## 1 Introduction  
Plant cell cultures have received great attention as a valuable tool for the production of specific metabolites. In recent years many efforts have been made in order to develop and optimize strategies for enhancing the yields of the desired plant metabolites by eliciting their biosynthesis or increasing the efficiency of product recovery. To this regard, release of secondary metabolites into the culture medium can be particularly helpful since it facilitates downstream production processing also at a commercial level [1].  
Cyclodexttrins are non-reducing cyclic oligomers of 1,4-a-d-linked glucopyranose units possessing a cone shape with a lipophilic cavity and a hydrophilic exterior. Beta-cyclodextrintrins (\(\beta\)-CDs), which are formed by seven \(\beta\)-d-glucopyranose units, can form inclusion complexes with guest molecules of a wide range of different molecular weights [2]. For this reason, they are largely used as complexing agents to increase the water solubility of various compounds [3]. Recently, \(\beta\)-CDs have been also used as agents able to induce secondary metabolism thus acting as elicitors in plant cell cultures by enhancing metabolite biosynthesis [4]. The ability of \(\beta\)-CDs to elicit resveratrol production in grapevine cell cultures was likely due to their chemical similarity to pectic oligosaccharides releases from the cell wall after fungal infection [5]. Furthermore, when applied as elicitors, \(\beta\)-CDs enhanced the accumulation of specific metabolites outside the cells in the culture medium [6]. Thus, among the approaches to enhance secondary metabolite yields in plant cell cultures, the use of cyclodextrins has the potential to be biotechnologically relevant.  
Terpenoids are a large family of natural products serving essential plant processes such as respiration (ubiquinone Q9 and Q10) and photosynthesis (carotenoids and chlorophylls) but also being important healthful compounds for humans due to the known powerful antioxidant activity [7, 8]. Particularly, dietary carotenoids including \(\beta\)-carotene in the class of carotenes, and lutein and zexanthin in the class of xanthophylls, are considered to be beneficial in the prevention of a variety of major diseases, including certain cancers and eye diseases [9]. In plant cells, terpenoids can derive from two distinct biosynthetic routes, the cytosolic mevalonate (MVA) and the plastidial MVA-independent pathway. Although these routes operate independently in plants, there is a communication and an exchange of intermediates between the cytosolic and the plastidial pathways of terpenoid biosynthesis [10].  
_Artemisia annua_ L. represents one of the most known examples of plant used in traditional medicine as well as in modern pharmacology. The genus _Artemisia_ is one of the largest of the family _Asteraceae_ showing rich phytochemical diversity. For many centuries _A. annua_ plant extracts were used against fever. The discovered antimalarial properties of this plant led to the identification of the compound artemisinin, a sesquiterpene lactone, active against malarial agents. Due to the importance of such metabolite, we established and characterized _A. annua_ L. cell cultures as for the production of artemisinin and the response to different elicitors, such as methyl jasmonate and miconazole [11].  
We also applied \(\beta\)-CDs which significantly increased the production of artemisinin and its release into the culture medium [6].  
The aim of this work was to use these established _A. annua_ L. suspension cultures to investigate the effects of \(\beta\)-CDs on the production of other important bioactive compounds belonging to the isoprenoid class such as carotenoids and quinones.