Pyran Compounds Research Articles

Integrated Metabolomics and Proteomics Analysis Provides Insights into the Formation of Volatile Compounds in Three Different Polyembryonic Mango Cultivars.

Understanding volatile compound formation is critical for enhancing the flavor quality of mangoes. Integrated untargeted metabolomics and proteomics were employed to explore volatile compound formation in three different polyembryonic mango cultivars ("Ah Ping," "Rosa," and "Rosigold"). A total of 87 volatile compounds were identified using SPME-GC-MS. Untargeted metabolomics and proteomics resulted in identification of 508 metabolites and 4481 proteins, respectively. Integrative analysis revealed that the volatile compound formation was influenced by fatty acids, amino acids, pentose, and hexose, as well as terpenoid metabolisms. Specifically, upward expression of core enzymes in lipoxygenanse pathway was responsible for the higher levels of some C6 and C9 volatile compounds in "Ah Ping." The differential expression of key enzymes in fatty acid degradation facilitates the varied contents of straight-chain volatile compounds. The upregulation of glutamate decarboxylase and branched-chain amino acid aminotransferase upstream of butanoate metabolism led to the highest levels of butyl esters in "Ah Ping." Furthermore, the different levels of volatile furan and pyran compounds might be attributed to differential expression of critical enzymes in pentose and hexose metabolism. These findings established a metabolic and proteomic map unraveling the biosynthesis of specific volatile compounds and provided insights into understanding the characteristic flavor of mango.

A study on the chemical stability of cholesterol-lowering drugs in concomitant simple suspensions with magnesium oxide

BackgroundDifficulty in taking solid medicines is a common issue particularly for the elderly because of a decline in swallowing function, also known as dysphagia. For patients with such a dysfunction, a simple suspension method, in which solid medicines are disintegrated and suspended using warm water, has been developed and widely used in Japanese clinical settings. However, there is little information on drug stability in the simple co-suspension of multiple formulations especially including acidic or alkaline ones. In this study, the chemical stability of typical cholesterol-lowering drugs was investigated in a simple co-suspension with alkaline magnesium oxide (MgO) which is frequently used as a laxative or antacid in Japan.MethodsA cholesterol-lowering drug (one tablet) was soaked with or without MgO in warm water (55°C), and the vessel was left at room temperature for 10 min or 5 h. The suspensions prepared were then analyzed by high-performance liquid chromatography. Degradation products were analyzed by nuclear magnetic resonance spectroscopy and mass spectrometry for the structural elucidation.ResultsIn the simple co-suspension with MgO, no significant degradation was observed for atorvastatin or pravastatin, while a significant decrease of the recovery from the co-suspension was observed for rosuvastatin after 5 h. On the other hand, simvastatin and ezetimibe co-suspended with MgO were partially degraded to simvastatin acid and a pyran compound, respectively.ConclusionsA simple co-suspension with MgO is feasible for atorvastatin, pravastatin, and rosuvastatin, although the rosuvastatin tablet should not be left soaking for a long time. Further it is inadvisable to suspend simvastatin or ezetimibe together with MgO because of their partial degradation.

Synthesis of phenylthiourea-based pyrazole, thiazole and/or pyran compounds: molecular modeling and biological activity

The significant biological activity of phenylthiourea derivatives prompted the synthesis of a new phenylthiourea-based heterocyclic ring systems (pyrazole, thiazole, and pyran), and their chemical structures were elucidated by spectral data. The DFT/B3LYP methodology was applied to explore the configuration and energetic features of the FMO’s of the compounds. The derivatives exhibited comparable energy gap, ranging from 2.13 to 2.56 eV, and were arranged in the following order: 5 < 8 < 7 < 6 < 4b < 4a. The antitumor activity of the new phenylthiourea-based derivatives was investigated against diverse cell lines, such as HepG2, HCT-116, MCF-7, PC3, and WI38, using Doxorubicin as a reference drug. The hybrids 5, 6, and 8 revealed strong cytotoxic against HCT-116 (IC50 = 2.29 ± 0.46-9.71 ± 0.34 µM). Furthermore, the molecular docking studies of the compounds indicated that the hybrids 5, 6 and 8 exhibited the greatest docking score values, in accordance to the antitumor activity.

Physico-chemical parameters complemented with aroma compounds fired up the varietal discrimination of wine using statistics

Wine comprises a beloved food and human companion since the early times of humans on earth. In this study, wine samples of different type (red, white, and rose) and variety (Agiorgitiko, Augoustiatis, Cabernet Sauvignon, Syrah, Vlahiko, Assyrtiko, Chardonnay, Debina, Moschofilero, Vidiano, Syrah plus Mandilari, and Xinomavro) were subjected to physico-chemical and aroma compounds analyses, in an effort to characterize their identity and discriminate these samples according to variety using statistics. Results showed significant differences (p < 0.05) for wine samples of different variety in regard to the measured physico-chemical parameters (pH, electrical conductivity, total dissolved solids, salinity, L*, a*, b*, and Chroma*) and aroma compounds (alcohols, esters, phenolic compounds, pyran compounds, and terpenoids/norisoprenoids). Application of multivariate analysis of variance, linear discriminant analysis, and weighted least-squares regression analysis fired up the perfect varietal discrimination (~ 100%) of wine samples and modeling of results, contributing to new information in the literature about the identity of these wine varieties.

Benzofuran pyran compound rescues rat and human osteoblast from lipotoxic effect of palmitate by inhibiting lipid biosynthesis and promoting stabilization of RUNX2

Obesity and ageing increases bone marrow fat which in turn is associated with lower bone mass. Marrow adipocytes by secreting cytokines, adipokines and free fatty acids change the bone marrow milieu and thus the number of osteoblasts. Palmitate is the common saturated fatty acid, an unavoidable ingredient we consume with food, which kindles cell apoptosis. Compound 4e is osteogenic in nature. We examine the effect of compound 4e in palmitate induced lipotoxicity in rat osteoblasts. Design of benzofuran Pyran hybrid compound (4e) was found to be effective in inhibiting palmitate induced cell apoptosis. In this study an in vitro model of palmitate was contrived. Anti-apoptotic effect of compound 4e was assessed by Annexin/PI and LDH (Lactate dehydrogenase) assay. Compound 4e also increased osteoblast differentiation and mineralization. It also increased expression of osteogenic markers (RUNX2 and BMP2), assessed by Real time PCR and immunofluorescence, which was impeded by palmitate. Acetyl Co-Carboxylase (ACC) and Fatty acid synthase (FAS), two prominent mediators of lipid biosynthesis were increased by palmitate exposure. Compound 4e modulated lipid biosynthesis by inhibiting ACC and FAS as reflected visually and after quantification of less lipid droplet formation suggesting that 4e is osteogenic and simultaneously anti-lipotoxic.

SPME-GC/MS Analysis of Methanol in Biospecimen by Derivatization with Pyran Compound.

Methanol is metabolized in the body to highly toxic formaldehyde and formate when consumed accidentally. Methanol has been typically analyzed with gas chromatography-flame ionization detector (GC-FID). However, its retention time may overlap with other volatile compounds and lead to confusion. Alternative analysis of methanol using gas chromatography/mass spectrometry (GC/MS) also has limitations due to its similar molecular weight with oxygen and low boiling point. In this study, methanol and internal standard of deuterium-substituted ethanol were derivatized with 3,4-dihydro-2H-pyran under acid catalysis using concentrated hydrochloric acid. The reaction products including 2-methoxytetrahydropyran were extracted with solid-phase microextraction followed by GC/MS analysis. This method was successfully applied to measure the lethal concentration of methanol in the blood of a victim with a standard addition method to overcome the complex matrix effect of the biospecimen. Identification of the metabolite formate by ion chromatography confirmed the death cause to be methanol poisoning. This new method was a much more convenient and reliable process to measure methanol in complex matrix samples by reducing sample pretreatment effort and cost.

Synthesis and Molecular Modeling Studies on Novel C2 Alkylated Benzoazonine Scaffold and Corresponding 2-Pyrazoline Derivatives as Acetylcholinestrase Enzyme Inhibitors

A rapid and efficient methodology was performed for the synthesis of α,β-unsaturated ketones 2a–k containing benzoazonine core through Claisen-Schmidt reaction of the benzoazonine-2,7-dione 1 and various aldehydes in acidic medium. The obtained exocyclic α,β-unsaturated ketones were subjected to an irradiating microwave gave unexpected asymmetric spiro pyran compound 3 via a self-Diels–Alder reaction. The initially formed exocyclic α,β-unsaturated ketones underwent cyclocondesation with phenylhydrazine to afford 2-pyrazoline derivatives 4. The structure of the synthesized scaffolds was characterized using 1H-NMR, APT and 2DNMR spectra. A molecular modeling study using Molecular Operating Environment was performed to investigate their binding modes to the Acetylcholinestrase enzyme active site. Docking results demonstrated that the newly synthesized compounds recognized the active sites of Acetylcholinestrase and form different types of bonding interactions with key active site amino acid residues.

Recent Advances in Three-Component Cyclocondensation of Dimedone with Aldehydes and Malononitrile for Construction of Tetrahydrobenzo[b]pyrans Using Organocatalysts

Background: The majority of naturally occurring compounds, pharmaceuticals, and drug-candidate molecules possess heterocyclic scaffolds. In this context, tetrahydobenzo[b]pyrans are of considerable importance. In the line with the synthesis of these valuable heterocyclic compounds, the researchers tried to synthesize these molecules using different organocatalysts. The development of new strategies for three-component condensation of dimedone, various aldehydes and malononitrile for construction of tetrahydrobenzo[b]pyrans is of particular interest to organic chemists and pharmacologists. Objective: In this review, three-component catalyzed synthesis of tetrahydrobenzo[b]pyran compounds is introduced, focusing on the developments in the use of organocatalysts. Organocatalytic approaches were investigated for the synthesis of tetrahydrobenzo[b]pyrans. This contribution covers the literature concerning the synthesis of heterocycles referred to, in recent times. Conclusion: This review article is associated with the study of the three-component synthesis of tetrahydrobenzo[b]pyrans using organocatalysts. This review also provides an insight into the importance of these heterocycles. In the vast majority of these reactions, water and water-ethanol system have been used as green solvent media for implementation of them. The use of green solvents, the development of less toxic and promising reagents/catalysts as well as the design of inexpensive and reliable approaches are some of the principles of green chemistry, and most of the methods are benefited from them. Tetrahydrobenzo[b]pyrans and organocatalysts open avenue ofnew horizons. The recyclability of the many of these organocatalysts offers an additional merit for the use of these catalysts in 3-CR of aldehydes, dimedone, and malononitrile reactions.

ChemInform Abstract: Iron‐Catalyzed Radical [2 + 2 + 2] Annulation of Benzene‐Linked 1,7‐Enynes with Aldehydes: Fused Pyran Compounds.

An iron-catalyzed radical [2 + 2 + 2] annulation of benzene-linked 1,7-enynes with aldehydes has been developed. With this method, a variety of fused [6.6.6] pyran molecules are built in an efficient and selective manner. The aldehydic radical-mediated strategy exhibits a particularly attractive dual role, which triggers and terminates the domino cyclization.

Iron-Catalyzed Radical [2 + 2 + 2] Annulation of Benzene-Linked 1,7-Enynes with Aldehydes: Fused Pyran Compounds.

An iron-catalyzed radical [2 + 2 + 2] annulation of benzene-linked 1,7-enynes with aldehydes has been developed. With this method, a variety of fused [6.6.6] pyran molecules are built in an efficient and selective manner. The aldehydic radical-mediated strategy exhibits a particularly attractive dual role, which triggers and terminates the domino cyclization.

ChemInform Abstract: Covalently Anchored n‐Propyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane Chloride on SBA‐15 as a Basic Nanocatalyst for the Synthesis of Pyran Heterocyclic Compounds.

In the present study, highly ordered n-propyl-1,4 diazoniabicycle[2.2.2]octane chloride functionalized mesoporous SBA-15, SBA-DABCO, with high surface area and narrow pore-size distribution was synthesized and characterized by TEM, SEM, FT-IR, CHN, TGA, XRD and BET. The organic-modified SBA-15 has hexagonal crystallographic order, pore diameter up to 54.2 A, and the content of DABCO groups up to 1.38 mmol g−1. The catalyst shows an environmentally benign character, which can be easily prepared, stored and recovered without obvious significant loss of activity. The synthesized basic organocatalyst provides a green and useful method for the one-pot synthesis of pyran annulated heterocyclic compounds, and especially spirooxindole pyran compounds in aqueous media. The significant features of the present protocol are simple, environmentally benign, high yields, no chromatographic separation and recyclability of the catalyst.

Covalently anchored n-propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride on SBA-15 as a basic nanocatalyst for the synthesis of pyran heterocyclic compounds

In the present study, highly ordered n-propyl-1,4 diazoniabicycle[2.2.2]octane chloride functionalized mesoporous SBA-15, SBA-DABCO, with high surface area and narrow pore-size distribution was synthesized and characterized by TEM, SEM, FT-IR, CHN, TGA, XRD and BET. The organic-modified SBA-15 has hexagonal crystallographic order, pore diameter up to 54.2 A, and the content of DABCO groups up to 1.38 mmol g−1. The catalyst shows an environmentally benign character, which can be easily prepared, stored and recovered without obvious significant loss of activity. The synthesized basic organocatalyst provides a green and useful method for the one-pot synthesis of pyran annulated heterocyclic compounds, and especially spirooxindole pyran compounds in aqueous media. The significant features of the present protocol are simple, environmentally benign, high yields, no chromatographic separation and recyclability of the catalyst.

Flexible and biomimetic analogs of triple uptake inhibitor 4-((((3S,6S)-6-benzhydryltetrahydro-2H-pyran-3-yl)amino)methyl)phenol: Synthesis, biological characterization, and development of a pharmacophore model

In this study we have generated a pharmacophore model of triple uptake inhibitor compounds based on novel asymmetric pyran derivatives and the newly developed asymmetric furan derivatives. The model revealed features important for inhibitors to exhibit a balanced activity against dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET). In particular, a ‘folded’ conformation was found common to the active pyran compounds in the training set and was crucial to triple uptake inhibitory activity. Furthermore, the distances between the benzhydryl moiety and the N-benzyl group as well as the orientation of the secondary nitrogen were also important for TUI activity. We have validated our findings by synthesizing and testing novel asymmetric pyran analogs. The present work has also resulted in the discovery of a new series of asymmetric tetrahydrofuran derivatives as novel TUIs. Lead compounds 41 and 42 exhibited moderate TUI activity. Interestingly, the highest TUI activity by lead tetrahydrofuran compounds for example, 41 and 42, was exhibited in a stereochemical preference similar to pyran TUI for example, D-161.

Fluidised bed pyrolysis of lignocellulosic biomasses and comparison of bio-oil and micropyrolyser pyrolysate by GC/MS-FID

The fast pyrolysis of spruce (Picea abies), short rotation willow coppice (Salix alba), Miscanthus (Miscanthus x giganteus), and wheat straw (Triticum aestivum) was compared on a laboratory scale bubbling fluidized bed reactor at 460–475°C. The presence of ash, ranging from 0.26wt.% for spruce to 3.76wt.% for wheat straw (moisture free basis) favoured decomposition of cell-wall constituents to char (spruce [11.4wt.%]<Salix [16.2wt.%]<Miscanthus [21.8wt.%]<wheat straw [21.5wt.%]) with a reduction of liquid organic product (spruce [53.8wt.%]>Salix [45.4wt.%]>Miscanthus [37.3wt.%]>wheat straw [37.2wt.%]). Bio-oils from Miscanthus and wheat straw were inhomogeneous. Differences between absolute masses of compounds determined by GC/MS-FID of the bio-oils compared with Py-GC/MS-FID suggested a greater role of secondary reactions at the fluidised bed scale, with reduced concentrations of certain lignin-derived, furan and pyran compounds.

Synthesis and photochromic properties of substituted naphthopyran compounds

A group of 3,3-diaryl-3 H-naphtho[2,1-b]pyran compounds with functional substituents at the 5- and 6-positions of the naphthopyran skeleton and the para positions at the 3-aryl moieties were prepared through condensation reactions between 2-naphthol derivatives and 1,1-diarylprop-2-yn-1-ol derivatives. The chemical structures of the compounds were confirmed by NMR and MS. The crystal structure of 3,3-diphenyl-6-morpholino-3 H-naphtho[2,1-b]pyran ( 4b) was determined and the relationship between the pyran substructure and photochromism was discussed. The photochromic properties were studied as well, and decoloration kinetics of colored forms was fitted to the biexponential model. Among these compounds, 4b was considered to be the best one due to the large ΔOD of colored form, which is one of the most important properties used in the photochromic material.

Transient absorption studies of the photochromic behavior of 3H-naphtho[2,1-b]pyran linked to a p-nitroaniline group

The photophysical and photochemical behavior of a 3H-naphtho[2,1-b]pyran compound substituted at position 8 by a p-nitroaniline group has been investigated by transient absorption spectroscopy in the femto/picosecond and nano/microsecond time domains. Measurements were undertaken at two different pump excitation wavelengths, adjusted in resonance with the lowest energy transition S0–S1 (abs λmax 392 nm) and with a higher energy transition S0–Sn (abs λmax 265 nm), respectively. In both cases, the results show the contribution of three transient species to the photoinduced processes: the excited S1 and T1 states of the initial ring-closed molecule and a long-lived colored species ascribed to a ring-opened photoproduct, attesting the presence of some photochromic activity. The S1 and T1 states are mainly localized on the p-nitroaniline substituent and do not contribute highly to the photochromic efficiency. The ring-opening photochromic process occurs essentially in ≤0.4 ps following excitation of the Sn state, in competition with the relaxation to the S1 state via internal conversion.

Analysis of volatile compounds of eucalyptus honey by solid phase extraction followed by gas chromatography coupled to mass spectrometry

Solid-phase extraction (SPE) followed by gas chromatography coupled to mass spectrometry has been used for the analysis of volatile compounds of eucalyptus honey. Different amounts of honey and dichloromethane were employed to optimize solid-phase extraction conditions. The best result was obtained with 20 g of honey eluted with 60 mL of dichloromethane. This method presented a good precision for volatile compounds usually found in honeys and allowed the quantification of 35 volatile compounds (terpenes and derivatives, furan and pyran compounds, ketones, benzene compounds, acids, and norisoprenoids) of eucalyptus honey.

Polyfunctionalized Aryllead Triacetates in a Cascade Synthesis of Tetracyclic Isochromanocoumarin‐Type Compounds.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Discovery of Novel Trisubstituted Asymmetric Derivatives of (2S,4R,5R)-2-benzhydryl-5-benzylaminotetrahydropyran-4-ol, Exhibiting High Affinity for Serotonin and Norepinephrine Transporters in a Stereospecific Manner

In our structure-activity relationship study on 3,6-disubstituted pyran derivatives, we have carried out asymmetric synthesis and biological characterization of trisubstituted (2S,4R,5R)-2-benzhydryl-5-benzylaminotetrahydropyran-4-ol and (3S,4R,6S)-6-benzhydryl-4-benzylaminotetrahydropyran-3-ol derivatives and their enantiomers. All synthesized derivatives were tested for their affinities for the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) in the brain by measuring their potency in inhibiting the uptake of [(3)H]DA, [(3)H]-5-HT, and [(3)H]NE, respectively. Compounds were also tested for their binding affinity at the DAT by their inhibition of [(3)H]WIN 35,428. Biological results indicated that regioselectivity and stereoselectivity played important roles in determining activity for monoamine transporters as only (-)-isomers of 2-benzhydryl-5-benzylaminotetrahydropyran-4-ol derivatives exhibited appreciable potency for the monoamine transporters, in particular for the SERT and NET. Among the active analogues, (-)-9d exhibited potent and selective affinity at the NET (K(i), [(3)H]NE = 4.92 nM; DAT/NET = 91 and SERT/NET = 140). One of the derivatives with p-methoxybenzyl substitution, (-)-9a, was potent at both SERT and NET (K(i), [(3)H]-5-HT = 25.9 and [(3)H]NE = 15.8 nM, respectively). In the active analogue series ((-)-9a-(-)-9e), a cis-relationship between the biphenyl and the amino moiety was maintained for the SERT and NET interactions, as was observed with our earlier 3,6-disubstituted pyran compounds for the DAT interaction. To the best of our knowledge, this current series of compounds represents a novel class of pyran derivatives as blockers for monoamine transporters.

Polyfunctionalized Aryllead Triacetates in a Cascade Synthesis of Tetracyclic Isochromanocoumarin-Type Compounds

The three-step one-pot α-arylation-annulation sequence leading to the reaction of 4-hydroxycoumarins with in situ generated 2-(bromomethyl)aryllead triacetates carried out in the presence of a combination of ortho-phenantroline-potassium tert-butoxide afforded tetracyclic benzo[b]pyran compounds in good to high yields.