|
Abstract
|
Oliveria decumbens Vent, an annual herb, belonging to the Apiaceae family, traditionally used to cure diseases
such as gastrointestinal, infections, diarrhea and fever. In this study, we aimed to investigate the effect of ultrasonic pre-treatment prior to hydrodistillation (US-HD) on extraction of O. decumbens essential oil (EO).
Optimization of three independent variables including ultrasonic temperature, ultrasonic duration, and ultrasonic power to obtain EO with high yield and biological activity was performed recruiting Box-Behnken design
(BBD) of the Response Surface Methodology (RSM). According to the RSM results, the maximum yield of EO was
achieved with the ultrasonic temperature of 38.63◦C, duration of 25.61 min, and power of 149.71 W. The results
showed that the UA-HD of O. decumbens produced the highest yield of EO (5.82 %) compared with conventional
hydrodistillation (HD) method (as the yield is 4.40 %). EOs extracted using UA-HD and HD methods were
analyzed hiring GC and GC–MS, and the findings showed that thymol and carvacrol were the main compounds
which made up more than 60 % of EOs obtained by both methods. Moreover, the ultrasonic pre-treatment
significantly increased the percentage of thymol, while the percentage of carvacrol underwent no change. The
antioxidant study showed that the EO extracted by the UA-HD method (IC50 = 29.61 μg/mL) is of higher
antioxidant activity than the EO of HD method (IC50 = 141.11 μg/mL). Also, no significant difference was
observed with respect to the cytotoxic activities of the EOs extracted using UA-HD and HD methods. Moreover,
the EO obtained via US-HD method had significantly high insecticidal activity with LD50 value of 32.69 μg/larva,
compared to HD method (LD50 = 63.21 μg/larva). So, US-HD method is obviously an effective method to
improve the EO yield, then to reduce the extraction time and energy consumption, and also increase antioxidant
and insecticidal activities, comparing to HD method
|