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At least 91 records · Page 5Linked to original sources
PubMed2002

Oxidative degradation of a sulfonamide-containing 5,6-dihydro-4-hydroxy-2-pyrone in aqueous/organic cosolvent mixtures.

PURPOSE: To predict the oxidative stability of a sulfonamide-containing 5,6-dihydro-4-hydroxy-2-pyrone in lipid-based delivery systems, N-(3-(1[(3alpha,6R)-4-hydroxy-2-oxo-6-phenyl-6-propyltetrahydro-2H-pyran-3-yl]propyl)phenyl)-5-(trifluoromethyl)-2-pyridinylsulfonamide (DHP) was oxidized by peroxides and peroxyl radicals in binary mixtures of water and organic cosolvents. METHODS: DHP was oxidized by hydrogen peroxide, t-butylhydroperoxide, or peroxyl radicals derived from the thermal decomposition of 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) in 40% (v/v) organic cosolvent and 5 mM buffer at or near 40 degrees C. Interactions between DHP and ]propane sulfonic acid and imidazole) and DH- were assessed by 1H-NMR spectroscopy. The formation of CO likely involves a free radical mechanism. RESULTS: The reaction of DHP with peroxides in 40% (v/v) acetonitrile yields epimeric monohydroxylation products, R-OH and S-OH, at C-3 of the pyrone ring, and a keto-derivative (CO). Hydroxylation rates depend on the protonation state of DHP, and the nature of buffer and the organic cosolvent. Organonitriles accelerate the oxidation through formation of peroxycarboximidic acid. Peroxyl radicals do not yield significant amounts of R/S-OH or CO. CONCLUSIONS. The hydrogen peroxide-induced degradation of DHP in the presence of acetonitrile involves two reactions, hydroxylation and carbonyl formatin. Hydroxylation proceeds via nucleophilic attack by the monodeprotonated form of DHP (DH-) on peroxycarboximidic acid. The oxidation rate is slowed by ion pairing between nitrogen-containing buffers ([3-N-morpholino]propane sulfonic acid and imidazole) and DH-. The formation of CO likely involves a free radical mechanism.

Organic Chemicals↗
PubMed1993

Treatment of lymphedema of the arms and legs with 5,6-benzo-[alpha]-pyrone.

BACKGROUND: Benzopyrones can reduce the volume of high-protein edema fluid by stimulating proteolysis. These compounds provide a method for removing excess protein and its consequent edema and reduce its clinical sequelae, such as chronic inflammation and secondary infections. METHODS: We conducted a randomized, double-blind, placebo-controlled, crossover trial of 5,6-benzo-[alpha]-pyrone in 31 patients with postmastectomy lymphedema of the arm and 21 patients with lymphedema of the leg of various causes (this agent, also known as 56 BaP, 1,2-benzopyrone, or coumarin, is not an anticoagulant). The patients received 400 mg of the active drug or placebo, each for six months. RESULTS: During the placebo period, lymphedema often worsened, especially in the arms. Measurements of limb volume showed that the active drug reduced the mean amount of edema fluid in the arms from 46 percent above normal to 26 percent above normal (P < 0.001) and the amount in the legs from 25 percent to 17 percent above normal (P < 0.001). The circumference of the arms was reduced from 17 percent to 13 percent above normal, and the circumference of the legs from 11 percent to 7 percent above normal (P < 0.001). The softness of the limb tissue was increased (P < 0.001), and elevated skin temperatures were reduced (P < 0.001). There were fewer attacks of secondary acute inflammation (P = 0.01). Bursting pains and feelings of hardness were decreased, as were feelings of tightness, tension, swelling, and heaviness; limb mobility also improved. The active drug was preferred to the placebo by 93 percent of the patients (P < 0.001). Side effects--mild nausea or diarrhea--occurred in seven patients taking the active drug. None withdrew from the trial, and the side effects disappeared after the first month of therapy. CONCLUSIONS: 5,6-Benzo-[alpha]-pyrone results in slow but safe reduction of lymphedema of the extremities.

Arm↗
PubMed1993

Reduction of filaritic lymphoedema and elephantiasis by 5,6 benzo-alpha-pyrone (coumarin), and the effects of diethylcarbamazine (DEC).

Chronic filaritic lymphoedema and elephantiasis, in India, were treated orally with 5,6 benzo-alpha-pyrone (56 BaP; 1,2 benzo-alpha-pyrone; coumarin) in a double-blind, randomized, matched-group trial. Each group finally contained 40-55 patients. Patients were observed for about 2 years (ranging from 6 to 45 months, with 75% completing the 2 years). The 56 BaP slowly, but very significantly (P < 0.0001), reduced all grades of lymphoedema and elephantiasis. Two thirds of the oedema was lost by grade 2 over 2 years. Grades 3 to 5 were reduced by a fifty over that time. The greater the initial oedema, the greater was its rate of resolution. A slowly worsening condition thus became a slowly improving one. Slowness has its advantages: compression stockings, that are impractical in hot, wet or dirty conditions, are not necessary. The slowly remodelling fibrous tissue, while lessening in amount, is still able to hold the tissues together. The 56 BaP considerably improved many symptoms and complications, particularly bursting-pains, inflammation and ulcers. It is cheap and of very low toxicity. Diethylcarbamazine (DEC) was studied with and without 56 BaP. DEC alone gave some reduction of the oedema, but this was much smaller than that with 56 BaP. It considerably worsened the reductions by 56 BaP, while 56 Bap slightly improved those by DEC and reduced the fever caused by DEC. Together, they reduced feelings of swelling and bursting-pain, fungal infections, lymphangitis and lymphadenitis more than when used alone.

Adult↗
PubMedDate not supplied

Benzo-pyrones: their selective injury to rabbit vascular endothelium.

1. Three benzo-pyrones were tested in two types of high protein oedema. 2. In general, they prevented increases in permeability in superficial venules. 3. In the absence of an injurious stimulus they caused injury to the superficial capillaries and deep venules. 4. The injurious results may be due to a direct effect on the vessel walls or to an increase in intravascular pressure and flow. This would enhance leakage from already existing defects. 5. Despite the minor injuries the effectiveness of these drugs is so great that a net removal of protein by proteolysis from the tissues occurs, thus reducing the oedema. 6. The study contributes further to an understanding of the mode of action of the benzo-pyrones.

Albumins↗
PubMed1979

Lymph and blood enzymes and pathologic alterations in canine experimental pancreatitis after administration of benzo-pyrones.

The effect of Venalot, a combination of two benzo-pyrones, on canine experimental acute pancreatitis was examined. Activities of lymph and blood plasma enzymes, thoracic duct lymph flow, and morphological changes of the pancreas were compared with those of a control group of dogs. The drug was found to enhance the removal of amylase and trypsin via lymph from the gland and to decrease the elevation of plasma amylase and lactate dehydrogenase. When administered simultaneously with the induction of pancreatitis, benzo-pyrones were effective in the reduction of pancreatic edema and necroses.

Acute Disease↗
PubMed1977

The effect of macrophage poisoning by silica on experimental pulmonary contusion and its benzo-pyrone treatment.

The effect of poisoning the macrophages with silica on the fine structure of pulmonary contusion was studied in rats. It was found that this causes an increase in the concentration of protein in the interstitial tissue and in the air spaces. It also causes a consequent increase in the amount of interstitial oedema. While the benzo-pyrones normally cause a considerable reduction both in the protein concentrations and in the amount of oedema, they do not act in these ways when the macrophages are poisoned. These results imply that the macrophages normally lyse some of the protein and that this effect is considerably enhanced by the action of the benzo-pyrones.

Animals↗
PubMed1978

A fine structural study of the removal of the effectiveness of benzo-pyrone treatment of lymphoedema by the destruction of the macrophages by silica.

Macroscopical, light microscopical and electronmicroscopical observations were made of the diaphragm, skin and brain of rats, some of which were treated with intraperitoneal silica for 8 days (after being given it i.v. for 2 days). The diaphragms showed a most remarkable increase in fibroblast activity and fibrosis beneath the peritoneal mesothelium (which was disintegrating). Deep to this there were many disintegrating macrophages, and much oedema and increased protein concentration. Ligation of the cervical lymphatics produced the usual changes of lymphoedema in the skin and brain. This was greatly reduced in the animals treated with a mixture of benzo-pyrones. However, in those animals also treated with silica, the benzo-pyrones had no effect on the amount of oedema or of protein. In all the animals except those treated with silica, lymphoedema was accompanied by considerable numbers of macrophages entering the affected tissues; in those treated with silica, these numbers were greatly reduced.

Animals↗
PubMed1988

Deleterious effect of Brij 35 on alkyl 2-pyrones and other hydrophobic inhibitors of human sputum and leucocyte elastase.

Brij 35 significantly reduced the inhibitory activity of hydrophobic alkyl 2-pyrones, oleic acid and alkyl peptides towards human sputum and leucocyte elastase, whereas 4-methoxy-6-(2'-hydroxy-2'-(carbobutyloxy)-vinyl)-2-pyrone, alpha-1-proteinase inhibitor and a sulfated chitosan were unaffected. The effect of Brij 35 on elastase appeared to be irreversible, since dialysis against Brij-free buffer was not accompanied by a return to inhibitory activity by the first group of inhibitors. However, passage through an ionic-exchange column was effective in removing the detergent from the enzyme. Brij 35 is also an activator of the elastases: kcat for Boc-Ala-4-nitrophenyl ester and methylsuccinyl-Ala-Ala-Pro-Val-4-nitroanilide increased by 20% and 40%, respectively in the presence of 0.015% Brij 35. Binding of the substrates to the enzyme is unaffected, since Km is unchanged.

Detergents↗
PubMed1994

Fusapyrone and deoxyfusapyrone, two antifungal alpha-pyrones from Fusarium semitectum.

A strain of Fusarium semitectum Berk. & Rav. from maize stalk rot in southern Italy produced bioactive metabolites when cultured on autoclaved rice kernels at room temperature for 4 weeks. The organic extracts of fungal culture showed a strong antibiotic activity towards Geotrichum candidum in disk diffusion assays, but they were not toxic to Artemia salina larvae. Two antifungal metabolites were isolated and characterized by chemical and spectroscopic methods as two 3-substituted-4-hydroxy-6-alkyl-2-pyrones, in particular, the 3-(4-deoxy-beta-xylo-hexopyranosyl)-4-hydroxy-6-[2-hydroxy-7-hydroxymeth yl- 1,1,5,9,11-pentamethyl-3,5,8-heptadecatrienyl]-2H-pyran-2-one and its 6-[2-hydroxy-1,1,5,7,9,11-hexamethyl] analog, which were named fusapyrone and deoxyfusapyrone, respectively.

Animals↗
PubMed1996

Maltol (3-hydroxy-2-methyl-4-pyrone) toxicity in neuroblastoma cell lines and primary murine fetal hippocampal neuronal cultures.

Maltol (3-hydroxy-2-methyl-4-pyrone), a product of carbohydrate degradation, is known to enhance aluminium-induced neurofibrillary degeneration in neuronal systems, but few toxicological studies have been conducted. We report maltol toxicity in neuroblastoma cell lines of mouse (Neuro 2a) and human (IMR 32) origin, and in primary murine fetal hippocampal neuronal cultures. As determined by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2 -(4-sulfophenyl)-2H-tetrazolium, inner salt] conversion, maltol exhibited a dose-dependent toxicity on the viability of both neuroblastoma cell lines, but the toxicity was more pronounced in Neuro 2a cells. Maltol was also toxic in a dose-dependent manner in primary murine fetal hippocampal neurons at micromolar concentrations. Electrophoresis of DNA extracted from maltol-intoxicated cells showed a laddering pattern, suggestive of apoptotic cell death. In the maltol-exposed hippocampal neuronal cultures, fragmented DNA ends were visualized in situ in morphologically condensed nuclei by terminal deoxynucleotidyl transferase with digoxigenin-labelled UTP and subsequent immunohistochemistry. Collectively, our findings suggest that the toxic effect of maltol is mediated through apoptosis. Further toxicological investigations are warranted, since maltol is found in the daily diet of humans.

Animals↗
PubMed1984

Specific inhibition of human leukocyte elastase by substituted alpha-pyrones.

Several a-pyrones have been synthesized and investigated for their in vitro inhibitory activity using a-chymotrypsin (a-CT), porcine pancreatic elastase (PPE) and human leukocyte elastase (HLE). 4-Hydroxy-6-undecyl-2H-pyran-2-one 4, 4-Hydroxy-6-[(1-butyl)heptyl]-2H-pyran-2-one 5 and 4-Methoxy-6-[(1-butyl) heptyl]-2H-pyran-2-one 6 were found to be specific inhibitors of HLE. These compounds constitute a promising new class of HLE inhibitors.

Chemical Phenomena↗
PubMed2002

Production and biotransformation of 6-pentyl-alpha-pyrone by Trichoderma harzianum in two-phase culture systems.

The final concentration of 6-pentyl-a-pyrone (6PP) produced in cultures of Trichoderma spp. is limited by the fact that inhibition of biomass growth occurs at 6PP concentrations as low as 100 mg/l. The aim of this work was to evaluate liquid-liquid extractive fermentation systems as an alternative to overcome the toxicity problems and to increase the production of 6PP by this fungus. Two alkanes (n-decane and n-hexadecane) and two dicarboxylic esters (dibutyl phthalate and dioctyl phthalate) were evaluated in shake flask cultures. The highest 6PP production (173 ppm) was achieved when n-hexadecane was used, being 3.5-fold the maximum 6PP concentration of a culture without the solvent. Cultivation of Trichoderma harzianum in a 10-1 bioreactor with n-hexadecane yielded 6PP production ninefold higher than that from control cultures. However, 6PP production in the bioreactor (83 ppm) was lower than in shake flasks. Differences in the power drawn to the fluid at each scale could account for such behavior. Even in the presence of the solvent, 6PP content decreased after reaching its maximal concentration.

Bioreactors↗
PubMed2001

In vitro study of the insulin-like action of vanadyl-pyrone and -pyridinone complexes with a VO(O4) coordination mode.

The insulin-like action of a novel class of potential insulin-mimetic complexes was investigated in terms of free fatty acid (FFA) release from isolated rat adipocytes. Vanadyl complexes such as VO(ema)2 [(bis(2-ethyl-3-hydroxy-4-pyrone)VO], VO(mpp)2 [bis (3-hydroxy-2-methyl-4(1H)-pyridinone)VO], VO(dmpp)2 [bis(1,2-dimethyl-3-hydroxy-4(1H)-pyridinone)VO] and VO(empp)2 [bis(2-ethyl-3-hydroxy-1-methyl-4(1H)-pyridinone)VO] were tested together with vanadyl sulfate for comparison. The inhibitory effect of the vanadium complexes on FFA release, from rat adipocytes treated with epinephrine, is dependent on concentration and for that reason the results are reported in terms of the IC50 value, the 50% inhibition concentration. The results show that all the complexes have an inhibitory effect on FFA release and that two pyridinone complexes, VO(mpp)2 and VO(empp)2, have a significantly better insulin-mimetic activity than that of vanadyl sulfate.

Adipocytes↗
PubMedDate not supplied

Novel tricyclic pyrone compounds prevent intracellular APP C99-induced cell death.

Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by the progressive and global loss of cognitive functions. Pathological features include a loss of neurons in vulnerable brain regions and the extracellular deposition of abnormal protein aggregates known as amyloid plaques. Amyloid-beta protein (A beta is the major component of amyloid plaques and is derived from a larger transmembrane glycoprotein, termed amyloid beta protein precursor (APP), by proteolysis. The AD research has focused on A beta production and metabolism, its extracellular deposition, and its cellular toxicity. Recent evidence, however, suggests that A beta as well as the C-terminal fragments (CTF) of APP can accumulate intraneuronally. The neuronal loss and synaptic transmission deficit in AD may therefore depend on intraneuronal accumulation of A beta/CTF rather than on extracellular plaque formation. Accordingly, we propose that one of the primary targets of therapeutic intervention should be intracellular A beta/CTF and its toxic cellular effect. We have established a cell-culture model in which the neurons degenerate on induction of endogenous expression of A beta/CTF of APP. These cultures have been used to test whether tricyclic pyrone (TP) compounds may prevent A beta/CTF-mediated neuronal death. The results to date have been encouraging. Lead compounds will now be selected for their abilities to ameliorate A beta/CTF-mediated pathology in transgenic mice. Our hope is that these compounds may eventually prove beneficial for the prevention and treatment of AD.

Alzheimer Disease↗
PubMed1995

Pyrone hydroperoxide formation during the Maillard reaction and its implication in biological systems.

Hydroperoxide formation during Maillard reaction (amino-carbonyl reaction) was investigated using luminol-chemiluminescence-high performance liquid chromatography (CL-HPLC). From the equimolar reaction mixture of 1 M beta-alanine/D-glucose in phosphate buffer (pH 8.0) at 95 degrees C, two hydroperoxides and H2O2 were detected as chemiluminescent products in CL-HPLC, and the yields were proportional to the browning development. One of these hydroperoxides was isolated and identified as 3-hydroxy-5-hydroperoxy-2-methyl-5,6-dihydropyran-4-one (HMDP, pyrone hydroperoxide) by fast atom bombardment mass spectrometry. The HMDP formation was also confirmed in L-lysine/D-glucose and in bovine serum albumin/D-glucose with the physiological incubation at 37 degrees C for 4 days and 3 wk, respectively. Incubation at 37 degrees C of human plasma containing 5.5-25.0 mM of D-glucose for 60 h showed the glucose concentration-dependent formation of HMDP (10-35 microM of H2O2 equivalence). The HMDP was negative to thiobarbituric acid reaction and was degraded by peroxidases such as horseradish peroxidase, Athromyces ramosus peroxidase, heated cytochrome c, and microperoxidase. The results strongly suggested the formation of such hydroperoxide even in biological Maillard reaction termed as glycation, and implied its contribution in pathogenesis and oxidative lesions associated with hyperglycemia.

Animals↗
PubMed2001

Passifloricins, polyketides alpha-pyrones from Passiflora foetida resin.

Three polyketides alpha-pyrones, named passifloricins, were isolated from Passiflora foetida resin; their structures and relative configurations were assigned through 2D NMR spectroscopic analyses. These types of compounds were not detected in other passion flowers.

Magnetic Resonance Spectroscopy↗