Synthesis of free and sulphoconjugated 16-androstene steroids by the Leydig cells of the mature domestic boar

This study examined the involvement of sulphoconjugation in the biosynthesis of the 16-androstene steroids in Leydig cells of the mature boar, since the formation of steroid sulphoconjugates can reduce the levels of these steroids that accumulate in fatty tissue. Leydig cells were purified from testes of mature male pigs and incubated with pregnenolone, or various individual 16-androstene steroids for 10 min, 1, 4 and 8 h. Sulphoconjugated steroids were recovered by solid-phase extraction followed by solvolysis. Profiles of unconjugated and sulphoconjugated steroids were analysed by HPLC. Steroids present in the sulphoconjugated fractions were purified, derivatised as O-methoxime/trimethylsilyl ethers (MO–TMS), and subsequently identified using gas chromatography–mass spectrometry (GC–MS). The principal metabolite produced from incubations with pregnenolone, androstadienol, androstadienone and 5α-androstenone was 3β-androstenol. 16-Androstene steroids that were sulphoconjugated included 5α-androstenone, 3β-androstenol and 3α-androstenol. Approximately 70% of the total amount of each 16-androstene steroid was in its sulphoconjugated form after incubations for 4 h or more. The finding that sulphoconjugated 5α-androstenone was present in large amounts suggests that this steroid may be converted from a 3-keto to a 3-enol form which is subsequently sulphoconjugated. These findings emphasise the need to consider the impact of sulphoconjugation of the 16-androstene steroids and their role in contributing to boar taint.