Enantiomeric separation of amlodipine and its two chiral impurities by nano-liquid chromatography and capillary electrochromatography using a chiral stationary phase based on cellulose tris(4-chloro-3-methylphenylcarbamate).

In this work, a novel polysaccharide-based chiral stationary phase, cellulose tris(4-chloro-3-methylphenylcarbamate), also called Sepapak 4 has been evaluated for the chiral separation of amlodipine (AML) and its two impurities. AML is a powerful vasodilatator drug used for the treatment of hypertension. Capillary columns of 100 µm id packed with the chiral stationary phase were used for both nano-LC and CEC experiments. The optimization of the mobile phase composed of ACN/water, (90:10, v/v) containing 15 mM ammonium borate pH 10.0 in nano-LC allowed the chiral separation of AML and the two impurities, but not in a single run. With the purpose to obtain the separation of the three pairs of enantiomers simultaneously, CEC analyses were performed in the same conditions achieving better enantioresolution and higher separation efficiencies for each compound. To fully resolve the mixture of six enantiomers, parameters such as buffer pH and concentration sample injection have been then investigated. A mixture of ACN/water (90:10, v/v) containing 5 mM ammonium borate buffer pH 9.0 enabled the complete separation of the three couples of enantiomers in less than 30 min. The optimized CEC method was therefore validated and applied to the analysis of pharmaceutical formulation declared to contain only AML racemate.

Antiallergic and antihistaminic effect of two extracts of Capparis spinosa L. flowering buds.

The antiallergic properties of two lyophilized extracts obtained from Capparis spinosa L. flowering buds (capers) by methanol extraction, carried out at room temperature (CAP-C) or with heating at 60 degrees C (CAP-H), were investigated. The protective effects of CAP-H and CAP-C, orally administered (14.28 mg[sol ]kg), were evaluated against Oleaceae antigen challenge-induced and histamine-induced bronchospasm in anaesthetized guinea-pigs. Furthermore, the histamine skin prick test was performed on humans, applying a gel formulation containing 2% CAP-C (the only extract able to protect against histamine-induced bronchospasm) on the skin for 1 h before histamine application and monitoring the erythema by reflectance spectrophotometry. The CAP-H showed a good protective effect against the bronchospasm induced by antigen challenge in sensitized guinea-pigs; conversely, a significant decrease in the responsiveness to histamine was seen only in CAP-C pretreated animals. Finally, the CAP-C gel formulation possessed a marked inhibitory effect (46.07%) against histamine-induced skin erythema. These two caper extracts displayed marked antiallergic effectiveness; however, the protective effect of CAP-H was very likely due to an indirect mechanism (for example, inhibition of mediator release from mast cells or production of arachidonic acid metabolites); conversely, CAP-C is endowed with direct antihistaminic properties. The different mechanisms of action of CAP-H and CAP-C may be related to a difference in the extraction procedure and, thus, in their qualitative[sol ]quantitative chemical profile.