Scope of partial least-squares regression applied to the enantiomeric composition determination of ketoprofen from strongly overlapped chromatographic profiles

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.

Method to evaluate the quality of herbal medicines based on the dynamic changes of chemical compounds and pharmacological activity

Quality control has been one of the key scientific issues in the modernization of traditional Chinese medicine. This study explored a novel method for quality evaluation of herbal medicines. High-performance liquid chromatography fingerprints and the osteoblast proliferation activity of 18 batches of Achyranthes bidentata, which were prepared with salt, were determined to establish a chromatographic database and an activity database. Correlation analyses of these databases were performed using partial least squares to obtain regression coefficients (positive and negative correlation coefficients). Then, the sums of the products of the positive and negative correlation peak areas and the corresponding coefficients, respectively, were calculated for each sample. The absolute value of the ratios of the sums of the positive and negative products were calculated, our studies showed that this ratio was significantly correlated with the proliferation activity, particularly when the activity was in the best and worst ranges. Therefore, we developed a parameter that was used to evaluate the quality of samples osteoblast proliferation activity. The quality of another ten batches of samples was assessed to verify this method. The results indicated that this method can be used for quality evaluation of herbal medicines according to the dynamic changes in the chemical compounds and activity.