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Spectrophotometric study on the oxidation of rutin by horseradish peroxidase and characteristics of the oxidized products.

Rutin (3',4',5,7-tetrahydroxyflavone-3-rutinoside) was oxidized by a horseradish peroxidase-H2O2 system to an ascorbate-reducible product which had an absorption maximum at about 290 nm and a shoulder at about 440 nm at pH 4. At pH 7.8, ascorbate-reducible compounds and sodium hydrosulfite-reducible and -nonreducible compounds were formed by the oxidation. The ascorbate-reducible compounds consisted of at least two components, the absorption bands of which were at 460-480 nm and about 620 nm. The sodium hydrosulfite-reducible compounds also consisted of two components, and one of the components which had an absorption maximum at about 480 nm seems to be formed from the ascorbate-reducible component of an absorption maximum at the blue region by a nonenzymatic reaction. A mixture of oxidized products of rutin formed by tert-butyl hydroperoxide-dependent oxidation was similar to that formed by the enzymatic reaction. It is discussed that the 3'- and 4'-OH groups of rutin were oxidized by the horseradish peroxidase-H2O2 system and that the oxidized product which could be reduced by ascorbate is an o-quinone derivative.

Ascorbic Acid↗

Potassium sodium tin selenide, K3NaSn3Se8

The title compound, tripotassium sodium tritin octaselenide, K(3)NaSn(3)Se(8), has a molecular (zero-dimensional) structure containing trimeric [Sn(3)Se(8)](4-) units which consist of three edge-sharing SnSe(4) tetrahedra. The [Sn(3)Se(8)](4-) anions and the tetrahedrally coordinated Na(+) cations are arranged in an alternating fashion along the c axis to form SiS(2)-like chains, which are then separated by eight-coordinate K(+) cations. The Sn-Se bond distances are normal, being in the range 2.477 (1)-2.612 (1) A.

Journal Article↗

Mode of interaction of beta-hydroxy-beta-methylglutaryl coenzyme A reductase with strong binding inhibitors: compactin and related compounds.

The sodium salts of compactin (1) and trans-6-[2-(2,4- dichloro-6-hydroxyphenyl)ethyl]-3,4,5,6-tetrahydro-4-hydroxy-2H-pyran- 2-one (3) are inhibitors of yeast beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase. The dissociation constants are 0.24 X 10(-9) and 0.28 X 10(-9) M, respectively. Similar values have been reported for HMG-CoA reductase from mammalian sources [Endo, A., Kuroda, M., & Tanzawa, K. (1976) FEBS Lett. 72, 323; Alberts, A. W., et al. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 3957]. The structures of these compounds marginally resemble that of any substrates of HMG-CoA reductase. We, therefore, investigated the basis for the strong interaction between HMG-CoA reductase and these inhibitors. HMG-CoA and coenzyme A (CoASH), but not reduced nicotinamide adenine dinucleotide phosphate (NADPH), prevent binding of compactin to the enzyme. HMG-CoA, but not CoASH or NADPH, prevents binding of 3 to the enzyme. We also investigated the inhibitory activity of molecules that resemble structural components of compactin. Compactin consists of a moiety resembling 3,5-dihydroxyvaleric acid that is attached to a decalin structure. The sodium salt of DL-3,5-dihydroxyvaleric acid inhibits HMG-CoA reductase competitively with respect to HMG-CoA and noncompetitively with respect to NADPH. The dissociation constant for DL-3,5-dihydroxyvaleric acid, derived from protection against inactivation of enzyme by iodoacetic acid, is (2.1 +/- 0.9) X 10(-2) M. Two decalin derivatives (structurally identical with or closely related to the decalin moiety of compactin) showed no detectable inhibition. If the lack of inhibition is due to their limited solubility, the dissociation constant of these decalin derivatives may be conservatively estimated to be greater than or equal to 0.5 mM. Simultaneous addition of decalin derivatives and DL-3,5-dihydroxyvaleric acid does not lead to enhanced inhibition. The sodium salt of (E)-6-[2-(2-methoxy-1-naphthalenyl)ethenyl]-3,4,5,6- tetrahydro-4-hydroxy-2H-pyran-2-one (6) inhibits HMG-CoA reductase competitively with respect to HMG-CoA and noncompetitively with respect to NADPH. The inhibition constant (vs. HMG-CoA) is 0.8 microM. CoASH does not prevent binding of 6 to enzyme. Compound 6, therefore, behaves analogously to compound 3. We propose that these inhibitors occupy two sites on the enzyme: one site is the hydroxymethylglutaryl binding domain of the enzyme active site and the other site is a hydrophobic pocket located adjacent to the active site.(ABSTRACT TRUNCATED AT 400 WORDS)

Acyl Coenzyme A↗

Evaluation of neutrophil labeling techniques using the chemotaxis radioassay.

Neutrophils isolated from human blood were labeled by various methods and exposed to a chemotactic gradient. The chemotactically functional cells that migrated into the gradient were isolated. The portion of radioactivity of the original cell suspension carried with the chemotactically responsive cells was related to the relative number of migrating cells as determined microscopically. Of the radionuclides used, P-32 diisopropylfluorophosphate (DFP), In-111 oxine, and Tc-99m sulfur colloid provided cell preparations with the highest relative portion of radioactivity confined to functionally intact (chemotactic) neutrophils. Results with Na2(51)CrO4 and with SnCl2-reduced 99mTcO4- were less than optimal. Neutrophils exposed to Ga-67 citrate apparently took up the label and retained chemotactic responsiveness. However, little or no radioactivity was detected in the neutrophils that migrated from the suspensions of Ga-67-labeled cells. The results indicate that the chemotaxis radioassay can yield unique information pertaining to the extent to which a radiotracer is specifically associated with viable neutrophils in a suspension of labeled cells.

Chemotaxis, Leukocyte↗

Inhibition of antigen- and mitogen-induced human lymphocyte proliferation by gold compounds.

Gold sodium thiomalate (GST) inhibited in vitro antigen- and mitogen-triggered human lymphocyte DNA synthesis. Inhibition of responsiveness was observed with concentrations of GST equivalent to gold levels found in serum or tissues of patients receiving chrysotherapy, Inhibition was dependent upon the gold ion itself since GST and gold chloride were both inhibitory whereas thiomalic acid was not. Inhibition could not be explained by nonspecific killing of cells or by an alteration in the kinetics of the responses. GST inhibited mitogen-induced proliferation most effectively when present from the initiation of culture and could not inhibit the responsiveness of cells which previously had been activated by concanvalin A. These findings indicated that GST blocked a critical early step in lymphocyte activation. The degree of GST-induced inhibition of proliferation was increased in cultures of cells partially depleted of monocytes. Moreover, inhibition was reversed by supplementation of these cultures with purified monocytes. These observations suggested that GST blocked thymus-derived (T)-lymphocyte activation by interfering with a requisite function of the monocyte population in initiating such responses. Prolonged incubation of peripheral blood mononuclear cells with GST resulted in diminished mitogen responsiveness upon subsequent culture in the absence of gold. The addition of fresh monocytes restored responsiveness to these populations. Furthermore, preincubation of purified monocytes with GST rendered them deficient in their ability to support mitogen-induced T-lymphocyte proliferation on subsequent culture. These observations indicate that the major effect of GST results from interference with the functional capability of the monocyte population.

Antigens↗

Acute migraine attack therapy: comparison of naproxen sodium and an ergotamine tartrate compound.

The efficacy of safety of naproxen sodium and ergotamine tartrate were compared for the treatment of acute migraine attack in a randomized, parallel trial with 114 participating patients. At the start of symptoms, patients took either three tablets of naproxen sodium (275 mg each) or one of an ergotamine combination (containing 2 mg ergotamine tartrate, 91.5 mg caffeine, and 50 mg cyclizine chlorhydrate). Patients were followed for three months or until six attacks were monitored, whichever came first. Both medications substantially shortened the duration of migraine attacks and reduced the severity of symptoms. When the test medications were taken within 2 h of onset of attack, naproxen sodium was statistically significantly more effective than the ergotamine combination in reducing the severity of headache pain, nausea, and lightheadedness. The ergotamine combination was associated with significantly more vomiting, need for rescue medication, and side effects than was naproxen sodium. Four patients required discontinuation of the ergotamine combination and one of naproxen sodium. Both patients and investigators rated tolerance for naproxen sodium as superior to tolerance for the ergotamine combination. Naproxen sodium seems to be an effective and safe treatment for migraine attacks.

Acute Disease↗

Elevation of ouabainlike compound levels with hypertonic sodium chloride load in rat plasma and tissues.

A major biologically active endogenous digitalis-like factor in the mammalian body may be an isomer of ouabain (ouabainlike compound, OLC). However, the exact role of OLC in sodium homeostasis is still unclear, and acute isotonic volume expansion does not enhance the secretion of OLC. We tested the hypothesis that OLC may be more important in the response to acute hypertonic NaCl load rather than isotonic volume expansion. We injected intraperitoneally 2 mL of 20% NaCl solution into male Wistar rats (n=34) and measured OLC levels in plasma, hypothalamus, pituitary, and adrenal at baseline (n=10) and 1, 2, and 4 hours (n=8 for each). In response to hypertonic NaCl loading, plasma Na-K ratio was elevated at 2 and 4 hours (P<.01). OLC levels in pituitary increased (P<.01) at 1 hour. Thereafter, plasma OLC levels increased at 2 and 4 hours (P<.05; basal, 75+/-11 pmol/L [+/-SEM]; 1 hour, 55+/-11; 2 hours, 130+/-24; 4 hours, 156+/-20). Concomitantly, OLC levels in adrenal increased at 2 and 4 hours (P<.01; basal, 1.7+/-0.2 pmol/g; 1 hour, 4.5+/-0.9; 2 hours, 5.0+/-0.7; 4 hours, 6.8+/-2.2). A significant correlation was observed between OLC levels in plasma and adrenal (P<.05). Plasma Na-K ratio positively correlated with OLC levels in plasma (r=.51, P<.01) and adrenal (r=.48, P<.01). Similar injection of physiological saline solution or hypertonic sucrose solution in physiological saline did not increase OLC levels in plasma and tissues. These findings indicate the elevation of OLC levels in plasma, pituitary, and adrenal in response to acute hypertonic NaCl load in rats and suggest that OLC may be involved in the response to the hypernatremic state.

Adrenal Glands↗

Reduction of cisplatin nephrotoxicity by sodium selenite. Lack of interaction at the pharmacokinetic level of both compounds.

Administration of sodium selenite (Na2SeO3) 1 hr before cis-diamminedichloroplatinum(II) (referred to herein as cisplatin) can protect against the nephrotoxicity of cisplatin. The pharmacokinetic aspects of this interaction were studied in rodents with radiolabeled selenite and cisplatin. Total [75Se]selenium in plasma consisted of [75Se] selenium in plasma proteins and [75Se]selenite in plasma ultrafiltrate. After a short distribution phase, the elimination of [75Se]selenite and total [75Se]selenium proceeded biphasically in the rat, with an initial plasma elimination half-life of [75Se]selenite of 22 +/- 2 min. Coadministration of cisplatin had no effect on the initial nor on the much slower terminal elimination phase of [75Se]selenite nor of total [75Se] selenium. Sodium selenite, in doses protecting against the nephrotoxicity of cisplatin, did not significantly affect areas under the plasma concentration time curve from 0-6 hr nor the initial plasma half-lives of [195mPt]cisplatin (t1/2, 28 +/- 2 min) and total [195mPt]platinum (t1/2, 30 +/- 3 min) in plasma. The much slower terminal elimination phases in plasma and the cumulative urinary excretion of [195mPt] cisplatin and total [195mPt]platinum were neither influenced by sodium selenite. Sodium selenite does not react chemically with cisplatin in vitro. Apparently, bioactivation of selenite is required for its protective effect in vivo. Distribution studies in a mice tumor model indicated that [75Se]selenium is concentrated strongly in the kidney and that the bioactivation of selenite also most likely occurs primarily in the kidneys. We conclude that sodium selenite protects rodents against cisplatin-induced nephrotoxicity without influencing the systemic availability of cisplatin and total platinum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Salt effect on the complex formation between cationic gemini surfactant and anionic polyelectrolyte in aqueous solution.

Salt effect on the interaction of anionic polyelectrolyte sodium carboxymethylcellulose (NaCMC) with cationic gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) [C12H25(CH3)2N(CH2)6N(CH3)2C12H25]Br2 (C12C6C12Br2) has been investigated using turbidimetric titration, steady-state fluorescence, and mobility measurement. It is found that the critical aggregation concentration(cac) for C12C6C12Br2/NaCMC complexes depends little on addition of sodium bromide (NaBr). However, in the presence of nonionic surfactant Triton X-100 (TX100), the critical ionic surfactant mole fraction for the onset of complex formation (Yc) increases markedly with increasing NaBr concentration. These salt effects are supposed as the overall result from competition between the increase of interaction and the screening of interaction. The increase of interaction is referred to as the effect that the larger micelle with higher surface charge density induced by salt has a stronger interaction with oppositely charged polyelectrolyte. The screening of interaction is referred to as the salt screening of electrostatic attraction between the polymer chain and the surfactant. For complex formation between C12C6C12Br2 and NaCMC, the increase of interaction probably compensates the screening of interaction, leading to constant cac values at different salt concentrations. For complex formation between the C12C6C12Br2/TX100 mixed micelle and NaCMC, the screening of interaction probably plays a dominant role, leading to higher suppression of electrostatic binding of micelles to polyelectrolyte.

Alkenes↗

Activation of ferret erythrocyte Na+-K+-2Cl- cotransport by deoxygenation.

Deoxygenation of ferret erythrocytes stimulates Na+-K+-2Cl- cotransport by 111% (s.d., 46) compared to controls in air. Half-maximal activation occurs at a PO2 of 24 mmHg (s.d., 2) indicating that physiological changes in oxygen tension can influence cotransport function. Approximately 25-35% of this stimulation can be attributed to the rise of intracellular free magnesium concentration that occurs on deoxygenation (from 0.82 (S.D., 0.07) to 1.40 mm (S.D., 0.17)). Most of the stimulation is probably caused by activation of a kinase which can be prevented or reversed by treating cells with the kinase inhibitors PP1 or staurosporine, or by reducing cell magnesium content to submicromolar levels. Stimulation by deoxygenation is comparable with that caused by calyculin A or sodium arsenite, compounds that cause a 2- to 3-fold increase in threonine phosphorylation of the cotransporter which can be detected with phospho-specific antibodies. However, the same approach failed to detect significant changes in threonine phosphorylation following deoxygenation. The results suggest that deoxygenation causes activation of a kinase that either phosphorylates the transporter, but probably not on threonine, or phosphorylates another protein that in turn influences cotransporter behaviour. They also indicate that more than one kinase and phosphatase are involved in cotransporter phosphorylation.

Animals↗

Brain sodium channels and ouabainlike compounds mediate central aldosterone-induced hypertension.

Central nervous system (CNS) effects of mineralocorticoids participate in the development of salt-sensitive hypertension. In the brain, mineralocorticoids activate amiloride-sensitive sodium channels, and we hypothesized that this would lead to increased release of ouabainlike compounds (OLC) and thereby sympathetic hyperactivity and hypertension. In conscious Wistar rats, intracerebroventricular infusion of aldosterone at 300 or 900 ng/h in artificial cerebrospinal fluid (aCSF) with 0.145 M Na+ for 2 h did not change baseline mean arterial pressure (MAP), renal sympathetic nerve activity (RSNA), or heart rate (HR). Intracerebroventricular infusion of aCSF containing 0.16 M Na+ (versus 0.145 M Na+ in regular aCSF) did not change MAP or RSNA, but significant increases in MAP, RSNA, and HR were observed after intracerebroventricular infusion of aldosterone at 300 ng/h for 2 h. Intracerebroventricular infusion of aCSF containing 0.3 M Na+ increased MAP, RSNA, and HR significantly more after intracerebroventricular infusion of aldosterone versus vehicle. After intracerebroventricular infusion of aldosterone, the MAP, RSNA, and HR responses to intracerebroventricular infusion of aCSF containing 0.16 M Na+ were blocked by blockade of brain OLC with intracerebroventricular infusion of Fab fragments or of brain sodium channels with intracerebroventricular benzamil. Chronic intracerebroventricular infusion of aldosterone at 25 ng/h in aCSF with 0.15 M Na+ for 2 wk increased MAP by 15-20 mmHg and increased hypothalamic OLC by 30% and pituitary OLC by 60%. Benzamil blocked all these responses to aldosterone. These findings indicate that in the brain, mineralocorticoids activate brain sodium channels, with small increases in CSF Na+ leading to increases in brain OLC, sympathetic outflow, and blood pressure.

Aldosterone↗

Synthesis, analgesic and anti-inflammatory activities of some novel 2,3-disubstituted quinazolin-4(3H)-ones.

A series of novel 2-benzylamino-3-substituted quinazolin-4(3H)-ones have been synthesized by treating 3-amino-2-benzylamino quinazolin-4(3H)-one, with different aldehydes and ketones. The starting material 3-amino-2-benzylamino quinazolin-4(3H)-one was synthesized by nucleophilic substitution of thiomethyl group of 3-amino-2-methylthio quinazolin-4(3H)-one by benzylamine. The title compounds were investigated for analgesic and anti-inflammatory activities. All the test compounds exhibited significant analgesic activity, whereas the compound III is equipotent with diclofenac sodium. The compounds I, II and III showed more potent anti-inflammatory activity than diclofenac sodium.

Analgesics↗