Sequential Injection Chromatography with Monolithic Column for Phenothiazines Assay in Human Urine and Pharmaceutical Formulations

Methods:

Sequential injection chromatography (SIC) with monolithic column has been proposed with potential benefits for separation and quantification.

Objective:

To utilize SIC to develop a new assay method for the separation and quantification of some phenothiazines (promethazine, chlorpromazine and perphenazine) in human urine and synthetic pharmaceutical formulations.

Methods:

The 32 full-factorial design was adopted to study the effect of mobile phase composition on separation efficiency, retention time, peak height and baseline. The separation was conducted on a C18 monolithic column (100 × 4.6 mm) using a mobile phase composition of phosphate: acetonitrile:methanol (60:28:12) at pH 4.0. The detection was carried out using a miniaturized fiber optic spectrometer at 250 nm.

Results:

Satisfactory analytical features, including number of theoretical plates (1809-6232), peak symmetry (1.0-1.3), recovery (95.5-99.1% in pharmaceutical formulations and 91.6-94.7% in urine), intra-day precision (0.36-1.60% for pharmaceutical formulation and 2.96-3.67 for urine), inter-day precision (1.47-2.28% for pharmaceutical formulation), limits of detection (0.23-0.88 μg/ml) and limits of quantification (0.77-2.90 μg/ml), were obtained.

Conclusion:

The remarkable advantages of the proposed SIC method are the inexpensiveness in terms of instrumentation and reagent consumption.

Evaluation of Phytochemicals, Antioxidants, Trace Elements in Kigelia africana Fruit Extracts and Chemical Profiling Analysis Using UHPLC-qTOF-MS2 Spectrometry

The study aimed at evaluating the phytochemical composition, antioxidant potentials and the levels of trace elements in the fruit extract of Kigelia africana obtained by different extraction solvents in order to ascertain its numerous pharmacological activities and identify the different chemical compounds responsible for these activities. The crude extract in ethanol and four other solvent fractions (hexane, ethylacetate, butanol and aqueous) were obtained for phytochemical screening. Antioxidant potentials of K. africana fruit were investigated spectrophotometrically using hydroxyl ion scavenging (OH^-) activity, metal ion chelating activity, anti-lipid peroxidation activity as well as total antioxidant capacity assays. Trace element (Mn, Zn, Cd, Ni, Cu, Pb, Cr, Co and Fe) levels were measured using a plasma-emission spectrometer that has an auto sampler AS 93-plus and coupled with Nebulizer CETAC U-6000AT⁺ after microwave acid digestion of the fruit extracts. Chemical identification was performed using ultra-high-pressure liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UHPLC-qTOF-MS²). Kigelia africana fruit extracts obtained showed a variety of bioactive phytochemical compounds including phenolic acids, flavonoids, saponins, tannins and glycosides. The total antioxidant capacity activities of the aqueous, butanol, ethanol, hexane and ethylacetate extracts are 15.04, 52.11, 44.95, 79.27 and 175.20 mg AAE/g. Metal ion chelating activity showed significant correlation with lipid peroxidation inhibition activity at p ≤ 0.01 and with OH^- scavenging activity at p ≤ 0.05. PCA analysis revealed that all the extract/fractions have higher total antioxidant activities compared to aqueous extract with hexane extract exhibiting the highest radical scavenging potential. HCA showed similarities with three well-defined clusters and PLS regression was used to predict total antioxidant activity. High sensitivity by low values of limits of detection and quantification was observed ranging from 0.021 to 0.085 mg/ml and 0.063 to 0.258 mg/ml for Zn and Fe respectively. Ethylacetate extract had high concentration of Fe (0.5656 mg/kg). For the standardization of the K. africana fruit extract, 244 chemical compounds were identified by measuring m/z values with threshold override of 100,000 and analysing mass spectrometer fragmentation behaviour while 16 of these were confirmed. Kigelia africana fruit extract is a good source of antioxidant and possess maximum accepted concentration of trace elements according to European legislation (1881/2006/EC). The metabolites identified exhibited numerous pharmacological activities. The method and results suggest the applicability for commercial use of this K. africana fruit in the treatment of oxidative-related diseases. Graphical abstract The phytochemical, antioxidant and trace element composition of crude ethanol extract, hexane, butanol, aqueous and ethylacetate extracts of Kigelia africana fruit were determined. The fruit extracts were found to possess good antioxidant activity, maximum acceptable amount of essential trace elements as well as the presence of bioactive phytochemicals. K. africana fruit would be an ideal candidate in improving human health and thus the management of oxidative-related diseases such as diabetes, by involving in the antioxidant defense system against free radical generation.