Gas chromatographic and gas chromatographic/tandem mass spectrometric characterization of precursors on the sesterterpene pathway for steroid biosynthesis

Abstract

An increasing amount of evidence is accumulating to support the proposal that steroidogenesis can occur by a sesterterpene pathway as well as the cholesterol pathway. Key intermediates on the sesterterpene pathway are 23,24-dinor-5-cholen-3 beta-ol (guneribol) and some of its metabolites, e.g. 23,24-dinor-4-cholen-3-one (guneribone). It has been reported that these intermediates are biosynthesized and converted to steroid hormones by a range of endocrine tissues in vitro. Monitoring the pentafluorobenzyloxime derivatives by negative ion chemical ionization mass spectrometry in the electron capture mode provided evidence for the presence of guneribone in extracts of bovine testicular and human adrenal tumour tissue. Complementary evidence was obtained from gas chromatographic/tandem mass spectrometric data generated on a triple-quadrupole instrument by monitoring daughter ions (in the multiple ion detection, MID mode) of the molecular anion of derivatized guneribone in both standards and tissue extracts. The present findings that sesterterpene pathway intermediates are present as endogenous compounds in tissue extracts, together with the previously reported radiochemical data, give further support to the sesterterpene pathway hypothesis.

High-Throughput and Multiplexed LC/MS/MRM Method for Targeted Metabolomics

“…The potential power of utilizing a triple quadrupole mass spectrometrybased quantitation technique, namely, multiple reaction monitoring (MRM), for metabolomics has not been fully recognized until recently. A triple quadrupole mass spectrometry-based quantitation for small molecules has been heavily used by analytical chemists for analyzing drug metabolites, 22,23 hormones, 24 pesticides, 25,26 and herbicides 27 with great precision (CV < 10%). 28,29 To further increase selectivity and sensitivity of the triple quadrupole mass spectrometry-based quantitation assay, a front-end separation technique, such as LC, GC, or CE, is often added as the third dimension of separation.…”

“…The potential power of utilizing a triple quadrupole mass spectrometry-based quantitation technique, namely, multiple reaction monitoring (MRM), for metabolomics has not been fully recognized until recently. A triple quadrupole mass spectrometry-based quantitation for small molecules has been heavily used by analytical chemists for analyzing drug metabolites, , hormones, pesticides, , and herbicides with great precision (CV < 10%). , To further increase selectivity and sensitivity of the triple quadrupole mass spectrometry-based quantitation assay, a front-end separation technique, such as LC, GC, or CE, is often added as the third dimension of separation. While a variety of separation techniques can be used to couple a triple quadrupole mass spectrometer, the polarity-based liquid chromatography (LC) stands out for its speed, simple sample pretreatment, and numerous choices of types of commercially available columns based on different separation mechanisms such as reverse phase, normal phase, or hydrophilic interaction, etc.…”