Structure elucidation of a process-related impurity of dapoxetine

Unknown by-product associated with the synthesis of dapoxetine was isolated. The structure elucidation of this new compound using accurate mass data and NMR spectroscopy is presented herein. The unambiguous resonance assignment concluded to the formation of a tricyclic compound 4-phenyl-2H,3H,4H-naphtho[1,2-b]pyran, a new impurity of dapoxetine which has never been reported previously. A proposed mechanism for the formation of the new carbon-carbon bond is discussed. For the separation of dapoxetine and the process-related impurities, a gradient HPLC method was developed.

Characterisation of diarylheptanoid- and flavonoid-type phenolics in Corylus avellana L. leaves and bark by HPLC/DAD-ESI/MS

INTRODUCTION

The leaves of Corylus avellana L. (common hazel, Betulaceae), a plant with a wide distribution in Europe, have been used in folk medicine for various diseases, but phytochemical exploration of C. avellana is still incomplete. To the best of our knowledge there is no previous report concerning diarylheptanoids in C. avellana, although these compounds show a frequent occurrence among Betulaceae plants.

OBJECTIVE

To improve existing online chromatographic methods for the investigation of the phenolic compounds in C. avellana leaves and bark, focusing on diarylheptanoid-type molecules.

METHODS

Dried and powdered leaves and bark of C. avellana were extracted with increasing polarity solvents (n-hexane, chloroform, ethyl acetate and methanol) in Soxhlet extractor apparatus. For the characterisation of the phenolic compounds in the ethyl acetate and methanolic extracts, UV spectral data, obtained by LC with a diode-array detector (DAD), accurate molecular mass and formula, acquired by LC and electrospray ionisation (ESI) with time-of-flight (TOF) MS and fragmentation pattern, given by LC-ESI/MS/MS analyses were used. Quantitation of the compounds was performed by LC-MS/MS.

RESULTS

In the methanolic and ethyl acetate extracts of C. avellana bark four flavonoid glycosides and a caffeoyl hexoside derivative were detected and characterised, while in C. avellana leaves, seven diarylheptanoid-type molecules were tentatively identified in addition to six flavonoid components. As far as we know this is the first study where the presence of diarylheptanoids in C. avellana is reported.

CONCLUSION

The improved HPLC/DAD-ESI/MS method was successfully utilised for the characterisation and quantitation of the phenolic compounds in C. avellana bark and leaves extracts.

Spinal interaction between the highly selective μ agonist DAMGO and several δ opioid receptor ligands in naive and morphine-tolerant mice

Since the discovery of opioid receptor dimers their possible roles in opioid actions were intensively investigated. Here we suggest a mechanism that may involve the μ-δ opioid heterodimers. The exact role of δ opioid receptors in antinociception and in the development of opioid tolerance is still unclear. While receptor up-regulation can be observed during the development of opioid tolerance no μ receptor down-regulation could be detected within five days. In our present work we investigated how the selective δ opioid receptor agonists and antagonists influence the antinociceptive effect of the selective μ receptor agonist DAMGO in naïve and morphine-tolerant mice. We treated male NMRI mice with 200 μmol/kg subcutaneous (s.c.) morphine twice daily for three days. On the fourth day we measured the antinociceptive effect of DAMGO alone and combined with delta ligands: DPDPE, deltorphin II (agonists), TIPP and TICPψ (antagonists), respectively, administered intrathecally (i.t.) in mouse tail-flick test. In naive control mice none of the δ ligands caused significant changes in the antinociceptive action of DAMGO. The treatment with s.c. morphine resulted in approximately four-fold tolerance to i.t. DAMGO, i.e. the ED₅₀ value of DAMGO was four times as high as in naive mice. 500 and 1000 pmol/mouse of the δ₁ selective agonist DPDPE enhanced the tolerance to DAMGO while 1000 pmol/mouse of the δ₂ selective agonist deltorphin II did not influence the degree of tolerance. However, both δ antagonists TIPP and TICPψ potentiated the antinociceptive effect of i.t. DAMGO, thus they restored the potency of DAMGO to the control level. The inhibitory action of DPDPE against the antinociceptive effect of DAMGO could be antagonized by TIPP and TICPψ. We hypothesize that during the development of morphine tolerance the formation of μδ heterodimers may contribute to the spinal opioid tolerance. δ ligands may affect the dimer formation differently. Those, like DPDPE may facilitate the dimer formation hence inhibit the antinociceptive effect of DAMGO by causing virtual μ receptor down-regulation. Ligands that do not affect the dimer formation do not influence antinociception either but ligands with the presumed capability of disconnecting the dimers may decrease the spinal tolerance to DAMGO.

Mitochondrial D-loop analysis reveals low diversity in Mangalica pigs and their relationship to historical specimens

The genetic relationship between 195 Mangalica and 79 non-Mangalica pigs was studied using mitochondrial D-loop SNP genotyping. Altogether, 35 polymorphic sites and 27 haplotypes were identified. Of the haplotypes, eight and 16 are Mangalica and non-Mangalica specific, respectively, while three contain both Mangalica and non-Mangalica individuals. Genetic distance values and phylogenetic analysis indicate that Mangalica individuals are very closely related, and five haplotypes represent approximately 92% of the Mangalica pigs involved in the study, thus determining the major maternal lineages. In contrast to previous microsatellite studies, individuals of Mangalica could not be distinguished as three separate breeds using mtDNA genotyping. Comparing modern and archaeological mtDNA sequences revealed that present day Mangalica is related to pigs that lived in the Carpathian basin where postulated ancestors of Mangalica also lived. This is the first DNA-based genetic evidence to support the described breeding history of Mangalica.

Chiral recognition of dapoxetine enantiomers with methylated-gamma-cyclodextrin: a validated capillary electrophoresis method

The enantiomers of dapoxetine, a serotonin transporter inhibitor for the treatment of premature ejaculation have been separated by cyclodextrin modified capillary zone electrophoresis using uncoated fused-silica capillary. Over 20 cyclodextrins were screened as chiral selectors, investigating the stability of the inclusion complexes and enantioseparating properties. According to the preliminary experiments as chiral selector randomly methylated-γ-cyclodextrin was chosen. The basic chemical and instrumental parameters of enantioseparation as concentration of buffer, chiral selector and organic additive, pH, temperature and applied voltage were optimized afterwards using an orthogonal experimental design. Using this methodology not only the optimal parameter values for chiral separation (15 °C, +15 kV, 70 mM acetate, 20 v/v% MeOH, pH*=4.5, 3 mM methylated-γ-CyD) but also the significance order of factors on resolution was determined. Applying these parameters an optimal resolution of 7.01 was achieved. The optimized method was then validated according to the ICH guideline Q2 (R1) with regard to repeatability, linearity range, LOD, LOQ, accuracy and robustness.

Anxiolytic action of urocortin 3 fragments in mice

In the present experiments, the anxiolytic action of Ucn 3 fragments were studied in an elevated plus maze in mice following icv administration in an attempt to identify the biologically active center of the molecule. Ucn 3, Ucn 3 (18-38), Ucn 3 (19-27), Ucn 3 (28-38), Ucn 3 (34-38), and Ucn 3 (36-38) but not Ucn 3 (34-36), demonstrated anxiolytic action by increasing the time the mice spent in open arms, and Ucn 3 and Ucn 3 (34-38) did so by increasing the number of entries into open arms. The shortest molecule which elicited anxiolytic effects was the tripeptide Ucn 3 (36-38), H-Ala-Gln-Ile-NH(2). The results indicate that the total sequence of Ucn 3 is not necessary for the anxiolytic action of Ucn 3. Establishment the smallest active sequence of Ucn 3 will allow the synthesis of analogs or mimetics for anxiolytic action.

Antidepressant-like effects of urocortin 3 fragments

Urocortin 3 (Ucn 3) and various Ucn 3 fragments were tested with regard to antidepressive action in a modified forced swimming test following icv administration to mice. The fragment Ucn 3 (34-36) proved ineffective, whereas Ucn 3 (18-38), Ucn 3 (19-27), Ucn 3 (28-38), Ucn 3 (34-38), and Ucn 3 (36-38) demonstrated antidepressive-like action by shortening the immobility time and increasing the climbing and swimming times. The shortest molecule which elicited most of the antidepressive effects was the tripeptide Ucn 3 (36-38), H-Ala-Gln-Ile-NH(2). The results indicate that the total sequence of Ucn 3 is not necessary for the antidepressive action of Ucn 3. Furthermore, the antidepressant actions of Unc3 (19-27) and Ucn 3 (36-38) can be blocked by the CRF2 receptor antagonist Astressin 2β. Establishment of the smallest active sequence of the molecule may allow the synthesis of analogs or mimetics for antidepressive drugs.

Permutationally invariant quantum tomography

We present a scalable method for the tomography of large multiqubit quantum registers. It acquires information about the permutationally invariant part of the density operator, which is a good approximation to the true state in many relevant cases. Our method gives the best measurement strategy to minimize the experimental effort as well as the uncertainties of the reconstructed density matrix. We apply our method to the experimental tomography of a photonic four-qubit symmetric Dicke state.