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Supercritical Fluid Extraction as a Sample Preparation Tool in Analytical Toxicology
Published in Steven H. Y. Wong, Iraving Sunshine, Handbook of Analytical Therapeutic Drug Monitoring and Toxicology, 2017
Robert J. Maxwell, Janet F. Morrison
Off-line analyte recovery has been used by Magard et al.91 in the extraction of steroids from animal tissues. Androsterone, a steroid responsible for the boar taint odor in pork, was extracted from fortified boar fat using SF-CO2. The recovered androsterone was detected by GC-MS. However, whereas the SFE procedure extracted 77% of the steroid, it also co-extracted 10% of the fat, thereby increasing the potential for regular fouling of the GC column and the MS ion source. Although steroids are constituents of fats and are easily extracted by SFE at moderate temperatures and pressures, they too, like sulfonamides, may be retained on in-line sorbent beds. Parks and co-workers92developed an SFE method for the recovery of melengesterol acetate (MGA) in bovine fat at or below the tolerance level of 25 ppb set by federal regulatory agencies.89 This steroidal hormone is used in feeds to suppress estrus in heifers, and the current regulatory method used for its analysis is a 26-step procedure93 that requires 1.7 1 of organic solvent per sample. The SFE method developed by this team involved blending 1 g of incurred bovine fat with 4 g of Hydromatrix, followed by the addition of 0.75 ml of water. This mixture was poured into an extraction vessel prepacked with an alumina sorbent in a manner similar to that illustrated in Figure 5–7. Extraction of the mixture for 20 min with SF-CO2 at 68 MPa and 50°C resulted in complete retention of MGA on the in-line trap, whereas co-extracted fat was collected off-line. Recoveries (GC-MS) averaged 98.4 ± 4.5% for incurred samples ranging in MGA content from 25 to 98 ppb.
2-Oxidation, 3-methyl hydroxylation, and 6-hydroxylation of skatole, a contributor to the odour of boar-tainted pork meat, mediated by porcine liver microsomal cytochromes P450 1A2, 2A19, 2E1, and 3A22
Published in Xenobiotica, 2023
Yasuhiro Uno, Saho Morikuni, Norie Murayama, Hiroshi Yamazaki
Although male pigs could potentially provide a significant positive economic impact on the pork industry, pork from uncastrated male pigs can be highly objectionable to consumers, partly because of boar taint (Lin et al. 2004). Boar taint results in an unfavourable odour and taste of the pork product (Wiercinska et al. 2012), which results in part from the accumulation of skatole (3-methylindole, structure shown in Figure 1), a digestive by-product formed in the intestines. The accumulation of skatole in pigs is highly dependent on its metabolic clearance mediated by cytochrome P450 enzymes (P450s) (Thornton-Manning et al. 1996; Diaz et al. 1999; Rasmussen and Zamaratskaia 2014). In recent years, porcine P450s have attracted widespread attention, both in relation to meat quality (Lin et al. 2004) and to the potential use of pigs as animal models for human P450s during drug development (Sakai et al. 2016; Uno, Murayama et al. 2022; Uno, Ushirozako et al. 2022; Ushirozako et al. 2023). For example, the 7-hydroxylation activities towards the food compound coumarin catalysed by P450s in the liver are reportedly roughly similar in male and female conventional pigs, but are higher in female than in male Göttingen minipigs (Skaanild and Friis 1999; Ushirozako et al. 2023).