Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.6.1 (sulfatase)
 3,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To better understand the importance of drug-metabolizing enzymes in carcinogenesis and anticancer drug sensitivity of human non-small cell lung cancer, we studied the main drug-metabolizing enzyme systems in both lung tumors and their corresponding nontumoral lung tissues in 12 patients. The following enzymes were assayed by Western blot analysis: cytochromes P-450 (1A1/A2, 2B1/B2, 2C8-10, 2E1, 3A4); epoxide hydrolase; and glutathione S-transferase isoenzymes (GST-alpha, -mu, and -pi). The activity of the following enzymes or cofactor were determined by spectrophotometric or fluorometric assays: glutathione S-transferase (GST); total glutathione; UDP-glucuronosyltransferase; beta-glucuronidase; sulfotransferase; and sulfatase. Results showed the presence of cytochrome P-450 1A1/1A2 in both tumoral and nontumoral tissues. P-450 1A1/1A2 levels were 3-fold lower in tumors compared to corresponding nontumoral tissues (P < 0.05). None of the other probed cytochromes P-450 were detected in either tumoral or nontumoral lung tissues. For the glutathione system, no significant difference between tumoral and nontumoral tissues was observed (GST activity, glutathione content, GST-alpha, -mu, and -pi). A positive linear correlation was observed between GST activity and GST-alpha or GST-pi. No significant difference was observed for the glucuronide and the sulfate pathways and their corresponding hydrolytic enzymes. Epoxide hydrolase was significantly decreased in tumors compared to nontumoral lung tissues (P < 0.05). In conclusion, these results showed differences between non-small cell lung tumors and nontumoral tissues for cytochrome P-450 1A1/1A2 and epoxide hydrolase. These differences between tumors and peritumoral tissues with regard to these drug-metabolizing enzymes could reflect differences occurring after malignant transformation and may play a role in drug sensitivity to anticancer drugs.
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PMID:Main drug- and carcinogen-metabolizing enzyme systems in human non-small cell lung cancer and peritumoral tissues. 840 35

Non-Hodgkin's lymphomas (NHL) are one of the most chemosensitive human malignancies. Complete response (CR) is often achieved, but many patients relapse and a second CR is difficult to obtain because of the development of chemoresistance. In an attempt to better understand the biology and the chemosensitivity of these lymphoid tumors, we assessed the main drug-metabolizing enzyme systems in normal lymphocytes, chemosensitive NHL and chemoresistant NHL. Cytochromes P-450 (1A1/A2, 2B1/B2, 2C8-10, 2E1, 3A4), epoxide hydrolase and glutathione S-transferases (GST-alpha, -mu, -pi) were assayed by immunoblotting. UDP-glucuronosyltransferase, beta-glucuronidase, sulfotransferase, sulfatase, GST activity, and glutathione (GSH) content, were determined by spectral assays. Results showed the absence of all probed cytochromes P-450 in normal lymphocytes and NHL cells tested. GST activity was significantly lower in chemoresistant NHL compared to normal lymphocytes. GST-alpha was not detected in either normal lymphocytes or NHL cells. GST-pi was the predominant isoenzyme, and GST-mu was not detected in chemosensitive NHL. GSH content was significantly lower in chemoresistant NHL compared to other lymphoid tissues tested. The conjugating enzymes UDP-glucuronosyltransferase and sulfatase were similar in either chemoresistant NHL compared to chemosensitive NHL. The activity of the hydrolytic enzyme beta-glucuronidase was lower in chemoresistant compared to chemosensitive NHL, whereas sulfatase was higher in sensitive NHL compared to normal lymphocytes. Epoxide hydrolase was not detected in either normal or NHL cells tested. In conclusion, these studies did not show any cytochrome P-450 in human lymphoid cells tested, but pointed out noteworthy differences for other enzyme systems tested.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Main drug-metabolizing enzyme systems in human non-Hodgkin's lymphomas sensitive or resistant to chemotherapy. 853 97

Tacrolimus is extensively metabolized by the cytochrome P-450 system. Hepatic metabolic phase I reactions of tacrolimus include mainly demethylation and/or hydroxylation. No valid data have been published on phase II pathways (glucuronide- or sulfo-conjugation). In order to investigate these pathways, different beta-glucuronidase/sulfatase enzyme preparations were used to hydrolyse the conjugates potentially present in human bile extracts. Two analytical methods were used: a non-specific method, MEIA, and a specific combined HPLC/MEIA method. The influence of the extraction pH was investigated. After beta-glucuronidase hydrolysis and extraction at pH 5, tacrolimus concentrations, obtained either from HPLC-MEIA or MEIA, always appeared significantly higher, suggesting the presence of glucuronides in the bile. When the extraction was performed at pH 1.5, only the HPLC-MEIA concentrations appeared higher after hydrolysis. MEIA concentrations obtained before and after hydrolysis were similar. These data are consistent with the fact that glucuronides are extracted at pH 1.5 but not at pH 5 and suggest first that, without hydrolysis, the extracted glucuronides are separated from the tacrolimus fraction in the HPLC-MEIA procedure, and second, that the glucuronides are cross-detected by the monoclonal antibody in the immunoassay. From these data, it is concluded that clues have been found, suggesting the presence in human bile of tacrolimus glucuronides, which cross-react with the monoclonal antibody, provided they are extracted in the sample tested.
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PMID:Excretion of tacrolimus glucuronides in human bile. 935 2

The metabolism of the nonprovitamin A carotenoid astaxanthin was investigated in primary cultures of rat hepatocytes. In a time course study based on HPLC and gas chromatography-mass spectrometry analyses, one main metabolite, (rac)-3-hydroxy-4-oxo-beta-ionone, was found. This metabolite was conjugated mainly into glucuronides, as demonstrated by glusulase treatment of the conjugates under sulfatase-inhibiting conditions. Within 24 h more than 50% astaxanthin was metabolized and conjugated. Deconjugation of the polar conjugates with glusulase and analyses with HPLC and gas chromatography-mass spectrometry identified two metabolites, (rac)-3-hydroxy-4-oxo-beta-ionone and its reduced form (rac)-3-hydroxy-4-oxo-7,8-dihydro-beta-ionone, indicating that the former was reduced in the conjugated form. We confirmed that the ketocarotenoid astaxanthin induces xenobiotic-metabolizing enzymes in rat liver in vivo. However, there were no differences in the metabolism of astaxanthin in cultured hepatocytes from rats that were pretreated with astaxanthin and, thus, with induced cytochrome P-450 systems compared with control hepatocytes. Neither liver microsomes from astaxanthin-pretreated nor control rats metabolized astaxanthin. These results indicated that the cytochrome P-450 enzymes were not involved in the metabolism of astaxanthin in rat hepatocytes. We conclude that astaxanthin was metabolized in primary cultures of rat hepatocytes into (rac)-3-hydroxy-4-oxo-beta-ionone and its reduced form (rac)-3-hydroxy-4-oxo-7,8-dihydro-beta-ionone independent of the xenobiotic-metabolizing enzymes induced by astaxanthin.
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PMID:Characterization of metabolites of astaxanthin in primary cultures of rat hepatocytes. 1010 Nov 40

A high proportion (approximately 40%) of breast cancers are hormone dependent. The female hormones estradiol and androstenediol are believed to play a key role in the initiation and promotion of this disease. In the fight against hormone dependent breast cancers, extensive research has been undertaken to produce compounds which are potent inhibitors against the cytochrome P-450 enzyme aromatase (AR), which converts the C19 androgens to the C18 estrogens. However, the administration of AR inhibitors alone has failed to produce the expected decrease in plasma levels of estrone. The major impetus to the development of steroid sulfatase inhibitors has therefore been the realisation that in order to improve therapeutic response for women with hormone-dependent breast cancer, not only must the AR enzyme be inhibited, but also the synthesis of estrogens via alternative routes. The steroid sulfatase enzyme regulates the formation of estrone (which can subsequently be converted to the potent estrogen estradiol) from estrone sulfate, a steroid conjugate present in high concentrations in tissue and blood in women with breast cancer. The sulfatase enzyme system also controls the formation of dehydroepiandrosterone (DHEA) from the DHEA-sulfate. This is important since DHEA can be converted to 5-androstene-3 beta,17 beta-diol, which possesses estrogenic properties capable of stimulating the growth of breast cancer cells in vitro and in vivo. Considerable progress has been made in recent years in the development of a number of potent steroid/estrone sulfatase inhibitors, as such both steroidal and non-steroidal compounds have been considered and a number of highly potent inhibitors have been produced and evaluated against what is now considered a crucial enzyme in the fight against hormone dependent breast cancer. The review therefore considers the work that has been undertaken to date, as well as possible future development with respect to dual inhibitors of both estrone sulfatase and AR.
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PMID:Review of estrone sulfatase and its inhibitors--an important new target against hormone dependent breast cancer. 1186 Mar 58

The alkaloid L-(-)-scopolamine [L-(-)-hyoscine] competitively inhibits muscarinic receptors for acetylcholine and acts as a nonselective muscarinic antagonist, producing both peripheral antimuscarinic properties and central sedative, antiemetic, and amnestic effects. The parasympatholytic scopolamine, structurally very similar to atropine (racemate of hyoscyamine), is used in conditions requiring decreased parasympathetic activity, primarily for its effect on the eye, gastrointestinal tract, heart, and salivary and bronchial secretion glands, and in special circumstances for a CNS action. Therefore, scopolamine is most suitable for premedication before anesthesia and for antiemetic effects. This alkaloid is the most effective single agent to prevent motion sickness. Scopolamine was the first drug to be made commercially available in a transdermal therapeutic system (TTS-patch) delivering alkaloid. Recently, pharmacokinetic data on scopolamine in different biozlogic matrices were obtained most efficiently using liquid chromatographic-tandem mass spectrometric (LC-MS/MS) or gas chromatography online coupled to mass spectrometry. Pharmacokinetic parameters are dependent on the dosage form (oral dose, tablets; parenteral application; IV infusion; SC and IM injection). Scopolamine has a limited bioavailability if orally administered. The maximum drug concentration occurs approximately 0.5 hours after oral administration. Because only 2.6% of nonmetabolized L-(-)-scopolamine is excreted in urine, a first-pass metabolism is suggested to occur after oral administration of scopolamine. Because of its short half-life in plasma and dose-dependent adverse effects (in particular hallucinations and the less serious reactions, eg, vertigo, dry mouth, drowsiness), the clinical use of scopolamine administered orally or parenterally is limited. To minimize the relatively high incidence of side effects, the transdermal dosage form has been developed. The commercially available TTS-patch contains a 1.5-mg drug reservoir and a priming dose (140 microg) to reach the steady-state concentration of scopolamine quickly. The patch releases 0.5 mg alkaloid over a period of 3 days (releasing rate 5 microg/h). Following the transdermal application of scopolamine, the plasma concentrations of the drug indicate major interindividual variations. Peak plasma concentrations (Cmax) of approximately 100 pg/mL (range 11-240 pg/mL) of the alkaloid are reached after about 8 hours and achieve steady state. During a period of 72 hours the plaster releases scopolamine, so constantly high plasma levels (concentration range 56-245 pg/mL) are obtained, followed by a plateau of urinary scopolamine excretion. Although scopolamine has been used in clinical practice for many years, data concerning its metabolism and the renal excretion in man are limited. After incubation with beta-glucuronidase and sulfatase, the recovery of scopolamine in human urine increased from 3% to approximately 30% of the drug dose (intravenously administered). According to these results from enzymatic hydrolysis of scopolamine metabolites, the glucuronide conjugation of scopolamine could be the relevant pathway in healthy volunteers. However, scopolamine metabolism in man has not been verified stringently. An elucidation of the chemical structures of the metabolites extracted from human urine is still lacking. Scopolamine has been shown to undergo an oxidative demethylation during incubation with CYP3A (cytochrome P-450 subfamily). To inhibit the CYP3A located in the intestinal mucosa, components of grapefruit juice are very suitable. When scopolamine was administered together with 150 mL grapefruit juice, the alkaloid concentrations continued to increase, resulting in an evident prolongation of tmax (59.5 +/- 25.0 minutes; P < 0.001). The AUC0-24h values of scopolamine were higher during the grapefruit juice period. They reached approximately 142% of the values associated with the control group (P < 0.005). Consequently, the related absolute bioavailabilities (range 6% to 37%) were significantly higher than the corresponding values of the drug orally administered together with water (range 3% to 27%). The effect of the alkaloid on quantitative electroencephalogram (qEEG) and cognitive performance correlated with pharmacokinetics was shown in studies with healthy volunteers. From pharmacokinetic-pharmacodynamic modeling techniques, a direct correlation between serum concentrations of scopolamine and changes in total power in alpha-frequency band (EEG) in healthy volunteers was provided. The alkaloid readily crosses the placenta. Therefore, scopolamine should be administered to pregnant women only under observation. The drug is compatible with nursing and is considered to be nonteratogenic. In conclusion, scopolamine is used for premedication in anesthesia and for the prevention of nausea and vomiting associated with motion sickness. Pharmacokinetics and pharmacodynamics of scopolamine depend on the dosage form. Effects on different cognitive functions have been extensively documented.
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PMID:Pharmacokinetics and pharmacodynamics in clinical use of scopolamine. 1617 41


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