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PubMed2000

Studies on the 1,1-diphenyl-2-picrylhydrazyl radical scavenging mechanism for a 2-pyrone compound.

The radical scavenging mechanisms for the 2-pyrone compound, 4-hydroxy-3,6-dimethyl-2H-pyrane-2-one (1), and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (4) in several solvent systems were evaluated by the quantitative change in compounds detected at 270 nm and subsequent HPLC analyses. The HPLC profile for each condition suggested that the reaction proceeded by a different mechanism in each solvent system. In organic solvents (CHCl3, iso-propanol, and EtOH), 1-[4-(3,4-dihydro-3,6-dimethyl-2,4-dioxo-2H-pyran-3-yl) phenyl]-1-phenyl-2-picrylhydrazine (2) was produced as an adduct of the DPPH radical and 1. On the other hand, the reaction in a buffer solution (an acetate buffer at pH 5.5) gave several degradation products with 1[4-(2,3-dihydro-2,5-dimethyl-3-oxo-fur-2-yl) phenyl]-1-phenyl-2-picrylhydrazine (5), this being structurally elucidated by spectroscopic analyses. The decrease of the DPPH radical in each reaction system suggests that compound 1 could scavenge about 1.5-1.8 equivalents of the radical in organic solvents and about 3.5-3.9 in the buffer solution.

Bepridil↗
PubMed1989

Effect of Cu2+ and Zn2+ on the inhibition of human leucocyte elastase by 6-alkyl-3-(omega-carboxyalkyl)-2-pyrone, oleic acid and sulindac sulfide.

Inhibition of human leucocyte elastase by oleic acid and the structurally related 3-(1'-oxo-7'-carboxyheptyl)-4-hydroxy-6-octyl-2-pyrone is considerably enhanced by the addition of Cu2+, Zn2+ and, to a lesser extent, Co2+ and Ca2+. Sulindac sulfide and diflunisal also respond to changes in copper concentration, while Boc-Ala-Pro-Val-NH[CH2]10CO2H does not. Binding of the -CO2H group in the vicinity of the S5 subsite is proposed for all but the last compound to account for this effect. Incubation experiments indicate that Cu2+ binds more rapidly to the enzyme than does the inhibitor. Local changes in conformation result in improved binding of the inhibitor, but do not affect the substrate (Km unchanged). Chelation by EDTA is time-dependent, indicating that the Cu2+ is shielded by the inhibitor. The results may partially explain the well-known anti-arthritic and anti-inflammatory properties of copper and zinc and their organic salts.

Copper↗
PubMedDate not supplied

Pyrone glycosides from Acosmium panamense (Benth.) Yacovlev.

Besides caffeic acid three pyrones have been isolated from aquous bark extracts from Acosmium panamense and their structures were determined using spectroscopical methods. Besides the already described desmethylyangonine its O4'-mono as well as the di(1-6)glucoside are found the first time.

Fabaceae↗
PubMed1998

Tricyclic pyrone analogs: a new class of microtubule-disrupting anticancer drugs effective against murine leukemia cells in vitro.

Novel 1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano [4,3-b][1]benzopyrans were synthesized in Hua's laboratory (code names H5, H10, H14 and H15) and tested for their ability to prevent L1210 leukemic cells from synthesizing macromolecules and growing in vitro. The aryl groups of these tricyclic pyrone (TP) analogs are either 3, 4-dimethoxyphenyl in H5 and H15 or 3-pyridyl in H10 and H14. Since 50 M H5 and H10 both inhibit DNA synthesis and tumor cell growth by 79-100%, concentrations 25 M were used in this study to assess the structure-activity relationships for this class of compounds. At 10-25 M, H5 and H14 are more potent inhibitors of DNA, RNA and protein synthesis than H10. In contrast, at 5-25 M, H10 is much more effective than H5 and H14 at inhibiting the growth of L1210 cells over a 4-day period. Interestingly, H15 inhibits DNA synthesis as much as H10 but fails to alter tumor cell growth. This discrepancy between the ability of TPs to inhibit macromolecule synthesis and leukemic cell growth suggests that other molecular targets may be involved in the antitumor action of these drugs. Their short-term inhibition of nucleic acid synthesis is reversible following drug removal but their long-term inhibition of tumor cell growth is not. Moreover, 25 M H5 and H10 are not cytotoxic at 2 days but equally decrease cell viability at 4 days, suggesting that the potent and irreversible inhibition of cell proliferation observed 1-4 days after H10 treatment is not solely caused by drug cytotoxicity. The effectiveness of H10 as inhibitor of L1210 cell growth is comparable to that of a spectrum of representative anticancer drugs. A critical finding is that 5 M H10 blocks the polymerization of purified tubulin by 90% and, therefore, may be a novel microtubule de-stabilizing drug. Indeed, H10 inhibits tubulin polymerization and L1210 cell growth as much as 5 M of vincristine (VCR). In contrast, 5 M H5 alters neither tubulin polymerization nor tumor cell growth. The ability of H10 to disrupt microtubule dynamics indirectly suggests that TPs may be novel cell cycle-specific anticancer drugs useful for arresting mammalian cells in mitosis.

Animals↗
PubMed1999

Tricyclic pyrone analogs: a new synthetic class of bifunctional anticancer drugs that inhibit nucleoside transport, microtubule assembly, the viability of leukemic cells in vitro and the growth of solid tumors in vivo.

Tricyclic pyrones (TPs) may represent a novel synthetic class of microtubule (MT) de-stabilizing anticancer drugs previously shown by us to inhibit macromolecule synthesis, tubulin polymerization, and the proliferation of leukemic and mammary tumor cells in vitro. A linear skeleton with a N-containing aromatic ring attached at C3 of the top A-ring, a central pyran B-ring and a six-membered bottom C-ring with no alkylation at C7 are required for the antitumor activities of the lead compounds, a 3-pyridyl benzopyran (code name H10) and its somewhat weaker 2-pyridyl regioisomer (code name H19). Increasing concentrations of H10 do not alter the binding of [3H]vinblastine and [3H]GTP to tubulin but mimic the ability of unlabeled colchicine (CLC) to reduce the amount of [3H]CLC bound to tubulin, suggesting that TPs may interact with the CLC binding site to inhibit tubulin polymerization. Exogenous Mg2+ cations absolutely required for the binding of GTP to tubulin and MT assembly cannot overcome the antitubulin action of H10. H10 reduces the viability of L1210 cells in vitro (IC50: 0.5 microM) but its antitumor activity may be related to its ability to inhibit tubulin polymerization and rapidly increase the mitotic index rather than to induce DNA cleavage and apoptosis. The anticancer potential of TPs in vivo is demonstrated by the fact that i.p. injections of the water-soluble H10-HCl decrease the growth of solid tumors in mice inoculated s.c. with Lewis lung carcinoma. A critical finding is that the antimitotic H10 is a bifunctional anticancer drug, which also blocks the cellular transport of nucleosides (IC50: 6 microM) to inhibit DNA synthesis. Since few CLC site-binding antimitotic agents are active in solid tumor models in vivo, the ability of these new MT destabilizing TPs to totally block nucleoside transport might be valuable in polychemotherapy to arrest tumor cells at several phases of their cycle, potentiate the action of antimetabolites and sensitize multidrug-resistant tumor cells.

Animals↗
PubMed2003

[The isolation and identification of a new alpha-pyrone from Opuntia dillenii].

AIM: To study the chemical composition of Opuntia dillenii Haw. METHODS: Many kinds of chromatography methods were used to separate the chemical constituents. Their structures were determined by NMR and MS spectral analysis. RESULTS: A new compound, together with five known compounds, were isolated from the 80% ethanolic extract of the stems. CONCLUSION: The new compound was identified as 4-ethoxyl-6-hydroxymethyl-alpha-pyrone. Compounds 1, 3, 4 and 5 were obtained for the first time from the genus of Opuntia, and they were: 3-O-methyl isorhamnein, 1-heptanecanol, vanillic acid, isorhamnetin-3-O-beta-D-rutinoside. Ruin was isolated from this plant for the first time.

Molecular Structure↗
PubMedDate not supplied

[Pharmacological and radioprotective properties of some gamma-pyrone derivatives (flavanones and flavanols)].

In experiments set up on mice, rats and guinea pigs 8 gamma-pyron derivatives were studied. They proved to be little toxic, do not change significantly the arterial pressure and respiration, exercise a depressing action on the central nervous system, produce a marked antiphlogistic (normal and irradiated animals), radio-protective and antihistaminic effects and influence norephinephrine, homovanillic acid and dopamine metabolism in the brain.

Animals↗
PubMed1986

Benzo-pyrones in the treatment of chronic schizophrenic diseases.

Sixteen chronic schizophrenic subjects were treated for 3 months each with either a benzo-pyrone (Paroven/Venoruton, Zyma) or a placebo in a randomized, double-blind crossover trial. They continued to take their previous drug therapies. Therapeutic effects were measured by the Brief Psychiatric Rating Scale (BPRS), by self-assessment, and by assessment by a relative. Eleven patients completed the trial in relation to BPRS assessment. When on the active substance, as compared with the placebo, they showed a mean improvement of 27% (significant at the 1% level). Ten patients completed the trial in relation to the self and relative's assessments. There were improvements of 16% and 13%, respectively (significant at the 5% levels). Half the patients showed improvements on all the tests. Their improvements were 49%, 31%, and 21%, respectively. There was evidence that the active substance began to have an effect within 2 weeks. No side effects were observed with the active substance.

Adult↗
PubMed2000

The chemotaxonomic significance of the phenyl pyrone aloenin in the genus Aloe.

The phenyl pyrone, aloenin was positively identified in 16 species in a greater chemotaxonomic study on 380 species of Aloe. A large number of species have previously been suggested to be related on the basis of their macromorphological characters. The leaf exudate composition of the 16 species are presented together with a summary of the salient morphological characters. The possible taxonomic relationships between aloenin producing species, not previously thought to be associated with one another are discussed and illustrates the need to explore additional characters of taxonomic value in this large genus of ca. 420 species where no natural classification system exists.

Journal Article↗
PubMed1985

Photochemistry of the furan-side 8-methoxypsoralen-thymidine monoadduct inside the DNA helix. Conversion to diadduct and to pyrone-side monoadduct.

We have studied the photochemical reactions of 8-methoxypsoralen (8-MOP) with calf thymus DNA. Analysis of the photoproducts formed was carried out by enzymatic digestion of the 8-MOP-modified DNA, followed by HPLC separation of photoadducts by high-pressure liquid chromatography (HPLC). The 4',5' (furan-side) monoadduct of 8-MOP bound to thymidine is converted to cross-linked thymidine-8-MOP-thymidine diadduct by 341.5 nm light with a quantum yield of 0.028 +/- 0.004. This is 4 times greater than the quantum yield for initial adduct formation (0.0065 +/- 0.0004). When low levels of 8-MOP are covalently bound to DNA by using 397.9 nm light, less than 10% of the adducts formed are diadducts yet nearly 70% are in 5'-TpA cross-linkable sites. The furan-side monoadducts in these sites can subsequently be converted to diadduct or to a lesser extent 3,4 (pyrone-side) monoadduct.

Animals↗
PubMed1984

8-Methoxypsoralen-nucleic acid photoreaction. Effect of methyl substitution on pyrone vs. furan photoaddition.

We have synthesized a series of 8-[3H]methoxypsoralens in which methyl and hydrogen are systematically varied at the 4- and 5'-positions. Analysis of the products resulting from the photoaddition of these four psoralens with the nucleic acid poly(dA-dT) reveals that the product distribution depends on the presence or absence of a 4-methyl substituent. Compounds with the 4-methyl group show an overwhelming preference (approximately 98%) for addition to the furan double bond, while compounds without the 4-methyl show a substantial amount (approximately 18%) of addition to the pyrone double bond.

Chemical Phenomena↗
PubMed2003

Synthesis of isocoumarins and alpha-pyrones via electrophilic cyclization.

A variety of substituted isocoumarins and alpha-pyrones are readily prepared in excellent yields under very mild reaction conditions by the reaction of o-(1-alkynyl)benzoates and (Z)-2-alken-4-ynoates with ICl, I(2), PhSeCl, p-O(2)NC(6)H(4)SCl, and HI. This methodology accommodates various alkynyl esters and has been successfully extended to the synthesis of polycyclic aromatic and biaryl compounds.

Journal Article↗
PubMed2003

Studies on K2CO3-catalyzed 1,4-addition of 1,2-allenic ketones with diethyl malonate: controlled selective synthesis of beta,gamma-unsaturated enones and alpha-pyrones.

The K2CO3 (10 mol %)-catalyzed 1,4-addition reaction of diethyl malonate with various substituted 1,2-allenic ketones leading to polyfunctionalized beta,gamma-unsaturated enones 3 or 4 was studied. With 3-unsubstituted 1-substituted-1,2-allenyl ketones, the highly selective formation of beta,gamma-unsaturated enones 4 was observed; with 1,2-allenyl ketones bearing one or two 3-substituents in the allenyl group, only beta,gamma-unsaturated enones 3 with an unmigrated carbon-carbon double bond were produced; with 3-monosubstituted-1,2-allenyl ketones Z-beta,gamma-unsaturated enones 3 were formed with excellent stereoselectivity (E:Z > 96:4); with propadienyl ketones, mixtures of beta,gamma-unsaturated enones 3 and 4 were formed. alpha-Pyrone derivatives were synthesized via the K(2)CO(3)-catalyzed or -promoted reaction of 1,2-allenic ketones with diethyl malonate via a sequential Michael addition-carbon-carbon double bond migration-lactonization process.

Journal Article↗
PubMed1996

3-Hydroxy-4-pyrones as Precursors of 4-Methoxy-3-oxidopyridinium Ylides. An Expeditious Entry to Highly Substituted 8-Azabicyclo[3.2.1]octanes.

3-Hydroxy-4-pyridones, which are easily prepared from commercially available 3-hydroxy-4-pyrones, can be readily transformed into 4-methoxy-3-oxidopyridinium ylides by treatment with methyl trifluoromethanesulfonate and subsequent deprotonation with a non-nucleophilic base. These ylides are capable of undergoing cycloaddition to several electron-deficient alkenes, thus allowing the synthesis of highly functionalized azabicyclo[3.2.1]octane moieties. The rich substitution patterns of these frameworks might allow their divergent conversion to a variety of natural and non-natural tropane alkaloids.

Journal Article↗
PubMed1994

Murayalactone, a dibenzo-alpha-pyrone from Streptomyces murayamaensis.

Murayalactone, 6, has been isolated from Streptomyces murayamaensis, and its structure assigned with the use of inverse nmr spectroscopy. This constitutes the first occurrence of a dibenzo-alpha-pyrone in a Streptomyces species, and the first biogenesis of this ring system from a decaketide.

Chromatography, High Pressure Liquid↗
PubMed2001

Reversal of stereoselectivity in [5 + 2] pyrone--alkene cycloadditons using a sulfoxide-to-sulfoximine switch. Enantiodivergent synthesis of 8-oxabicyclo[3.2.1]octane systems.

[reaction: see text] Switching from a sulfinyl to a sulfonimidoyl group allows the reversal of the sense of asymmetric induction in thermal [5C + 2C] intramolecular pyrone-alkene cycloadditions. Removal of the sulfoximine unit from the resulting cycloadducts yields optically active oxabicyclic systems that are enantiomeric to those obtained using the sulfinyl chiral auxiliary.

Journal Article↗
PubMed1993

Sex pheromone for the brownbanded cockroach is an unusual dialkyl-substituted alpha-pyrone.

Female brownbanded cockroaches, Supella longipalpa, emit a sex pheromone that attracts males from a distance. This pheromone was isolated and identified as 5-(2,4-dimethylheptanyl)-3-methyl-2H-pyran-2-one (which we refer to as supellapyrone), and its structure was confirmed by synthesis. A racemic blend of the synthetic compound elicited behavioral and electrophysiological responses comparable to the natural pheromone across a range of doses. This compound is not only a very different type of cockroach pheromone but also makes up an additional class of natural products--namely, 3,5-dialkyl-substituted alpha-pyrones.

Journal Article↗