In vitro antiproliferative and cytotoxic activities of novel kojic acid derivatives: 5-benzyloxy-2-selenocyanatomethyl- and 5-methoxy-2-selenocyanatomethyl-4-pyranone.

Some kojic acid (KA) derivatives and selenium containing compounds possess antiproliferative properties. The present study tested novel selenocyanatomethyl derivatives of KA for growth inhibitory and LDH cytotoxic activities. Human skin carcinoma (A431) and human breast carcinoma (MCF7) cells were treated with 5-benzyloxy-2-selenocyanatomethyl-4-pyranone (P763) and 5-methoxy-2-selenocyanatomethyl-4-pyranone (P764) in selected concentrations for 24, 48 and 72 h. Cell viability tests aimed at intracellular injury of mitochondria (MTT) and lysosomes (neutral red uptake, NR) revealed (a) higher growth inhibitory activity of the benzyloxy-selenocyanatomethyl derivative of KA (P763) compared with the methoxy derivative (P764) in both cell lines, (b) an intensified effect with time of exposure (MTT test only). The results demonstrate that NR cell survival/viability assay is more sensitive than the MTT test to detect subcellular changes induced by test compounds. Cell membrane integrity determined by LDH leakage confirmed an exaggerated cytotoxic effect of P763 but similar sensitivity of both cell lines to membrane injury. The ED50 values for all three tests used indicate that injury of intracellular mitochondria and lysosomes precedes the loss of membrane integrity. Cell growth inhibitory activities of new selenium containing kojic acid derivatives are preferentially aimed at the intracellular compartment rather than the plasma membrane and enlarge the group of antiproliferative active compounds.

Alcohol intake modulates hormonal activity of adipose tissue.

White adipose tissue (WAT) is now recognized as a highly active metabolic tissue and important endocrine organ producing numerous peptides and proteins with broad biological activity. The term adipokines has been coined to refer to a series of adipocyte-derived biologically active molecules, which may influence the function as well as the structural integrity of other tissues. Adipokines are implicated in control of food intake, energy balance and body weight (leptin), glucose homeostasis (e.g., adiponectin, resistin, adiponutrin), lipid metabolism (e.g., retinol-binding protein, cholesterolester transfer protein), angiogenesis (vascular endothelial growth factor VEGF), fibrinolytic system (plasminogen activator inhibitor-1 PAI-1), pro- and anti-inflammatory effects (e.g., tumor necrosis factor-alpha TNF-alpha, interleukin-6 IL-6) or sexual development and reproduction (leptin). Alterations of WAT mass in obesity or lipoatrophy effect the production of most adipose secreted factors. Besides others, alcohol consumption affects also hormonal system leading to non-physiological increase/decrease of hormone gene expression and plasma hormone concentrations appearing as final poor or stronger effects on target tissues. As mentioned above, white adipose tissue is important endocrine organ, so alcohol intake can alter also adipokines expression in WAT and adipokines plasma levels and in this way it can affect the adipokine-targeted tissues and their functions.

Cytotoxicity of water extracts from leaves and branches of Philadelphus coronarius L.

Philadelphus coronarius L. is big, leggy and deciduous old-fashioned shrub known for its fragrant white flowers in the late spring. Some members of genus Philadelphus L. are known for their antibacterial, antiradical and immunomodulatory effects. Therefore, these herbs represent prospective sources for the isolation of active substances with desired effects. We have investigated the cytotoxicity effects of water extracts from leaves and branches of Philadelphus coronarius L. (Hydrangeaceae). A431 cells (human skin carcinoma cell line) and the human breast adenocarcinoma cell line (MCF-7) were treated with various doses of individual extracts (0,1-100 microg dry matter/ml) for 24 h and 72 h. The highest toxic effects of both plant parts extracts were observed on MCF-7 cells regardless the time of treatment. Cells A431 were less sensitive to toxic effects of leaves and branches extracts but the time dependence was present with the tendency of increased toxicity after chronic treatment. There were no differences in the extent of toxic effects between branches and leaves extracts. The results obtained so far will provide the basis for the future studies with isolated active substances from these extracts.

Downregulation of the nuclear-encoded subunits of the complexes III and IV disrupts their respective complexes but not complex I in procyclic Trypanosoma brucei.

The function, stability and mutual interactions of selected nuclear-encoded subunits of respiratory complexes III and IV were studied in the Trypanosoma brucei procyclics using RNA interference (RNAi). The growth rates and oxygen consumption of clonal cell lines of knock-downs for apocytochrome c1 (apoc1) and the Rieske Fe-S protein (Rieske) of complex III, and cytochrome c oxidase subunit 6 (cox6) of complex IV were markedly decreased after RNAi induction. Western analysis of mitochondrial lysates using specific antibodies confirmed complete elimination of the targeted proteins 4-6 days after induction. The Rieske protein was reduced in the apoc1 knock-down and vice versa, indicating a mutual interdependence of these components of complex III. However, another subunit of complex IV remained at the wild-type level in the cox6 knock-down. As revealed by two-dimensional blue native/SDS-PAGE electrophoresis, silencing of a single subunit resulted in the disruption of the respective complex, while the other complex remained unaffected. Membrane potential was reproducibly decreased in the knock-downs and the activities of complex III and/or IV, but not complex I, were drastically reduced, as measured by activity assays and histochemical staining. Using specific inhibitors, we have shown that in procyclics with depleted subunits of the respiratory complexes the flow of electrons was partially re-directed to the alternative oxidase. The apparent absence in T. brucei procyclics of a supercomplex composed of complexes I and III may represent an ancestral state of the respiratory chain.