SAT-744 Spiral Steroid Lactones Are Synthesized by Condensation of a Steroid Precursor with Coenzyme a Derivatives

Background: Szent-Gyorgyi proposed that digoxin wasn’t really drug but was a substitute for an endogenous cardiotonic steroid (ECS). Endogenous ouabain and marinobufagenin have been proposed as ECS. Hypothesis: Ionotropin, our first candidate for the ECS, is unique among steroids because it is the phosphocholine ester of a steroid with 23 carbon atoms. Logically, either there must be a novel mechanism for adding carbon atoms to a pregnenolone-like precursor or a novel mechanism for side-chain cleavage from a cholesterol-like precursor. Experimental design: Serum samples were extracted with acetonitrile, filtered and analyzed by MS-N on an LTQ-XL ion trap mass spectrometer. The instrument permits multiple rounds of fragmentation and identification of the parent ion and each fragment ion. This process permitted recognition of ions that were phosphocholine esters and of the mass of the steroid fragments. The chemical formula of each steroid fragment was determined by trial and error analysis. Although not every mass ion has a unique chemical formula, in fact, each of the steroid ions had a unique formula. Possible isomers were resolved by consideration of knowledge of steroid biosynthetic pathways. Major results: In brief, human serum samples had steroid fragment ions consistent with 23 (354 Da) and 25 (398 Da) carbon atoms. This provides an additional constraint as the synthetic mechanism must account for both products. These mass ions were consistent with condensation of either acetyl-CoA or acetoacetyl-CoA with the phosphocholine ester of pregna-5,7-diene-3β,17α-diol-20-one. After condensation, the steroid adduct would be dehydrated and cyclized to form the corresponding spiral steroid phosphocholine ester. This pathway is similar to the mechanism of addition of 2 carbon fragments to a long chain fatty acid. This is the first explanation for the biosynthesis of endogenous mammalian ECS. Spiral lactones would be expected to cross react with many antibodies specific for digoxin, ouabain or marinobufagenin. Either one of the spiral lactones would satisfy Szent-Gyorgyi’s suggestion as the endogenous digoxin-like material. Conclusions: In summary, we have isolated 2 spiral steroid lactones from mammals and identified the mechanism of their biosynthesis. We propose, as the spiral steroids share structural features with the spironolactone class of potassium sparing diuretics, that they also share functions. Nicholls proposed that a candidate for ECS should not be accepted without [a] isolation, [b] precursors, and [c] a biosynthetic path. As there has been no satisfaction of these requirements for ouabain or marinobufagenin, their existence as ECS in mammals needs to be reconsidered.

Glucocorticoid Activity of Adrenal Steroid Precursors in Untreated Patients With Congenital Adrenal Hyperplasia

Context and Objective We describe the clinical features and biochemical characteristics of a unique population of severely affected untreated patients with congenital adrenal hyperplasia (CAH) from an Indonesian population with proven cortisol deficiency but without clinical signs of cortisol deficiency. We evaluated the in vitro glucocorticoid activity of all relevant adrenal steroid precursors occurring in patients with CAH. Design Cross-sectional cohort study and translational research. Intervention/Main Outcome Measures Adrenal steroid precursor concentrations before and 60 minutes after ACTH administration to 24 untreated patients with CAH (3 to 46 years) with proven cortisol deficiency (<500 nmol/L post-ACTH) measured by liquid chromatography–tandem mass spectrometry were compared with six control patients (Mann-Whitney U test). Glucocorticoid receptor (GR) activation was determined by dual-luciferase assays in human embryonic kidney cells transfected with the GR and exposed to increasing amounts of adrenal steroid precursors for 24 hours. Results Blood concentrations of the steroid precursors 11-deoxycortisol (457 nmol/L, P = 0.003), 11-deoxycorticosterone (55 nmol/L, P = 0.003), 17-hydroxyprogesterone (610 nmol/L, P < 0.001), progesterone (29 nmol/L, P < 0.001), and 21-deoxycortisol (73 nmol/L) were strongly elevated compared with control subjects. The GR was activated with comparable potency to cortisol by corticosterone and 21-deoxycortisol or with 4 to 100 times lower potency by 11-hydroxyprogesterone, 11-deoxycortisol, aldosterone, 11-deoxycorticosterone, progesterone, and 17-hydroxyprogesterone. Conclusions We identified strongly elevated adrenal steroid precursor concentrations in blood from untreated patients with CAH and demonstrated glucocorticoid activity of these adrenal precursors in vitro, suggesting a possible role of these precursors in the clinical phenotype of these patients. Further studies are necessary to evaluate the role of these precursors in more detail.

SUBSTRATE CARRIERS FOR C-1(2)-DEHYDROGENATION OF 6-METHYLENE ANDROSTENEDIONE TO EXEMESTANE BY GROWING AND IMMOBILIZED ARTHROBACTER SIMPLEX NCIM 2449

Objective: Permeability of hydrophobic steroid substrates across cell membrane is a critical factor during microbial bioconversion. To increase substrate intake, the feasibility of some organic solvents and emulsifiers as substrate carrier on the bioconversion of 6-methylene androstenedione to exemestane was assessed.Methods: Androstenedione, a commonly available steroid precursor, was chemically converted 6-methylene androstenedione. The time course of exemestane accumulation was estimated after addition of 6-methylene androstenedione dissolved in some organic solvents or dispersed with emulsifiers by growing and immobilized cells of Arthrobacter simplex NCIM 2449 in shake flask cultures. Results: The use of substrate carriers for addition of 6-methylene androstenedione enhanced the bioconversion several folds. With growing bacterium in triplicate flasks, a peak mol % bioconversion recorded was- ethanol (67.25, 72 h); soybean oil + tween 80 (50.37, 48 h); acetone (38.84, 48 h); soybean oil (38.36, 48 h); lecithin (32.73, 48 h), methanol (32.71, 48 h) and tween 80 (10.37, 48 h). As compared to the growing cells, the bioconversion with Ca-alginate immobilized cells was delayed and peak mol % bioconversion was recorded as ethanol (60.78, 120 h); soybean oil + tween 80 (42.98, 120 h); methanol (40.50, 72 h); soybean oil (38.36, 48 h); acetone (31.18, 72h ) and lecithin (33.67, 120 h); tween 80 (13.87, 120 h).Conclusion: The use of substrate carriers for addition of 6-methylene androstenedione increased the permeability of substrate and may be used to increase the yield of exemestane and reduce incubation time.

Analysis of Salvia Coccinea from Jamaican Populations

This is the first report of a phytochemical investigation of Jamaican populations of a local folk medicinal plant Salvia coccinea (Lamiaceae/Labiatae). Apart from the presence of β-sitosterol, phytochemical profiling of the aerial parts yielded compounds other than those previously reported from Indian and Italian populations. The triterpenes betulinic acid and betulin, the phytosterols β-sitosterol and β-sitosterol-3- O-β-D-glucopyranoside, as well as the steroid precursor squalene were isolated. The structures of the compounds were established by comparison of NMR spectroscopic data with those reported in literature.

Phase I study of continuous oral dosing of an irreversible CYP17 inhibitor, abiraterone (A), in castration refractory prostate cancer (CRPC) patients (p) incorporating the evaluation of androgens and steroid metabolites in plasma and tumor

5063 Background: Despite androgen deprivation therapy, recent studies indicate high levels of intra-tumor androgens and continued androgen receptor (AR) signalling in CRPC. Methods: A phase I trial to evaluate the safety and tolerability of A administered once daily at 250, 500, 750, 1,000 and 2,000 mg to chemotherapy-naïve CRPC p. Extensive endocrine evaluation and CTC enumeration were undertaken. Tumor biopsies pre- and post-therapy were evaluated for androgen levels and TMPRSS2/ETS gene translocations. To investigate secondary resistance due to activation of a promiscuous AR by raised precursor steroids upstream of CYP17, all p who progressed were offered combination treatment of A with dexamethasone 0.5mg od (D). Results: 15 p were treated in 3-p cohorts with PSA declines >70% in 9/16 p ( table ) and subsequent expansion of the maximum biologically available dose of 1,000mg (19 p treated to date). All p had progressed on LHRH agonists and antiandrogens, 7/15 on diethylstilboestrol and 7/15 on steroids. No dose limiting toxicities were observed and the only = grade 2 toxicity was reversible hypertension (5 pts) due to CYP17 inhibition. Pharmacokinetics were dose-proportional; mean drug clearance was 803L/hour; mean Vd was 11680L; mean elimination half-life was 10.6 hours. At all dose levels, treatment was associated with increased steroid precursor levels upstream of CYP17, including up to a 300-fold rise in corticosterone levels, as well as loss of detection of adrenal androgens. Circulating testosterone levels were in the castrate range (<50 ng/dl) at baseline, rapidly becoming undetectable (<1 ng/dl) in all p. Conclusion: A can be safely administered to CRPC pts with CYP17 suppression and important anti-tumor activity suggesting that at least 60% of CRPC are still hormone driven. Phase II evaluation of 1,000 mg is ongoing. [Table: see text] [Table: see text]