Pregnenolone 714 Tests

Since the predatory water beetles cannot biosynthesise the steroid skeleton de novo, steroidal precursors must be obtained from exogenous sources. Bacillus-strains, isolated from the foregut of the water beetle Agabus affinis, were tested for their ability to transform steroids [101]. After incubation with androst-4-en-3,17-dione two Bacillus strains produced 13 different transformation products. Hydroxylation took place at C6, C7, Cll and C14 resulting in the formation of 6fi-, 7a-, 1 la-, and 14a-hydroxyandrost-4-en-3,17-diones. After incubation with pregnenolone the two Bacillus strains produced a variety of steroids among which 7a-hydroxypregnenolone was the major product [102]. 

The apocrine glands in the axilla can secrete enormous amounts of steroids such as dihydrotestosterone and pregnenolone (Brooksbank, 1970). Three single steroid compounds have also been tested on T-shirts. Surprisingly, both sexes attributed androstenol to females. Two other synthetic compounds were attributed to one or the other sex, depending on concentration, and one was perceived as very negative. Androstenol and the two synthetic compounds have very low olfactory thresholds for humans. 

Several compounds have been developed that inhibit the 17-hydroxylation of progesterone or pregnenolone, thereby preventing the action of the side chain-splitting enzyme and the further transformation of these steroid precursors to active androgens. A few of these compounds have been tested clinically but have been too toxic for prolonged use. As noted in Chapter 39, abiraterone, a newer 17-hydroxylase inhibitor, may prove to be clinically successful. 

Fig. 2. Schematic representation of tests using exogenous ACTH, dbcAMP and pregnenolone (indicated by black horizontal arrows) of the functional integrity of teleost adrenocortical cells exposed to an adrenotoxicant (TOX). A lack of secretory response to ACTH (pattern A, black vertical arrow with X to show disrupted pathways) indicates a general dysfunction of the secretory pathways, possibly involving the ACTH receptor. No response to ACTH but a secretory response to dbcAMP, an analog of cAMP (pattern B), indicates that the steps downstream from cAMP are functional (white arrow bar) but steps upstream are disrupted by the toxicant. No response to ACTH or dbcAMP with a response to pregnenolone (pattern C) indicates that steps downstream from this precursor of cortisol are functional. Note that the concentrations of ACTH, dbcAMP and pregnenolone used in these functional in vitro tests should be physiological rather than pharmacological.

Liu et al. (2003) focused their method paper on the instrumental set-up for on-line capillary LC coupled with MS-MS via a low flow-rate interface, hoping that miniaturization would improve sensitivity for many biomedical applications. The system design and perfonnance were tested on DHEA sulfate and pregnenolone sulfate quantitation from 5 pL of plasma from one male volunteer. Sample preparation was simple - addition of aqueous methanol and of the deuterated analog internal standards, protein precipitation, supernatant filtration through a Cig bed, evaporation and reconstitution in 100 pL of mobile phase, of which 20 pL were injected for LC-MS-MS analysis. The DHEA sulfate concentration found was in agreement with literature values based on GC-MS and LC-MS studies. 

The disorder is due to a deficiency in the cholesterol side chain-splitting enzyme responsible for converting cholesterol to pregnenolone (P14). The adrenal cortex is hyperplastic and yellow due to accumulated cholesterol. Adrenal insufficiency is indicated clinically and incomplete masculiniza-tion of male fetuses is due to the inadequacy of testosterone production by the testes in early fetal life. A mild form of the disorder has been described by Camacho et al. (C2). 

A second enzyme system targeted for androgen inhibition is 17a-hydroxylase/17,20-lyase, which is the key enzyme that converts pregnenolone to DHAand, subsequently, to testosterone (Fig. 45.3). Because testosterone has androgenic activity, inhibition of its biosynthesis would be useful in treating androgen-dependent diseases, such as prostate cancer (130). Inhibitors of 17o-hydroxylase/17,20-lyase inhibitors could prevent androgen biosynthesis from both testes and adrenals and may provide effective treatment of patients with prostate cancer. 

Fig. 4. Transformations of pregnenolone in the fetal and placental compartments. (1) This transformation does not take place in the adrenals but it does to a limited extent in the fetal testes.

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