There are several extraction techniques described in literature for the herb extraction such as hydrodistillation, conventional organic solvent extraction, ultrasound-assisted solvent extraction and subcritical or supercritical extractions. All of these techniques have their own pros and cons with respect to operating cost, capital cost, yield, and quality of obtained extracts. Ultrasound-assisted extraction (UAE), as an efficient extraction, was used for extraction of bioactive substances from plant because of improving extraction efficiency and shortening the time required (Yang et al, 2010). Various preparation techniques have been employed to produce nanoparticles. It is demonstrated that ultrasonication which can apply extreme pressure and temperature variations, is a common method used for enhancing mass transfer. Moreover, microwaves offer a clean, rapid, convenient and cost effective method for heating that can cause an athermal effect by polarizing macromolecules, resulting in alignment with electromagnetic field poles that may cause the breakage of hydrogen bonds. In this regard, the combined ultrasonic/microwave technique can accelerate the extraction process for adsorption and desorption of target compounds from the herb matrix. While ultrasonic/microwave assisted process has been widely investigated, its application to the production of nano herb particles has not been reported yet. Sonication treatment of proteins has been shown to typically reduce the size of protein associates, ascribed to disruption of non-covalent and electrostatic interactions maintaining the structure of these aggregates (O’Connell et al. 2003; Monti et al., 2013).
As far as we know, no reports of effect of nanotechnology particles produced from ultrasound and microwave digestion extraction methods on the nutraceutical characteristic and antidiabetic activity of sage, wild thyme and milk thistle have been published. Based on that these objectives need to be studied and investigated.