## 1 Introduction  
_Salvia_ is the most multitudinous genus of the Lamiaceae family, embracing over than 800 species around the globe [1]. Several tens of _Salvia_ species are considered plants with high pharmacological potency, being an integral part of folk medicine in many countries [2]. The therapeutic properties of _Salvia_ plants have been mostly attributed to major constituents, such as terpenoids and phenolic acids, yet a wide diversity of flavonoid compounds may also occur in _Salvia_ specimens [3, 4].  
The biological significance of medicinal plants has triggered the development of a high number of extraction techniques, which aim at the effective recovery of polyphenolic substances. These techniquesmay involve the use of volatile and toxic solvents, while the extracts obtained may afterwards require several steps of downstream processes for effective solvent removal and extract recovery. On the other hand, contemporary trends in polyphenol extraction, driven by the need for less environmentally aggravating and safer processes, dictate the development of extraction methodologies that would minimize cost, energy consumption, and emission of volatile substances [5]. On this philosophy, the replacement of conventional extraction media by novel, green, and non-toxic ones is imminent.  
Cyclodext (CDs) are cyclic oligosaccharides, composed of \(\alpha\) (1\(\rightarrow\)4)-linked subunits of D-glucopyrannose. The most common CDs are \(\alpha\)-, \(\beta\)-, and \(\gamma\)-CDs, composed of six, seven, and eight glucose units, respectively, obtained by enzymic degradation of starch, possessing a truncated cone shape, with the hydroxyl functions located towards to the outer cavity surface (Figure 1). This three-dimensional structure of the CD molecules is characterized by a hydrophilic outer surface and an internal hydrophobic cavity and provides both water solubility and ability to encapsulate within the cavity hydrophobic molecules of suitable size, thus forming inclusion complexes [6].  
Applications of CDs have been increasing on an annual basis in pharmaceutical, chemical, and other disciplines, but most uses are related to food [7]. The utilization of CDs in food products pertains mainly to stabilization of flavors, solubilization of poorly water-soluble substances, protection of labile additives, and so on. However, CDs use for extraction of polyphenic compounds is a state-of-the-art trend, offering unprecedented opportunities in the so-called \"green extraction\". This is because, although common organic solvents regularly used for polyphenol recovery (e.g., ethanol, ethyl acetate) display excellent potency for polyphenols dissolution and extraction, their use poses serious environmental concerns. Aqueous systems containing CDs may be regarded as green solvents, with a prospect of replacing organic solvents in relevant processes [8].  
In this frame, this investigation was performed with the objective to study the use of various cyclodext, namely, \(\beta\)-cyclodextrintrin (\(\beta\)-CD), hydroxypropyl \(\beta\)-cyclodextrintrin (HP-\(\beta\)-CD), and methyl \(\beta\)-cyclodextrintrin (m-\(\beta\)-CD), on the extraction of polyphenols from _S. fruticosa_, using aqueous solutions. The investigation was based on experimental design considering critical extraction parameters, such as the CD concentration, the liquid-to-solid ratio, and pH. Finally, temperature effects were assayed by carrying out kinetics, while selectivity issues were checked with liquid chromatography-mass spectrometry analyses.  
Figure 1: Cyclodextrin structures tested in this study. Assignments: m-\(\beta\)-CD, methyl \(\beta\)-cyclodextrintrin; HP-\(\beta\)-CD, hydroxypropyl \(\beta\)-cyclodextrintrin; \(\beta\)-CD, \(\beta\)-cyclodextrintrin.