LAUSR

Abstract Fingered citron (Citrus medica L. var. sarcodactylis Swingle, Foshou in Chinese) is well known as an excellent and popular Chinese herbal medicine and functional vegetable. Fingered citron is rich of essential oil, which exhibits antioxidant, antiradical, and antimicrobial properties. In order to improve the extraction rate of essential oil from three kinds of fingered citrons and understand their activities, the optimal auxiliary extraction conditions of essential oils and their antibacterial activities were analyzed in this work. Fingered citron essential oil (FEO) extracted by the reflux method was analyzed by Gas Chromatography Mass Spectrometry (GC–MS), and their antimicrobial activities were detected by the disc diffusion method. The results showed that the best auxiliary condition for FEO extraction was ultrasonic combined with 9 % NaCl. The extraction rate of 9 % NaCl combined with ultrasonic was the highest (1.80 %) compared with the control (1.15 %). The compositions of FEOs extracted from three kinds of fingered citrons were mainly composed of alkenes, such as d -limonene and γ-terpinene. However, contents of the compositions were significantly different in three kinds of fingered citrons. The Gold fingered citron essential oil possessed the highest content of d -limonene which close to 50 %, and that in the Cantonese fingered citron essential oil was only 27.60 %. A certain amount of ethanol contained in the Sichuan fingered citron essential oil and aldehyde contained in the Cantonese fingered citron essential oil. Moreover, the three FEOs had different antibacterial effects. In three kinds of fingered citron, the antibacterial effect of the Gold fingered citron essential oil on Staphylococcus aureus was the strongest. The Cantonese citron essential oil had the strongest antibacterial effect on Enterococcus faecalis, and the Sichuan citron essential oil had the strongest antibacterial activity against Escherichia coli. These findings could help us to develop citron essential oils as natural antibacterial agents, new drugs, food additives and other products.