Electrospray mass spectrometric characterization of a corticosteroid dimer

Area of Science:

• Biochemistry
• Analytical Chemistry
• Endocrinology

Background:

• 18-Hydroxy-11-deoxycorticosterone (18-OH-DOC) is a steroid hormone.
• Steroid hormone dimerization can alter their biological activity and detection.
• Understanding dimerization is crucial for accurate hormone quantification.

Purpose of the Study:

• To characterize the dimer of 18-Hydroxy-11-deoxycorticosterone formed under acidic conditions.
• To investigate the structure of the dimer.
• To determine the presence of the dimer in rat adrenal extracts.

Main Methods:

• Purification of the dimer using high-performance liquid chromatography (HPLC).
• Analysis of the dimer's molecular weight and functional groups using electrospray mass spectrometry (ESI-MS).
• Analysis of rat adrenal extracts using microbore HPLC/ESI-MS.

Main Results:

• 18-Hydroxy-11-deoxycorticosterone forms a non-polar dimer under acidic conditions.
• The dimer has a molecular weight of 656 Da, two free ketone groups, and no free hydroxyl groups.
• Mass spectrometry data suggest a 20,21,20',21'-anhydro dimer structure.
• Rat adrenal extracts contained 18-Hydroxy-11-deoxycorticosterone and 18-Hydroxycorticosterone, but no 18-OH-DOC dimer was detected.

Conclusions:

• A novel anhydro dimer of 18-Hydroxy-11-deoxycorticosterone can form under acidic conditions.
• The dimer structure was elucidated using advanced chromatographic and mass spectrometric techniques.
• The 18-OH-DOC dimer was not detected in rat adrenal tissue, suggesting it may not be biologically relevant in vivo or is present at very low levels.