Pyrrolizidine alkaloid profiles of some Senecio species from Egypt

Alkaloid profiles of two Egyptian Senecio species (Senecio aegyptius var. discoideus and S. desfontainei) in addition to a cultivated species (S. cineraria) were studied using capillary GLC and GLC-mass spectrometry with respect to pyrrolizidine alkaloids (PAs). Four alkaloids were identified in S. aegyptius var. discoideus, 8 in S. desfontainei and 13 in S. cineraria. Some of these alkaloids have not been reported from these plants. The alkaloidal pattern of different plant organs (flowers, leaves, stem, root) were also investigated. Senecionine has been found to be a one of the major alkaloid in all studied species, it was isolated and its structure was elucidated by 1H- and 13C-NMR.     

Investigation into the production of bacteriostatic substances by fungi

A method is suggested for estimating the degree of potency and, to some extent, the specificity of bacteriostatic substances produced by fungi. It is based on the examination of several hundred fungi over a period of 2 years. It consists essentially of the placing of a few drops of the substance to be tested in the centre of a plate of bacteria-incorporated agar with the consequent production of a zone of inhibition which varies in width in proportion to the concentration of the bacteriostatic substance. The test is made against two representative types of bacteria— Bact. coli and Staph, aureus. The permissible technical latitude in the application of the test has been summarized. By using a standard inhibitor (mercuric chloride) the accuracy of the method has been statistically proved. This 'zonation' method has been compared with the standard 'dilution' method and close correlation has been established.     

L-lysine-alpha-oxidase activity of some Trichoderma species

Trichoderma cultures were tested for their ability to produce L-lysine-alpha-oxidase. The highest enzyme activity was manifested by T. harzianum (MGU), T. longibrachiatum Rifai VKM F-2025 and T. aureoviride Rifai VKM F-2026. The biosynthesis of the enzyme did not depend on the growth of the cultures and did not vary among the species.     

Identification and characterization of some bacterial membrane sulfhydryl groups which are targets of bacteriostatic and antibiotic action

Covalent modification of sulfhydryl groups which become sensitive toward sulfhydryl agents during germination of Bacillus cereus spores exerts a profound bacteriostatic effect, resulting in outgrowth inhibition. The modified spore components are membrane species of 13,000, 28,000, and 29,000 daltons. Detergent disruption of the membrane inactivated the sulfhydryl groups. A highly sigmoid inhibition curve (n = 11.8) with diamide suggested the participation of closely neighboring sulfhydryl groups. Substate and substrate analogs of the lactose and dicarboxylic acid permeases protected the sulfhydryl groups against modification. Nisin, a 34-residue peptide antibiotic, inhibited spore outgrowth and sulfhydryl modification at a concentration of about 0.1 microM. Since these sulfhydryl groups have been implicated as involved with the bacteriostatic action of nitrite, substances directed toward them may be a useful new class of bacteriostatic agents and antibiotics.     

The impact of synthetic nitriles on the morphology and viability of some bacterial species

The toxic effects of synthetic nitriles and nitrile herbicides on some bacterial species were estimated. Biotests based on bioluminescence revealed that aromatic nitriles including herbicides had the most significant toxic effect on bacteria, which differed from their effect on eukaryotic cells. It was shown that soil strains of nitrile-utilizing bacteria were resistant to high concentrations of the studied compounds. The minimal bactericidal concentrations for most of nitriles were 0.5 M or above. It was demonstrated that exposure to 0.1 and 1 mM bromoxynil solution resulted in a decrease in the linear parameters of the cells of all strains and sufficient changes in the cell surface of Gram-negative bacteria. It was proposed that the toxic effect of aromatic herbicides was caused not only by inactivation of an enzyme of the electron-transport chain but also by damage to the surface structures.     

UV-mediated antibiotic activity of some compositae species

Roots, leaves, and flowers of 80 species of Compositae were tested for phototoxic activity against Candida albicans. Many genera showed activity, especially in the roots. No active genera were found in the tribe Cichorieae. Phototoxic compounds were isolated from Chrysanthemum leucanthemum florets and Cirsium arvense roots. Chemotaxonomic evidence plus preliminary chemical data suggests that the compounds are polyacetylenic in nature. Unlike other phototoxic compounds, these are inactive against human skin.     

Antimicrobial activity screening of some sulfonamide derivatives on some Nocardia species and isolates

Nocardia are aerobic, catalase-positive, Gram-positive microorganisms and typically acid-alcohol fast at some stage of the growth cycle. The genus Nocardia, a member of Mycolata group, is clinically important because it is an opportunistic pathogen. The sulfonamide derivative medicines are prefered to cure infection caused by Nocardia, such as nocardiaosis and mycetoma. Antimicrobial activities of seven sulfonamide derivatives have been investigated against some Nocardia species and isolates using the disk diffusion method on Sensitest agar medium (Oxoid). Thirty-six organisms, which consisted of 10 soil isolates selected from different clusters of Aymen study (2003), six clinical isolates provided by Ege University, Medical School, Microbiology and Clinical Microbiology Department, four reference strains, 15 type strains and a control strain of Staphylococcus aureus ATCC 43300 were tested. The strongest inhibition was observed in the cases of IV [N-(2-hydroxy-4-nitro-phenyl)-4-methyl-benzensulfonamid], V [N-(2-hydroxy-5-nitro-phenyl)-4-methyl-benzensulfonamid] and III [N-(2-Hydroxy-phenyl)-4-methyl-benzenesulfonamide] against Nocardia. Introducing a hydroxyl group into the ortho position on the ring increased the antimicrobial activity. Substitution of the electron withdrawing groups such as a nitro group increased the antimicrobial activity remarkably.     

Investigation into the production of bacteriostatic substances by fungi; preliminary examination of more of the larger Basidiomycetes and some of the larger Ascomycetes

This paper may be regarded as an addendum to previous work along the same lines, more particularly the work which dealt with some 700 of the larger Basidiomycetes. Both Ascomycetes and Basidiomycetes were tested for their antibiotic properties by means of sporophore extract. Of the ninety-nine fungi tested, twenty-eight showed a positive and seventy-one a negative reaction against the test bacteria, Bacterium coli and Staphylococcus aureus.