4H-1,2,4-Pyridothiadiazine 1,1-dioxides and 2,3-dihydro-4H-1,2, 4-pyridothiadiazine 1,1-dioxides chemically related to diazoxide and cyclothiazide as powerful positive allosteric modulators of (R/S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid receptors: design, synthesis, pharmacology, and structure-activity relationships

A series of 4H-1,2,4-pyridothiadiazine 1,1-dioxides and 2, 3-dihydro-4H-1,2,4-pyridothiadiazine 1,1-dioxides bearing various alkyl and aryl substituents on the 2-, 3-, and 4-positions was synthesized and tested as possible positive allosteric modulators of the (R/S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors. Many compounds were found to be more potent than the reference compounds diazoxide and aniracetam as potentiators of the AMPA current in rat cortex mRNA-injected Xenopus oocytes. The most active compound, 4-ethyl-2,3-dihydro-4H-pyrido[3,2-e]-1,2, 4-thiadiazine 1,1-dioxide (31b), revealed an in vitro activity on Xenopus oocytes not far from that of cyclothiazide, the most potent allosteric modulator of AMPA receptors reported to date. Moreover, 31b, but not cyclothiazide, was found to potentiate the duration and the amplitude of the excitatory postsynaptic field potentials induced by electric stimulation in rat hippocampal slices. Such an effect could indicate, for 31b, but not for cyclothiazide, a possible interaction with postsynaptic AMPA receptor binding sites located on hippocampal CA1 neurons. Structure-activity relationships indicated that the structural requirements responsible for a biological activity on AMPA receptors are different from those responsible for an inhibitory activity on the insulin releasing process (putative ATP-sensitive K+-channel openers). For instance, 31b and other related dihydropyridothiadiazines were found to be ineffective as inhibitors of insulin release from rat pancreatic B-cells, in contrast to diazoxide and known pyridothiadiazines reported as ATP-sensitive K+-channel openers. Conversely, the pyridothiadiazines active on B-cells were found to be ineffective as potentiators of the AMPA currents in Xenopus oocytes. Thus, 31b appeared to be more specific than diazoxide as an AMPA receptor modulator. This compound may be considered as a new pharmacological tool, different from diazoxide and cyclothiazide, for studying AMPA receptors. Moreover, 31b can also constitute a new therapeutic agent for the treatment of cognitive disorders.

Selective blockade of serotonin2C/2B receptors enhances dopamine release in the rat nucleus accumbens

The effects of mesulergine (100 and 200 microg/kg s.c.), SB 206553 (1 and 2.5 mg/kg i.p.), RP 62203 (2.5 and 4 mg/kg i.p.) and ritanserin (630 microg/kg i.p.) were studied on the extracellular concentration of dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens of chloral hydrate-anesthetized rats, using intracerebral microdialysis. Mesulergine, a non selective serotonin2C/2B/2A (5-HT2C/2B/2A) receptor antagonist, significantly increased DA release, which reached a peak level (+ 20%) 60 min after drug injection and slowly returned back to baseline values. Mesulergine also caused a dose-dependent increase in DOPAC outflow. Pretreatment with mesulergine (200 microg/kg) did not change the inhibition of DA release induced by apomorphine (100 microg/kg), whereas it prevented the reduction of DOPAC outflow induced by apomorphine (100 microg/kg). Administration of SB 206553, a selective blocker of 5-HT2C/2B receptors, dose-dependently increased DA outflow. The dose of 2.5 mg/kg SB 206553 caused a linear increase of DA output which reached a peak (+75%) 40 min after injection, while 1 mg/kg induced a more gradual increase of DA release which peaked (+54%) 60 min after administration of the drug. Treatment with RP 62203, a selective 5-HT2A receptor antagonist, did not produce any significant effect on DA outflow. Administration of ritanserin, a mixed 5-HT2A/2C receptor antagonist, did not cause any significant change of DA and DOPAC outflow. Taken together, these data indicate that selective blockade of 5-HT2/2B receptor subtypes increases DA release in the rat nucleus accumbens.

Sulfonylamido derivatives of 2-aminophenoxathiin-10,10-dioxide and related compounds possess antifungal action due to the possible inhibition of lanosterol-14-alpha-demethylase

Aryl/alkyl-sulfonylamido-, arylsulfenylamido-, arylcarboxamido-, and ureido/thioureido derivatives of 2-aminophenoxathiin-10,10-dioxide were prepared by reaction with sulfonyl/sulfenyl halides, sulfonic acid anhydrides, acyl chlorides, tosyl isocyanate, aryl/allyl isocyanates or isothiocyanates. Some of these derivatives, containing free amino groups, were further derivatized by reaction with 2,4,6-trisubstituted-pyrylium salts, aryl/allyl isocyanate/isothiocyanates or tosyl isocyanate. Several of the newly synthesized compounds act as effective antifungal agents against Aspergillus and Candida spp., some of them showing activities comparable to ketoconazole, with minimum inhibitory concentrations in the range of 0.3-0.5 microgram/mL. Their mechanism of antifungal action is hypothesized to be due to inhibition of lanosterol-14-alpha-demethylase.

Effect of central acute administration of cadmium on drinking behavior

The effect of acute third ventricle cadmium administration on the drinking behavior of adult male rats under different situations was studied. Injections of cadmium chloride (0.07, 0.7,and 7.0 ng/rat) significantly attenuated water intake in dehydrated rats. Drinking behavior induced by acute intracerebroventricular injections of carbachol (2 micrograms/rat) or angiotensin II (5 ng/rat) was also inhibited by central cadmium injections. Cadmium-induced blockade in water intake in dehydrated animals was reverted by the previous administration of a 5-HT2 antagonist (RP62203) in different doses (5 and 10 micrograms/rat). The data clearly reveal that cadmium elicits very fast actions on the central nervous system. It is suggested that cadmium-induced attenuation of water intake may rely on at least three different mechanisms: impairment of cholinergic and angiotensinergic systems in the brain and stimulation of a central serotonergic drive acting on 5-HT2 receptors. The study of cadmium neurotoxicity by observation of drinking behavior, a behavioral parameter easy to be recorded and measured, is proposed.

Selectivity of oxomemazine for the M1 muscarinic receptors

The binding characteristics of pirenzepine and oxomemazine to muscarinic receptor were studied to evaluate the selectivity of oxomemazine for the muscarinic receptor subtypes in rat cerebral microsomes. Equilibrium dissociation constant (KD) of (-)-[3H]quinuclidinyl benzilate([3H]QNB) determined from saturation isotherms was 64 pM. Analysis of the pirenzepine inhibition curve of [3H]QNB binding to cerebral microsome indicated the presence of two receptor subtypes with high (Ki = 16 nM, M1 receptor) and low (Ki = 400 nM, M3 receptor) affinity for pirenzepine. Oxomemazine also identified two receptor subtypes with about 20-fold difference in the affinity for high (Ki = 84 nM, OH receptor) and low (Ki = 1.65 microM, OL receptor) affinity sites. The percentage populations of M1 and M3 receptors to the total receptors were 61:39, and those of OH and OL receptors 39:61, respectively. Both pirenzepine and oxomemazine increased the KD value for [3H]QNB without affecting the binding site concentrations and Hill coefficient for the [3H]QNB binding. Oxomemazine had a 10-fold higher affinity at M1 receptors than at M3 receptors, and pirenzepine a 8-fold higher affinity at OH receptors than at OL receptors. Analysis of the shallow competition binding curves of oxomemazine for M1 receptors and pirenzepine for OL receptors yielded that 69% of M1 receptors were of OH receptors and the remaining 31% of OL receptors, and that 29% of OL receptors were of M1 receptors and 71% of M3 receptors. However, M3 for oxomemazine and OH for pirenzepine were composed of a uniform population. These results suggest that oxomemazine could be classified as a selective drug for M1 receptors and also demonstrate that rat cerebral microsomes contain three different subtypes of M1, M3 and the other site which is different from M1, M2 and M3 receptors.

Substituted 3-oxo-1,2,5-thiadiazolidine 1,1-dioxides: a new class of potential mechanism-based inhibitors of human leukocyte elastase and cathepsin G

A series of substituted 3-oxo-1,2,5-thiadiazolidine 1,1-dioxides has been synthesized and their in vitro inhibitory activity toward human leukocyte elastase and cathepsin G was investigated. These compounds were found to inactivate the two enzymes efficiently and in a time-dependent fashion.

Autoradiographic studies of RP 62203, a potent 5-HT2 receptor antagonist. In vitro and ex vivo selectivity profile

In this study, quantitative autoradiography was used to determine the selectivity of RP 62203, a novel naphtosultam derivative, for 5-HT2 receptors in vitro and ex vivo, using [125I]7-amino-8-iodo-ketanserin ([125I]AMIK) and [3H]mesulergine as radioligands. The density of [125I]AMIK or [3H]mesulergine binding sites was determined by quantitative image analysis. In in vitro experiments, RP 62203 displaced [125I]AMIK from 5-HT2 receptors with an IC50 of 0.21 nM in rat frontal cortex. Its affinity for 5-HT1C receptors was 100-fold lower (IC50 25 nM versus [3H]mesulergine in rat choroid plexus). RP 62203 showed moderate affinity for alpha 1-adrenoceptors in the rat thalamus (IC50 14 nM) and for histamine H1 receptors in the guinea-pig cerebellum (IC50 13 nM). The tetrabenazine sites were not affected by RP 62203 at a concentration of 30 nM. In ex vivo experiments, RP 62203 was about 4 times more potent than ritanserin in displacing [125I]AMIK from 5-HT2 receptors (ED50 0.58 mg/kg p.o.). A dose of 10 mg/kg of RP 62203 did not displace [3H]mesulergine from 5-HT1C receptors or [125I]AMIK from alpha 1-adrenoceptors and tetrabenazine sites in the rat brain and from histamine H1 receptors in the guinea-pig brain. These results demonstrate that RP 62203 specifically recognizes 5-HT2 receptors in rodent brain.

[3H]RP 62203, a ligand of choice to label in vivo brain 5-HT2 receptors

There are only a few ligands available for labelling brain receptors simply because in vivo binding requires more severe experimental conditions than in vitro binding. We now describe the in vivo binding properties of [3H]RP 62203, a new potent and selective 5-HT2 antagonist. After intravenous injection into rats, [3H]RP 62203 accumulated predominantly in brain regions containing 5-HT2 receptors, with a frontal cortex/cerebellum ratio of 6 to 7. A good correlation was obtained between the regional distribution of [3H]RP 62203 in the brain and the density of 5-HT2 receptors measured in vitro. In vivo binding of [3H] RP 62203 was saturable in the frontal cortex but not in the cerebellum. The Bmax in the frontal cortex was equal to 42.5 fmol/mg, thus in the same range as was found in vitro. The 5-HT2 selectivity was ascertained by displacement (prevention) experiments; 5-HT2 antagonists or the agonist 2,5-dimethoxy- 4-iodophenylisopropylamine could prevent specific labelling of [3H]RP 62203 only in brain regions containing 5-HT2 receptors. Interestingly, the radioactivity remaining in various brain regions after displacement with pipamperone corresponded exactly to that measured in the cerebellum, with or without pipamperone. In conclusion, [3H]RP 62203 possesses striking properties of in vivo binding which make it a suitable candidate for examining 5-HT2 receptors in human brain by positron emission tomography scanning.

2',5'-Bis-O-(tert-butyldimethylsilyl)-3'-spiro-5''-(4''-amino-1'',2''- oxathiole-2'',2'-dioxide)pyrimidine (TSAO) nucleoside analogues: highlyselective inhibitors of human immunodeficiency virus type 1 that are targeted at the viral reverse transcriptase

A series of pyrimidine nucleoside analogues containing [2',5'-bis-O-(tert-butyldimethylsilyl)-3'-spiro-5''-(4''-amino- 1'',2''-oxathiole-2'',2''-dioxide)]-beta-D-ribofuranose as the pentose were found to inhibit human immunodeficiency virus type 1 [HIV-1(IIIB)] replication at a concentration of 0.06-0.8 microM but were not cytotoxic at a 1000- to 10,000-fold higher concentration. These nucleoside derivatives were also effective against various other HIV-1 strains, including those resistant to 3'-azido-3'-deoxythymidine, but not against HIV-2, simian immunodeficiency virus, Moloney murine sarcoma virus, or other RNA or DNA viruses. They proved to be highly specific inhibitors of the RNA-dependent DNA polymerase function of the HIV-1 reverse transcriptase, showing no marked inhibition of the HIV-1 reverse transcriptase-associated DNA-dependent DNA polymerase activity, HIV-2 reverse transcriptase, DNA polymerase alpha, herpes simplex virus 1 DNA polymerase, or Thermus aquaticus DNA polymerase.

RP 62203, a 5-hydroxytryptamine2 antagonist, enhances deep NREM sleep in rats

RP 62203, a naphtosultam derivative, is an antagonist at the 5-hydroxytryptamine2 (HT2) receptor. The sleep pattern of rats treated orally with RP 62203 was studied at doses ranging from 0.5 to 4 mg/kg. Following RP 62203 administration, the duration of deep nonrapid eye movement (NREM) sleep was found to increase at the expense of wakefulness in a dose-dependent manner from 0.5 mg/kg. The 5-HT2 receptor agonist DOI and the 5-HT1a receptor agonist 8 OH-DPAT induced a dose-related increase in wakefulness; treatment with RP 62203 reversed the enhancement of wakefulness produced by DOI but not that produced by 8 OH-DPAT. These data provide further evidence for the involvement of 5-HT2 receptors in the regulation of NREM sleep in rats. RP 62203 could therefore be of clinical interest in the management of sleep disorders, particularly those developing within a psychiatric context.

Pharmacological characterization of RP 62203, a novel 5-hydroxytryptamine 5-HT2 receptor antagonist

1. RP 62203 (2-[3-(4-(4-fluorophenyl)-piperazinyl)propyl]naphto[1,8- ca]isothiazole-1,1-dioxide) is a novel naphtosultam derivative which shows very high affinity for 5-HT2 receptors in the rat cerebral cortex (Ki = 50.0 pM). 2. RP 62203 is relatively selective for this sub-type of 5-hydroxytryptamine (5-HT) receptor, having lower affinity for the 5-HT1A receptor and very low affinity for the 5-HT, receptor. RP 62203 displayed low to moderate affinity for alpha 1-adrenoceptors, dopamine D2 receptors and histamine H1 receptors. 3. In vivo binding experiments demonstrated that oral administration of low doses of RP 62203 led to a long-lasting (greater than 6 h) occupation of cortical 5-HT2 receptors (ID50 = 0.39 mgkg-1). 4. In cortical slices from the neonatal rat, RP 62203 potently inhibited inositol phosphate formation evoked by 5-HT, with an IC50 of 7.76 nM. 5. The activity of neurones in the raphé and their responses to microiontophoretically applied 5-HT were studied with extracellular recording electrodes in the anaesthetized rat. RP 62203 potently and dose-dependently blocked excitations evoked by 5-HT when administered at doses of 0.5-4.0 mg kg-1, i.p. In contrast, neither 5-HT-evoked depressions nor glutamate-evoked excitations of raphé neuronal firing were blocked by RP 62203 at doses as high as 8.0 mg kg-1, i.p. 6. Head twitches induced by 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) could be abolished by low doses of RP 62203 in mice (ED50 = 0.44 mg kg-1, p.o.) and in rats (ED50 = 1.54 p.o.). Similar results were obtained with mescaline and 5-hydroxytryptophan (5-HTP). 7. The potency of RP 62203 was compared with that of three other 5-HT2 receptor antagonists, ritanserin, ICI 169,369 and ICI 170,809. In all models, RP 62203 showed similar activity to ritanserin, whilst either ICI 169,369 or ICI 170,809 was several fold less active. 8. It is concluded that RP 62203 is a potent and selective antagonist at 5-HT2 receptors in the rodent central nervous system.

The novel 5-HT2 receptor antagonist, RP 62203, selectively blocks serotoninergic but not dopaminergic-induced inhibition in the rat prefrontal cortex

The influence of the novel 5-hydroxytryptamine2 (5-HT2) receptor antagonist, RP 62203, on serotoninergic neurotransmission was investigated using an in vivo electrophysiological technique. For this purpose, the ability of RP 62203 (1-3 mg/kg i.p.) to block the inhibitory responses of prefrontal cortical neurons induced by electrical stimulation of the median raphe nucleus was examined in anesthetized rats. In addition, the effects of RP 62203 on the dopaminergic inhibitory responses induced in the prefrontal cortex by stimulation of the ventral tegmental area and on the enhancement of these responses by lysergic acid diethylamide (LSD, a 5-HT2 receptor agonist, 30 or 60 micrograms/kg i.p.), were analyzed. RP 62203 blocked the inhibition induced by median raphe nucleus stimulation in a dose-dependent and reversible fashion. In contrast, RP 62203 failed to affect the inhibitory responses induced in prefrontal cortical cells by stimulation of the ventral tegmental area. However, the enhancement by LSD of the inhibition induced by stimulation of the ventral tegmental area in the prefrontal cortex was blocked by RP 62203. These results demonstrate that RP 62203 selectively blocks serotoninergic, but not dopaminergic, neurotransmission in the prefrontal cortex.

Naphthosultam derivatives: a new class of potent and selective 5-HT2 antagonists

A series of 2-(aminoalkyl)naphth[1,8-cd]isothiazole 1,1-dioxides was synthesized and examined in various receptor binding tests. Most compounds demonstrated high affinity for the 5-HT2 receptor with moderate to high selectivity. A member of this series, compound 24 (RP 62203), displays high 5-HT2 receptor affinity (Ki = 0.26 nM), which is respectively more than 100 and 1000 times higher than its affinity for alpha 1 (Ki = 38 nM) and D2 (Ki greater than 1000 nM) receptors. This compound is a potent orally effective and long lasting 5-HT2 antagonist in the mescaline-induced head-twitches test in mice and rats.

Are 5-HT2 antagonists endowed with anxiolytic properties in rodents?

The precise role of serotonin (5-HT) in anxiety remains unclear. We report here on the effects of RP 62203, a new 5-HT2 antagonist, and ritanserin in different animal models of anxiety. In the elevated plus-maze in mice, RP 62203 increased dose-dependently the percentage of entries onto, and time spent on open arms, over the dose range 0.25-4 mg.kg-1 p.o. By contrast, ritanserin was ineffective up to the dose of 4 mg.kg-1 p.o. In addition, both compounds were tested against the anxiogenic compound FG 7142 (20 mg.kg-1, i.p.) in the plus-maze test in mice and via electrocorticographic recordings (ECoG) in rats. The anxiolytic effect of RP 62203 is antagonized by FG 7142 at a dose devoid of anxiogenic properties. A similar interaction between RP 62203 and FG 7142 is observed in ECoG studies. In contrast, ritanserin seemed to potentiate the anxiogenic and awakening activities of FG 7142. These results demonstrate that RP 62203, a selective 5-HT2 antagonist, possesses anxiolytic properties in rodents suggesting that 5-HT2 receptors are involved in the control of anxiety.

Heteroarylalkanoic acids with possible antiinflammatory activities. Part 8: The scavenging of the oxygen-free radicals

The scavenging activity of some isosteric antiinflammatory heteoarylalkanoic acids with respect to oxygen-free radicals has been studied. All the compounds were found to inhibit the depolymerization of hyaluronic acid due to enzymatically or chemically generated hydroxyl radicals. The reduced consumption of oxygen by xanthine oxidase indicates a cotemporaneous phenomenon of enzymatic inhibition.

Synthesis and structure-activity relationship of substituted tetrahydro- and hexahydro-1,2-benzisothiazol-3-one 1,1-dioxides and thiadiazinones: potential anxiolytic agents

Several novel substituted tetrahydro- and hexahydro-1,2-benzisothiazol-3-one 1,1-dioxides and thiadiazinones were prepared and examined in a series of in vitro and in vivo tests to determine their pharmacological profile. Most compounds were orally active in blocking the conditioned avoidance response (CAR) but did not antagonize apomorphine-induced stereotyped behavior. Several compounds demonstrated moderate to high affinity for the 5-HT1A receptor binding site, with compounds 37 and 38 containing 2-pyrimidinylpiperazinyl and [3-(trifluoromethyl)phenyl]piperazinyl moieties and compound 47 containing the 2-pyrazinylpiperazinyl moiety displaying the highest affinity (Ki values of 10, 4, and 9 nM, respectively). Compound 37, 3-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]hexahydro-4, 7-etheno-1H-cyclobut [f]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, buspirone, and ipsapirone showed similarities in their neurochemical and behavioral profiles. They were similar in potency in blocking CAR with AB50 values of 39, 32, and 42 mg/kg, respectively. They also demonstrated high affinity and selectivity for the 5-HT1A receptor site (Ki = 10 nM) and exhibited partial agonist/antagonist activity in the serotonin syndrome test. In addition, compound 37 inhibited apomorphine-induced climbing behavior much more potently (ED50 of 3.4 mg/kg) than stereotyped behavior (ED50 of 32.2 mg/kg) and will be evaluated further. Structure-activity relationships within this series of compounds are discussed.

Cardiovascular activity of 1,2,4-benzothiadiazine-1,1-dioxide derivatives. Part 10(3): Dialkylamino-, pyrrolidyl- and morpholyl-alkyl-derivatives of 3-amino-1,2,4-benzothiadiazine-1,1-dioxide, 7- or 5,7-halogen substituted

A series of dialkylamino, pyrrolidyl and morpholyl-alkyl-derivatives of 3-amino-1,2,4-benzothiadiazine-1,1-dioxide, 7- or 5,7-halogen substituted in the benzenoid moiety, was prepared and their cardiovascular activity studied. Most of the substances in question were capable of inducing a significant decrease in mean arterial blood pressure; some of them tended to increase pulse pressure or to cause bradycardia, an effect which was noted particularly in the case of compound 10 which reduced heart-rate by 85%. The structure/activity relationship of these substances, of the 6- and 6,7-halogen substituted isomers and of their corresponding non-substituted progenitors is examined.

A novel system: 2H-pyrido[3,2-e]-1,2-thiazine-1,1-dioxide. Synthesis and properties of some derivatives

A rearrangement of 2H-2-acetonyl(phenacyl)-4,6-dimethyl- pyrido[3,2-d]isothiazoline-3-one-1,1-dioxides (I), (II) to derivatives of the unknown system of 2H-pyrido[3,2-e]-1,2-thiazine-1,1-dioxide (V), (XIII) is described; the synthesis of 2-N-substituted derivatives (VI - XII), (XIV - XVI) is also given. The structures of the new compounds were confirmed with elemental analyses and spectral data (I.R., N.M.R., MS). Some of the newly obtained compounds showed strong analgesic activity upon pharmacological screening.

Inhibition of liver alcohol dehydrogenase and ethanol metabolism by 3-substituted thiolane 1-oxides

3-Substituted thiolane 1-oxides (methyl, n-butyl, n-hexyl, and phenyl) were prepared and tested as inhibitors of horse, monkey, and rat liver alcohol dehydrogenases and of ethanol metabolism in rats. These compounds inhibit alcohol oxidation in an uncompetitive manner with respect to ethanol as a varied substrate. Lengthening the alkyl substituent increased the inhibitory potency because of tighter binding in the hydrophobic substrate binding pocket of the alcohol dehydrogenases. Thus, the 3-hexyl derivative was the most potent inhibitor of the purified rat liver alcohol dehydrogenase, with a Kii value of 0.13 microM. The 3-butyl derivative was the best inhibitor of ethanol metabolism in rats, with a Kii value of 11 mumol/kg. The acute toxicity in mice of the butyl derivative was 1.4 mmol/kg. Since high concentrations of alcohol do not prevent the inhibitory effects of these compounds, they may be particularly useful for preventing poisoning by methanol or ethylene glycol.

Studies on 1,2,3-triazoles. 10. Synthesis and antiallergic properties of 9-oxo-1H,9H-benzothiopyrano[2,3-d]-1,2,3-triazoles and their S-oxides

Selected derivatives of 9-oxo-1H,9H-benzothiopyrano[2,3-d]-1,2,3-triazole, a new heterocyclic ring system, and their S-oxides have been prepared and evaluated for antiallergic activity in the rat passive cutaneous anaphylaxis screen. Several of the compounds show intravenous potencies similar to or greater than that of disodium cromoglycate, the most potent being 6,7-dimethyl-9-oxo-1H,9H-benzothiopyrano[2,3-d]-1,2,3-triazole and its 4,4-dioxide.

Effects of 3-chloromethylthiochromone-1,1-dioxide on nucleic acid, protein, and aerobic and anaerobic metabolism of Ehrlich ascites tumor cells

3-Chloromethylthiochromone-1,1-dioxide was observed to be a potent inhibitor of Ehrlich ascites carcinoma growth and a moderate inhibitor of P-388 lymphocytic leukemia growth at 10 mg/kg/day. Preliminary in vitro studies showed that the agents significantly inhibited RNA and DNA synthesis in Ehrlich ascites cells. In vivo studies after dosing on Days 6, 7, and 8 demonstrated the same reductions in nucleic acid synthesis and a moderate reduction in protein synthesis. The primary site of nucleic acid synthesis, which was blocked by 3-chloromethylthiochromone, was at orotidine monophosphate decarboxylase in the primidine pathway. Other enzymes, in anaerobic and aerobic glycolysis, which were blocked include hexokinase, phosphofructokinase, succinic and alpha-ketoglutarate dehydrogenases, as well as States 3 and 4 of oxidative phosphorylation.

Sulfolane-induced convulsions in rodents

In rodents oral or parenteral administration of sulfolane (tetrahydrothiophene-1,1-dioxide) produced hyperactivity, followed by clonic-tonic convulsions. The analeptic effects of sulfolane were nearly additive with those of Metrazol. When injected simultaneously with pentobarbital, sulfolane decreased pentobarbital sleeping time in mice. But sulfolane increased sleeping time when the barbiturate was administered 1 hr after sulfolane.