scholarly journals Disturbance in hemoglobin metabolism and in vivo antimalarial activity of azole antimycotics

2011 ◽  
Vol 53 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Juan Ricardo Rodrigues ◽  
Diana Lourenco ◽  
Neira Gamboa
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Post Infection ◽  
Free Amino ◽  
Antimalarial Activity ◽  
Sds Page ◽  
Ic50 Values ◽  
Hemoglobin Metabolism

Plasmodium parasites degrade host hemoglobin to obtain free amino acids, essential for protein synthesis. During this event, free toxic heme moieties crystallize spontaneously to produce a non-toxic pigment called hemozoin or ß-hematin. In this context, a group of azole antimycotics, clotrimazole (CTZ), ketoconazole (KTZ) and fluconazole (FCZ), were investigated for their abilities to inhibit ß-hematin synthesis (IßHS) and hemoglobin proteolysis (IHbP) in vitro. The ß-hematin synthesis was recorded by spectrophotometry at 405 nm and the hemoglobin proteolysis was determined by SDS-PAGE 12.5%, followed by densitometric analysis. Compounds were also assayed in vivo in a malaria murine model. CTZ and KTZ exhibited the maximal effects inhibiting both biochemical events, showing inhibition of β-hematin synthesis (IC50 values of 12.4 ± 0.9 µM and 14.4 ± 1.4 µM respectively) and inhibition of hemoglobin proteolysis (80.1 ± 2.0% and 55.3 ± 3.6%, respectively). There is a broad correlation to the in vivo results, especially CTZ, which reduced the parasitemia (%P) of infected-mice at 4th day post-infection significantly compared to non-treated controls (12.4 ± 3.0% compared to 26.6 ± 3.7%, p = 0.014) and prolonged the survival days post-infection. The results indicated that the inhibition of the hemoglobin metabolism by the azole antimycotics could be responsible for their antimalarial effect.

scholarly journals Amino acid regulation of synthesis of ribonucleic acid and protein in the liver of rats

1971 ◽  
Vol 124 (2) ◽  
pp. 385-392 ◽  
Author(s):  
R. W. Wannemacher ◽  
C. F. Wannemacher ◽  
M. B. Yatvin
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Cellular Protein ◽  
Deficient Diet ◽  
Cellular Protein Content ◽  
Regulate Protein

Weanling (23-day-old) rats were fed on either a low-protein diet (6% casein) or a diet containing an adequate amount of protein (18% casein) for 28 days. Hepatic cells from animals fed on the deficient diet were characterized by markedly lower concentrations of protein and RNA in all cellular fractions as compared with cells from control rats. The bound rRNA fraction was decreased to the greatest degree, whereas the free ribosomal concentrations were only slightly less than in control animals. A good correlation was observed between the rate of hepatic protein synthesis in vivo and the cellular protein content of the liver. Rates of protein synthesis both in vivo and in vitro were directly correlated with the hepatic concentration of individual free amino acids that are essential for protein synthesis. The decreased protein-synthetic ability of the ribosomes from the liver of protein-deprived rats was related to a decrease in the number of active ribosomes and heavy polyribosomes. The lower ribosomal content of the hepatocytes was correlated with the decreased concentration of essential free amino acids. In the protein-deprived rats, the rate of accumulation of newly synthesized cytoplasmic rRNA was markedly decreased compared with control animals. From these results it was concluded that amino acids regulate protein synthesis (1) by affecting the number of ribosomes that actively synthesize protein and (2) by inhibiting the rate of synthesis of new ribosomes. Both of these processes may involve the synthesis of proteins with a rapid rate of turnover.

ACTION OF THYROTROPHIN (TSH) ON THYROID PROTEIN SYNTHESIS IN VIVO AND IN VITRO

1973 ◽  
Vol 72 (3) ◽  
pp. 453-463 ◽  
Author(s):  
Gustav Wägar ◽  
Ragnar Ekholm ◽  
Ulla Björkman
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino ◽  
Microsomal Fraction ◽  
Inhibitory Effect ◽  
Leucine Incorporation ◽  
Bovine Thyroid ◽  
Stimulation Of

ABSTRACT The effect of TSH on the incorporation of L-14C-leucine into thyroid proteins was studied in vivo in rats as well as in vitro on bovine thyroid slices and a microsomal subfraction. It was found that TSH reduced the incorporation of radio-leucine into the proteins of slices during the first 2 hours when the concentration of non-labelled leucine in the incubation medium was low. When cold leucine was added to the medium this inhibitory effect was no longer observed. After 6 hours a stimulatory effect on the radio-leucine incorporation by TSH was obvious at both low and high leucine concentrations. The incorporation of 14C-leucine into proteins by the microsomal fraction incubated with a pH 5-fraction was reduced by TSH but this inhibitory effect of TSH disapperaed when post-microsomal supernatant, containing free amino acids, was added to the incubation mixture. It is suggested that the apparent inhibitory effect of TSH on protein synthesis in thyroid slices is due to an altered ratio labelled/non-labelled leucine, caused by stimulation of proteolysis by TSH. This explanation does not seem applicable, however, to the similar apparently inhibitory effect of TSH on protein synthesis observed in the microsomal fraction. In the in vivo experiments a stimulation of the incorporation of labelled leucine could not be observed until 4 hours after the TSH administration. It is suggested that this apparently slow effect of TSH on protein synthesis might be explained either by an indirect effect of TSH on protein synthesis or by a TSH-induced change of the ratio labelled/non-labelled leucine.

Discovery of 3-Cinnamamido-N-Substituted Benzamides as Potential Antimalarial Agents

2020 ◽  
Vol 16 ◽  
Author(s):  
Haicheng Liu ◽  
Yushi Futamura ◽  
Honghai Wu ◽  
Aki Ishiyama ◽  
Taotao Zhang ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Antimalarial Activity ◽  
In Vitro Assays ◽  
Compound Library ◽  
Antimalarial Agents ◽  
Phenotypic Screen ◽  
Ic50 Values ◽  
Substituted Benzamides

Background: Malaria is one of the most devastating parasitic diseases, yet the discovery of antimalarial agents remains profoundly challenging. Very few new antimalarials have been developed in the past 50 years, while the emergence of drug-resistance continues to appear. Objective: This study focuses on the discovery, design, synthesis, and antimalarial evaluation of 3-cinnamamido-N-substituted benzamides. Method: In this study, a screening of our compound library was carried out against the multidrug-sensitive Plasmodium falciparum 3D7 strain. Derivatives of the hit were designed, synthesized and tested against P. falciparum 3D7 and the in vivo antimalarial activity of the most active compounds was evaluated using the method of Peters’ 4-day suppressive test. Results: The retrieved hit compound 1 containing a 3-cinnamamido-N-substituted benzamide skeleton showed moderate antimalarial activity (IC50 = 1.20 µM) for the first time. A series of derivatives were then synthesized through a simple four-step workflow, and half of them exhibited slightly better antimalarial effect than the precursor 1 during the subsequent in vitro assays. Additionally, compounds 11, 23, 30 and 31 displayed potent activity with IC50 values of approximately 0.1 µM, and weak cytotoxicity against mammalian cells. However, in vivo antimalarial activity is not effective which might be ascribed to the poor solubility of these compounds. Conclusion: In this study, phenotypic screen of our compound library resulted in the first report of 3-cinnamamide framework with antimalarial activity and 40 derivatives were then designed and synthesized. Subsequent structure-activity studies showed that compounds 11, 23, 30 and 31 exhibited the most potent and selective activity against P. falciparum 3D7 strain with IC50 values around 0.1 µM. Our work herein sets another example of phenotypic screen-based drug discovery, leading to potentially promising candidates of novel antimalarial agents once given further optimization.

scholarly journals Antimalarial Effect of the Total Glycosides of the Medicinal Plant, Ranunculus japonicus

Pathogens ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 532
Author(s):  
Hae-Soo Yun ◽  
Sylvatrie-Danne Dinzouna-Boutamba ◽  
Sanghyun Lee ◽  
Zin Moon ◽  
Dongmi Kwak ◽  
...  
Keyword(s):  
Chinese Medicine ◽  
Traditional Chinese Medicine ◽  
Plasmodium Berghei ◽  
Antimalarial Activity ◽  
Hematological Parameters ◽  
Significant Inhibition ◽  
Ic50 Values ◽  
The Republic

In traditional Chinese medicine, Ranunculus japonicus has been used to treat various diseases, including malaria, and the young stem of R. japonicus is consumed as a food in the Republic of Korea. However, experimental evidence of the antimalarial effect of R. japonicus has not been evaluated. Therefore, the antimalarial activity of the extract of the young stem of R. japonicus was evaluated in vitro using both chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2) strains; in vivo activity was evaluated in Plasmodium berghei-infected mice via oral administration followed by a four-day suppressive test focused on biochemical and hematological parameters. Exposure to extracts of R. japonicus resulted in significant inhibition of both chloroquine-sensitive (3D7) and resistant (Dd2) strains of P. falciparum, with IC50 values of 6.29 ± 2.78 and 5.36 ± 4.93 μg/mL, respectively. Administration of R. japonicus also resulted in potent antimalarial activity against P. berghei in infected mice with no associated toxicity; treatment also resulted in improved hepatic, renal, and hematologic parameters. These results demonstrate the antimalarial effects of R. japonicus both in vitro and in vivo with no apparent toxicity.

Turnover of total proteins and ornithine aminotransferase during liver regeneration in rats

1980 ◽  
Vol 238 (1) ◽  
pp. E46-E52
Author(s):  
S. L. Augustine ◽  
R. W. Swick
Keyword(s):  
Amino Acids ◽  
Liver Regeneration ◽  
Protein Degradation ◽  
Partial Hepatectomy ◽  
Free Amino ◽  
Liver Protein ◽  
Ornithine Aminotransferase ◽  
Fractional Rate

The recovery of approximately 40% of the total liver protein during the first day after partial hepatectomy was shown to be due to the near cessation of protein breakdown rather than to an increase in protein synthesis. The decrease in degradation of total protein was less if rats were adrenalectomized or protein-depleted prior to partial hepatectomy. The effect of these treatments originally suggested that changes in free amino acid levels in liver might be related to the rate of protein degradation. However, no correlation was found between levels of total free amino acids and rates of breakdown. Measurements of individual amino acids during liver regeneration suggested that levels of free methionine and phenylalanine, amino acids that have been found to lower rates of protein degradation in vitro, are not correlated with rates of breakdown in vivo. The difference between the fractional rate of ornithine aminotransferase degradation (0.68/day and 0.28/day in sham-hepatectomized and partially hepatectomized rats, respectively) was sufficient to account for the higher level of this protein 3 days after surgery in the latter group.

Effect of Cycloheximide on In Vitro and In Vivo Protein Synthesis by Certain Tissues of Rats and Pigeons with Special Reference to Muscle

1973 ◽  
Vol 51 (12) ◽  
pp. 933-941 ◽  
Author(s):  
Njanoor Narayanan ◽  
Jacob Eapen
Keyword(s):  
Amino Acids ◽  
Body Weight ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Amino Acid Incorporation ◽  
Contrast Administration ◽  
Acid Incorporation ◽  
Tissue Homogenates

The effect of cycloheximide in vitro and in vivo on the incorporation of labelled amino acids into protein by muscles, liver, kidneys, and brain of rats and pigeons was studied. In vitro incorporation of amino acids into protein by muscle microsomes, myofibrils, and myofibrillar ribosomes was not affected by cycloheximide. In contrast, administration of the antibiotic into intact animals at a concentration of 1 mg/kg body weight resulted in considerable inhibition of amino acid incorporation into protein by muscles, liver, kidneys, and brain. This inhibition was observed in all the subcellular fractions of these tissues during a period of 10–40 min after the administration of the precursor. Tissue homogenates derived from in vivo cycloheximide-treated animals did not show significant alteration in in vitro amino acid incorporation with the exception of brain, which showed a small but significant enhancement.

scholarly journals The rate-limiting step of protein synthesis in vivo and in vitro and the distribution of growing peptides between the puromycinlabile and puromycin-non-labile sites on polyribosomes

1971 ◽  
Vol 122 (3) ◽  
pp. 267-276 ◽  
Author(s):  
D. C. N. Earl ◽  
Susan T. Hindley
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Donor Site ◽  
Peptide Bond ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Donor And Acceptor ◽  
Rate Limiting

1. At 3 min after an intravenous injection of radioactive amino acids into the rat, the bulk of radioactivity associated with liver polyribosomes can be interpreted as growing peptides. 2. In an attempt to identify the rate-limiting step of protein synthesis in vivo and in vitro, use was made of the action of puromycin at 0°C, in releasing growing peptides only from the donor site, to study the distribution of growing peptides between the donor and acceptor sites. 3. Evidence is presented that all growing peptides in a population of liver polyribosomes labelled in vivo are similarly distributed between the donor and acceptor sites, and that the proportion released by puromycin is not an artifact of methodology. 4. The proportion released by puromycin is about 50% for both liver and muscle polyribosomes labelled in vivo, suggesting that neither the availability nor binding of aminoacyl-tRNA nor peptide bond synthesis nor translocation can limit the rate of protein synthesis in vivo. Attempts to alter this by starvation, hypophysectomy, growth hormone, alloxan, insulin and partial hepatectomy were unsuccessful. 5. Growing peptides on liver polyribosomes labelled in a cell-free system in vitro or by incubating hemidiaphragms in vitro were largely in the donor site, suggesting that either the availability or binding of aminoacyl-tRNA, or peptide bond synthesis, must be rate limiting in vitro and that the rate-limiting step differs from that in vivo. 6. Neither in vivo nor in the hemidiaphragm system in vitro was a correlation found between the proportion of growing peptides in the donor site and changes in the rate of incorporation of radioactivity into protein. This could indicate that the intracellular concentration of amino acids or aminoacyl-tRNA limits the rate of protein synthesis and that the increased incorporation results from a rise to a higher but still suboptimum concentration.

Effects of food deprivation on protein synthesis and degradation in rat skeletal muscles

1976 ◽  
Vol 231 (2) ◽  
pp. 441-448 ◽  
Author(s):  
JB Li ◽  
AL Goldberg
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Food Deprivation ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Rna Content ◽  
Fasted Rats ◽  
Synthesis And Degradation

The effects of food deprivation on protein turnover in rat soleus and extensor digitorum longus (EDL) were investigated. Muscles were removed from fed or fasted growing rats, and protein synthesis and breakdown were measured during incubation in vitro. Rates of synthesis and degradation were higher in the dark soleus than in the pale EDL. One day after food removal protein synthesis and RNA content in the EDL decreased. On the 2nd day of fasting, rates of protein catabolism in this muscle increased. Little or no change in synthesis and degradation occurred in the soleus. Consequently, during fasting the soleus lost much less weight than the EDL and other rat muscles. In unsupplemented buffer or in medium containing amino acids, glucose, and insulin, the muscles of fasted rats showed a lower rate of protein synthesis expressed per milligram of tissue but not per microgram of RNA. Thus the decrease in muscle RNA on fasting was responsible for the reduced synthesis observed under controlled in vitro conditions. In vivo the reduction in muscle protein synthesis on fasting results both from a lower RNA content and lower rate of synthesis per microgram of RNA. Reduced supply of glucose, insulin, and amino acids may account for the lower rate of synthesis per microgram of RNA demonstrable in vivo.

Correlation between osmoregulation and cell volume regulation

1987 ◽  
Vol 252 (4) ◽  
pp. R768-R773
Author(s):  
M. A. Lang
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Free Amino Acids ◽  
Volume Regulation ◽  
Free Amino ◽  
Cell Volume Regulation

The euryhaline crab, Callinectes sapidus, behaves both as an osmoregulator when equilibrated in salines in the range of 800 mosM and below and an osmoconformer when equilibrated in salines above 800 mosM. There exists a close correlation between osmoregulation seen in the whole animal in vivo and cell volume regulation studied in vitro. Hyperregulation of the hemolymph osmotic pressure and cell volume regulation both occurred in salines at approximately 800 mosM and below. During long-term equilibration of the crabs to a wide range of saline environments, the total concentration of hemolymph amino acids plus taurine remained below 3 mM. During the first 6 h after an acute osmotic stress to the whole animal, the hemolymph osmotic pressure and Na activity gradually decreased, whereas the free amino acids remained below 3 mM. As the hemolymph osmotic pressure decreased below approximately 850 mosM, the amino acid level began to increase to 17-25 mM. This change was primarily due to increases in glycine, proline, taurine, and alanine. The likely source of the increase in hemolymph free amino acids in vivo is the free amino acid loss from muscle cells observed during cell volume regulation in vitro.

scholarly journals Albumin, fibrinogen and transferrin synthesis in isolated rat hepatocyte suspensions. A model for the study of plasma protein synthesis

1975 ◽  
Vol 146 (1) ◽  
pp. 141-155 ◽  
Author(s):  
K N Jeejeebhoy ◽  
J Ho ◽  
G R Greenberg ◽  
M J Phillips ◽  
A Bruce-Robertson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Plasma Protein ◽  
Plasma Proteins ◽  
Horse Serum ◽  
Rat Hepatocyte ◽  
Isolated Rat

A system using hepatocyte suspensions in vitro was developed for studying the synthesis of albumin, fibrinogen and transferrin. Conditions for optimum survival of the hepatocyte and for synthesis of these plasma proteins were defined for this system. These conditions included the use of horse serum (17.5 percent, v/v, heat-inactivated), an enriched medium (Waymouth's MB 752/1), an O2 tension of between 18.7 times 10(3) and 26.7 times 10(3) Pa and constant stirring. Albumin, fibrinogen and transferrin synthesis rates were obtained of 0.32 p 0.094(10), 0.12 p 0.030(11) and 0.097 p 0.017(10) [mean p S.D. (n)]mg/h per g of hepatocytes respectively. These rates were maintained for the first 12h of study and synthesis continued at a diminished rate up to 48h. The synthesis of albumin was decreased in a medium containing less amino acids and glucose, but that of fibrinogen was substantially unaffected. ATP concentrations up to 12h and RNA/DNA ratios up to 24h were comparable with values in vivo. The ability to study cells up to 48h permitted us to find that the addition of a mixture of hormones consisting of glucagon, cortisol, tri-iodothyronine and growth hormone enhanced fibrinogen synthesis. Addition of insulin to the above mixture resulted in increased synthesis for albumin and transferrin but not for fibrinogen.

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