Local effects of lysophosphatidylserine in rats

To study the inflammatory properties of lysophosphatidylserine (a phospholipid acting as a histamine releaser), rats were subjected to local treatment with this compound. In the paw a rapid and dose-dependent edematous reaction occurred within 30-60 min (ED50 2.5 micrograms/rat). The effect was dependent on the intact configuration of serine head group since lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidic acid and N-acetimidyl-lysophosphatidylserine were uneffective. Indomethacin produced a weak inhibition but chlorpheniramine and cyproheptadine inhibited 50 and 70%, respectively. Consistently, the histamine stores of the paw were found to be decreased at the end of the lysophosphatidylserine effect. Increase in vascular permeability was observed also after the injection of lysophosphatidylserine into the dorsal skin and pleural cavity although the phospholipid was less effective in these regions. The fluid extravasation in the pleural cavity was 75% prevented by cyproheptadine. Parallel in vitro experiments showed that the effect of lysophosphatidylserine on isolated pleural and peritoneal mast cells is increased when a leukocyte lysate was also added. After centrifugation the activity was retained in the insoluble fraction. It is concluded that lysophosphatidylserine, injected locally, elicits an inflammatory reaction mediated by the components of mast cell granulus. The response may be amplified by the migration of other inflammatory cells into the exudate.     

Sensory irritation of the upper airways by airborne chemicals

Twenty-seven chemicals all containing the >CC< group have been tested for their potential sensory irritation properties to the upper respiratory tract when administered in an aerosol form to mice. An analytical model for the data is suggested for comparison of the activity of these compounds, and the essential molecular features for sensory irritant activity in these compounds are delineated. Correlation between the biological and chemical reactivity data suggests that these compounds initiate the sensory irritation reaction by associating with SH groups of a receptor molecule on the free nerve endings of the afferent trigeminal which are located at the surface of the nasal mucosa.     

Biotransformation of coumarin derivatives. (2). Oxidative metabolism of 7-alkoxycoumarin by microsomal enzymes and a simple assay procedure for 7-alkoxycoumarin O-dealkylase

The in vitro biotransformation of 7-alkoxycoumarin by rat liver microsomes was studied to develop a simple and accurate assay procedure for 7-alkoxycoumarin O-dealkylase. 7-Alkoxycoumarin was converted to the O-dealkylated metabolite, 7-hydroxycoumarin, by aerobic incubation of the parent compound with microsomes and NADPH, but the decreased amount of 7-alkoxycoumarin in the reaction mixture was several times higher than that of the 7-hydroxycoumarin produced during the incubation. The thin-layer chromatogram of the ether extractable metabolites in the reaction mixture showed the existence of several fluorescent metabolites including 7-hydroxycoumarin. Fluorescent properties of the parent compound, 7-alkoxycoumarin, and most of the metabolites differed from that of 7-hydroxycoumarin, but the reaction cofactor, NADPH, showed similar properties. Treatment of the reaction mixture with perchloric acid resulted in conversion of NADPH to the non-fluorescent form without any effect upon the fluorescent properties of 7-hydroxycoumarin and its related compounds. Based on these properties, an improved and simple in vitro fluorometric assay of the O-dealkylation of 7-alkoxycoumarin was developed. The method is applicable to routine determination of O-dealkylase activity in both isolated microsomes and whole homogenate. Species differences in the substrate specificity of the O-dealkylation reaction and in the responsiveness of animals to the inducer were observed even with use of the liver homogenate obtained from untreated and phenobarbital- or beta-naphthoflavone-pretreated animals, similar to what was observed with the microsomal system.     

Relationship between the effect of cyclophosphamide on adjuvant arthritis severity, skin allograft rejection and spleen cell cytotoxic activity in rats

Cyclophosphamide, which has a poor immunosuppressive effect on adjuvant arthritis in rats, evokes an aggravating form of the disease when applied at a single low dose before rats' sensitization with complete Freund's adjuvant. However, cyclophosphamide administered by this method of treatment has no such enhancement effect on skin allograft rejection reaction; on the contrary, the rejection reaction was inhibited. Spleen cell cytotoxic activity against 51-Cr labelled chondrocytes significantly decreased in adjuvant arthritis, while in skin allograft rejection it increased during the latent period before the rejection reaction appeared. The addition of cyclophosphamide to the rats' treatment decreased more strongly spleen cell cytotoxic activity, especially in rats with adjuvant arthritis. We conclude that cyclophosphamide-sensitive spleen cytotoxic cells are playing a dual role in the pathogenesis of these two cell-mediated immunological processes: as immunosuppressive regulatory cells in adjuvant arthritis and as effector cells in skin allograft rejection reaction.     

对称的奎宁环类和托品类双季铵和多季铵化合物的合成及其神经肌肉阻断作用

本文报道22个奎宁环类和托品类双季铵和多季铵化合物的合成及其对膈肌膈神经标本的抑制作用。初步试验表明,带有草酰胺链的化合物较其他链[—(CH₂)₆—或—CH₂OCH₂—]的好。通过这两类化合物的构效分析,看出化合物中即便具有神经节阻断剂作用的短链(3,6或8个原子),但如在分子的氨基部分以较庞大的环状基团奎宁环或托品(分别带有适当取代基)替代成为大季铵头时,则转化为神经肌肉阻断作用。     

钴、铁、锰卟啉与含氮类药物轴向配位反应电化学性质研究

利用三电极体系研究了四（对 甲氧基苯基）卟啉钴（Ⅱ）,氯合四（间三甲基苯基）卟啉铁（Ⅲ）,氯合四（间三甲基苯基）卟啉锰（Ⅲ）分别与药物甲巯基咪唑,克霉唑和氨苯砜轴向配位反应的电化学性质,结果表明,轴向配位反应发生后,其金属卟啉的半波电位发生了改变．     

Possible involvement of 5-hydroxytryptamine in the antidepressant activity of narcotic analgesics.

The intraperitoneal injection of 5-hydroxytryptophan (5-HTP) elicits in mice a head twitching reaction which is proportional to the amount of free 5-hydroxytryptamine (5-HT) within the brain. This effect is markedly potentiated by the monoamine oxidase inhibitor isocarboxazid and attenuated by (+)-amphetamine and desmethylimipramine. The narcotic agonist morphine, the partial agonist cyclazocine and the antagonist naloxone were examined for their effects upon this head twitching reaction and each of these three agents antagonized it. Recent studies in man and animals have linked some of the pharmacological properties of these narcotics with those of established antidepressant agents. Although the drugs studied do not have identical effects upon the central excitatory effects of 5-HT an interaction with this amine is common to all and, in view of the various hypotheses linking clinical depression with abnormal indole metabolism, it may be of importance in any antidepressant activity possessed by them.     

The tryptolines: Effect of intraventricular administration on spontaneous motor activity of rats

The pharmacologic properties of the tryptolines, hindered analogues of the tryptamines, were studied behaviorally in rats. Following intraventricular injections, it was found that spontaneous motor activity decreased markedly during the initial 25 mins when compared with saline. Since both the tryptolines and tryptamines have been shown to be inhibitors of 5-hydroxytryptamine uptake, it may be possible that these compounds are acting indirectly through an effect on the serotonergic system.     

Effect of triton X-100 on the conjugation of tetrahydrocortisone, in vitro

The detergent, Triton X-100, increased the conjugation of estrone, estradiol and tetrahydrocortisone (THE) by uridine diphosphate glucuronyl transferase (UDPGT) in rat liver microsomes; the maximal increase of the conjugation of these substrates was measured when the concentration of Triton in the incubation mixtures was 0.05 per cent. However, the magnitude of the increase and the effect seen with varying Triton concentration were substrate dependent, which is consistent with the hypothesis that multiple forms of UDPGT may be present in hepatic microsomes. The effects of various compounds which had previously been shown to either increase or decrease the conjugation of THE in non-activated enzyme preparations were re-examined in Triton-activated preparations. Compounds such as β-diethylaminoethyldiphenylpropylacetate (SKF-525A) and 7-hydroxychlorpromazine which inhibited conjugation in non-activated preparations also inhibited conjugation in Triton-activated preparations. Alternatively, the demethylated metabolites of chlorpromazine, which increased activity in non-treated preparations, decreased activity slightly in preparations maximally stimulated by Triton. Bisubstrate kinetic analysis of the THE conjugation of UDPGT also revealed differences between the properties of the non-treated and Triton-activated enzyme preparations. Triton activation caused an increase in the V_max of the reaction in the forward direction while having an insignificant effect on the dissociation constant for THE.     

Effect of the mitochondrial transition pore inhibitor, S-15176, on rat liver mitochondria: ATP synthase modulation and mitochondrial uncoupling induction

S-15176 is a new inhibitor of the permeability transition pore (PTP) which has been shown to display anti-ischemic properties. We show here that S-15176 prevented PTP, cytochrome c release and maintained mitochondrial membrane potential when low concentrations of S-15176 were used (not exceeding 50 nmol/mg protein). For higher concentrations S-15176 is able to collapse mitochondrial potential. This effect was reversed by the recoupling agent 6-ketocholestanol (6-KCh) suggesting that S-15176 has uncoupling properties. In addition, S-15176 is able to inhibit ATP synthase activity and to stimulate the hydrolytic activity of the enzyme but none of these effects appears to be related to its PTP inhibiting property. These data demonstrate that S-15176 interacts with several targets in mitochondria and these pharmacological properties should be considered in the examination of its health benefits as well as its potential cytotoxicity.     

Reactions of methylphosphonic difluoride with human acetylcholinesterase and oximes – Possible therapeutic implications

Highly toxic organophosphorus (OP) nerve agents are well characterized regarding chemical, biological and toxicological properties and the effectiveness of standard atropine and oxime therapy. Open literature data on the key nerve agent precursor methylphosphonic difluoride (DF) are scarce. To fill this gap the reactions of DF and its main degradation product methylphosphonofluoridic acid (MF) with human acetylcholinesterase (AChE) and the oximes obidoxime, HI-6 and 2-PAM were investigated in vitro. DF and MF were found to be weak inhibitors of human AChE being at least five orders less potent compared to the nerve agent sarin. Incubation of human AChE with millimolar DF and MF and subsequent addition of obidoxime and HI-6 resulted in a concentration-dependent decrease of AChE activity. This effect was not observed when incubating highly diluted AChE with oximes. The most likely explanation for this phenomenon is an inhibitory effect of phosphonyloximes formed by direct reaction of DF or MF with obidoxime and HI-6. These data indicate that high DF doses, resulting in millimolar blood and tissue DF/MF concentrations, are necessary to induce cholinergic signs and that under these conditions treatment with obidoxime and HI-6 may even worsen the poisoning.     

Antithrombotic and antiallergic activities of daidzein,a metabolite of puerarin and daidzin produced by human intestinal microflora

To evaluate the antithrombotic activities of puerarin and daidzin from the rhizome of Pueraria lobata, in vitro and ex vivo inhibitory activities of these compounds and their metabolite, daidzein, were measured. These compounds inhibited ADP- and collagen-induced platelet aggregation. Daidzein was the most potent. However, when puerarin and daidzin were intraperitoneally administered, their antiaggregation activities were weaker than when these compounds were administered orally. When in vivo antithrombotic activities of these compounds against collagen and epinephrine were measured, these compounds showed significant protection from death due to pulmonary thrombosis in mice. To evaluate the antiallergic activity of puerarin, daidzin, and daidzein, their inhibitory effects on the release of beta-hexosaminidase from RBL 2H3 cells and on the passive cutaneous anaphylaxis (PCA) reaction in mice were examined. Daidzein exhibited potent inhibitory activity on the beta-hexosaminidase release induced by DNP-BSA and potently inhibited the PCA reaction in rats. Daidzein administered intraperitoneally showed the strongest inhibitory activity and significantly inhibited the PCA reaction at doses of 25 and 50mg/kg with inhibitory activity of 37 and 73%, respectively. The inhibitory activity of intraperitoneally administered daidzein was stronger than those of intraperitoneally and orally administered puerarin and daidzin. Therefore we believe that puerarin and daidzin in the rhizome of Pueraria lobata are prodrugs, which have antiallergic and antithrombotic activities, produced by intestinal microflora.     

Lysolecithin:lysolecithin acyltransferase from rabbit lung.

The enzyme lysolecithin:lysolecithin acyltransferase from rabbit lung has been found to have a relatively disordered conformation in solutions of high ionic strength. The protein exhibited an ordering of structure when salt was suppressed. This conformational change was concomitant with the loss of transacylase activity, the hydrolytic reaction remaining unchanged. Addition of NaCl caused a progressive disordering of structure with a parallel increase of transacylase activity. The acid denaturation of the protein, at low and high ionic strengths, showed that the ionization of groups with pK in the range 5.9–6.4 was essential for denaturation. The structure was stable at basic pH. The addition of lipids resulted in a non-specific stabilization of the disordered conformation, in the same manner as the addition of NaCl. From these results, it is suggested that there are two conformations for this protein which differ in their ability to bind lysolecithin molecules in the enzyme deacylation step of the reaction. This hypothesis agrees with previously published properties of the enzyme, concerning aggregation with other proteins and kinetic data. From the amino acid composition and conformational properties, the authors suggest that this enzyme could be a peripheral membrane protein.     

In vivo pharmacological characterisation of bilastine, a potent and selective histamine H1 receptor antagonist

OBJECTIVE: We set out to establish the in vivo histamine H(1) receptor antagonistic (antihistaminic) and antiallergic properties of bilastine. METHODS: In vivo antihistaminic activity experiments consisted of measurement of: inhibition of increase in capillary permeability and reduction in microvascular extravasation and bronchospasm in rats and guinea pigs induced by histamine and other inflammatory mediators; and protection against lethality induced by histamine and other inflammatory mediators in rats. In vivo antiallergic activity experiments consisted of measurement of passive and active cutaneous anaphylactic reactions as well as type III and type IV allergic reactions in sensitised rodents. RESULTS: In the in vivo antihistaminic activity experiments, bilastine was shown to have a positive effect, similar to that of cetirizine and more potent than that of fexofenadine. The results of the in vivo antiallergic activity experiments showed that the properties of bilastine in this setting are similar to those observed for cetirizine and superior to fexofenadine in the model of passive cutaneous anaphylactic reaction. When active cutaneous anaphylactic reaction experiments were conducted, bilastine showed significant activity, less potent than that observed with cetirizine but superior to that of fexofenadine. Evaluation of the type III allergic reaction showed that of the antihistamines only bilastine was able to inhibit oedema in sensitised mice, although its effect in this respect was much less potent than that observed with dexamethasone. In terms of the type IV allergic reaction, neither bilastine, cetirizine nor fexofenadine significantly modified the effect caused by oxazolone. CONCLUSIONS: The results of our in vivo preclinical studies corroborate those obtained from previously conducted in vitro experiments of bilastine, and provide evidence that bilastine possesses antihistaminic as well as antiallergic properties, with similar potency to cetirizine and superior potency to fexofenadine.     

Antithrombotic and antiallergic activities of rhaponticin from Rhei Rhizoma are activated by human intestinal bacteria

To evaluate the antithrombotic and antiallergic properties of rhaponticin extracted from Rhei Rhizoma, the in vitro and ex vivo inhibitory activities of rhaponticin and its metabolite, rhapontigenin, were measured. These compounds inhibited in vitro ADP- and collagen-induced platelet aggregation. Rhapontigenin was more potent, with IC50 values of 4 and 70 microg/ml, respectively. In ex vivo ADP- and collagen-induced rat platelet aggregation, these compounds also exhibited a potent inhibitory effect. The antiplatelet aggregation effects of rhaponticin and rhapontigenin were more potent than those of aspirin. Rhapontigenin showed significant protection from death due to pulmonary thrombosis in mice. Rhapontigenin also showed the strongest inhibitory activity against beta-hexosaminidase release induced by DNP-BSA. These compounds inhibited PCA reaction in mice. Rhapontigenin intraperitoneally administered showed the strongest inhibitory activity and significantly inhibited PCA at doses of 25 and 50 mg/kg, with inhibitory activities of 48 and 85%, respectively. The inhibitory activity of orally administered rhaponticin was stronger than that of intraperitoneally administered rhaponticin. These results suggest that rhaponticin, in the rhizome of Rhei Rhizoma, is a prodrug that has extensive antiallergic and antithrombotic properties.     

Mutagenicity and DNA-damaging activity caused by decomposed products of potassium sorbate reacting with ascorbic acid in the presence of Fe salt.

Although potassium sorbate (PS), ascorbic acid and ferric or ferrous salts (Fe-salts) are used widely in combination as food additives, the strong reactivity of PS and oxidative potency of ascorbic acid in the presence of Fe-salts might form toxic compounds in food during its deposit and distribution. In the present paper, the reaction mixture of PS, ascorbic acid and Fe-salts was evaluated for mutagenicity and DNA-damaging activity by means of the Ames test and rec-assay. Effective lethality was observed in the rec-assay. No mutagenicity was induced in either Salmonella typhimurium strains TA98 (with or without S-9 mix) or TA100 (with S-9 mix). In contrast, a dose-dependent mutagenic effect was obtained when applied to strain TA100 without S-9 mix. The mutagenic activity became stronger increasing with the reaction period. Furthermore, the reaction products obtained in a nitrogen atmosphere did not show any mutagenic and DNA-damaging activity. PS, ascorbic acid and Fe-salts were inactive when they were used separately. Omission of one component from the mixture of PS, ascorbic acid and Fe-salt turned the reaction system inactive. These results demonstrate that ascorbic acid and Fe-salt oxidized PS and the oxidative products caused mutagenicity and DNA-damaging activity.     

Chemistry and pharmacology of pyran derivatives. XVII. Synthesis of 2-(dialkylamino)-5-hydroxychromones and their transformation to derivatives of 2H-pyran[4,3,2-de]-1-benzopyran

Through the reaction of resorcin with N,N-dialkylethoxy-carbonylacetamides in suitable conditions 2-(dialkylamino)-5-hydroxychromones (II) were available. Transformation of these compounds into [5-acetoxy-2-(dialkylamino)-4H-chromen-4-ylidene] malononitriles (VII) by reaction with malononitrile in acetic anhydride and treatment of (VII) with hydrochloric acid gave rise to the formation of 5-(dialkylamino)-2-imino-2H-pyrano [4,3,2-de]-1-benzo-pyrans (VIII). Furthermore 5-hydroxychromones (II) when treated with methyl iodide gave the corresponding 5-methoxychromones (III) which in turn yielded 4H-chromen-4-ylidene derivatives (X) by reaction with malononitrile in acetic anhydride. The hydrolysis of the latter compounds with hydrochloric acid resulted in the formation of 2-(dialkylamino)-4-methyl-5-methoxychromenilium salts (XI). Among the compounds which were submitted to pharmacological screening for their antiallergic properties 5-methoxychromone (III a) and 2H-pyrano [4,3,2-de]-1-benzopyran (VIII b) showed a notable activity but also high toxicity.     

Hydrophobic vancomycin derivatives with improved ADME properties: discovery of telavancin (TD-6424)

Novel derivatives of N-decylaminoethylvancomycin (2), containing appended hydrophilic groups were synthesized and their antibacterial activity and ADME properties were evaluated. The compounds were prepared by reacting amines with the C-terminus (C-) of 2 using PyBOP mediated amide formation, or with the resorcinol-like (R-) position of 2 using a Mannich aminomethylation reaction. These analogs retained the antibacterial activity of 2 against methicillin-resistant staphylococci and vancomycin-resistant enterococci. Compounds with a negatively charged auxiliary group also exhibited improved ADME properties relative to 2. In particular, R-phosphonomethylaminomethyl derivative 21 displayed good in vitro antibacterial activity, high urinary recovery and low distribution to liver and kidney tissues. Based on these results, 21 was advanced into development as TD-6424, and is currently in human clinical trials. The generic name telavancin has recently been approved for compound 21.     

Antinociceptive Activities of Aqueous and Ethanol Extracts of Piper betle. Leaves in Rats

Abstract

Leaves of Piper betle. Linn (Piperaceae) possess a broad spectrum of pharmacological and therapeutic properties. However, its antinociceptive activity has not been investigated so far. The aim of this study therefore, was to examine the antinociceptive activity of hot water extract (HWE) and cold ethanol extract (CEE) of P. betle. leaves using rats and three models of nociception (tail flick, hot plate, and formalin tests). Different concentrations of HWE (125, 200, 300, 500 mg/kg) and CEE (125, 200, 300, 500 mg/kg) were made and orally administrated to rats, and the reaction times were determined. The results showed that the extracts have marked antinociceptive activity when evaluated in the hot plate and the formalin tests but not in the tail-flick test. The overall antinociceptive effect of CEE was higher than that of HWE. The antinociceptive effect was mediated via opioid mechanisms.     

Bioactivation of nitroglycerin by ascorbate

Bioactivation of nitroglycerin (GTN) into an activator of soluble guanylate cyclase (sGC) is essential for the vasorelaxant effect of the drug. Besides several enzymes that catalyze GTN bioactivation, the reaction with cysteine is the sole nonenzymatic mechanism known so far. Here we show that a reaction with ascorbate results in GTN bioactivation. In the absence of ascorbate, GTN did not affect the activity of purified sGC. However, the enzyme was activated to approximately 20% of maximal NO-stimulated activity by GTN in the presence of 10 mM ascorbate with an EC(50) value of 27.3 +/- 4.9 microM GTN. The EC(50) value of ascorbate was 0.11 +/- 0.011 mM. Activation of sGC was sensitive to oxyhemoglobin, superoxide, and a heme-site enzyme inhibitor. GTN had no effect when ascorbate was replaced by 1000 U of superoxide dismutase per milliliter. Ascorbate is known to reduce inorganic nitrite to NO. In the presence of 10 mM ascorbate, approximately 30 microM nitrite caused the same increase in sGC activity as 0.3 mM GTN. Determination of ascorbate-driven 1,2- and 1,3-glycerol dinitrate formation indicated that a 140 nM concentration of products was generated from 0.3 mM GTN within 10 min, excluding nitrite as a relevant intermediate. Our results suggest that a reaction between GTN and ascorbate or an ascorbate-derived species yields an activator of sGC with NO-like chemical properties. This reaction may contribute to GTN bioactivation in blood vessels under conditions of GTN tolerance and ascorbate supplementation.