Shar S. Al-Shihry

African Cucurbita pepo L.: properties of seed and variability in fatty acid composition of seed oil

Pumpkin (Cucurbita pepo) seeds are used locally in Eritrea to treat tapeworm. Seeds were found to be rich in oil (approximately 35%), protein (38%), alpha-tocoferols (3 mg/100 g) and carbohydrate content (approximately 37%). The physico-chemical properties and fatty acid composition of the seed oil were examined. The four dominant fatty acids found are: palmitic C16:0 (13.3%), stearic C18:0 (8.0%), oleic C18:1 (29.0%) and linoleic C18:2 (47.0%). The oil contains an appreciable amount of unsaturated fatty acids (78.0%) and found to be a rich source of linoleic acid (47.0%). Within the three localities of the study, variations exist in seed properties and the fatty acid composition of the oil.

Fluorescence enhancement of 1-napthol-5-sulfonate by forming inclusion complex with β-cyclodextrin in aqueous solution

Fluorescence enhancement of 1-naphthol-5-sulfonate (1N5S) upon inclusion in beta-cyclodextrin is studied by spectrophotometry and spectrofluorimetery techniques. The spectral shifts were only observed in the emission spectra in different solvents and were found to be directly correlated to the solvents hydrogen-bond donor strength (alpha). Spectral changes in the absorption spectra upon the addition of beta-cyclodextrin to 1N5S in aqueous medium were too small to allow for the determination of the binding constant. On the other hand; fluorescence measurements show that the emission of both the anionic and neutral forms of 1N5S increase upon the addition of beta-cyclodextrin with an increase in the quantum yield by about 60%. Fluorescence measurements show 1:1 inclusion of 1N5S in the beta-cyclodextrin cavity with an association constant of 88+/-10M(-1). (1)H NMR studies are used to confirm the inclusion and to provide information on the geometry of 1N5S inside the cavity of beta-cyclodextrin.

Synthesis, characterization and biological studies of some novel thieno[2,3-d]pyrimidines.

Several 2-unsubstituted thieno[2,3-d]pyrimidines have been prepared from 2-aminothiophene-3-carboxylic acid esters and their carbonitrile analogs. Some triazolo-thienopyrimidine and 2-thioxothienopyrimidine representatives have also been synthesized using thermal and microwave (MW) irradiation techniques. Structures of the prepared compounds were elucidated on the basis of IR, NMR, 2D NMR and mass spectral data. The biological activity of some selected synthesized compounds was also examined.

Unsupported MoO3Fe2O3 catalysts: characterization and activity during 2-propanol decomposition

Abstract The catalytic decomposition of 2-propanol (2-PrOH) was studied as probe reaction, in the gas phase, over unsupported MoO3Fe2O3 mixed catalysts. The samples were prepared by mixing MoO3 (as ammonium heptamolybdate) with different x mol% Fe2O3 (as ferric nitrate) and calcined at 500°C in air for 5 h. All catalysts were characterized by TPR, IR, XRD and XPS analyses. The surface area of these samples were determined using the BET method. Also, the acidity and the basicity of all catalysts were estimated thermogravimetrically using the adsorption of pyridine and formic acid as probe molecules. The catalytic decomposition of 2-PrOH was studied over the catalysts in the temperature range of 150–260°C. A correlation between the catalytic activity and the acidity or the basicity of these catalysts has been made. The activation energies for both propene and acetone formation, over MoO3Fe2O3 catalysts, were calculated.

Synthesis of Substituted Stilbenes via the Knoevenagel Condensation

Knoevenagel condensations between aldehydes and substrates containing active methylene groups were carried out in ethanol at room temperature, in the presence of potassium phosphate, to afford unsymmetrical olefins. These condensations have been shown to afford only the E-isomers in greater than 80% yields. Salicylaldehyde first produces the Knoevenagel condensation products, which undergo a subsequent heterocyclization to give coumarin derivatives. The structures of the synthesized compounds were established on the basis of UV, IR, MS and NMR spectroscopy.

A new heterocyclic glucoside from the fruits of Xanthium pungens.

A new thiazinedione glucoside, 7-(β-D-glucopyranosyloxymethyl)-8,8-dimethyl-4,8-dihydrobenzo[1,4]thiazine-3,5-dione (1) and named xanthiside, was isolated from the methanol extract of the fruits of Xanthium pungens. Its structure was determined by spectroscopic techniques including, IR, CIMS, high-resolution-EIMS, and extensive 400 MHz one- and two-dimensional NMR-analysis (1H, 13C-NMR, DEPT, 1H-1H COSY, HMQC, COLOC, and NOE experiments).

Catalytic Reactions of 1-Butanol Over AlPO4 Catalysts Induced by B2O3

A series of AlPO4–B2O3 samples containing 5–50 wt% B2O3 were prepared. Their textural properties were determined from studies of the adsorption of nitrogen at −196°C. The structural characteristics were investigated using DTA, TG, XRD and FT-IR methods. Surface acidity was determined from the adsorption of n-butylamine in non-aqueous media. The vapour-phase catalytic conversion of 1-butanol over the prepared catalysts was followed using a micro-catalytic pulse technique. The incorporation of B2O3 into AlPO4, as well as the calcination temperatures employed, led to significant changes in the textural parameters and crystallinity of the catalysts and in their surface acidity. The dehydration of 1-butanol to 1-butene and dibutyl ether (DBE) was strongly influenced by the surface acidity and the boron content of the samples.

Biological Activity of a Phloroglucinol Glucoside Derivative from Conyza aegyptiaca

The phloroglucinol glucoside derivative [2,4-dihydroxy-6-(β-D-glucopyranosyloxy)phenyl]- butan-1-one (1), roseoside (2), and kaempferol-3-O-β-D-glucopyranoside (3) were isolated from the aerial parts of Conyza aegyptiaca (L.). To the best of our knowledge, this is the first isolation of compounds 1 - 3 from C. aegyptiaca. Their structures were determined by spectroscopic techniques including, IR, HR-EIMS, and extensive 500 MHz 1D- and 2D-NMR analyses (1H, 13C NMR, DEPT, 1H-1H COSY, HMQC and HMBC experiments). The antioxidant activity of 1, using the DPPH assay, was investigated; in addition, 1 was investigated against different types of cell lines, including Hep-G2, HCT-116, and RAW 264.7 for its cytotoxic effects. Also, this is the first report on the activity of 1.

Synthesis, antimicrobial activity and molecular modeling study of substituted 5-aryl-pyrimido[5,4-c]quinoline-2,4-diones

A series of pyrimido[5,4-c]quinoline-2,4-dione derivatives 5a–k were synthesized in moderate yields via a thermolysis reaction of equimolar ratio of 5-arylidine-1,3-dimethylbarbituric acid derivatives 3a–d with aniline derivatives 4a–d at 150–180 °C for 1–2 h. Eight of the synthesized compounds were chosen for a primary in vitro one-dose anticancer assay performed using the full NCI 60 cell panel. Only compound 5b showed moderate GI% at the used dose (10 μM) against four of the tested cell lines corresponding to leukemia SR (GI%: 51), non small-cell lung cancer HOP-92 (GI%: 63), melanoma UACC-62 (GI%: 53) and renal cancer UO-31 (GI%: 69). On the other hand, antimicrobial screening of the whole set of the synthesized compounds was performed against three Gram +ve and two Gram −ve bacterial strains. Results of the antimicrobial screening showed that compounds 5d, 5e, 5f, 5h and 5k have broad-spectrum antibacterial efficacy being moderately active against all the tested Gram +ve and two Gram −ve bacteria. Also, compound 5a showed interesting results being only active against Streptococcus faecalis and both tested Gram −ve strains viz. E. coli and P. aeruginosa. In order to compare the binding mode of the most active compounds 5e and 5f along with the inactive compound 5c we docked these compounds into the empty binding site of topoisomerase II DNA gyrase (PDB ID: 1KZN), and results were compared with the bound inhibitor Clorobiocin.

Physicochemical properties of the Co3O4/Al2O3, Ag2O/Al2O3 and Ag2O-Co3O4/ Al2O3 systems and their catalytic activities towards acid-base and redox reactions

A Co3O4/Al2O3 catalyst containing 0.20 mol% Co3O4 and an Ag2O/Al2O3 catalyst containing 0.2 mol% Ag2O were prepared using the impregnation method. Co3O4–Ag2O/Al2O3 samples containing 0.2 mol% Co3O4 and varying small molar percentages of Ag2O were also prepared. Portions from the catalysts thus obtained were calcined at 773, 973 and 1173 K. The textural properties of the catalysts were determined from the adsorption of N2 at 77 K, while their structural properties were investigated using TG, DTA, XRD and TPR techniques. The surface acidities of the catalysts were determined via titration with n-butylamine in a non-aqueous medium. The conversion of propan-2-ol at 573 K was followed using the micro-catalytic pulse technique, whereas the decomposition of H2O2 at 298–313 K was followed by determining the volume of oxygen released with time. Solid-solid interactions between the components of the systems resulted in the formation of Co3O4 and CoAl2O4, their ratio depending on the chemical composition and heat-treatment temperature employed with Ag in its metallic form. The textural properties of the investigated catalysts also depended on the chemical composition and calcination temperature. The surface acidity of the catalysts is an important factor in determining their catalytic activity towards the conversion of propan-2-ol whereas the redox-reactive ion-pairs formed between Ag and Co determine their activity towards H2O2 decomposition.