Physicochemical characterization and deodorant activity of essential oil recovered from Asiasarum heterotropoides using supercritical carbon dioxide and organic solvents
Graphical abstract
Introduction
For more than two millenniums different kinds of pharmacologically active herbs have been used in Chinese traditional medicines to treats several ailments. Asiasarum heterotropoides var. mandshuricum, also known as Xixin in Chinese, is one such pharmacologically active recurrent herb native to China [1]. The essential oil from A. heterotropoides has been used in oriental Chinese medicine as an analgesic, antitussive, and ant-allergic [2]. The chemical composition of the essential oil had been studied using GC/MS [3], [4]. In the studies, a total of about 82 compounds were identified and among the identified compounds methyleugenol was found to be the most abundant compound comprising nearly 60% of the total composition [5], [6]. Methyleugenol has a wide variety of applications in food, cosmetics, and pharmaceutical industries as a flavoring agent in foods and drinks, as a fragrance in cosmetics, soaps, shampoos, and as an antimicrobial and antifungal agent in herbal products [6], [7]. Several types of pharmacological studies have shown that oil from A. heterotropoides has different biological activities including, anti-tumor, antimicrobial, antioxidant, anti-inflammatory, and larvicidal activities owing to its high amount of methyleugenol and other pharmacologically active phytochemicals, [8], [9], [10], [11].
Despite its pharmaceutical importance and availability, the extraction yield of A. heterotropoides oil remains very law. Traditionally, natural active compounds from different sources have been extracted using organic solvents from their sample matrixes. However, this method has limitations including longer extraction time, use of huge volume of toxic solvents, and a need to separate the solvent after extraction. Thus, these limitations have encouraged rising interest in developing an alternative extraction method. Recently, the use of supercritical fluid extraction (SFE) has gained momentum for the extraction of organic compounds from different terrestrial and marine sources. Supercritical carbon dioxide (Sc-CO2) extraction is considered as one of an environmentally friendly and efficient, process for the extraction and fractionation of essential oil from different sources [12], [13], [14]. Sc-CO2 extraction process has several advantages over other extraction methods including the use of nontoxic and non-flammable fluid, the possibility of changing physical properties of the solvent by tuning the extraction parameters such as temperature and pressure. Moreover, since the extraction process is conducted in a closed system the extracted oil suffers a much lesser oxidative degradation as compared to the conventional extraction process [15].
Although a lot of works have been conducted in the extraction of oils from A. heterotropoides using organic solvents and hydro distillations, information about extraction using Sc-CO2 is very few and to the best of our knowledge, there is no reported data on using co-solvents with Sc-CO2. Therefore, the aim of this study was to extract oil from A. heterotropoides using neat Sc-CO2 and modified Sc-CO2 at different conditions and compare with other organic solvent extraction so as to maximize the oil yield. The physicochemical properties and the volatile organic compounds (VOCs) along with their deodorant activity of the oil were also determined. Moreover, methyeugenol and safrole content of the oil were evaluated due to their pharmacological importance and toxicty effect respectively.
Section snippets
Experimental materials and chemical
Asiasarum heteropoides var. mandshuricum root was purchased from Dongeui Hanjae Company (2914-57, Geumgang-ro, Naechon-meyon, Pochean si, Gyeonggi-do, Korea). Carbon dioxide 99.9% purity) was supplied by KOSEM, Korea. All other reagents used in this study were of analytical or high-performance liquid chromatography (HPLC) grade.
Sample preparation
Dried root was grounded by a mechanical blender (PN, SMKA-4000, Ansan, Korea) and sieved with a 710 μm mesh size sieve and the powder passed through the sieve was
Extraction curve and oil yield
Fig. S1 and S2 show the extraction curves of Sc-CO2 with ethanol as co-solvent and Sc-CO2 only respectively. As shown in the figures, the extraction yield exponentially increased for the first one hour and became constant for the next one hour. This indicated that most of the extraction of the oil was conducted in the first one hour of the extraction process. Increasing extraction pressure at constant temperature increased the extraction yield by enhancing the solvent (Sc-CO2) density, and at
Conclusion
Essential oils from plants have been used for centuries to treat different kinds of ailments. Extracting oils from aromatic plants traditionally employed either using steam distillation or organic solvents. However the yield obtained using these methods are usually very low and the quality of the essential oils also not good, as the oil is exposed to the atmosphere that might be affected by oxidative degradation. In this study, extraction using Sc-CO2 and ethanol as co-solvent, we were able to
Acknowledgments
This work was supported by the Korea Technology and Information Promotion Agency for SMEs (TIPA) grant funded by the Korea government (Ministry of SMEs and Startups) (No. S2570935).
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