Evaluation of antioxidant and antimicrobial activities of citrus leaves essential oils extracted by hydro - distillation and microwave assisted hydro - distillation methods

Abstract

Essential oils (EOs) obtained from many plants have recently gained a great popularity and scientific interest, because of their antioxidant and antimicrobial potentials, the important biological characteristics. In the present study, citrus leaves EOs of four Vietnamese specific varieties (Bearss lime, King mandarin, Xoan orange and Thanh Tra pomelo) were collected and extracted by two methods, hydro-distillation (HD) and microwave assisted hydro-distillation (MAHD). Then, antioxidant and antimicrobial activities of EOs were investigated. Both hydro-distillation and microwave assisted hydro-distillation essential oils exhibited strong antioxidant and antimicrobial activities. For antioxidant capacity, leaves EO of King mandarin showed the strongest antioxidant ability and EOs extracted by hydro-distillation also displayed higher antioxidant activity than microwave assisted hydro-distillation method. The EOs were found to have moderate to good antimicrobial activities against all microorganisms tested (Staphylococcus aureus; Bacillus subtilis; Enterococcus faecalis; Escherichia coli; Pseudomonas aeruginosa), excepted for Samonella typhimurium . In general, the tested EOs were more pronounced against Gram-positive than against Gramnegative bacteria. This study indicates that citrus leaves essential oils extracted using different extraction methods possessed different antioxidant and antimicrobial activities. Key words: Citrus leaf Essential oil Antioxidant activity Antimicrobial activity Hydro-distillation Microwave assisted hydro-distillation