Research On Extraction, Component Analysis Of Essential Oil From Litsea Cubeba And Its Antimicrobial, Antioxidant Activity

Litsea cubeba, a perennial deciduous shrub, is an important aromatic oil plant resource in China. In this study, response surface method was used to optimize the ultrasound-assisted extraction of volatile oil from L. cubeba fruit. Chemical composition of the volatile oil in different months was determined by gas chromatography mass spectrometry (GC-MS). The antibacterial activity and antioxidant activity of volatile oil from L. cubeba fruits in different months were measured. The main results were as follows:1. The ultrasonic-assisted steam distillation was used to study the extraction process of volatile oil from L. cubeba fruit. From the results, extraction rate of volatile oil was influenced by extraction time, liquid to solid ratio and ultrasonic time within a certain range of variable values. And the best extraction process was obtained as follows: extraction time of 3.4 h, liquid-solid ratio of 18:1 (mL/g), ultrasonic time of 12 min. Under these conditions, the theoretical extraction rate was 5.72%, and the practical extraction rate of volatile oil was 5.33%.2. The extraction rate and GC-MS components of volatile oil from L. cubeba fruit in June, July and August were analyzed. The extraction rate of the volatile oil was highest in August and reached to 5.64±0.12%, and the amount of chemical components were maximum with 20 species identified with the identified rate of 98.97%. The content of volatile oil continued to increase as new chemical substances synthesised within maturity process of L. cubeba fruit. So the relative content and the composition of essential oils had some differences in each period. On the one hand, with the growth of Litsea fruit, its chemical components of essential oi 1 had changed:some increased and some other decreased. On the other hand, the kinds of chemical components increased as new components generated. The biggest increase of kinds were in July and August, and the new components were monoterpenes and sesquiterpenes substances. According to the test results, (Z)-citral, (E)-lemon citral were characteristic aroma components of L. Cubeba fruit in Chongqing Wanzhou.3. The antibacterial activity of volatile oil in June, July and August were analyzed.All volatile oil samples of three months had antibacterial activities on Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella. The antimicrobial effect of volatile oil from L. cubeba in July was significantly higher than that in June and August for Staphylococcus aureus, E. coli and Salmonella. The antimicrobial effect of volatile oil from L. cubeba in August was highest for Bacillus subtilis. The minimum inhibitory concentration (MIC) of volatile oil from L. cubeba in July with MIC<0.5% on Staphylococcus aureus was lower than that in June and August. The volatile oil in July on Salmonella and E. coli with MIC<0.8%was stronger than that in June and August. The MIC of volatile oil in August on Bacillus subtilis with the concentration<0.5% was stronger than that of June and July.4. The antioxidant activity of volatile oil in June, July and August were analyzed. DPPH radical and hydroxyl radical scavenging activtity, and the Iron reducing power of volatile oil samples from L. cubeba in three months were determined to explore the change of antioxidant activity in maturating process. Volatile oil samples in June, July and August can scavenge DPPH radical and hydroxyl radical, and reduce Fe3+, and the capacity followed a dose-dependent manner. The order of antioxidant activity among volatile oil samples in three months were August> July> June.