# Ultrasound-Assisted Extraction of \(\beta\)-Asarone from Sweet Flag (_Acorus calamus_) [PERSON]
## 1 Introduction  
_Acorus calamus_ is commonly known as sweet flag, Bacha or Jerangau Puthi [1]. Asarone is a naturally occurring phenylpropanol usually found in the Acoraceae (Acorus) and Aristolchiaceae (Asarum) plant families [2; 3; 4; 5; 6; 7]. All of its variations, the \(\alpha\)-, \(\beta\)- and \(\gamma\)-asarone are commonly used in naturopathy due to their significant medicinal and pharmacological values [4; 5; 8; 9]. Amongst the proven benefits of asarone is the treatment of various physiological disorders such as hyperlipidemia, respiratory, circulation problems, neurological disorders, epilepsy, Alzheimer's and ischemia [3; 5; 10; 11; 12]. Asarone is also known to relieve inflammation and gas or colic, and treatment for diarrhea, ulcers and intestine-related issues. Moreover, asarone can act as an antidepressant, relaxant or calm inducer, thus helping with sleeping problems and minor psychological issues. Asarone provides quick relief due to its ability to cross the blood-brain barrier, thus directly affecting the body's central nervous system [13].  
However, there are numerous reports on the concerns over the safety of asarone. It was reported that prolonged exposure to _A. calamus_ could cause toxification and excessive vomiting [14]. It was also reported that both \(\alpha\)- and \(\beta\)-asarone are cytotoxic, genotoxic and hepatocarcinogenic [12; 15; 16]. Due to the reported toxicity effects of asarones, the use of _A. calamus_ in food and flavoring is prohibited by law in certain countries, including the United States of America [17]. Despite the decision of certain countries to refuse the use of asarone, there are an increasing number of studies that prove the benefits of the compound in treating various health issues. Therefore, instead of a complete ban, some countries introduce regulations that limit the intake of \(\beta\)-asarone [9; 10; 18; 19; 20]. Hence, it is importantto have an efficient and reliable method to determine accurately the amount of \(\beta\)-asarone in _A. calamus_ to reduce the risk of toxication.  
Ultrasound is known to aid the extraction process by increasing extract yield and improving the experimental feasibility. The phenomenon of microbubble oscillation and collapse causes the physical effect necessary to aid the extraction process. The oscillation of the microbubbles may result in macro turbulences that could improve solute in solvent micro-mixing. The event would also promote materials collision, thus fragmenting and rupturing the plant material structure. On the other hand, the collapse of the microbubble results in violent phenomena such as micro-jetting and shockwaves with extreme temperature and pressure released locally. Such occurrences on the plant surface result in the fragmentation and disruption of the material matrix, detachment and erosion of the sacs and glands, and sonoporation that could aid the release of its active compounds bound by the structure. Therefore, there have been many reports on the improved extraction efficiency by ultrasound aidance. The ultrasound-assisted extraction efficiency is also known to be affected by many experimental factors, such as material particle size [21; 22] and moisture contents [23; 24]; and ultrasound parameters such as frequency, power and sonication time [25; 26].  
Several studies on the extraction and quantification of asarone by HPTLC [27; 28], HPLC [29], GCMS [30; 31], LC-MS/MS [32; 33; 34] and near-infrared reflection (NIR) spectroscopy [35] have been reported. In this study, an ultrasound-assisted extraction coupled with HPLC analysis is developed to provide an efficient and simple method to quantify \(\beta\)-asarone in the _A. calamus_. The effects of experimental conditions such as the size of plant materials, solvent medium, and sonication power were investigated, while the ultrasound reactor design was kept constant. The extraction efficiency of the ultrasound assisted method was compared with the conventional solvent extraction method.