**1. Introduction**

In general, cyclodextrins (CDs) comprise sugar molecules, which are combined together in the form of rings. The sugar molecules that specifically constitute cyclodextrins are "Glucopyranosides," that is, glucose molecules arranged in pyranose configuration. The first indication to a substance that is eventually identified as cyclodextrin was reported in 1891 after Villiers isolated a crystalline substance while working on enzymatic digestion of starch. After Villiers, Schardinger studied these crystalline substances and described the essentials of cyclodextrin molecules known to us in detail [1].

Chemically, cyclodextrin molecules are cyclic oligosaccharides consisting of alpha-14 linked D-glucopyranose units. Depending upon the number of glucopyranosides, cyclodextrin molecules can be categorized as alpha α (6), beta β (7), and gamma γ (8) cyclodextrins, respectively (**Figure 1**) [3].

As complicated as they sound, the CDs are comparatively easy to constitute. Like discussed above, cyclodextrins are typically obtained by treating starch with a variety of enzymes notably amylase or glucosyl transferases. Similar to the enzymes, sources of starch can also be variable resulting in particular ratio of α, β, and γ cyclodextrins [4].

**Figure 1.** *Chemical structure of the α-, β-, and γ-cyclodextrins [2].*

Furthermore, the CD molecules are large, but owing to stoichiometric constraints, it is not possible to acquire smaller CD molecules having less than six glucopyranosides residues. In contrast, those with higher glucose residues have been reported though concerns such as poor yield, and limited complexing ability renders them unacceptable for pharmaceutical use [5].
