Use of cyclodextrins to improve the production of plant bioactive compounds

Cyclodextrins are cyclic oligosaccharides consisting ofd-glucopyranose units bound via alpha-(1,4)-glycosidic linkages. They are obtained from starch enzymatic degradation by the action of cyclodextrinases or glycosyltransferases. Among the modified-cyclodextrins, 2-hydroxypropylated and methylated beta-cyclodextrins are produced on industrial scale. Particularly, methylated beta-cyclodextrins are more suitable than native beta-cyclodextrins to form stable inclusion complexes with organic molecules of low molecular weight, making these complexes more soluble in aqueous solutions. Cyclodextrins have often been considered useful carriers of antitumor- and immuno-regulatory drugs, and they have also been used as additives for food industry. It is also important to note that cyclodextrins are used for improving bioactive compound production in plant cell cultures because of cyclodextrins ability as hosts of bioactive compounds favoring their accumulation in aqueous media. In fact, the treatment of plant cell cultures with cyclodextrins and their derivatives increases the production of secondary metabolites such as resveratrol, ajmalicine, serpentine, lutein, arachidin, among other antioxidant compounds, enhancing the capability of plant in vitro cultures to produce high levels of different bioactive compounds which have beneficial properties for human health. In addition, metabolomic, transcriptomic, and proteomic studies have been carried out on both control and cyclodextrins-treated cell cultures offering important clues about how cyclodextrins are capable of substantially increasing the production of bioactive compounds in plant in vitro cultures. This review focuses on the effect of cyclodextrins on both bioactive compound production and their accumulation, which could be of great interest for chemical and pharmaceutical industries.