Identification and structural elucidation of an oxidation product generated during stability studies of Cabergoline drug product.

Cabergoline is a dopamine agonist with applications as anti-Parkinson drug and prolactin inhibitor. The cabergoline drug product Laktostop® 50 µg/mL is used in veterinary medicine for lactation suppression in cats and dogs e.g. during false pregnancy. Recently, during ongoing HPLC stability testing of Laktostop® 50 µg/mL a new oxidation product of Cabergoline was identified. A synthesis starting from Cabergoline was developed, followed by full characterization of the unknown impurity. Preliminary HPLC and LC-MS analyses indicated the unknown impurity as mono-oxygenated product of Cabergoline (Cabergoline N-oxide) that is presumably formed with oxygen by a radical mechanism. Thus, Cabergoline was treated with oxidizing agents such as m-chloroperoxybenzoic acid to afford the desired Cabergoline-N-oxide as a byproduct. After isolation by column chromatography, NMR and LC-MS-MS studies provided evidence that oxidation occurred at the N-allyl nitrogen of Cabergoline to form Cabergoline-N-oxide. © 1905 Elsevier Science. All rights reserved.

Integrating UPLC-MS/MS with in Silico and in Vitro Screening Accelerates the Discovery of Active Compounds in Stephania epigaea.

Traditional Chinese medicines (TCMs) are popular in clinic because of their safety and efficacy. They contain abundant natural active compounds, which are important sources of new drug discovery. However, how to efficiently identify active compounds from complex ingredients remains a challenge. In this study, a method combining UHPLC-MS/MS characterization and in silico screening was developed to discover compounds with dopamine D2 receptor (D2R) activity in Stephania epigaea (S. epigaea). By combining the compounds identified in S. epigaea by UHPLC-MS/MS with reported compounds, a virtual library of 80 compounds was constructed for in silico screening. Potentially active compounds were chosen based on screening scores and subsequently tested for in vitro activity on a transfected cell line CHO-K1-D2 model using label-free cellular phenotypic assay. Three D2R agonists and five D2R antagonists were identified. (-)-Asimilobine, N-nornuciferine and (-)-roemerine were reported for the first time as D2R agonists, with EC50 values of 0.35 ± 0.04 µM, 1.37 ± 0.10 µM and 0.82 ± 0.22 µM, respectively. Their target specificity was validated by desensitization and antagonism assay. (-)-Isocorypalmine, (-)-tetrahydropalmatine, (-)-discretine, (+)-corydaline and (-)-roemeroline showed strong antagonistic activity on D2R with IC50 values of 92 ± 9.9 nM, 1.73 ± 0.13 µM, 0.34 ± 0.02 µM, 2.09 ± 0.22 µM and 0.85 ± 0.08 µM, respectively. Their kinetic binding profiles were characterized using co-stimulation assay and they were both D2R competitive antagonists. We docked these ligands with human D2R crystal structure and analyzed the structure-activity relationship of aporphine-type D2R agonists and protoberberine-type D2R antagonists. These results would help to elucidate the mechanism of action of S. epigaea for its analgesic and sedative efficacy and benefit for D2R drug design. This study demonstrated the potential of integrating UHPLC-MS/MS with in silico and in vitro screening for accelerating the discovery of active compounds from TCMs.

Dissolving microarray patches loaded with a rotigotine nanosuspension: A potential alternative to Neupro® patch.

Parkinson's disease (PD), affecting about ten million people globally, presents a significant health challenge. Rotigotine (RTG), a dopamine agonist, is currently administered as a transdermal patch (Neupro®) for PD treatment, but the daily application can be burdensome and cause skin irritation. This study introduces a combinatorial approach of dissolving microarray patch (MAP) and nanosuspension (NS) for the transdermal delivery of RTG, offering an alternative to Neupro®. The RTG-NS was formulated using a miniaturized media milling method, resulting in a nano-formulation with a mean particle size of 274.09 ± 7.43 nm, a PDI of 0.17 ± 0.04 and a zeta potential of -15.24 ± 2.86 mV. The in vitro dissolution study revealed an enhanced dissolution rate of the RTG-NS in comparison to the coarse RTG powder, under sink condition. The RTG-NS MAPs, containing a drug layer and a 'drug-free' supporting baseplate, have a drug content of 3.06 ± 0.15 mg/0.5 cm2 and demonstrated greater amount of drug delivered per unit area (∼0.52 mg/0.5 cm2) than Neupro® (∼0.20 mg/1 cm2) in an ex vivo Franz cell study using full-thickness neonatal porcine skin. The in vivo pharmacokinetic studies demonstrated that RTG-NS MAPs, though smaller (2 cm2 for dissolving MAPs and 6 cm2 for Neupro®), delivered drug levels comparable to Neupro®, indicating higher efficiency per unit area. This could potentially avoid unnecessarily high plasma levels after the next dose at 24 h, highlighting the benefits of dissolving MAPs over conventional transdermal patches in PD treatment.

Synthetic aporphine alkaloids are potential therapeutics for Leigh syndrome.

Mitochondrial diseases are mainly caused by dysfunction of mitochondrial respiratory chain complexes and have a variety of genetic variants or phenotypes. There are only a few approved treatments, and fundamental therapies are yet to be developed. Leigh syndrome (LS) is the most severe type of progressive encephalopathy. We previously reported that apomorphine, an anti- "off" agent for Parkinson's disease, has cell-protective activity in patient-derived skin fibroblasts in addition to strong dopamine agonist effect. We obtained 26 apomorphine analogs, synthesized 20 apomorphine derivatives, and determined their anti-cell death effect, dopamine agonist activity, and effects on the mitochondrial function. We found three novel apomorphine derivatives with an active hydroxy group at position 11 of the aporphine framework, with a high anti-cell death effect without emetic dopamine agonist activity. These synthetic aporphine alkaloids are potent therapeutics for mitochondrial diseases without emetic side effects and have the potential to overcome the low bioavailability of apomorphine. Moreover, they have high anti-ferroptotic activity and therefore have potential as a therapeutic agent for diseases related to ferroptosis.

Novedosos agentes dopaminérgicos centrales derivados del 2-aminoindano-4,7 disustituido atípico. Síntesis y perfil farmacológico central / Novel central dopaminergic agents derived from atypical di-substituted 2-aminoindane-4, 7. Synthesis and central pharmacological profile

En las últimas décadas son muchos los compuestos con actividad dopaminérgica central que se han diseñado, sintetizado y evaluado farmacológicamente. A pesar de ello, no se ha logrado obtener un fármaco capaz de mejorar o curar las patologías que involucran la regulación dopaminérgica en el sistema nervioso central tales como la Enfermedad de Parkinson y la esquizofrenia, entre otras. Tomando en consideración el término de “farmacóforo atípico” y a partir del compuesto 5, se incorporó el fragmento aralquil y se sintetizaron los compuestos 10, 11, 13a-h y 14a-h. Tanto los compuestos 10 y 13a-h bajo su forma metoxilada como los compuestos 11 y 14a-h bajo su forma fenólica, fueron evaluados farmacológicamente para determinar su actividad agonística y antagonística sobre el sistema dopaminérgico central. Para ello se determinó el efecto de la inyección intracerebroventricular de dichos compuestos sobre el balance hidromineral y la conducta estereotipada en ratas. Los resultados de la evaluación farmacológica preliminar muestran una acción central a través de mecanismos dopaminérgicos, siendo que los compuestos 10, 11, 13d-h y 14a mostraron respuestas como agonistas, mientras que los compuestos 14b-h, tuvieron respuestas como antagonistas.

In recent decades, many compounds with central dopaminergic activity have been designed, synthesized and evaluated pharmacologically. However, it has not been possible to obtain a drug able to improve or cure diseases involving dopaminergic regulation in the central nervous system, such as Parkinson’s disease and schizophrenia, among others. Taking into consideration the term “atypical pharmacophore” and from the compound 5, the aralkyl fragment was incorporated, and the compounds 10, 11, 13a-h and 14a-h were synthesized. Both the compounds 10 and 13a-h under its methoxylated form and the compounds 11 and 14a-h under the phenolic form, were evaluated to determine their pharmacologically agonistic and antagonistic effects on central dopaminergic activity. For this, the effect of intracerebroventricular injection of said compounds on the hydromineral balance and stereotyped behavior in rats, was determined. The results of the preliminary pharmacological evaluation show a centrally acting action through dopamine mechanisms, in which the compounds 10, 11, 13d-h and 14a showed responses as agonists, whereas compounds 14b-h, had responses as antagonists.