Encapsulation of two distinct Cistus essential oils in β- and γ-cyclodextrins

Cistus shrubs are aromatic with terpene-rich antimicrobial essential oils that are used as food and cosmetic ingredients. Cistus creticus L. is native to Greece while C. ladanifer L. grows in the Western Mediterranean. Essential oil encapsulation protects the volatiles from degradation and reduces their volatility. Cyclodextrins increase their water solubility, as well. The aim of this study was the investigation of the chemical composition of commercially available essential oils of C. creticus and C. ladanider, and their encapsulation efficiency in β- and γ-cyclodextrins. GC-MS analysis showed that the oil of C. creticus comprised mainly of sesquiterpenes (48%) and diterpenes (> 18%), whereas monoterpenes were only 10%. C. ladanifer essential oil contained mostly monoterpenes (70%); sesquiterpenes constituted 22% and diterpenes less than 1%. The main ingredient in C. creticus oil was manoyl oxide, while in C. ladanifer, α-pinene. The percentages of the C. creticus and C. ladanifer oils encapsulated in γ-cyclodextrin (89 and 87%, respectively) were higher than those in β-cyclodextrin (73 and 79%). In addition, the determination of surface oils revealed that the monoterpene-rich oil was entirely trapped in cyclodextrinsʼ cavity, whereas a significant percentage (about 50%) of the C. creticus volatiles were adsorbed only on the surface of β-cyclodextrin; γ-cyclodextrin larger cavity accommodated more C. creticus volatiles and only 10% were adsorbed on its surface. The ongoing GC-MS analysis will shed light on these mechanisms. This study illustrates the species-specific differences in Cistus essential oils and the impact of those differences on the encapsulation in cyclodextrins of different size.

Publication History

Article published online:
12 December 2022