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PubMed1976

Products from furans. 1. Sunthesis and anticoccidial and antimicrobial activity of 5-amino-5,6-dihydro-6-methoxy-2-methyl-2-(4'-biphenylyl)-2H-pyran-3(4H)-ones and related compounds.

A Michael type addition of an amine to 6-methoxy-2-methyl-2-(4'-biphenylyl)-2H-pyran-3(6H)-one (1) dissolved in ether, benzene, or THF gave 5-amino derivatives of 5,6-dihydro-6-methoxy-2-methyl-2-(4'-biphenylyl)-2H-pyran-3(4H)-one (2). These by subsequent reduction with LiAlH4 were converted to 5-amino derivatives of 6-methoxy-2-methyl-2-(4'-biphenylyl)tetrahydro-2H-pyran-3-ol (3). Both isomers A and B of 1 (in regard to the methoxy group at C6) were used for the synthesis of 2 and 3. The in vitro antimicrobial activity of the amine adducts 2 was of the same order of magnitude as the starting material. Amine adducts in general, however, were by far more active as coccidiostats than the starting material and retained their activities when they were reduced. 5,6-Dihydro-6-methoxy-2-methyl-2-(4'-biphenylyl)-5-(dimethylamino)-2H-pyran-3(4H)-one hydrochloride (A) and 5,6-dihydro-6-methoxy-2-methyl-2-(4'-biphenylyl)-5-(dimethylamino)-2H-pyran-3(4H)-one hydrochloride (B), prepared from isomer A and B of 1, respectively, were the most active as coccidiostats. These compounds when administered orally to chickens 1 day prior to infection at a concentration 0.05% in their diet gave them total protection against Eimeria tenella.

Anti-Bacterial Agents↗
PubMed2005

Synthesis of epoxyquinol A and related molecules: probing chemical reactivity of epoxyquinol dimers and 2H-pyran precursors.

Total syntheses of the epoxyquinoid dimers, epoxyquinols A, B, and epoxytwinol A (RKB-3564 D), have been accomplished employing [4 + 2] and [4 + 4] dimerization of 2H-pyran epoxyquinol monomers. Modifications of 2H-pyran precursors have been explored, including alteration of epoxy alcohol and diene stereochemistry. A stable 2H-pyran prepared by alteration of the epoxyquinol 2H-pyran nucleus was evaluated as a diene in Diels-Alder cycloaddition with reactive dienophiles. Extensive studies for improving the [4 + 4] dimerization of selectively protected 2H-pyran monomers to afford the novel epoxyquinoid dimer epoxytwinol A were carried out, and valuable insight regarding competitive [4 + 2] and [4 + 4] dimerization processes has been obtained. In addition, chemical reactivities and structural modifications of epoxyquinol dimers have been evaluated, including [2 + 2] photocycloaddition and [3,3] sigmatropic rearrangement, indicating the possibility for production of novel structural diversity from dimeric epoxyquinoid natural product frameworks.

Alcohols↗
PubMed1976

Enhancement of a tumor allograft in BALB/c x DBA/2 F1 mice by pyran copolymer.

Pyran copolymer (NSC 46015) was evaluated with respect to its effect on the rejection of a murine leukemic allograft by BALB/c x DBA/2 F1 (CD2F1) mice. Significant prolongation of allograft survival with production of progressively growing lethal tumors was found following pyran administration. This phenomenon occurred at nontoxic doses of the drug and appeared to be closely related to the timing of pyran injection. Nonspecifically stimulated lymphocyte blast transformation by concanavalin A was not impaired by pyran when lymphocytes were exposed in vitro to the drug. The mechanism of tumor allograft enhancement remains obscure but may be related to allograft size at the time of pyran administration.

Animals↗
PubMed1984

Mobilization of canine hemopoietic stem cells by pyran copolymer (NSC 46015).

Pyran copolymer (NSC 46015), a divinyl ether maleic anhydride of broad spectrum molecular weight, was infused into six normal mongrel dogs. The effect on canine blood and bone marrow colony forming units in culture (CFU-C) was followed over an 11-day period. Significant elevation of circulating CFU-c was noted 2 days after pyran infusion; normalization occurred by day 7 postinfusion. Bone marrow CFU-C were decreased 2 days and 5 days after pyran administration. A further increase in circulating CFU-C was noted when pyran was administered twice, 5 days apart. The mobilizing effect of pyran copolymer appears promising enough to warrant further exploration of blood as a source of hemopoietic stem cells for transplantation purposes.

Animals↗
PubMed1992

Synthesis and antimicrobial properties of 2H-pyran-3(6H)-one derivatives and related compounds.

The synthesis of several derivatives of 2H-pyran-3(6H)-ones and their Michael adducts is described. Phenylthio, benzenesulfonyl, p-acetylaminobenzenesulfonyl, and p-bromophenyl substituents are beneficial for activity against gram-positive bacteria. 2-[4-(Phenylthio)phenyl]-2-methyl-6-methoxy-2H-pyran-3(6H)-one (8a) showed a minimum inhibitory concentration of 1.56 micrograms/mL against Staphylococcus aureus ATCC 2593, and 2-[4-(phenylthio)phenyl]-2-methyl-6-[(p-nitrobenzoyl)oxy]-2H-pyran-3 (6H)-one (9) showed a minimum inhibitory concentration of 0.75 microgram/mL against Streptococcus sp. C203M. In general, derivatives of 6-hydroxy-2H-pyran-3(6H)-ones with substituents at C-2 and C-6 showed significant activity against gram-positive bacteria. More specifically, the bulkier the C-2 substituent, the greater the antibacterial activity. Michael adducts of thiols (13) showed activity, which may be due to a retro-Michael reaction. In conclusion, the alpha,beta-enone system is essential for the activity of 6-hydroxy-2H-pyran-3(6H)-ones, and the size and nature of substituents at C-2 are associated with antimicrobial activity.

Anti-Bacterial Agents↗
PubMed2003

Computational and experimental investigation of the Diels-Alder cycloadditions of 4-chloro-2(H)-pyran-2-one.

4-Chloro-2(H)-pyran-2-one undergoes thermal Diels-Alder cycloaddition with electron-deficient dienophiles to afford, without any significant selectivity, 6-endo- and 5-endo-substituted bicyclic lactone cycloadducts. In contrast to 3- and 5-bromo-2(H)-pyran-2-one, 4-chloro-2(H)-pyran-2-one does not undergo thermal cycloadditions with electron-rich dienophiles. The regio- and stereochemical preferences of the cycloadditions of 4-chloro-2(H)-pyran-2-one and other related 2(H)-pyran-2-ones are investigated computationally. Calculations were carried out on the transition states leading to the four possible regio- and stereoisomeric cycloadducts using density functional theory (B3LYP/6-31G). These studies allow prediction of the regio- and stereoselectivity in these reactions which are in line with experimental observations.

Journal Article↗
PubMed2005

An experimental and computational investigation of the Diels-Alder cycloadditions of halogen-substituted 2(H)-pyran-2-ones.

[reaction: see text] Diels-Alder reactions of 3- and 5-halo-subsituted 2(H)-pyran-2-ones with both electron-rich and electron-deficient dienophiles afford stable and readily isolable bridged bicyclic lactone cycloadducts. These cycloadditions proceed with excellent regioselectivity and very good stereoselectivity. In contrast, Diels-Alder reactions of 4-halo-subsituted 2(H)-pyran-2-ones afford cycloadducts which are very prone to loss of bridging CO(2) and the subsequent formation of barrelenes ([2.2.2]cyclooctenes). Furthermore, these cycloadditions proceed with only moderate regio- and stereoselectivity. For both series of the 3- and 5-halo-subsituted 2(H)-pyran-2-ones and 4-halo-subsituted 2(H)-pyran-2-ones, the reactivity patterns do not significantly change between the halogens. The regio- and stereochemical preferences of the cycloadditions of halo-substituted 2(H)-pyran-2-ones are investigated computationally. Calculations were carried out on the transition states leading to the four possible regio- and stereoisomeric cycloadducts by using density functional theory (B3LYP/6-31G). These studies allow prediction of the regio- and stereoselectivity in these reactions which are broadly in line with experimental observations.

Journal Article↗
PubMed2003

Facile one-pot synthesis of photochromic pyrans.

[reaction: see text]. Photochromic pyrans, including [3H]naphtho[2,1-b]pyrans, [2H]naphtho[1,2-b]pyrans, indeno-fused naphtho[1,2-b]pyrans, and heteroannulated pyrans, were synthesized in excellent yields through a facile one-pot procedure by reaction of propargyl alcohol and naphthol or phenol derivatives in the presence of 5 mol % PPTS and 2 equiv of (MeO)3CH. Symmetrical and nonsymmetrical bispyrans can also be prepared using the protocol.

Journal Article↗
PubMed2002

Mechanism of biochemical action of substituted 4-methylbenzopyran-2-ones. Part 9: comparison of acetoxy 4-methylcoumarins and other polyphenolic acetates reveal the specificity to acetoxy drug: protein transacetylase for pyran carbonyl group in proximity to the oxygen heteroatom.

The evidences for the possible enzymatic transfer of acetyl groups (catalyzed by a transacetylase localized in microsomes) from an acetylated compound (acetoxy-4-methylcoumarins) to enzyme proteins leading to profound modulation of their catalytic activities was cited in our earlier publications in this series. The investigations on the specificity for transacetylase (TA) with respect to the number and positions of acetoxy groups on the benzenoid ring of coumarin molecule revealed that acetoxy groups in proximity to the oxygen heteroatom (at C-7 and C-8 positions) demonstrate a high degree of specificity to TA. These studies were extended to the action of TA on acetates of other polyphenols, such as flavonoids and catechin with a view to establish the importance of pyran carbonyl group for the catalytic activity. The absolute requirement of the carbonyl group in the pyran ring of the substrate for TA to function was established by the observation that TA activity was hardly discernible when catechin pentacetate and 7-acetoxy-3,4-dihydro-2,2-dimethylbenzopyran (both lacking pyran ring carbonyl group) were used as the substrates. Further, the TA activity with flavonoid acetates was remarkably lower than that with acetoxycoumarins, thus suggesting the specificity for pyran carbonyl group in proximity to the oxygen heteroatom. The biochemical properties of flavonoid acetates, such as irreversible activation of NADPH cytochrome C reductase and microsome-catalyzed aflatoxin B(1) binding to DNA in vitro were found to be in tune with their specificity to TA.

Acetates↗
PubMed1979

Effect of pyran on latency after herpes simplex virus infections.

The immunomodulator pyran protected mice against both herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) infections. In infections of the lip with HSV-1, prophylactic administration of pyran reduced the severity of the herpetic lesions and enhanced their resolution, but did not decrease the high incidence of development of latent HSV-1 infection of the trigeminal ganglia. In vaginal infections with HSV-2, prophylactic administration of pyran either systemically or locally reduced mortality, reduced the incidence of mice with vaginal HSV-2 infection, and did not alter the low incidence of latent infection of the spinal dorsal root ganglia. Pyran treatment before systemic herpetic infection after intravenous inoculation of HSV-2 also reduced mortality and virus replication, as evidenced by a decreased antibody response in the survivors, and it either reduced latent infection in the spinal dorsal root ganglia or did not predispose mice to latent infection. Treatment with the immunomodulator appeared to inhibit or reduce HSV infection early in viral pathogenesis in all three model systems, producing protection from clinical disease and resulting in less virus to induce a systemic antibody response, with either a reduction in latent virus infection or no enhancement of development of latency. In all of the HSV models, the development of latent herpetic infection was closely correlated with sufficient virus replication early in the infection to induce a systemic neutralizing-antibody response.

Animals↗
PubMed1980

Inhibition of purified wheat germ DNA dependent RNA polymerase by pyran copolymer.

The inhibition of DNA and RNA polymerases in vitro by pyran copolymer has been shown to be related to its affinity for divalent cations. The present investigation was designed to explore further the nature of this inhibition using completely purified eukaryotic RNA polymerase II from wheat germ. Inhibition was determined as a function of divalent ion concentration and, as previously seen with less pure enzyme preparation, was greatest at low (Mn2+) and least at higher concentrations. No inhibition was observed at concentrations greater than 4.8 mM MgCl2 in the presence of 10 micrograms pyran/mL. The inhibition by pyran copolymer was exerted immediately unlike other polyanions, such as heparin and polynucleotides. This indicates that it stops RNA chain growth immediately as do known chelators of divalent cations. The size of pyran copolymer was shown to affect the extent of inhibition when different sized polymers were fractionated from a heterogenous single lot. However, when sized fractions were obtained from different lots we could not show a size-dependent inhibition. Although the mechanisms by which pyran copolymer exerts its biological effect is unknown, it may well be related to its association with cations. The inhibition of enzymes requiring these cations appears to be a sensitive method of observing such an association.

DNA-Directed RNA Polymerases↗
PubMed1975

Tumor suppression by pyran copolymer: correlation with production of cytotoxic macrophages.

Intraperitoneal administration of pyran copolymer (pyran-2-succinic anhydride-4,5-dicarboxytetrahydro-6-methylanhydride polymer) protected C3H/HeN male mice against tumor development after intradermal challenge with cells of the transplantable, methylcholanthrene-induced, syngeneic fibrosarcoma 1038. Peritoneal cells from pyran-treated but not from normal animals suppressed tumor development in local passive-transfer experiments. Adherent peritoneal cells from pyran-treated mice were cytotoxic in vitro to several syngeneic murine tumor cell lines including 1038.

Animals↗
PubMed1975

Inhibition and enhancement of Friend leukemia virus by pyran copolymer.

Inhibition or enhancement of Friend leukemia virus disease could be produced by treatment of mice with the immunopotentiator, pyran copolymer. The result depended on the route of inoculation of the drug. Prophylactic administration of the drug i.p. retarded splenomegaly, reduced splenic foci, and increased survival time of mice infected with Friend leukemia virus. Conversely, when the same dose and regimen of pyran was administered i.v., splenomegaly was enhanced, splenic foci were increased, and survival time was decreased. Histopathological examination of the spleens of mice revealed that i.p. pyran administration caused a marked increase in the splenic marginal zone with some increase in erythropoiesis in the red pulp, while i.v. pyran administration did not markedly change the splenic marginal zone but caused an early and sustained increase in erythropoiesis in the red pulp.

Animals↗
PubMed1981

The interaction of histone H1 with pyran co-polymer.

Complexes formed by the interaction of histone H1 and the immunomodulator Pyran co-polymer, were evaluated using nephelometric titration. At a constant concentration of histone (10 microgram/ml), maximum turbidity was obtained at a Pyran concentration of 2 microgram/ml. Titration of H1 by Pyran was found to be sensitive to ionic strength. Concentration of Na+ greater than 200 mM or Mg+2 greater than 3 mM apparently blocked Pyran . H1 complex formation.

Chemical Phenomena↗
PubMed1995

Nonpeptidic potent HIV-1 protease inhibitors: (4-hydroxy-6-phenyl-2-oxo-2H- pyran-3-yl)thiomethanes that span P1-P2' subsites in a unique mode of active site binding.

Using molecular modeling and the information derived from the X-ray crystal structure of HIV-1 protease (HIV PR) complexed with the pyran-2-one 1, a series of (4-hydroxy-6-phenyl-2-oxo-2H-pyran-3-yl)thiomethanes was designed and analyzed as novel, nonpeptidic inhibitors of HIV PR. Structure-activity studies led to the discovery of inhibitor 19 having (RS)-1-(cyclopentylthio)-3-methylbutyl functionalization at the C-3 position, which exhibited a Kc of 33 nM. A X-ray crystallographic structure of 19 bound to HIV PR showed that structural water-301 (inhibitor-flap-bridging water) was displaced by the inhibitor. Interestingly, the enol moiety of the pyran-2-one formed a hydrogen bond directly with Asp125 and with Asp25 via a bridging water molecule, thus illustrating a unique mode of active site binding by an HIV PR inhibitor. The pendant cyclopentyl and isobutyl groups of 19 occupied the S1' and S2' binding sites, respectively, whereas the 6-phenyl group occupied a region in between the S1 and S3 pockets of HIV PR. Selected compounds were tested for antiviral activity on H9 cells infected with HIV-1IIIb. A correlation between enzymatic activity and antiviral activity was not found in this series. The best antiviral compound in this series, 18, contained (RS)-3-[cyclopentyl(cyclopentylthio)methyl] functionalization at the C-3 position of the pyran-2-one ring and exhibited a CIC50 of 14 microM and TC50 of 70 microM. These studies demonstrate that potent enzyme inhibition can be achieved by inhibitors that span only three subsites.

Amino Acid Sequence↗
PubMed2004

Synthesis and evaluation of anticonvulsant and antimicrobial activities of 3-hydroxy-6-methyl-2-substituted 4h-pyran-4-one derivatives.

In this study, thirteen 3-hydroxy-6-methyl-2-substituted 4H-pyran-4-one derivatives were synthesized for the evaluation of their potential anticonvulsant activity. Mannich bases were prepared by the reaction of substituted piperazine derivatives with allomaltol and formaline. The structures of the synthesized compounds were confirmed by IR, (1)H-NMR and elemental analysis. Their anticonvulsant activities were determined in vivo by maximal electroshock (MES), sub-cutaneous Metrazol (scMet), and rotorod toxicity tests for neurological deficits. The antimicrobial activities of the synthesized compounds were investigated in vitro against some bacteria and fungi using the microdilution broth method. Ac-cording to the activity studies, 3-hydroxy-6-methyl-2-[4-(2-trifluoromethyl-phenyl)-piperazin-1-ylmethyl]-4H-pyran-4-one (3i) was the compound determined to be most active in the scMet test for all doses at four hours and for the 300 mg/kg dose at half an hour. 2-[4-(4-Chloro-phenyl)-piperazin-1-ylmethyl]-3-hydroxy-6-methyl-4H-pyran-4-one (3f) was found to be protective against MES whereas 2-chlorophenyl derivative (3e) was not. Looking at the antifungal activity results, compounds 3b, 3h, and 3i were determined to have activity against all fungi.

Animals↗
PubMed1980

Macrophage activation and mobilization in nude mice by Corynebacterium parvum and pyran: a functional and histologic study.

Peritoneal macrophages from both congenitally athymic ("nude") mice and heterozygous littermates were activated by pyran copolymer or by Corynebacterium parvum vaccine. C parvum did not produce an increase in the number of peritoneal macrophages in nude mice, although it did produce a typical splenomegaly. Pyran produced an even greater influx of macrophages in the peritoneum of nude mice, when compared to normal mice, but did not produce splenomegaly in nude mice. Pyran- and C parvum-induced splenomegaly were accompanied by an increase in the apparent T-cell population of germinal centers. These experiments indicate that: 1) Macrophage activation, per se, by either C parvum, is a thymus-independent event; 2) Macrophage mobilization, as determined by organomegaly or PEC number, does not have an obligatory requirement for T-cells (depending on the agent used); 3) Macrophage activation may not always correlate with mobilization; and 4) Mechanisms for attracting and sequestering macrophages in the peritoneum may be different from those of the spleen.

Animals↗
PubMed2006

Genetic toxicity testing of 3-methyl-2H-furo[2,3-c]pyran-2-one, an important biologically active compound from plant-derived smoke.

Aerosol smoke, aqueous smoke solutions and 3-methyl-2H-furo[2,3-c]pyran-2-one isolated from plant-derived smoke stimulate seed germination and enhance seedling vigour of many species. Consequently, smoke technology has important potential applications in agriculture, horticulture and other environmental sectors. However, use of 3-methyl-2H-furo[2,3-c]pyran-2-one as a germination promoter and/or growth stimulant is only possible provided it can be shown that it is not hazardous, i.e. not toxic or genotoxic. We therefore performed an investigation to evaluate the genotoxic effects of this compound in five strains of Salmonella typhimurium in the Ames test (1.5microg/plate to 7.5ng/plate), and in the VITOTOX test (1500-0.045ppb). In all tests performed, no mutagenic activity was induced by 3-methyl-2H-furo[2,3-c]pyran-2-one, with or without S9 metabolic activation. Due to the potential wide use of this smoke-derived compound, it is of importance that no toxic and genotoxic effects were observed at the concentrations tested.

Dose-Response Relationship, Drug↗