Biomedical subjects

M Miko

Publications and source records attributed to M Miko.

At least 19 recordsLinked to original sources

PubMed2002

Cytotoxicity and mode of action of the potential cytostatic drug oracin.

Primary screening in vitro and study on the mode of action of oracin in Ehrlich ascites carcinoma cells have been performed. The measure of the cytotoxic effect was the degree of inhibition of 14C-adenine and 14C-valine incorporation into TCA insoluble fraction of Ehrlich ascites carcinoma (EAC) cells. The inhibitory effect was characterized by IC50 values. The biosynthesis of nucleic acides indicated by the incorporation of 14C-adenine was more sensitive (IC50 = 66 micromol/ l) than the biosynthesis of proteins indicated by the incorporation of 14C-valine (IC50 = 196 micromol/l). To elucidate the biochemical mode of action, the effect of oracin on dynamics of biosynthesis of macromolecules indicated by the incorporation rate of [14C] labeled precursors (adenine, thymidine, uridine, valine) into appropriate macromolecules of EAC cells was studied. Oracin inhibited incorporation of all four precursors into the trichloracetic acid - insoluble fraction of Ehrlich ascites cells. The extent of inhibition was dependent on both time and drug concentration. We found that oracin inhibited activity of topoisomerase II by 100% at concentration 5 to 15 micromol/l.

Adenine↗

PubMed2000

The distribution of aminoacylase I among mammalian species and localization of the enzyme in porcine kidney.

Aminoacylase I (Acy-1, EC 3.5.1.14) is found in many mammalian tissues, with highest activities occurring in kidney. The enzyme hydrolyzes a variety of N-acylated amino acids; however, the physiological role and the exact cellular localization of Acy-1 are still a matter of debate. The comparison of Acy-1 activities in kidney and liver homogenates of 11 mammalian species showed that the enzyme is most abundant in true herbivores such as sheep and cattle as well as in omnivores, while activities were very low in both rodents and the cat. Acy-1 activity was not detected in livers of dogs of five different breeds. Using in situ hybridization of porcine kidney sections with DIG-labeled RNA probes, Acy-1 mRNA was shown to be evenly distributed throughout the tubular system, while glomeruli and the interstitium were free of stain. During subcellular fractionation, porcine Acy-1 behaved like a typical cytosolic enzyme. Commonly, Acy-1 is thought to catalyze hydrolytic reactions, i.e., the formation of free amino acids from acylated derivatives. Based on the present results and literature data, we propose a novel hypothesis, i.e., that Acy-1 catalyzes the synthesis (rather than the hydrolysis) of hippurate that is formed as a detoxification product of aromatic compounds.

Amidohydrolases↗

PubMed1998

Cytoxicity of 1-alkylperhydroazepine N-oxides and quantitative structure-activity relationships.

A new class of nonaromatic amine oxides was tested for cytotoxic activity. The main aim of the present investigation was to screen a series of 1-alkylperhydroazepine N-oxides for in vitro cytotoxicity and to find out whether there is a quantitative structure-activity correlation (QSAR) between cytotoxic effect and structure (as a structural parameter the number of carbon atoms m in the alkyl chain was used). Cytotoxicity was determined here by inhibition of incorporation of [14C]adenine into nucleic acid or [14C]valine into proteins in Ehrlich ascites carcinoma (EAC) cells. On the basis of primary screening, one of the most active compounds, namely 1-tetradecylperhydroazepine N-oxide (TPNO), was chosen for further biochemical study. The drug inhibited the incorporation rate of [14C] labeled precursors (adenine, thymidine, uridine, valine) into appropriate macromolecules of Ehrlich cells. The extent of inhibition was dependent on both time and drug concentration. The lengthening of the alkyl chain in 1-alkylperhydroazepine N-oxides positively affected their cytotoxic activity in EAC cells. For these compounds the optimal m value is 12-14.

Adenine↗

PubMed1995

Effects of 1-tetradecylperhydroazepine and 1-pentadecylpiperidine N-oxides on Ehrlich ascites mitochondria.

Non-aromatic amine oxides are widely known and used compounds. A great number of amine oxides occurring in nature, or prepared synthetically, are biologically active compounds (antimetabolites and chemotherapics, cancerostatic compounds, etc.). From seven series of newly synthesized amine oxides (63 compounds), 1-alkylperhydroazepine N-oxides (PHNO) and 1-alkylpiperadine N-oxides (PINO) have been chosen for further investigation. The effects of 8 derivatives of PHNO and 8 derivatives of PINO on state 3 and 4 respiration of Ehrlich ascites mitochondria (EAM) have been studied. Derivatives with longer side-chain significantly affected respiration of EAM according to the substrates used. To elucidate the mode of action, the most potent amine oxides from each series, 1-tetradecylperhydroazepine N-oxide (tPHNO) and 1-pentadecylpiperidine N-oxide (pPINO) have been chosen for further study. Both amine oxides stimulated state 4 respiration with glutamate-malate and succinate as substrates. The effect on state 3 respiration depended on the substrates used. Both tPHNO and pPINO were able to release respiration of EAM previously inhibited by oligomycin, both decreased the level of ATP in EAM. ATPase activity was significantly stimulated by both drugs only in higher concentrations. A possible mode of action of amine oxides on oxidative phosphorylation and the relationship between chemical structure are discussed.

Adenosine Triphosphatases↗

PubMed1994

Effects of 4-alkylmorpholine N-oxides on ATP-producing processes in Ehrlich ascites and L1210 leukaemia cells.

The main purpose of the present investigation was to study the effect of the homologous series of 4-alkylmorpholine N-oxides on ATP-producing processes in Ehrlich ascites and L1210 murine leukaemia cells. The effects on aerobic glucose consumption, lactic acid formation, content of total (T-SH) and non-protein thiol groups (NP-SH), endogenous and exogenous respiration and the level of ATP in tumour cells incubated in vitro were investigated. 4-Dodecylmorpholine N-oxide (DMNO), one of the most active compounds, decreased the level of ATP immediately after addition to the suspension of Ehrlich cells in an ice bath. After 2 h incubation at 37 degrees C the drop in the ATP level was much lower. A possible explanation for the decrease in the ATP level might be interaction of the amine oxide with the cell membrane.

Adenosine Triphosphate↗

PubMed1994

Effect of N-tricyanovinylamines on the level of glutathione in hepatocytes.

The effects of N-substituted tricyanovinylamines (N-TCVA; RNHC(CN)=C(CN)2) have been studied on rat hepatocytes and liver mitochondria. Derivatives of N-TCVA act on oxidative phosphorylation as uncouplers, and react with thiols within pH 5.0-8.5. N-Isobutyl-, N-benzyl-, and N-cyclohexyl-TCVA influence the level of GSH and GSSG in isolated hepatocytes. They can act as oxidants, but the level of GSSG increases (about 40%) only if the concentration of N-TCVA is higher than 1 micromol/l. If N-TCVA is added to a final concentration higher than 50 micromol/l a decrease of GSH and GSSG level is observed. Derivatives of N-TCVA also influence the level of GSH and GSSG in mitochondria. At 40-400 micromol/l N-TCVA in the incubation medium the level of GSSG increased and the ratio GSH/GSSG was influenced, but the level of total SH groups did not decrease.

Amines↗

PubMed1993

In vitro cytotoxic activity of 1-alkylpiperidine N-oxides and quantitative structure-activity relationships.

The main objective of the present investigation was to screen a series of 1-alkylpiperidine N-oxides for in vitro cytotoxicity, and to find out whether there is a quantitative structure-activity correlation (QSAR) between cytotoxic effect represented here by inhibition of incorporation of [14C]adenine into nucleic acid or [14C]valine into proteins in Ehrlich ascites carcinoma (EAC) cells and structure (as a structural parameter the number of carbon atoms m in the alkyl chain was used). On the basis of primary screening, one of the most active compounds, i.e. 1-decylpiperidine N-oxide, was chosen for further biochemical study. The drug inhibited the incorporation rate of 14C-labeled precursors (adenine, thymidine, uridine, valine) into appropriate macromolecules of Ehrlich cells, the extent of inhibition being dependent on both time and concentration of the compound in the incubation medium. The lengthening of the alkyl chain in 1-alkylpiperidine N-oxides positively affected their cytotoxic activity in Ehrlich cells. For these compounds the optimal m value is 12-15.

Adenine↗

PubMed1993

Effect of membrane active 1-alkylpiperidine N-oxides on glycolysis, respiration and ATP level in tumor cells.

The aim of this study was to study the effect of the homologous series of 1-alkylpyrrolidine N-oxides on ATP-producing processes in Ehrlich ascites and L1210 murine leukemia cells. 1-Decylpiperidine N-oxide (deP-NO), one of the active compounds, significantly stimulated the course of aerobic glycolysis of Ehrlich cells. Derivatives with longer side-chains markedly inhibited endogenous respiration of both tumor cells. dePNO, immediately after addition to the suspension of Ehrlich cells in an ice bath, markedly decreased the level of ATP in Ehrlich ascites cells. The decrease in ATP level might be explained through impairment of cell membrane integrity.

Adenosine Triphosphate↗

PubMed1993

Effect of 1-alkylpyrrolidine N-oxides on energy metabolism of cancer cells.

The main purpose of the present investigation was to study the effect of a homologous series of 1-alkylpyrrolidine N-oxides on ATP-producing processes in Ehrlich ascites and L1210 murine leukemia cells. The effect on aerobic glucose consumption, lactic acid formation, content of total (T-SH) and non-protein thiol groups (NP-SH), endogenous respiration and the level of ATP in tumor cells incubated in vitro was investigated. 1-Tetradecylpyrrolidine N-oxide (TPNO), one of the most active compounds, immediately after addition to the suspension of Ehrlich cells in an ice bath, decreased the level of ATP to the same extent over the whole concentration range. After 2 h incubation at 37 degrees C the drop in the ATP level was lower. The decrease in ATP level might be explained through the interaction of the amine oxide with the cell membrane integrity.

Adenosine Triphosphate↗

PubMed1993

In vitro cytotoxicity and mode of action of 1-alkylpyrrolidine N-oxides.

A new class of nonaromatic amine oxides was synthesized and tested for cytotoxic activity in vitro. The aim of this study was to find if there is any correlation between the cytotoxic activity of the investigated 1-alkylpyrrolidine N-oxides and their structure (as a structural parameter the number of carbon atoms m in the alkyl chain was used). Maximum activity was achieved with 1-tetradecylpyrrolidine N-oxide (C14) which was chosen for further biochemical studies. Further lengthening led to decrease in activity. The drug inhibited the incorporation rate of [14C] precursors (adenine, thymidine, uridine, valine) into appropriate macromolecules of Ehrlich ascites cells, the extent of inhibition being dependent on both time and concentration of the compound in the incubation medium.

Adenine↗

PubMed1992

Cloturin: effect on energy-producing processes in Ehrlich ascites and P388 murine leukaemia cells.

The main purpose of the present investigation was to study the effect of cloturin on aerobic glycolysis, endogenous and exogenous respiration and the level of ATP in both Ehrlich ascites carcinoma (EAC) and P388 murine leukaemia cells incubated in vitro. Also its effect on the level of total (T-SH) and non-protein (NP-SH) thiol groups was investigated. A significant inhibition of aerobic glycolysis was found only in P388 cells after 60 min of cloturin action. Cloturin inhibited both endogenous and exogenous respiration of EAC with succinate as substrate. Cloturin decreased the level of ATP after 2 h incubation in both types of tumour cell. The level of NP-SH was decreased more than that of T-SH in both types of cell.

Adenosine Triphosphate↗

PubMed1992

Biochemical basis of cytotoxic activity of some new N'-oxides of N',N'-dimethylaminoalkylamides of dodecanoic acid.

The objective of the present investigation was to screen a series of new N'-oxides of N',N'-dimethylaminoalkylamides of dodecanoic acid for activity in vitro and to investigate the biochemical mode of action. On the basis of primary screening, one of the most active compounds, namely the N'-oxide of 10-(N',N'-dimethylaminodecyl)amide of dodecanoic acid (n = 10) was chosen for detailed biochemical study. This compound inhibited the incorporation of 14C-precursors (adenine, valine, thymidine, uridine) into appropriate macromolecules of P388 murine leukemia and Ehrlich ascites carcinoma cells. The amine oxide also interfered with energy-yielding processes (aerobic glycolysis, endogenous respiration). Cytotoxicity is a consequence of the cytolytic activity of the compounds mentioned above. Membranous effects were demonstrated by the measuring of the release of cytoplasmic materials absorbing at 260 and 280 nm, marker enzyme activities (LDH, MDH), release of protein from the cells into the culture medium, as well as by morphological examination. It is evident that the site of action of the amine oxides investigated was the biological membrane which, after interaction with the amine oxides, showed changes in molecular organization and osmotic and permeability characteristics.

Animals↗

PubMed1992

9-Hydroxybenfluron: effect on energy-yielding processes in Ehrlich ascites and P388 murine leukemia cells.

The main purpose of the present investigation was to study the effect of 9-hydroxybenfluron (HBF) on aerobic glucose consumption, lactic acid formation, content of total (T-SH) and non-protein thiol groups (NP-SH), endogenous respiration and levels of ATP in both Ehrlich ascites and P388 murine leukemia cells. The lowest concentrations of HBF significantly stimulated both glucose consumption and lactate formation in Ehrlich ascites cells. HBF decreased the level of both T-SH and NP-SH in Ehrlich cells. However, the decrease in the level of NP-SH was significantly higher. Both respiration and ATP levels were inhibited more markedly in Ehrlich than in P388 cells. In P388 cells a significant decrease in ATP level (67%) was noted only at the highest concentration of HBF (100 mumol/l).

Animals↗

PubMed1991

Effects of benfluron and its two metabolites on respiratory processes in P388 murine leukemia and Ehrlich ascites cells.

This paper presents data on the effects of benfluron and its two metabolites DBF and NOBF on both endogenous and exogenous, respiration in the presence of succinate as substrate, of both P388 murine leukemia and Ehrlich ascites carcinoma cells. The most efficient inhibitors of endogenous and exogenous respiration were benfluron and DBF. NOBF did not interfere with respiratory processes in Ehrlich cells, even at quite high concentration. BF and DBF exert an almost identical inhibitory effect on exogenous respiration, the least effective being NOBF (Ehrlich cells). The decrease in the respiratory rates in cancer cells might be due to the effects of benfluron and its metabolites on the cell membrane. P388 murine leukemia cells are less "sensitive" than Ehrlich ascites cells.

Animals↗

PubMed1991

Primary screening and inhibition of macromolecular biosynthesis in Ehrlich ascites cells by benzo(C)fluorene derivatives.

The main objective of the present investigation was to screen a series of new benzo(c)fluorene compounds for in vitro activity. It can be stated that each of the 9 newly synthesized benzo(c)fluorene derivatives was about 10 times as active as tilorone. To elucidate the biochemical mode of action, the effects of 2 new compounds (13468 and 14200) on biosynthesis of macromolecules indicated by the incorporation rate of [14C]adenine (DNA, RNA), [14C]-thymidine (DNA), [14C]uridine (RNA) and [14C]valine (protein) were studied in concentration and time dependence. Both compounds inhibited the incorporation of the 4 precursors into the TCA-insoluble fraction of Ehrlich ascites carcinoma cells.

Adenine↗

PubMed1991

Relationships between the chemical structure and cytotoxicity of 4-alkylmorpholine N-oxides.

The main objective of the present investigation was to screen a series of 4-alkylmorpholine N-oxides for in vitro cytotoxicity and to find out whether there is a quantitative structure-activity correlation (QSAR) between cytotoxic effect represented here by inhibition of incorporation of [14C]adenine into nucleic acid or [14C]valine into proteins in Ehrlich ascites carcinoma (EAC) cells and structure (as a structural parameter the number of carbon atoms m in the alkyl chain was used). On the basis of primary screening, one of the most active compounds, namely 4-dodecylmorpholine N-oxide, was chosen for further biochemical study. The drug inhibited the incorporation rate of [14C] precursors (adenine, thymidine, uridine, valine) into appropriate macromolecules of Ehrlich cells, the extent of inhibition being dependent on both time and concentration of the compound in the incubation medium. The lengthening of the alkyl chain in 4-alkyl-morpholine N-oxides positively affected their cytotoxic activity in Ehrlich cells. For these compounds the optimal m-value is 15-16.

Animals↗

PubMed1991

Pseudomonas aeruginosa toxins: effect on Ehrlich carcinoma and Vero cells in vitro.

The main objective of the present investigation was to screen P. aeruginosa toxins for in vitro activity and investigate biochemical mode of action. Toxins were isolated after concentration of the culture filtrate and separation of the filtrate on Sephadex G-100 column in four fractions. On the basis of primary screening results the dialysate and fractions 3 and 4 effectively inhibited incorporation of [14C]adenine (DNA, RNA) and [14C]valine (protein) into the TCA-insoluble fraction of both Ehrlich ascites carcinoma (EAC) and Vero cells. The toxins also interfered with energy-yielding processes (endogenous respiration). The dialysate decreased the level of ATP in EAC cells after two hours incubation in vitro.

ADP Ribose Transferases↗

PubMed1991

9-Hydroxybenfluron: cytostatic effects and inhibition of macromolecular biosynthesis in Ehrlich ascites and P388 murine leukemia cells.

Primary screening in vitro and study on the mode of action of 9-hydroxybenfluron (HBF) in both murine P388 leukemia and Ehrlich ascites carcinoma cells have been performed. Metabolite HBF is approximately twice as effective as a reference drug (benfluron). To elucidate the biochemical mode of action, the effect of HBF on the biosynthesis of macromolecules indicated by the incorporation rate of [14C]adenine (in DNA and RNA), [14C]thymidine (in DNA), [14C]uridine (in RNA) and [14C]valine (in protein) was studied in concentration and time dependence. HBF inhibited incorporation of all four precursors into the trichloroacetic acid-insoluble fraction of Ehrlich ascites cells. The fact that incorporation of these four precursors is inhibited suggests that the effect of HBF lies at an underlying level of energy generation or transfer rather than at specific reactions in the biosynthesis of DNA and proteins.

Adenine↗