Screening of radical scavenging activity and chemical constituents of the essential oil from star anise by ultra‐fast GC electronic nose coupled with DPPH, OH, and ABTS assays

Abstract

A sensitive and selective method of ultra-fast GC electronic nose (E-nose) coupled with chemical methodology was developed for both identifying the chemical constituents of essential oil from star anise (EOSA) and the screening of the radical scavenging activity of each compound in EOSA quickly without the isolation of monomers by comparing the change of the chromatographic peak area of every component in EOSA before and after the reaction with the free radicals. The results showed the main components of EOSA were anethole (36.42%), limonene (20.77%), α-terpinene (6.51%), and α-phellandrene(5.61%). Among all chemical components, p-menthatriene showed the strongest scavenging ability both in 1,1'-diphenyl-2-picrylhydrazine (DPPH) and hydroxyl (OH) radicals, and p-cymenene showed the strongest scavenging ability in 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulphonate) (ABTS) radical, with scavenging rates of 93.00 ± 0.56%, 79.50 ± 0.78%, and 70.80 ± 0.32%, respectively. The reliability and feasibility of using E-nose to identify chemical constituents of EOSA were verified by gas chromatography-tandem mass spectrometry(GC-MS/MS). Practical applications The essential oils are the complex mixtures and important constituents in natural edible spices. How to evaluate and screen the radical scavenging activity of each component in the mixtures is a very challenging project. The traditional chemical methods are mainly used to evaluate total radical scavenging activity and antioxidant activity of essential oils. The compounds in the mixture need to be separated into individuals in advance if we want to know the bioactivity of each component and their radical scavenging activity in the past. The paper has developed a simple and convenient ultra-fast GC E-nose method. This method can not only quickly identify the chemical components of essential oil from star anise, but also quickly evaluate the radical scavenging activity of each compound in the essential oil from star anise. The proposed method can be applied to almost any other essential oils and volatile mixtures.