Several Biological Functions (several + biological_function)

Distribution by Scientific Domains


Selected Abstracts


Effects of aluminum on activity of Krebs cycle enzymes and glutamate dehydrogenase in rat brain homogenate

FEBS JOURNAL, Issue 10 2000
P. Zatta
Aluminum is a neurotoxic agent for animals and humans that has been implicated as an etiological factor in several neurodegenerative diseases and as a destabilizer of cell membranes. Due to its high reactivity, Al3+ is able to interfere with several biological functions, including enzymatic activities in key metabolic pathways. In this paper we report that, among the enzymes that constitute the Krebs cycle, only two are activated by aluminum: ,-ketoglutarate dehydrogenase and succinate dehydrogenase. In contrast, aconitase, shows decreased activity in the presence of the metal ion. Al3+ also inhibits glutamate dehydrogenase, an allosteric enzyme that is closely linked to the Krebs cycle. A possible correlation between aluminum, the Krebs cycle and aging processes is discussed. [source]


Antiadult T-cell leukemia effects of brown algae fucoxanthin and its deacetylated product, fucoxanthinol

INTERNATIONAL JOURNAL OF CANCER, Issue 11 2008
Chie Ishikawa
Abstract Adult T-cell leukemia (ATL) is a fatal malignancy of T lymphocytes caused by human T-cell leukemia virus type 1 (HTLV-1) infection and remains incurable. Carotenoids are a family of natural pigments and have several biological functions. Among carotenoids, fucoxanthin is known to have antitumorigenic activity, but the precise mechanism of action is not elucidated. We evaluated the anti-ATL effects of fucoxanthin and its metabolite, fucoxanthinol. Both carotenoids inhibited cell viability of HTLV-1-infected T-cell lines and ATL cells, and fucoxanthinol was approximately twice more potent than fucoxanthin. In contrast, other carotenoids, ,-carotene and astaxanthin, had mild inhibitory effects on HTLV-1-infected T-cell lines. Importantly, uninfected cell lines and normal peripheral blood mononuclear cells were resistant to fucoxanthin and fucoxanthinol. Both carotenoids induced cell cycle arrest during G1 phase by reducing the expression of cyclin D1, cyclin D2, CDK4 and CDK6, and inducing the expression of GADD45,, and induced apoptosis by reducing the expression of Bcl-2, XIAP, cIAP2 and survivin. The induced apoptosis was associated with activation of caspase-3, -8 and -9. Fucoxanthin and fucoxanthinol also suppressed I,B, phosphorylation and JunD expression, resulting in inactivation of nuclear factor-,B and activator protein-1. Mice with severe combined immunodeficiency harboring tumors induced by inoculation of HTLV-1-infected T cells responded to treatment with fucoxanthinol with suppression of tumor growth, showed extensive tissue distribution of fucoxanthinol, and the presence of therapeutically effective serum concentrations of fucoxanthinol. Our preclinical data suggest that fucoxanthin and fucoxanthinol could be potentially useful therapeutic agents for patients with ATL. © 2008 Wiley-Liss, Inc. [source]


Efficient synthesis of polyoxygenated flavones from naturally occurring flavanones

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2007
Paolo Bovicelli
Flavonoids are constituents of the human diet (they are present in many beverages and food), and in organisms they are responsible for several biological functions, including that of antioxidant. Because of the increasing interest in these molecules, methods for their synthesis and structural modification are of great importance; studies on the biological activities of many of these compounds are insufficient because of their scarcity and/or high cost. We have developed an expeditious synthesis of polyoxygenated flavones, starting from available and inexpensive flavanones, using a bromination-methoxylation procedure. A series of flavonoids that are not otherwise accessible can be prepared using this method. As an example, 3,-demethoxysudachitin, a limited flavone possessing antimicrobial activity against methicillin-resistant Staphylococcus aureus and Helicobacter pylori and acting as a 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenger, was prepared in fairly satisfactory yield. [source]


Structure and chiroptical properties of supramolecular flower pigments

CHIRALITY, Issue 2 2006
George A. EllestadArticle first published online: 30 DEC 200
Abstract Research over the last 30 years has shown that at physiological concentrations of ca. 5 × 10,3 M, flower pigments composed of anthocyanins, either alone or complexed with flavone copigments, and frequently with metals, are self-assembled into non-covalent, chiral supramolecular complexes. This serves several biological functions including color stability, protection against UV radiation and provision for specific colors to attract insects for pollination. Self-association of the monomers takes place under conditions of molecular crowding by precise matching of the ,,, stacking interactions of the aromatic chromophores and intermolecular hydrogen bonding between the attached sugars. The resulting handedness is controlled by the chiral information provided by the sugars joined glycosidically at certain positions around the periphery of the aromatic nuclei. This review gives an overview of (i) the physicochemical evidence including circular dichroism, 1H NMR, and X-ray analysis for the structure and supramolecular chirality of these amphiphilic complexes, (ii) the role of the sugars on directing the chirality of the resulting supramolecules, (iii) the energetics of monomer association, and (iv) the possible influence of stacking chirality on insect pollination. © 2005 Wiley-Liss, Inc. Chirality 18:134,144, 2006. [source]