Trials for Gathering Information on an Unknown Peak in the GC-MS Spectra of Horse and Pony Hair Extracts

Maia Tsikolia,Ulrich Kauhl,Saundra H Tenbroeck,Till Opatz,Kenneth J Linthicum,Ulrich R Bernier,Betul Demirci,Nurhayat Tabanca

doi:10.4236/ae.2021.92009

Abstract

The volatile compounds from horse and pony hairs and skin were analyzed to determine bioactive molecules that are kairomones used for host location by blood-feeding diptera. In this study, horse and pony hair samples were extracted with organic solvents (pentane or hexane) and analyzed by gas chromatography-mass spectrometry analysis (GC-MS) with closed electron ionization (CEI). Using the GC-MS analysis, we observed a compound peak, which could not be identified by comparison to mass spectra in the mass spectral library. This unknown compound was often the largest peak in the chromatogram and had a retention index and mass spectral fragmentation similar to nonanal. However, there were several differences in the fragmentation pattern. When compared to a nonanal reference standard, it was evident that this was a different compound. Hydrodistillation of pony hair was another extraction method to obtain the unknown component in higher concentrations. Analysis of this extract with GC-flame ionization detector (FID) with GC-MS confirmed the same unknown peak. Further experiments and analysis with the various mass spectroscopy tools gave the possible molecular ion with mass-to-charge ratio (m/z) 142, corresponding to the unknown component.

Highlights

Blood-feeding diptera such as stable flies, Stomoxys calcitrans (L.), horse flies, Tabanus spp. and Hybomitra spp., as well as deer flies, Chrysops spp., can cause irritation and distress in mammals [1]
Horse and pony hair samples were extracted with organic solvents and analyzed by gas chromatography-mass spectrometry analysis (GC-MS) with closed electron ionization (CEI)
A study of the chemical composition of 20 different mammalian species showed a uniqueness of the sebum composition for each species, there were similarities within genera, e.g., intermediates of cholesterol biosynthetic pathway; variety of mono- and diesters, typically, containing unusual fatty acids [15] [16], identified anteiso-branched 18-methyl-eicosanoic acid (MEA), comprising approximately 40% of the total fatty acids in the integral lipid fraction in mammalian hair

Summary

Introduction

Blood-feeding diptera such as stable flies, Stomoxys calcitrans (L.), horse flies, Tabanus spp. and Hybomitra spp., as well as deer flies, Chrysops spp., can cause irritation and distress in mammals [1]. Analyses of the pelage chemistry of odd-toed ungulates (Perissodactyla) are confined to the domestic horse (Equus caballus) and other equids. These studies revealed giant (C28-C36) lactone rings of ω-hydroxy acids, known as equolides, among horses, asses, and zebras [19]. In the skin surface lipids from the sides of male and female horses (E. caballus), Downing and Colton [22] identified cholesterol, cholesteryl esters and the lactones of ω-hydroxy acids, each including a methyl group in the n − 1 position, mostly mono-unsaturated (n − 8 or n − 10), but, with small amounts of saturated and dienoic species. Ferreira et al [23] identified predominantly ethyl octanoate, ethyl deca-

Methods

Results

Conclusion