Honey extracts inhibit PTP1B, upregulate insulin receptor expression, and enhance glucose uptake in human HepG2 cells.

Honey is a food known for its medical properties. In this work, we have studied the impact of different types of honey on insulin signalling pathway. We found that honey extracts inhibit the enzyme PTP1B, one of the main negative regulators of insulin receptor signalling. HPLC-MS analysis allowed us to confirm the presence of several natural PTP1B inhibitors in the honey extracts analysed. Statistical analysis methods show a correlation between specific 1H-NMR resonance frequencies/HPLC peaks and the inhibitory power of the samples. This finding will allow the prediction of the biological properties of honey samples applying relative simple analytical methods. Finally, we demonstrated that the treatment of HepG2 cells with honey extracts enhances the expression of insulin receptor, and stimulates glucose uptake. For the first time, our results demonstrate that bioactive components of honey could improve glycaemic control by both inhibiting PTP1B and stimulating the expression of insulin receptor in liver cells.

FILO (field interaction ligand optimization): a simplex strategy for searching the optimal ligand interaction field in drug design.

A method (FILO, Field Interaction Ligand Optimization) for obtaining the optimal molecular interaction field was developed on the basis of the Simplex optimization procedure applied to a matrix of interaction energies obtained by performing a GRID computation on a suitable data set. The FILO procedure was tested on a set of nine HIV-1 protease inhibitors with known crystal structures. The results of FILO consist of the optimal molecular interaction field of a putative new ligand with optimal binding affinity. The final FILO model yields R2 and R2(CV) values of 0.993 and 0.936, respectively, and finds eight negative and four positive interaction nodes for the OH probe taken as an example. The eight H bonding interactions pointed out by FILO identified well the binding site AA-residues Gly A27, Asp A29, water 501, Gly B48 and Asp A25 of HIV-1 protease.

1H-NMR and molecular modelling techniques for the investigation of the inclusion complex of econazole with alpha-cyclodextrin in the presence of malic acid.

Carrying on a study where the combination of alpha-cyclodextrin and malic acid was found to be the most effective in improving the solubility of econazole, an antifungal drug very poorly water soluble, in the present work 1H-NMR and nuclear overhauser effect (NOE) experiments and molecular modelling studies were performed to gain insight into the interactions in solution between such three components and the structure of the supposed multicomponent complex. Findings demonstrated that two different complexes can be simultaneously present in solution involving, respectively, the inclusion of econazole monochloro-phenyl group within the host cavity from the primary hydroxyl side of the cyclodextrin cavity, or that of the other phenyl group through the opposite side of the cavity. It was shown that also malic acid is strictly involved in the molecular assembly of the complex, particularly through interactions with primary hydroxyl groups of the cyclodextrin molecule. Molecular modelling studies allowed to elaborate possible geometric models of the multicomponent complex and to select the more energetically favourable conformations which complied better with experimental data. Results suggested the possible formation in solution of stable oligomeric aggregates constituted by the repeated concatenation of the three components.

Interaction of naproxen with alpha-cyclodextrin and its noncyclic analog maltohexaose.

PURPOSE: To study the effect of mechanical grinding on crystallinity changes of naproxen (NAP) in mixtures with alpha-cyclodextrin (alphaCd), amorphous alphaCd, and maltohexaose (M6); and the possible formation of a pseudo-inclusion complex between NAP and M6 in aqueous solution. METHODS: NAP-additive physical mixtures at 0.30, 0.18, and 0.10 mass fraction of drug were tested, after increasing grinding times, by differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRD). Interaction in aqueous solution was examined by phase-solubility and fluorescence analyses supported by molecular modelling. RESULTS: In the mixtures with each additive the fusion enthalpy per unit mass of NAP decreased and the half width at half maximum of selected X-ray diffraction peaks of NAP increased with the progress of grinding time following the loss of crystallinity of the samples. The mechanical treatment apparently did not affect the chemical integrity of the drug. Particularly active in the equimolar mixture was the best amorphizing agent, M6. Solution studies and molecular modelling confirmed M6 may have the feature of a supermolecule for NAP, which forms a 1:1 pseudo-inclusion complex that was as stable as the true inclusion complex with alphaCd. CONCLUSIONS: The intrinsically amorphous linear analog of aCd might be a potential amorphism-inducing agent and solubilizer for scarcely water soluble drugs.

Synthesis and A1 and A2A adenosine binding activity of some pyrano[2,3-c]pyrazol-4-ones.

A series of pyrano[2,3-c]pyrazol-4-ones was synthesized and evaluated for bovine brain adenosine A1 and A2A receptor binding affinity. Substituents at positions 5 and/or 6 were varied in order to define the structure-activity relationships in these new kinds of adenosine receptor ligands. The most selective and potent ligand among the reported compounds was the 1,4-dihydro-1-phenyl-3-methyl-6-(3-aminophenyl)-pyrano[2,3-c]pyraz ol-4-one 11 which showed a 27-fold selectivity for A1 receptor and a Ki value of 84 nM.

Structure-activity relationships of 1,2,4-triazolo[1,5-a] quinoxalines and their 1-deaza analogues imidazo[1,2-a]quinoxalines at the benzodiazepine receptor.

The synthesis, BZR binding activity, and GABA ratio of some 1,2,4-triazolo[1,5-a]quinoxalines and imidazo[1,2-a]quinoxalines are reported. Both series of compounds displayed similar affinities while their efficacies were different. The structure-activity relationships have provided the opportunity to localize on the BZR accessory areas which are able to enhance the affinity and evaluate the importance of the presence or absence of a proton acceptor atom to determine different trends of efficacy.

Tricyclic heteroaromatic systems 1,2,4-triazolo[1,5-a]quinoxalines: synthesis and benzodiazepine receptor activity.

The synthesis, the benzodiazepine binding activity and the "in vitro" biological effect of some 1,2,4-triazolo[1,5-a]quinoxalines, 3-aza-analogues of some previously reported pyrazolo[1,5-a]quinoxalines, are described. Molecular modelling is used to define the structural requirements of the benzodiazepine recognition site which influence the affinity and different efficacy of these rigid ligands.

Reaction of 1-aminophthalazines with alpha-halocarbonyl compounds: imidazo[2,1-a]phthalazines and their benzodiazepine receptor activities.

The one-pot synthesis and the benzodiazepine receptor binding activity of some imidazo[2,1-a]phthalazines bearing different substituents at position-2 and/or 3 and/or 6 is reported. The dissimilar binding results of the reported compounds are discussed in relation to the nature and/or position of the substituents on the tricyclic ring system.

Novel adenosine receptor ligands: 1,3-disubstituted[1]benzopyrano[2,3-c]pyrazol-4-ones. Synthesis and structure-activity relationships.

A series of 1,3-disubstituted[1]benzopyrano[2,3-c]pyrazol-4-ones were synthesized and tested in vitro as A1 and A2 adenosine receptor ligands. The binding results and a molecular modelling study indicated that the presence of a proton donor group in the N6-H region of adenosine and the 7-NH region of xanthine, respectively and occupancy of the A2 lipophilic area by a moiety endowed with an electrostatic effect are essential for receptor affinity and A2-selectivity.

Tricyclic heteroaromatic systems. Synthesis and benzodiazepine binding activity of 1-substituted-3-methyl- and 3-phenylpyrazolo[4,5-c]quinolin-4-ones.

The synthesis and the benzodiazepine binding activity of some 3-methyl- and 3-phenylpyrazolo[4,5-c]quinolin-4-ones bearing a heterocyclic or a substituent which is different from an aryl moiety at position-1 are reported. Molecular modelling is used to correlate the binding affinity to the chemical features and to justify the reduced receptor affinities of the reported compounds with respect to that of CGS 8216 which is taken as the lead compound.

Carbon-13 nuclear magnetic resonance study of naproxen interaction with cyclodextrins in solution.

Changes in naproxen (NAP) 13C-chemical shifts were measured as a function of the concentration of alpha-, beta-, and gamma-cyclodextrin (alpha Cd, beta Cd, and gamma Cd, respectively) in aqueous solution in order to obtain details on the mechanism, geometry, and stoichiometry of the respective interactions. The probable structures of the inclusion compounds of NAP with natural cyclodextrins were constructed using a molecular graphics program. The higher stability of the beta Cd:NAP 1:1 (mol/mol) complex in comparison with alpha Cd:NAP 2:1 (mol/mol) and gamma Cd:NAP 1:1 or 1:2 (mol/mol) complexes was accounted for in terms of a deeper, more complete, and better fitting inclusion of the drug into the cavity of beta Cd. The inclusion behavior of NAP with some statistically substituted beta Cd derivatives [hydroxyethyl-beta Cd (HE beta Cd), hydroxypropyl-beta Cd (HP beta Cd), and methyl-beta Cd (M beta Cd)] was also investigated through 13C-NMR, UV, circular dichroism spectroscopy, and phase-solubility analysis. The stoichiometry of host:guest interactions was the same as with beta Cd, as were thermodynamics and basic complexation mechanisms. The binding between the host and guest molecules is thought to be mainly due to van der Waals, dipole-dipole, and hydrophobic interactions. The inclusion ability of the parent beta Cd was enhanced by the introduction of methyl, hydroxyethyl, and hydroxypropyl groups. The M beta Cd formed the most stable inclusion complex (apparent formation constant K(1:1) = 6892 L.mol-1 at 298 K); it was about three times more stable than those with HP beta Cd or HE beta Cd and four times more stable than that with beta Cd.(ABSTRACT TRUNCATED AT 250 WORDS)

Tricyclic heteroaromatic systems. Synthesis of 1,3 and 1,2 disubstituted [1]benzopyrano[4,3-b]pyrrol-4-ones and structure-activity relationships as benzodiazepine receptor ligands.

The synthesis of some 1,3- and 1,2- disubstituted [1]benzopyrano-pyrrol-4-ones is reported as well as their benzodiazepine receptor affinity, as measured by the ability to displace [3H]flunitrazepam from its specific central binding. The structure-activity relationships on the whole series of disubstituted [1]benzopyrano-pyrrol-4-ones show the importance of the presence of the 1-aryl substituent and the size limitation of the 3-substituent. The size of the latter seems also to be important for the "in vitro" efficacy.

Tricyclic heteroaromatic systems: [1]benzopyrano-pyrazol-4-ones as benzodiazepine receptor ligands.

The synthesis of a series of 8-substituted 1,4-dihydro-1-aryl-3-methyl-[1]benzopyrano[3,4-d]pyrazol-4-ones (series 7) 2,4-dihydro-2-aryl-3-methyl[1]benzopyrano[4,3-c]pyrazol-4-ones (series 8) is reported. Compounds of series 7 and 8 were tested for their ability to displace [3H]flunitrazepam from bovine brain membranes and for their in vitro biological activity. The results allowed some conclusions to be drawn about the structural requirements of the benzodiazepine recognition site within this class of unusual ligands.

Tricyclic heteroaromatic systems. [1]benzopyranopyrrol-4-ones and [1]benzopyrano-1,2,3-triazol-4-ones as benzodiazepine receptor ligands. Synthesis and structure-activity relationships.

The synthesis, ability to displace [3H]flunitrazepam binding from bovine brain membranes, and GABA ratio of some [1]benzopyranopyrroles 1a-i and [1]benzopyrano-1,2,3-triazoles 2a,b are reported. The GABA ratios of some previously synthesized pyrazoloquinolines A and [1]benzopyranopyrazoles C are also presented in order to draw some structure-activity relationships among our benzodiazepine receptor ligands. 1,3-Diarylpyrrole derivatives 1a-h show similar affinity and efficacy to that of diazepam, while the 1-aryltriazoles 2a,b have no receptor affinity. Comparison of the latter results with those on previously reported compounds suggests that there are several hydrophobic regions on the benzodiazepine recognition site whose occupation gives rise to different affinity and efficacy.

Dipyrazolo[5,4-b:3',4'-d]pyridines. Synthesis, inhibition of benzodiazepine receptor binding and structure-activity relationships.

Some 2,6,8-trisubstituted dipyrazolo[5,4-b:3',4'-d]pyridin-3-ones related to the CGS series were synthesized and tested for their ability to displace [3H]flunitrazepam binding from bovine brain membranes. However the affinity for the benzodiazepine receptor of the tested compounds was lower than that of the CGS series, although it was comparable to that of chlordiazepoxide. It follows that some structure-activity relationships on the tested compounds can be drawn.

Synthesis of 1,5-diaryl-3-methyl-1H-pyrazolo[4,5-c]isoquinolines and studies of binding to specific peripheral benzodiazepine binding sites.

Some 1,5-diaryl-3-methyl-1H-pyrazolo[4,5-c]isoquinolines were synthesized and tested for their ability to displace [3H]clonazepam or [3H]Ro 5-4864 from their specific binding on the central and peripheral benzodiazepine receptors. None of the tested compounds showed any activity as central binding inhibitors, while most of them were specific as peripheral binding inhibitors, although they were not very potent.

Tricyclic heteroaromatic systems: synthesis, [3H]flunitrazepam brain membrane binding inhibition, and structure-activity relationships of 2,3-dihydro-2-aryl-4-R-[1]benzopyrano[4,3-c]pyrazole-3-ones.

We report the synthesis and binding activity to the central benzodiazepine receptors of some 2,3-dihydro-2-aryl-4-R-[1]benzopyrano[4,3-c]pyrazole-3-ones, which are isosteres of the CGS series. Although the compounds of the CGS series are potent ligands of the benzodiazepine receptors, none of the isosteres tested showed any significant inhibiting potency. This may be due to the change in electronic properties brought about by the replacement of the NH of the CGS series with an oxygen atom.

1,3-Diarylpyrazolo[4,5-c]- and -[5,4-c]quinolin-4-ones. 4. Synthesis and specific inhibition of benzodiazepine receptor binding.

A series of 1,3-diarylpyrazolo[4,5-c]- and -[5,4-c]quinolin-4-ones were prepared and tested for their ability to displace [3H]flunitrazepam from bovine brain membranes. While the 1,3-diarylpyrazolo[4,5-c]quinoline derivatives showed affinity for the receptor site, their [5,4-c] isomers were devoid of binding activity.

Synthesis and binding study on pyrazolo[4,5-c] [1,8]naphthyridines.

Following our previous reports on pyrazolo[4,5-c]quinoline derivatives some isosteric pyrazolo[4,5-c] [1,8]naphthyridines were synthesized and tested for their ability to displace [3H]flunitrazepam from rat brain membranes. The lack of activity of the synthesized compounds and structure-activity relationships for the whole series are discussed.