Gas Chromatography-Mass Spectrometry Analysis and Comparison of Volatile Components Obtained by Hydrodistillation and Headspace Solid Phase Microextraction (HS-SPME) from Teucrium luteum subsp. flavovirens

The main purpose of this work is to investigate the comparative chemical analysis of essential oil (EO) isolated by hydrodistillation (HD) and volatile fraction (VF) detected by headspace solid-phase micro-extraction (HS–SPME) obtained from Teucrium luteum subsp. flavovirens using Gas Chromatography–Retention Indices (GC-RI) and GC–Mass Spectrometry (GC-MS). 63 volatile compounds identified in hydrodistilled essential oil (HD), representing 89.9% of the total oil, while HS-SPME revealed 50 components constituting 99.3% of the volatile material. The chemical composition of EO comprised mainly of of oxygenated sesquiterpenes (48.6%) while, hydrocarbon monoterpenes were detected in higher concentrations in VF (54.1%). The comparative analysis of two chemoprofiles obtained by two methods shows quantitative and semi-qualitative differences. The current study is the first report involving rapid analysis of volatile components of T. luteum subsp. flavovirens by HS-SPME

2,2′-Dimethyl-5,5′-dipropan-2-yl-4,4′-(phenyl­methyl­ene)diphenol

In the title mol­ecule, C27H32O2, the aromatic rings are in a propeller configuration. In the crystal, mol­ecules are linked through O—H⋯O hydrogen bonds forming a two-dimensional network which develops parallel to (010). Futhermore, weak C—H⋯π inter­actions involving the two substituted rings build up a three-dimensional network

4-Benzyl-6-p-tolyl­pyridazin-3(2H)-one

The title compound, C18H16N2O, is a new dihydro­pyridazin-3(2H)-one derivative synthesized in one step by condensation of α-benzyl­idene-γ-tolyl­butenolide with hydrazine. The mol­ecule is not planar; the tolyl and pyridazine rings are twisted with respect to each other making a dihedral angle of 27.35 (9)° and the benzyl ring is nearly perpendicular to the pyridazine ring with a dihedral angle of 85.24 (5)°. In the crystal structure, inversion dimers arise, being linked by pairs of N—H⋯O hydrogen bonds. Weak C—H⋯O hydrogen bonds and weak offset π–π stacking stabilize the packing. The π–π stacking occurs between the pyridazine rings of symmetry-related mol­ecules, with a centroid–centroid distance of 3.748 Å, an inter­planar distance of 3.605 Å and a slippage of 1.024 Å

Apprentissage de la stéréochimie : raisonnements et difficultés

Résumé — Nous présentons ici notre travail de recherche qui a pour objet l’enseignement et l’apprentissage de la stéréochimie lors de deuxième année de l’enseignement supérieur Marocain.Il semble exister un malaise dans l'enseignement et l’apprentissage de la chimie organique: une discipline reconnue comme difficile, des démarches d'enseignement dogmatiques et cumulatives, des étudiants qui mémorisent plus qu'ils ne comprennent et qui ont du mal à mettre en relation les différents éléments théoriques, une utilisation problématique du symbolisme, et une certaine insatisfaction des enseignants.Les résultats des recherches antérieures nous conduisent à orienter notre travail autour de certaines activités cognitives (communication, traitement et conversion) que permettent les systèmes de Cram et de Newman. Les activités choisies se rapportent aux capacités attendues des étudiants, à la fin de l’apprentissage de la stéréochimie.Apprentissage, stéréochimie, systèmes sémiotiques, étudiant marocai

Phytochemical screening and antioxidant activity of four Moroccan Thymus species: T. leptobotrys Murb. , T. pallidus Batt. , T. broussonetti Boiss. and T. maroccanus Ball

In this study, four species of Thymus (T. leptobotrys Murb. , T. pallidus Batt. , T. broussonetti Boiss. and T. maroccanus Ball.) were studied. The phytochemical screening revealed that leaves and steams of the four species, in general, contain tannins, flavonoids, coumarins, saponins, carotenoids, reducing sugars, quinones, terpenoids, steroids and triterpenoids. The antioxidant effects of methanolic extracts from Moroccan Thymus species were studied using two experiments having different mechanisms. The antioxidant activity was measured by 1,1-diphenyl-2- picrylhydrazyl (DPPH) reduction spectrophotometric method and ferric reducing antioxidant power (FRAP). The results of antioxidant activity were different for each species depending on the applied test. The highest activity is presented by DPPH in the stems methanolic extract of T. broussonetti Boiss. (IC50=0.132±0.034 mg/mL). However, the test of FRAP showed that T. pallidus Batt. has the highest antioxidant activity (EC50=0.095±0.001 mg/mL)

(3R*,6R*,4′S*,8′R*,3′′R*,6′′R*)-3,3′′-Diisopropyl-6,6′′-dimethyl-2′,6′-diphenyldispiro[cyclohexane-1,4′-(3,7-dioxa-2,6-diazabicyclo[3.3.0]octane)-8′,1′′-cyclohexane]-2,2′′-dione

The two oxazolidine rings (A and B) of the title compound, C34H44N2O4, display roughly half-chair conformations, which could be described as twisted on the C—O bond. Together, the fused oxazolidine rings have a butterfly shape, with the H atoms attached to the ring junction C atoms in a cis orientation. The cyclohexane rings of both p-menthone fragments display chair conformations. The absolute configuration could not be determined from the X-ray diffraction data, but the relative configuration of the stereocentres could be deduced

Effect of sliding wear on Tribocorrosion behaviour of stainless steels in 0.5M H2SO4 with and without addition of Thymus zygis subsp. gracilis essential oil

status: accepte

Comparative study of the chemical profiling, antioxidant and antimicrobial activities of essential oils of different parts of <i>Thymus willdenowii</i> Boiss & Reut

<p>The analysis of <i>Thymus willdenowii</i> Boiss & Reut essential oils (TW EOs) shows 33 components accounting for (96.3–97.7%) of all identified. The main constituents of TW EOs were thymol (35.5–47.3%), p-cymene (13.9–23.8%), γ-terpinene (8.9–20.3%). The antioxidant assays revealed that all TW EOs tested showed strong activities, the antimicrobial effect of TW EOs has been tested against isolated clinical strains of <i>Proteus mirabilis</i> (ATCC 35659), <i>Escherichia coli</i> (ATCC 25922), <i>Candida albicans</i> (ATCC 10231), <i>Bacillus cereus</i> (ATCC 10876), and <i>Aspergillus brasilliensis</i> (ATCC 16404). The antimicrobial test indicates that TW EOs show an inhibition effect against all the tested bacteria with a MIC of 6.9 to 27.6 μg/mL⁻¹. These results proving that the essential oils extracted from <i>Thymus willdenowii</i> Boiss & Reut may be a new potential source of natural antimicrobial applied in pharmaceutical and food industries.</p

Antifungal activity of essential oil from Santolina pectinata lag., against postharvest phytopathogenic fungi in apples

The purpose of this study was to investigate the chemical composition and antifungal activities of essential oil (EO) of Santolina pectinata aerial parts. The analysis of EO using gas chromatography (GC-FID) and gas chromatography-mass spectroscopy (GC-MS) allowed the identification of 34 components, which (Z)-heptadeca-10,16-dien-7-one was the major constituent with 28 % of the total oil. The antifungal activities of this oil in liquid and vapor-phase against three phytopathogenic fungi causing the deterioration for apples, including Botrytis cinerea, Penicillium expansum and Rhizopus stolonifer were evaluated in vitro by using the poisoned food (PF) and the volatile activity (VA) methods. The obtained results showed a significant inhibition of the studied EO inhibited significatively against the mycelial growth of all fungal strains tested (p<0.05). B. cinerea and P. expansum showed a strong sensitivity to the studied oil at all concentrations and VA assay was consistently found to be more effective than PF technique. The minimum inhibitory concentrations (MICs) of this oil were 0. 25 and 1 µL/mL against these strains when using VA and PF assays, respectively. The overall results suggest that S. pectinata EO could be used as an antifungal preservative to control post-harvest diseases of apples. The antifungal activities of S. pectinata EO from Morocco are reported for the first time