Anthelmintic activity of anethole, carvone, carvacrol, thymol, linalool, limonene, eucalyptol, vanillin, cinnamaldehyde and eugenol in in vitro tests

Abstract

The aim of this work was to evaluate anthelmintic activity of aromatic compounds found naturally in plants using in vitro test to determine their activity. Anthelmintic resistance has been a hindrance in animal production causing economic losses and because of the repetitive use of those chemicals, food and environment contamination. New sources of anthelmintic compounds have been investigated and plant extracts and natural compounds have demonstrated as promising candidates. The aromatic compounds were evaluated using in vitro egg hatch test. Eggs were collected from feces of sheep infected with gastrointestinal nematode Haemonchus contortus multi-resistant strain according to Bizimenyera et al. [1] technique. A hundred eggs were exposed to a solution with aromatic compounds diluted in water and with solvent Tween 80 in concentrations ranging from 2.08 mg/mL to 0.007 mg/mL (three fold concentrations) with six replicates using a 24 well plate to perform tests. Eggs were incubated for 24h at 27 ° C and the count of eggs hatched was done using an inverted microscope. Data were analyzed by SAS Probit to estimate LC50 with independent variables (dose) transformed by natural logarithm (log dose). The lowest LC50 has the best anthelmintic activity. In crescent order of LC50 (in mg/mL): Cinamaldehyde (0.018) < Anethol (0.070) < Carvone (0.085) < Carvacrol (0.11) < Thymol (0.13) < Linalool (0.29) < Eugenol (0.57) < Vanillin (0.57) < Eucalyptol (4.74) < Limonene (207.56). Among ten volatile compounds, the five promising anthelmintic compounds were Cinamaldehyde, Anethol, Carvone, Carvacrol and Thymol. Gas chromatography/mass spectrometry was performed and 97%, 98%, 99%, 100% and 98% were the similarity with authentic molecules, respectively. Acknowledgements: FAPESP proc. 2012/50587 – 5. Keywords: Essential oil, H. contortus, in vitro, anthelmintic, parasite, sheep, nematode