Enantioselective separation of nonsteroidal anti-inflammatory drugs with amylose tris(3-chloro-5-methylphenylcarbamate) stationary phase in HPLC with a focus on enantiomeric quality control in six pharmaceutical formulations containing racemic mixtures or single stereoisomers

Evaluation of amylose content: Structural and functional properties, analytical techniques, and future prospects

Amylose content (AC) is critical in evaluating starch properties, significantly influencing the food industry and human nutrition. Although amylose is not completely linear, its unique structure makes it a key research focus across various scientific fields. Understanding amylose's structural and functional properties is essential for its applications in medical, nutritional, and industrial sectors. Accurate determination of AC, from simple qualitative assessments to precise quantitative measurements, is vital for effectively processing and using starch-rich products. The choice of AC determination method depends on the specific application and the required accuracy and detail. This review summarizes amylose's structural and functional characteristics and recent advancements in qualitative and quantitative AC determination techniques. It also provides insights into future trends and prospects for these technologies, emphasizing the need for more rapid, convenient, accurate, and customizable methods. In conclusion, advancements in amylose determination should enhance accuracy, speed, and ease of use to improve quality control and applications across various sectors while expanding our understanding of amylose and its functionalities.

Study of the stereospecificity in the biotransformation of the four isomers of loxoprofen sodium in rats by chiral HPLC

Loxoprofen sodium is a chiral drug with two chiral centers. In our previous work, we found that the elimination of its four isomers showed stereospecificity in rats, while how the stereospecific behavior occurred in vivo was unclear. To clarify this issue, each single isomer of loxoprofen sodium was prepared by a chiral semi-preparative high-performance liquid chromatography (HPLC) and then administered to rats. By analysis of each isomer in rat plasma utilizing an analytical chiral HPLC, it was discovered that the chiral inversion occurred only to its (2R)-isomers, one from (1'S,2R)- to (1'S,2S)-isomer and the other from (1'R,2R)- to (1'R,2S)-isomer. The reduction of α-substituted cyclopentanone occurred only to its (1'R)-isomers, with (1'R,2R)-isomer reduced to (2'S,1'R,2R)-trans-alcohol and (1'R,2S)- to (2'S,1'R,2S)-trans-alcohol. Interestingly, both the inversion and the reduction reaction occurred to its (1'R,2R)-isomer due to the special stereo-structure with both (2R)- and (1'R)-configuration, and conversely, neither of them occurred to its (1'S,2S)-isomer, which caused the significantly different elimination rate in vivo. These new findings were meaningful for evaluation of the safety and efficacy of chiral drugs.

Determination of Chiral Impurity of Naproxen in Different Pharmaceutical Formulations Using Polysaccharide-Based Stationary Phases in Reversed-Phased Mode

A novel, validated, reversed-phase (RP), chiral high performance liquid chromatography (HPLC) method was developed for the enantiopurity control analysis of naproxen, a frequently used non-steroidal anti-inflammatory agent using polysaccharide-type chiral stationary phase (CSP). In the screening phase of method development, seven columns were tested in polar organic (PO) mode using mobile phases consisting of 0.1% acetic acid in methanol, ethanol, 2-propanol, and acetonitrile. Enantiorecognition was observed only in five cases. The best enantioseparation was observed on a Lux Amylose-1 column with 0.1% (v/v) acetic acid in ethanol with a resolution (R_s) of 1.24. The enantiomer elution order was unfavorable, as the distomer eluted after the eutomer. When the ethanolic mobile phase was supplemented with water, enantiomer elution order reversal was observed, indicating a difference in the enantiorecognition mechanism upon switching from PO to RP mode. Furthermore, by changing ethanol to methanol, not only lower backpressure, but also higher resolution was obtained. Subsequent method optimization was performed using a face-centered central composite design (FCCD) to achieve higher chiral resolution in a shorter analysis time. Optimized parameters offering baseline separation were as follows: Lux Amylose-1 stationary phase, thermostated at 40 °C, and a mobile phase consisting of methanol:water:acetic acid 85:15:0.1 (v/v/v), delivered with 0.65 mL/min flow rate. Using these optimized parameters, a R_s = 3.21 ± 0.03 was achieved within seven minutes. The optimized method was validated according to the ICH guidelines and successfully applied for the analysis of different pharmaceutical preparations, such as film-coated tablets and gel, as well as fixed-dose combination tablets, containing both naproxen and esomeprazole.

Cellulose tris-(3,5-dimethyl phenyl carbamate) as a chiral stationary phase for enantiomeric determination of ofloxacin enantiomers and molecular docking study on the chiral separation mechanism

The higher the BE value, the harder the enantiomer was to elute, which was in agreement with the enantiomer elution order.