Antimicrobial activity in the egg wax of the tick Amblyomma hebraeum (Acari: Ixodidae) is associated with free fatty acids C16:1 and C18:2

• Published in: Experimental & applied acarology Vol. 58; no. 4; pp. 453 - 470
• Main Authors: Yu, Zhijun, Thomson, Euan L. S, Liu, Jingze, Dennis, Jonathan J, Jacobs, René L, Kaufman, W. Reuben
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01-12-2012; Springer Netherlands; Springer Nature B.V
• Subjects: Acari; Amblyomma hebraeum; Animal Ecology; Animal Genetics and Genomics; Animal Systematics/Taxonomy/Biogeography; Animals; Anti-Infective Agents - pharmacology; Antimicrobial activity; antimicrobial properties; Bacteria; Biomedical and Life Sciences; CD95 antigen; Chemical Fractionation; Cholesterol; cholesteryl esters; Chromatography, High Pressure Liquid; Complex Mixtures - chemistry; Eggs; Entomology; Esters; Fas antigen; Fatty acids; Fatty Acids, Nonesterified - pharmacology; Female; Fractionation; free fatty acids; Gas chromatography; Gram-negative bacteria; Gram-Negative Bacteria - drug effects; Gram-positive bacteria; Gram-Positive Bacteria - drug effects; Ixodidae; Life Sciences; Lipids; mass spectrometry; Mass spectroscopy; Metabolites; Microbial Sensitivity Tests; N.M.R; NMR; Nuclear magnetic resonance; nuclear magnetic resonance spectroscopy; Nuclear Magnetic Resonance, Biomolecular; Ovum - chemistry; Solvent extraction; Solvents; ticks; Waxes - pharmacology; Antimicrobial activity; Antibiotic; Egg wax composition; Ticks; Gram-positive bacteria; Gram-negative bacteria; Fatty acids
• ISSN: 0168-8162; 1572-9702
• DOI: 10.1007/s10493-012-9586-1

Untreated eggs of the tick Amblyomma hebraeum Koch (Acari: Ixodidae) exhibited antimicrobial activity (AMA) against Gram-negative but not Gram-positive bacteria; eggs denuded of wax by solvent extraction showed no AMA. The unfractionated egg wax extract, however, showed AMA against Gram-positive but not Gram-negative bacteria, as also shown by Arrieta et al. (Exp Appl Acarol 39: 297–313, 2006). In this study we partitioned the egg wax into various fractions, using a variety of techniques, analyzed their compositions, and tested them for AMA. The crude aqueous extract exhibited AMA. However, although more than 30 metabolites were identified in this extract by nuclear magnetic resonance analysis, none of them seemed likely to be responsible for the observed AMA. In the crude organic extract, cholesterol esters were the most abundant lipids, but were devoid of AMA. Fatty acids (FAs), with chain lengths between C13 and C26 were the next most abundant lipids. After lipid fractionation and gas chromatography/mass spectroscopy, free FAs, especially C16:1 and C18:2, accounted for most of the AMA in the organic extract. The material responsible for AMA in the crude aqueous extract remains unidentified. No AMA was detected in the intracellular contents of untreated eggs.