was used for the antibacterial process. In this case, the MNP-amp compound was added in a natural amount of 20 μl a bacterial culture pattern overnight (In-vitro). The results showed that 95% of the bacteria were killed (confirmation of antibacterial properties of MNP). Therefore, it can be transmitted intentionally by controlling the magnetic field into living cells for the destruction of pathogenic bacteria.

Characterization of some archaeological ceramics and clay samples from Zamala - Far-northern part of Cameroon (West Central Africa)

Seventeen ceramics samples (515±95 BP, about 580 years old) and two clay raw materials from Zamala (Far-northern, Cameroon) were characterized by X-ray diffraction (XRD), thermal analysis (DTA/TG) and X-ray fluorescence spectroscopy. The aim of the work was the deduction of the production technology and provenance of these ceramics. With the exception of one sample the analysed ceramics formed a homogeneous chemical and mineralogical group. The observed mineralogical phases were quartz, mica (biotite), potassium feldspar (microcline) and plagioclase (albite and oligoclase). The XRD study of two local clays yielded the presence of quartz, kaolinite, mica, feldspar and plagioclase. The presence of the broad endothermic peak in the DTA/TG curves of the clays and its absence in the curves of the ceramics indicated that the firing temperature of the ceramics was above 550-600 °C, which is the temperature of the kaolinite-metakaolinite transformation. The firing experiments of the clay between 400-1200 °C in oxidizing atmosphere showed that mica disappeared above 900 °C. Therefore, the firing temperature of the sherds should have been between 600-900 °C. The chemical correlation between ceramics and local clay materials pointed out to a local production of these ceramics.