The word chiral is derived from “chir,” the Greek word for “hand.” It refers to the phenomenon of mirror images frequently found in nature; hands, eyes, and feet are identical opposites, or mirror images, of each other.
Many pharmaceutical products are “racemic” compounds: pairs of molecules known as “enantiomers,” whose structures are mirror images. Often, one enantiomer offers the desired therapeutic effect, while the other is ineffective or causes side effects. Many new pharmaceuticals and agrochemicals are single enantiomers. This can reduce the therapeutic dosage by half, improve efficacy, and may eliminate detrimental effects caused by the undesired enantiomer.
Professor Yoshio Okamoto of Nagoya University in Japan was conducting research in the field of synthetic optically active polymers in the 1980s when he invented polysaccharide-derived chiral stationary phases (CSPs). Daicel Corporation commercialized Prof. Okamoto’s invention, which is the foundation of the highly successful and widely used Daicel CSPs – Chiral Technologies’ core technology.
The chromatography of chiral molecules is a simple and elegant technique for rapid isolation of enantiomers of high purity. The chromatography of enantiomers relies on the availability of chiral stationary phases specifically designed to separate chiral molecules since their enantiomers have the same physical and chemical properties but different spatial orientations. Polysaccharide polymers form helical structures and can be derivatized to incorporate a number of functional chemical groups to provide a wide range of enantiorecognition for chiral compounds.
Enantioselective recognition can be attributed to the combination of two main phenomena: specific interactions between the enantiomers and the derivatized moieties of the polysaccharide derivatives and steric fitting of the enantiomers to the polymer grooves. The recognition would be modulated based on the type of polysaccharide backbone, its derivatization, as well as its 3D-conformation in the given mobile phase media.
In the last two decades, CSPs have become readily available. Daicel CSPs are the most widely employed stationary phases in the pharmaceutical industry to isolate pure enantiomers.