Effects of ultrasonic and microwave pretreatments on the extraction yield, chemical composition and antioxidant activity of hydrodistilled essential oil from anise (Pimpinella anisum L)

Abstract

Aromatic plants are rich in biologically active compounds that are act as antioxidant, antiviral and antitumor agents. There were different methods for the extraction of these bioactive compounds. Hydrodistillation (HD) is the most common method to get the essential oils. Ultrasonic and microwave pretreatments improve yields and quality of the bioactive compounds. The aim of the current study was to evaluate the effect of ultrasonic and microwave pretreatments followed by hydrodistillation (US-HD and MW-HD, respectively) on the quality of anise essential oil (EO) compared to conventional hydrodistillation (HD). Power and time of US-HD and MW-HD were optimized. Results revealed that MW-HD and US-HD, at optimum conditions, enhanced the extracted yield of EO compared with HD method, however the highest yield (3.0% w/w) was obtained at 60% of the maximum ultrasonic power for 30 min. The gas chromatography-mass spectrometry (GC-MS) analysis showed that at optimum conditions both extraction techniques improved the content of the phenylpropanoids compounds. There was direct correlation between the free radical scavenging activity of each extracted EO and its content of transanethole (the principle compound of anise EO). The principal component analysis (PCA) showed significant variations between the EO extracted by the different methods (MW-HD and US-HD) compare to HD. Finally, this study revealed that the best conditions to obtain better chemical composition and antioxidant activity of Egyptian anise EO was applying US-HD extraction at 60% of the maximum ultrasonic power for 30 min.

Antioxidant Activity of Essential Oils Extracted from Apiaceae Family Plants

“…The EO of anise seeds has been used as a flavoring agent, and an ingredient in perfumes and toothpastes [51]. The principle active compound of anise EO is trans-anethole.…”

“…The principle active compound of anise EO is trans-anethole. Trans-anethole is identified as the agent for the antioxidant activity and smell of anise EO [51,52]. Furthermore, the antioxidant activity of anise seed extracts is due to the total phenolic composition [53].…”