ABSTRACT
A peptide glucuronide (Exorphin C glucuronide) was labeled with 99mTc using glucoheptonate (GH) as a bifunctional chelating agent. Scintigraphic imaging was performed in male Albino rabbits. Exorphin C glucuronide showed rapid and efficient labeling with 99mTc using glucoheptonate as a bifunctional chelate. Results demonstrated that 99mTc-GEG may be a useful new type of glucuronide derivative of peptides for diagnosis of some cancer diseases.
Subject(s)
Glucuronides/pharmacokinetics , Hemoglobins/pharmacokinetics , Organotechnetium Compounds/pharmacokinetics , Peptide Fragments/pharmacokinetics , Radiopharmaceuticals/pharmacokinetics , Receptors, Opioid/metabolism , Technetium , Animals , Brain/diagnostic imaging , Brain/metabolism , Female , In Vitro Techniques , Male , Microsomes/metabolism , Microsomes, Liver/metabolism , Rabbits , Radionuclide Imaging , Rats , Rats, Wistar , Sugar Acids/chemistry , Tissue DistributionABSTRACT
The aim of the current study was to synthesize a derivative of estradiol glucuronide, which is able to be labeled with 99mTc and to investigate its radiopharmaceutical potential using imaging and biodistribution studies. An estrogen derivative, beta-estradiol (1,3,5,[10]-estratriene-3,17beta-diol) attached to diethylenetriamine pentaacetic acid (DTPA) was synthesized in six steps. At the end of these steps a compound of estradiol and DTPA derivative called deoxy demethyl homoestradiolyl diethylenetriamine pentaacetic acid (ESTDTPA) was synthesized. Afterwards, this compound was reacted with UDP-glucuronyl transferase (UDPGT). Following the glucuronidation reaction, the product called deoxy demethyl homoestradiolyl diethylenetriamine pentaaceticacid-glucuronide (ESTDTPAG) was obtained. Synthesized products were purified using high performance liquid chromatography (HPLC). The identification of the purified products and impurities were also established using HPLC. Synthesized compound was labeled with 99mTc. Thin layer radio chromatography (TLRC) technique was used to determine their radiochemical yields and stabilities. Labeling yield was over 96%. The biodistribution studies were performed on female Albino Wistar rats. The activity per gram tissue was calculated and time-activity curves were plotted. The target organs (tumor, as well as uterus, ovaries, adrenals and other ER containing tissues) retain the estradiol derivative longer than nontarget organs, but even these lost most of their activity within a few hours. In addition, the imaging studies were performed on normal and tumor bearing female Albino Wistar rats using Camstar XR/T gamma camera. In gamma-scintigraphic imaging studies with 99mTc-ESTDTPAG the breast tumors could be well visualized up to 24 h.
Subject(s)
Estradiol/analogs & derivatives , Glucuronides/chemical synthesis , Radiopharmaceuticals/chemical synthesis , Technetium/chemistry , Animals , Breast Neoplasms/diagnostic imaging , Breast Neoplasms/metabolism , Estradiol/chemical synthesis , Estradiol/chemistry , Estradiol/pharmacokinetics , Female , Glucuronides/chemistry , Glucuronides/pharmacokinetics , Isotope Labeling/methods , Liver/diagnostic imaging , Liver/metabolism , Radionuclide Imaging , Radiopharmaceuticals/chemistry , Radiopharmaceuticals/pharmacokinetics , Rats , Rats, Wistar , Spectrometry, Mass, Fast Atom Bombardment , Technetium Tc 99m Pentetate/chemistry , Technetium Tc 99m Pentetate/pharmacokinetics , Tissue DistributionABSTRACT
Exorphin C is a peptide with five amino acids [(Tyr-Pro-Ile-Ser-Leu) Trifluoroacetate salt] (Sigma) that has an affinity to opioid receptor-expressing tissues and tumors. Exorphin-C was labeled with 99mTc using glucoheptonate (GH) as bifunctional chelating agent. Then, we investigated its radiopharmaceutical potential as opioid receptor-expressing tissue on rabbits. Quality controls were performed by ITLC, paper electrophoresis and HPLC. Labeling efficiency was higher than 98%. The compound was stable for at least 5 h at room temperature. Scintigraphic imaging with 99mTc-GH-exorphin C (99mTc-GE) was performed on male Albino rabbits. Static images were obtained from anterior projection using a Camstar XR/T gamma camera at several time intervals. Although a significant amount of activity was seen in the brain, less activity was seen on receptor saturation studies at 30 min. Slight hepatobiliary excretion was seen, though the main excretion route was renal. After saturating, the receptor hepatobiliary excretion was not seen; the only excretion route was renal.
Subject(s)
Organotechnetium Compounds , Peptides , Radionuclide Imaging , Animals , Chromatography, High Pressure Liquid , Electrophoresis, Paper , Male , RabbitsABSTRACT
An enzyme electrode for the specific determination of catechol was developed by using catechol oxidase (EC 1.10.3.1) from eggplant (Solanum melangena L.) in combination with a dissolved oxygen probe. Optimization studies of the prepared catechol oxidase enzyme electrode established a phosphate buffer 50 mM at pH 7.0 and 35°C to provide the optimum conditions for affirmative electrode response. The enzyme electrode response depended linearly on a catechol concentration range of 5â¢10(-7)-30â¢10(-5) M with a response time of 25 sec and substrate specificity of the catechol oxidase electrode of 100%. The biosensor retained its enzyme activity for at least 70 days.
ABSTRACT
Rabbit hepatic microsomal UDP-glucuronyl transferase (EC 2.4.1.17) was immobilized by entrapment in chitosan which is an ionotropic gelation agent and the resulting preparation was used as a biocatalyst for the glucuronidation of 1-naphthol in order to study the drug metabolism in vitro and obtaining artificial liver support (detoxification). In this study, depending on the porous structure of the chitosan/UDPGT gel beads, mainly the diffusion characteristics of 1-naphthol from chitosan gel beads in well stirred solutions were investigated, and the values of the effective diffusion coefficients (Dc) indicate that UDP-glucuronyl transferase in chitosan beads has no additional diffusion barrier. Using the data, the capacity of the chitosan-gel as an immobilization matrix for microsomal UDP-glucuronyl transferase is discussed from the point of view of diffusion characteristics.
Subject(s)
Chitin/analogs & derivatives , Glucuronosyltransferase/chemistry , Microsomes, Liver/enzymology , Animals , Chitin/chemistry , Chitosan , Diffusion , Enzymes, Immobilized , Gels , Kinetics , Microspheres , Naphthols/chemistry , Naphthols/metabolism , RabbitsABSTRACT
Rabbit hepatic microsomal UDP-Glucuronyl transferase (EC.2.4.1.17) was immobilized in chitosan, which is an ionotropic gelatation agent, and the resulting preparation was used as a biocatalyst for the glucuronidation of toxic substances and drugs such as; 1-naphthol, phenol, 4-nitrophenol, bilirubin, testesterone, estrone, lamotrigine, imipramine and chlorpromazine. For studying the drug metabolism in vitro and obtaining artificial liver support (detoxification) chitosan-entrapped UDPGT towards 1-naphthol was tested by using two model reactor system. The conversion curves of 1-naphthol to its glucuronide indicated that the column reactor system was found to be better and seems suitable for detoxification with a high yield of glucuronide formation.
Subject(s)
Enzymes, Immobilized , Glucuronosyltransferase/metabolism , Microsomes, Liver/enzymology , Animals , Chitin/analogs & derivatives , Chitosan , Inactivation, Metabolic , Rabbits , Substrate SpecificityABSTRACT
The hepatic microsomal UDP-Glucuronyl transferase which catalyze the glucuronidation of drugs, pesticides, carcinogens and other xenobiotics, was immobilized by entrappment in chitosan. Chemical and physical characterization were made by using 1-naphthol as substrate. Thermal, storage and operational stabilities of the immobilized enzyme was also searched and found to be better in comparison with the free enzyme. In conclusion, chitosan gel beads appear to have good characteristics for use as UDPGT immobilization support suitable for large scale use and offer the prospect that immobilized UDPGT may become an important form of catalyst in medicine.
