Mamdouh Abdel-Mogib

Peculiar reaction behaviour of barbituric acid derivatives towards aromatic amines

Abstract 5-Benzoylethyl barbituric acid derivatives 2a-c were prepared as useful precursors for the synthesis of pyrimidine fused heterocycles. Their behaviour as 1,5-diketocompounds towards aniline derivatives afforded the pyrimidoquinoline derivatives 6a-e. On the other hand, fusion of o -substituted anilines with 1,3-dimethyl barbituric acid derivatives 8a,b gave the corresponding benzazoles 10a-e. Furthermore, the reaction of 1,3-dimethyl barbituric acid (1) with catechol/K3|Fe(CN)6| or β-ketoester (19)/SiCl4 gave the benzofuro adduct 13a and the diphenylphenyl barbituric acid derivative 18, respectively.

Prenylstilbenes and prenylflavanones from Schoenus nigricans

Abstract The extract of Schoenus nigricans afforded, in addition to a known stilbene and a known prenylflavanone, four new stilbenes and two new prenylflavanones. The structures were elucidated on the basis of spectral data.

A sesquiterpene glucoside from Reichardia tingitana

Abstract Reichardia tingitana var. orientalis afforded, in addition to lupeol, taraxasterol, and the corresponding acetates, three sesquiterpene lactones of the guaianolide type including a new glucoside. The structures were elucidated by spectral methods.

A sesquiterpene ether from Laurencia obtusa

Abstract A new sesquiterpene ether, named dactyloxene D, has been isolated from Laurencia obtusa . The structure was identified by spectroscopic methods and stereochemistry was established by NOE difference spectroscopy.

In vitro activity, extraction, separation and structure elucidation of antibiotic produced by Streptomyces anulatus NEAE-94 active against multidrug-resistant Staphylococcus aureus

ABSTRACT During the screening programme for antibiotic produced by actinomycetes, an antibiotic was isolated from the fermentation broth of Streptomyces anulatus NEAE-94. The ethyl acetate extract of S. anulatus NEAE-94 showed high biological activity against Staphylococcus aureus NRRL B-313, multidrug-resistant S. aureus and Bacillus subtilis NRRL B-543. Thin-layer chromatography of the ethyl acetate extract showed one yellowish orange spot with an Rf value of 0.83. The structural elucidation of the isolated compounds was carried out using ultraviolet–visible mass spectrometry (MS), Fourier transform-infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H-NMR) and gas chromatography–mass spectrometry (GC–MS) analyses. Characterization of the ethyl acetate extract revealed the presence of 22 compounds, including an unsaturated fatty acid, saturated fatty acids, fatty acid esters, alkanes, alkenes and a triterpene. The antimicrobial efficacy of S. anulatus NEAE-94 might be due to the synergistic effects of the identified compounds.

Molluscicidal activity of Balanites aegyptiaca against Monacha cartusiana

Context: Balanites aegyptiaca (L.) Delile (Zygophyllaceae) is a tropical tree that has many folk uses in various countries. The bark extract is used for the control of the fresh water snails that act as intermediary host of Schistosoma. Objective: Study the molluscicidal activity and chemical constituents of seed oil and seed glycosides of B. aegyptiaca against Monacha cartusiana and determine the structure-activity relationship. Materials and methods: Two bioassay methods (residual film application and the leaf dipping technique) were used to evaluate the toxicity effect of the seed oil and glycosides, in concentrations of 1.000, 0.500, 0.250 and 0.125%. The seed oil was analysed by GC/MS. Acid hydrolysis and chromatographic separation were used to study the seed saponins. Results: The bioassay of B. aegyptiaca against the land snail, M. cartusiana, indicated the activity of the seed oil and the high activity of the seed saponins. The seed glycosides gave 30.0, 53.3, 73.0 and 73.3% mortality for concentrations of 0.125, 0.250, 0.500 and 1.00%, respectively. The LC50 values were 0.335 and 0.256%, respectively. The seed oil was analysed by GC/MS. Acid hydrolysis of the seed saponins gave a mixture of diosgenin, yamogenin and 3,5-spirostadiene. Discussion and conclusion: To study the structure-activity relationship, a triterpenoidal saponin and a triterpenoidal saponins rich extract (of Zygophyllum coccenum) were proven to be inactive. Thus, the activity is associated with the steroidal, not triterpenoidal saponins. Moreover, a spirostane aglycone without sugar moiety, was found to be inactive and attained the activity by glycosidation.

Sucrose diester of aryldihydronaphthalene-type lignans from Echium angustifolium Mill. and their antitumor activity

Four previously undescribed sucrose diester of aryldihydronaphthalene-type lignans, named echiumins A-D, were isolated from the butanol fraction of Echium angustifolium Mill, in addition to a known compound, trigonotin A, which is reported for the first time from the title plant. The structures of isolated compounds were elucidated using spectroscopic methods such as HRESIMS and 1D and 2D NMR spectroscopy. The isolated compounds displayed strong to weak antitumor activity against HepG2 and MCF7 cancer cell lines, with echiumins A and D showed the most potent activity.