Spectroscopic Study of R- and S-Ketoprofen Inclusion Complexes With 2-Hydroxypropyl-β-cyclodextrin

Ketoprofen, also known as (RS)-2-(3-benzoylphenyl)-propionic acid, has the molecular formula C₁₆H₁₄O₃ and is classified as a non-steroidal anti-inflammatory medication. R-ketoprofen has stronger analgesic effects than S-K, and as a result, there is a growing interest in enantio-recognition research, which may be accomplished through supramolecular interactions, particularly host-guest reactions. A 1:1 molar ratio was used to produce the combination of separate RK and SK and a 0.01 M stock solution of HP-β-CD to get the final concentration of 6 × 10^-4 M. Ethanol was used to make stock solutions of ketoprofen enantiomers (1 mM). Researchers combined a specific volume of ketoprofen with 2-hydroxypropyl-beta-cyclodextrin (HPβ-CD) and then used spectroscopic methods to study how the S-ketoprofen (SK) and R-ketoprofen (RK) enantiomers interact with HPβ-CD to form inclusion complexes in an aqueous solution. The Benesi-Hildebrand plot was used to determine the inclusion complexes' stoichiometry ratio and binding constant; both enantiomers displayed a 1:1 stoichiometry ratio inclusion complex with HP-β-CD. Compared with SK (799 M^-1), RK has a higher binding constant (1038 M^-1). These results showed that HP-β-CD preferred to form inclusion complexes with RK over SK. At neutral pH, there are significant differences between RK and SK when HP-β-CD is present.