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At least 559 records · Page 31Linked to original sources

PubMed2006

The efficient direct synthesis of N,O-acetal compounds as key intermediates of discorhabdin A: oxidative fragmentation reaction of alpha-amino acids or beta-amino alcohols by using hypervalent iodine(III) reagents.

Hypervalent iodine(III) reagents are readily available, easy to handle, and have a low toxicity and similar reactivities to those of heavy metal reagents, and hence they are used for various oxidative reactions. The oxidative cleavage of alkynes or carbonyl compounds by using bis(trifluoroacetoxy)iodo(III) pentafluorobenzene (C(6)F(5)I(OCOCF(3))(2)) has been reported. Herein, the efficient direct synthesis of N,O-acetal compounds as key intermediates of discorhabdin A, by the oxidative fragmentation reaction of alpha-amino acids or beta-amino alcohols by using C(6)F(5)I(OCOCF(3))(2), is described.

Amino Acids↗

PubMed2002

Effects of a newly synthesized kappa-opioid receptor agonist, TRK-820, on the discriminative stimulus and rewarding effects of cocaine in rats.

RATIONALE: We previously demonstrated that the prototypical kappa-opioid receptor agonist U-50,488H did not affect the discriminative stimulus effects of cocaine, and the dose of U-50,488H which significantly induced aversive effects attenuated the rewarding effects of cocaine. OBJECTIVES: In the present study, the effects of a newly synthesized kappa-opioid receptor agonist, TRK-820, on the discriminative stimulus and rewarding effects of cocaine were examined in rats. METHODS: In the drug discrimination procedure, the effects of TRK-820 on the discriminative stimulus effects of cocaine were examined in rats that had been trained to discriminate between 10 mg/kg cocaine and saline. TRK-820-induced place preference or place aversion and the effects of TRK-820 on the cocaine (4 mg/kg)-induced place preference were examined using a conditioned place preference procedure in rats. RESULTS: TRK-820 did not engender cocaine-like responding in rats trained to discriminate between 10 mg/kg cocaine and saline. In combination tests, low doses of TRK-820, which did not affect the response rate, significantly attenuated the discriminative stimulus effects of cocaine, and these effects of TRK-820 were reversed by a kappa-opioid receptor antagonist, nor-BNI. In the conditioned place preference procedure, low doses of TRK-820, which did not affect the response rate in the drug discrimination, did not produce either place preference or place aversion, whereas, higher dose (80 microg/kg) of TRK-820 slightly but significantly induced a place aversion. Under these conditions, the cocaine-induced place preference was completely attenuated by low doses of TRK-820. These results may prompt further investigation of the effectiveness of the new kappa-opioid receptor agonist TRK-820 as a novel pharmacotherapeutic compound for the treatment of cocaine addiction.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed2005

Improving the antiviral efficacy and selectivity of HIV-1 reverse transcriptase inhibitor TSAO-T by the introduction of functional groups at the N-3 position.

Novel derivatives of the anti-HIV-1 agent, TSAO-T, bearing at the N-3 position a variety of polar, lipophilic, or aromatic groups linked to that position through flexible polymethylene linkers of different length, were prepared and evaluated for their anti-HIV activity. Several compounds (within the series of polar bearing groups) exhibited a 2-6-fold improved antiviral potency with regard to the lead compound, TSAO-T. Moreover, some of the most active N-3 TSAO derivatives retain antiviral activity against the TSAO-T-resistant HIV-1 strain (Glu138 --> Lys). Interestingly, the N-methylcarboxamide derivative 17 was 5- to 6-fold more active (IC50: 0.56 microM) against recombinant HIV-1 reverse transcriptase than the lead compound, thus becoming the most active TSAO derivative synthesized so far. On the other hand, the N-3 methylcarboxamide TSAO derivative 12 turned out to have the highest selectivity index yet reported for this class of compounds (around > or =12 000).

Anti-HIV Agents↗

PubMed2006

Decaspirones A-E, bioactive spirodioxynaphthalenes from the freshwater aquatic fungus Decaisnella thyridioides.

Decaspirones A-E (1-5), five new compounds related to the palmarumycins, were isolated from cultures of the freshwater aquatic fungal species Decaisnella thyridioides. The known compound palmarumycin CP1 (6) was also obtained. The structures of 1-5 were determined by analysis of NMR and MS data, and their relative configurations were assigned by analysis of 1H NMR J-values and NOESY data. The structure of the lead compound 1 was confirmed by X-ray crystallographic analysis. Compounds 1-5 possess a trans ring fusion not previously reported in members of this structural class. The absolute configuration of 1 was assigned using the modified Mosher method. Compounds 1-5 showed potent antifungal and antibacterial activity.

Anti-Bacterial Agents↗

PubMed1994

Synthesis and aldose reductase inhibitory activity of 2-substituted 6-fluoro-2,3-dihydrospiro[4H-1-benzopyran-4,4'-imidazolidine]-2',5'-dio nes.

Optically active and racemic 2-substituted 6-fluoro-2,3-dihydrospiro[4H-1- benzopyran-4,4'-imidazolidine]-2',5'-diones were synthesized stereoselectively from (+)-, (-)-, and (+/-)-6-fluoro-3, 4-dihydro-4-oxo-2H-1-benzopyran-2-carboxylic acid [(+)-1, (-)-1, and (+/-)-1], respectively, for evaluation as new aldose reductase inhibitors. Among these compounds, the 2S,4S compounds were found to be more potent inhibitors of aldose reductase in vitro and in vivo than the corresponding 2R,4R enantiomers. The chloromethyl compound [(+)-5] showed highly potent activities in inhibiting cataract formation in the lenses and polyol accumulation in the sciatic nerve of rats.

Aldehyde Reductase↗

PubMed1999

Recent advances in the chemistry of cholecystokinin receptor ligands (agonists and antagonists).

During the last few years, cholecystokinin (CCK) has emerged as an important hormone. This polypeptide has been located either in peripheral tissues such as the gastro-intestinal tract and the pancreas as well as in the central nervous system. High affinity CCK receptors are divided in two main subtypes: the CCK-A (A for (A for "alimentary") and the CCK-B (B for "brain") receptors. The latters are currently associated with the gastrin receptors. Since CCK is involved in many different biological processes such as gut function, digestive processes, control of feeding behaviour and neurotransmitter release, the therapeutical potential of cholecystokinin receptor ligands seems to be extremely broad and promising. Several families of CCK receptor ligands (peptides, peptidomimetics, peptoids or non-peptides) were prepared during the last twenty years. The main goal of these researches was to improve agonistic or antagonistic potency but also to find selective compounds for a specific CCK receptor subtype. This review presents the recent developments (since 1995) in the chemistry of CCK receptor ligands.

Animals↗

PubMed1991

[Studies on the toxic constituents of Illicium simonsii Maxim].

A new sesquiterpenelactone compound was isolated along with the known anisatin and shikimic acid from pericarps of the fruit of Illicium simonsii Maxim., family Magnoliaceae, collected in Sichuan province. This new sesquiterpene lactone compound exhibited high toxicity in mice. The structure of which was elucidated as 2-oxo-6-deoxyneoanisatin (I) based on spectral evidences. The detailed physical and chemical data were presented.

Animals↗

PubMed1992

Characterization of antigastrin activity in vivo of CR 2194, a new R-4-benzamido-5-oxo-pentanoic acid derivative.

The antigastrinic activity, in vivo, of CR 2194 (R-4-(3-chlorobenzamido)-5-(8-azaspiro[4.5]decan-8-yl) -5-oxo pentanoic acid) was assessed in various animal species. CR 2194 antagonized pentagastrin-stimulated gastric acid secretion in the rat (ID50 = 11 mg/kg i.v.), dog (ID50 = 5.9 mk/kg i.v. or 28.8 mg/kg os) and cat (ID50 = 15.5 mg/kg i.v.). CR 2194, in the cat, inhibited both competitively and non-competitively the gastric acid secretion stimulated with increased doses of pentagastrin, with a pA2 of 4.89. In the rat and in the dog the antagonism seemed to be non-competitive and the respective pD'2 calculated were 4.54 and 4.42. The interaction of CR 2194 with the gastrin receptors appeared reversible, as demonstrated by the return to normal values of the acid output after the conclusion of the i.v. infusion, during pentagastrin continuous stimulation in the dog. The antigastrin activity was specific: CR 2194 was unable to antagonize the gastric acid secretion stimulated by carbachol or histamine in the rat up to the dose of 100 mg/kg. CR 2194 was effective to antagonize the gastric acid secretion stimulated by gastrin release after meal ingestion in the Heidenhain pouch dog model. The ID50 calculated was 2.89 mg/kg after oral administration. All these characteristics make CR 2194 an important compound in the investigation of the biological effects of gastrin and a potential agent for diagnostic or therapeutic use.

Animals↗

PubMed2003

Unique spirocyclopiperazinium salt I: synthesis and structure-activity relationship of spirocyclopiperazinium salts as analgesics.

Based on the structure of compound 3, two series of spirocyclopiperazinium derivatives 7a-n and 10a-h were synthesized and evaluated for their in vivo analgesic and sedative activities. Compounds 7f and 10c were discovered to exhibit excellent analgesic activity. Structure-activity relationships revealed that anion of the quaternary salt affected the analgesic and sedative activity significantly; the allyl group is a most effective group among the compounds 7a-n; the electron-released substitute on the aromatic ring is favorable to increase the analgesic activity.

Alkenes↗

PubMed2001

Three-dimensional quantitative structure-activity relationships of cyclo-oxygenase-2 (COX-2) inhibitors: a comparative molecular field analysis.

The three-dimensional quantitative structure-activity relationship (3D-QSAR) approach using comparative molecular field analysis (CoMFA) was applied to an extensive series of 305 varied diarylheterocyclic derivatives known as COX-2 selective inhibitors. X-ray crystal structure of COX-2 bound with SC-558, a selective COX-2 inhibitor, was used to derive the putative bioactive conformation of these inhibitors. Five statistically significant models were obtained from the randomly constituted training sets (229 compounds) and subsequently validated with the corresponding test sets (76 compounds). The best predictive model (n = 229, q(2) = 0.714, N = 8, r(2) = 0.905, s = 0.291, F = 261.545) was selected for further comparison of the CoMFA contour maps obtained for steric, electrostatic, and lipophilic fields with the enzyme structure. The high level of compatibility with the COX-2 enzyme topology shows the great accuracy of this model that can predict inhibitory activities for a wide range of compounds and offers important structural insight into designing novel antiinflammatory drugs prior to their synthesis.

Benzene Derivatives↗

PubMed2006

Cytotoxic diacetylenic spiroketal enol ethers from Plagius flosculosus.

Three new diacetylenic spiroketal enol ethers named flosculins A (1), B (2), and C (3), along with five known compounds (4-8) of the same structural class, were isolated from the leaves of Plagius flosculosus. The structures were deduced by extensive 1D and 2D NMR spectroscopy and mass spectrometry. All isolated compounds exhibited significant cytotoxic activity against leukemia cells (Jurkat T and HL-60). Compounds 5-8 induced apoptosis in HL-60 cells with corresponding IC(50) values ranging from 4 to 6 microM.

Antineoplastic Agents, Phytogenic↗

PubMed1998

Novel bioactive oxazolomycin isomers produced by Streptomyces albus JA3453.

Two novel oxazolomycin isomers, oxazolomycins B (2) and C (3), were isolated from the fermentation broth of an oxazolomycin-producing strain, Streptomyces albus JA3453. Both compounds are geometrical isomers of oxazolomycin (1), the configurations of their triene moieties being (4'E, 6'E, 8'E) (2) and (4'Z, 6'E, 8'E) (3) while that of oxazolomycin (1) is (4'Z, 6'Z, 8'E). Compounds 2 and 3 exhibited potent inhibitory activity against crown gall formation with the same MIC (0.8 microgram/disk) as oxazolomycin. Compounds 2 and 3 showed no antibacterial activity against Agrobacterium tumefaciens, in contrast to oxazolomycin which has specific anti-A. tumefaciens activity.

Anti-Bacterial Agents↗

PubMed1993

[Studies on the chemical constituents of Croomia japonica Miq].

A new steroid alkaloid, namely croomionidine (II), together with four known compounds pachysamine A(I), croomine (III), didehydrocroomine (IV) and beta-sitosterol were isolated from the roots of Croomia japonica Miq. Their structures were identified by IR, MS, 1H NMR, 13C NMR and chemical conversion.

Drugs, Chinese Herbal↗

PubMed2004

5-HT1B receptors, alpha2A/2C- and, to a lesser extent, alpha1-adrenoceptors mediate the external carotid vasoconstriction to ergotamine in vagosympathectomised dogs.

It has previously been suggested that ergotamine produces external carotid vasoconstriction in vagosympathectomised dogs via 5-HT1B/1D receptors and alpha2-adrenoceptors. The present study has reanalysed this suggestion by using more selective antagonists alone and in combination. Fifty-two anaesthetised dogs were prepared for ultrasonic measurements of external carotid blood flow. The animals were divided into thirteen groups (n=4 each) receiving an i.v. bolus injection of, either physiological saline (0.3 ml/kg; control), or the antagonists SB224289 (300 microg/kg; 5-HT1B), BRL15572 (300 microg/kg; 5-HT1D), rauwolscine (300 microg/kg; alpha2), SB224289 + BRL15572 (300 microg/kg each), SB224289 + rauwolscine (300 microg/kg each), BRL15572 + rauwolscine (300 microg/kg each), rauwolscine (300 microg/kg) + prazosin (100 microg/kg; alpha1), SB224289 (300 microg/kg) + prazosin (100 microg/kg), SB224289 (300 microg/kg) + rauwolscine (300 microg/kg) + prazosin (100 microg/kg), SB224289 (300 microg/kg) + prazosin (100 microg/kg) + BRL44408 (1,000 microg/kg; alpha2A), SB224289 (300 microg/kg) + prazosin (100 microg/kg)+ imiloxan (1,000 microg/kg; alpha2B), or SB224289 (300 microg/kg) + prazosin (100 microg/kg) + MK912 (300 microg/kg; alpha2C). Each group received consecutive 1-min intracarotid infusions of ergotamine (0.56, 1, 1.8, 3.1, 5.6, 10 and 18 microg/min), following a cumulative schedule. In saline-pretreated animals, ergotamine induced dose-dependent decreases in external carotid blood flow without affecting arterial blood pressure or heart rate. These control responses were: unaffected by SB224289, BRL15572, rauwolscine or the combinations of SB224289 + BRL15572, BRL15572 + rauwolscine, rauwolscine + prazosin, SB224289 + prazosin, or SB224289 + prazosin + imiloxan; slightly blocked by SB224289 + rauwolscine; and markedly blocked by SB224289 + rauwolscine + prazosin, SB224289 + prazosin + BRL44408 or SB224289 + prazosin + MK912. Thus, the cranio-selective vasoconstriction elicited by ergotamine in dogs is predominantly mediated by 5-HT1B receptors as well as alpha2A/2C-adrenoceptor subtypes and, to a lesser extent, by alpha1-adrenoceptors.

Animals↗

PubMed1996

Characterisation of antimitotic products from marine organisms that disorganise the microtubule network: ecteinascidin 743, isohomohalichondrin-B and LL-15.

The effect of selected marine compounds with anti-tumoral activity on the cell microtubule network was tested by immunofluorescence analyses, or by other in vitro analyses involving competition with colchicine or with GTP for tubulin binding and tubulin polymerisation, studies that were carried out in parallel with other microtubule poisons used as controls. Three compounds were found to disorganise the microtubule network: isohomohalichondrin B, LL-15 and ecsteinascidin 743. The first two compounds prevent microtubule assembly and GTP binding to tubulin. Ecteinascidin 743 disorganises the microtubule network but it does not seem to interact directly with tubulin.

Actin Cytoskeleton↗

PubMed2004

Spirobicyclo[2.2.2]octane derivatives: mimetics of baccatin III and paclitaxel (Taxol).

The formylated spirobyclic alcohol was computer modeled to be a mimetic of paclitaxel. In this model, the formyl group was used as a truncated paclitaxel side chain in order to reduce the computational work. Compound , carrying the paclitaxel side chain, was synthesized in six steps from optically active 1,3-diketone . Microtubule stabilization was not observed for , indicating that the model needs to be adjusted.

Alkaloids↗

PubMed1978

Dopamine antagonistic effects of a series of analogues of oxiperomide and spiroxatrine measured behaviourally in the rodent.

The activity spectra of oxiperomide, spiroxatrine and analogues were determined in two experimental models of abnormal peri-oral movements (induced by intrastriatal dopamine and subcutaneously administered 2-(NN-dipropyl)amino-5,6-dihydroxy-1,2,3,4-tetrahydronaphthalene (NN-diPr-5,6-diOHATN) in the guinea-pig), and in a stereotypy test (induced by subcutaneous apomorphine in the guinea-pig); the ability of the test compounds to induce catalepsy or catatonia in the rat was also determined. The parent compounds oxiperomide and spiroxatrine possessed optimal activity in all tests, although responses to the series of compounds allowed clear differentiation between an ability to antagonize the peri-oral movements (dopamine- or NN-di Pr-5,6-diOHATN induced) and an ability to antagonize apomorphine stereotypy. However, all compounds that antagonized the abnormal peri-oral movements also caused catalepsy/catatonia. The results are considered in terms of the selection of suitable agent(s) for the treatment of peri-oral dyskinesias.

Animals↗

PubMedDate not supplied

2-(2-Aminoethyl)-quinoline (D-1997): a novel agonist at 5-hydroxytryptamine1-like receptors in the canine basilar artery.

This study aimed to investigate the mechanisms involved in the contractile effects produced by the novel quinoline derivative, 2-(2-aminoethyl)-quinoline (D-1997), in the canine isolated basilar artery. For comparison, the effects of D-1997 were also evaluated on rat aorta. Canine basilar artery and rat aortic rings were prepared and mounted in organ baths to record isometric tension changes. The contractile effects of D-1997 in the basilar artery were compared with those produced by 5-hydroxytryptamine (5-HT) and the 5-HT receptor agonist quipazine. Thus, 4-HT (10(-10)-10(-6)M), D-1997 (3.1 x 10(-8)-10(-4) M) and quipazine (3.1 x 10(-7)-10(-4) M) each caused concentration-dependent contractions of the canine basilar artery with a rank order of agonist potency of 5-HT > D-1997 > quipazine. 5-HT and D-1997 exhibited similar maximum effects which were higher than that of quipazine. Similar concentrations of D-1997 failed to produce contraction in rat aorta. The effects of D-1997 in the basilar artery were not modified by incubation with either the 5-HT2 receptor antagonist ketanserin (0.01-1 microM), the 5-HT3 and 5-HT4 receptor antagonist ICS205930 (tropisetron; 0.1-10 microM), the 5-HT1A receptor antagonist spiroxatrine (0.01-1 microM), the beta-adrenoceptor blocker with high affinity for 5-HT1A and 5-HT1B binding sites (+/-)-pindolol (0.01-1 microM), or the alpha 1-adrenoceptor antagonist prazosin (0.01-1 microM). In contrast, the D-1997-induced responses were potently and concentration-dependently antagonized by the mixed 5-HT1-like and 5-HT2 receptor antagonist methiothepin (0.01-1 microM). It is concluded that D-1997 contracts the canine basilar artery by stimulating 5-HT1-like receptors unrelated to either the 5-HT1A or 5-HT1B receptor subtypes. The compound seems to be devoid of 5-HT2 receptor agonist properties in rat aorta.

Animals↗