Identification of Steroids with 23 Carbons from Bovine Adrenals: A New Biosynthetic Pathway

Program: Abstracts - Orals, Poster Previews, and Posters
Session: SUN 203-235-Steroid Hormone Actions, Biosynthesis and Metabolism (posters)
Bench to Bedside
Sunday, April 3, 2016: 1:15 PM-3:15 PM
Exhibit/Poster Hall (BCEC)

Poster Board SUN 212
Fred I Chasalow*
IOMA LLC, Belmont, CA
While isolating the digoxin-cross reacting material (C-341) from bovine adrenals, we also identified a series of additional steroids with 23 carbons characterized as phosphocholine and phosphoethanolamine esters. There were three pairs of compounds. In each pair the m/z fragment was characteristic of a steroid with 23 carbons. The pairs were distinguished by a difference in m/z fragment of 42 Daltons. Thus, one of each pair was a phosphocholine and one was a phosphoethanolamine. For simplicity, each compound is designated by its m/z value for the steroid fragment with the prefix of C for phosphocholine compounds and E for phospho-ethanol-amine compounds. Synthetic DHEA-PC was used as a model compound.

                                Summary of Mass Spectra data

Compound          M+1       M+23       M-183     184                                   M+1       M+23      M-141      184

DHEA-PC              454         476         271         Yes                                           -              -            -             -

C-341                  524         544         341         Yes                   E-341       482         504         341         No         

C-339                  522         542         339         Yes                   E-339       480         502         339         No

C-337                  520         540         337         Yes                   E-337       478         500         337         No

The HPLC system that we used separates the C-compounds from the E-compounds but does not completely resolve them. Although we have not yet completely purified each of these compounds, the LC-MS patterns of each set of fragments have the same retention time. C-339 and C-337 are consistent with unreduced intermediates from the 7-dehydrosterol precursor. These six compounds fit together to form a pathway to C-341, the endogenous digoxin-like material.

                There are two known pathways for the biosynthesis of phosphocholine esters: [a] a salvage pathway from other phosphocholine esters and [b] a de novo pathway starting from CDP-serine with a phospho-ethanolamine ester intermediate. Based on the occurrence of the phosphoethanolamine esters, the de novo pathway must be in use. This is important because it indicates that the biochemical process is taking place in the adrenals.

                In summary, we have isolated six novel compounds that together form the biosynthetic pathway to C-341, the endogenous digoxin-like material. This is also the first report of the isolation of steroid phosphoethanolamine esters.

Nothing to Disclose: FIC

*Please take note of The Endocrine Society's News Embargo Policy at https://www.endocrine.org/news-room/endo-annual-meeting/pr-resources-for-endo

Sources of Research Support: Supported by Kerix, LLC and IOMA LLC