Date of Award
Bachelor of Science
Lippia alba (LA) is a flowering shrub native to Central and South America. Its essential oil has been used in herbal medicine as an anti-anxiety drug and in aquaculture; it is used to sedate fish during transport (Daniel 2014. Essential oils are derived from plants usually through steam distillation. They are labeled as “essential” because it contains the odor of the plant. Its physiological action is unknown. We use the fruitfly Drosophila melanogaster to further define its behavioral actions and determine its underlying physiological effects. We first tested whether Lippia alba produced had an anesthetic effect on the fruitfly. We then attempted to determine which components were responsible for the anesthesia. Based upon mass spectroscopy, the major components of LA are Citral (58.54%), Carvone (7.41%), and Limonene (7.32%) (Lopez et al. 2011). In the experiments, a 50ml centrifuge tube was used and each tube contained 10 flies. The cap of each tube contained a piece of paper with 10μL of essential oil. After 30 minutes the tube would be tapped and the flies that failed to crawl upwards were recorded. This was done for 150 minutes. After this test was conducted we would conduct a recovery test. In the recovery tests, a small thin piece of filter paper would be soaked in a 1% Sucrose solution. The purpose of this experiment was to examine how many flies would be able to move upwards and it would show that the oil had a sedative effect on the flies. The recovery test results would be recorded after 1 hour, 3 hours, and 6 hours. Lippia alba, Citral, and Carvone are shown to have an anesthetic effect. Limonene is shown to have an irreversible effect and Beta-caryophyllene is shown to have no effect. Propylene Glycol was mixed with the components to equalize the vapor pressure. We then tested the physiological effects of LA essential oil and its components. Since many drugs affect the nervous system by targeting synapses, we examine their effect on the neuromuscular junction. The nerve was stimulated and EPSPs were record from the muscle before, during and after applying the essential oil and its components. We found that LA produced a large reduction in transmitter release. This effect of Citral on synapses was very similar to that seen with LA. It is likely that LA produces its anesthetic effect by blocking synapses and Citral is largely responsible for its action.
Manimala, Jibin, "The Essential Oil of Lippia Alba Affects Drosophila Behavior and Physiology" (2016). Biological Sciences. 42.