Steroid conjugates

Watson et al. (1985) performed analysis of conjugated steroids by coupling EG to MS by means of a thermospray (Th)-LC/MS interface. In their studies, negative ion Th-mass spectra were recorded for several steroid conjugates. This interface vaporizes the sample before it passes through a small orifice at the tip of a heated stainless steel tube in the ion source. Ionization occurs at the same time, usually promoted by a volatile buffer, such as ammonium acetate. 

Dumasia MC, Houghton E, Bradley CV, Williams DH. 1983. Studies related to the metabolism of anabolic steroids in the horse the metabolism of 1-dehydrosterone and the use of fast atom bombardment mass spectrometry in the identification of steroid conjugates. Biomed Mass Spectrom 10 434-440. 

Shackleton CH, Straub KM. 1982. Direct analysis of steroid conjugates the use of secondary ion mass spectrometry. 

R8. Roy, A. B., Enzymological aspects of steroid conjugation. In Chemical and Biological Aspects of Steroid Conjugation (S. Bernstein and S. Solomon, eds.), pp. 74-130. Springer-Verlag, Berlin and New York, 1970. 

There are three major ionization sources now used for steroid LC-MS electrospray ionization MS (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI). Under optimal conditions, all ionization methods have similar absolute sensitivities. ESI is preferred for polar and charged (steroid conjugates) molecules, but derivatization or chemical modification of less-polar molecules may be necessary for this technique to match the sensitivity of APPI or APCI. 

Positive-ion MS is used in the majority of published works and is preferable for most hormonal steroids, with the possible exception of aldosterone. Estrogens and steroid conjugates have greater sensitivity in negative-ion mode. 

The use of positive-ion MS except for steroid conjugates, and possibly aldosterone and estrogens. 

The use of APPI or APCI for unconjugated steroids ESI for steroid conjugates or when derivatives are analyzed. 

Steroidal ketones are converted into gew-difluoro steroids in moderate to good yield by treatment with sulfur tetrafluoride and anhydrous hydrogen fluoride, usually in an inert solvent, at ambient or close to ambient temperature. The order of decreasing reactivity of steroidal carbonyl functions towards the sulfur tetrafluoride/hydrogen fluoride reagent is as follows 3-oxo = 6-formyl > 17-oxo > 20-oxo of an 11.20-dioxo steroid > 20-oxo of an 11-deoxy steroid > conjugated 3-oxo > 11-oxo.72... 

The hydrogen transfer from different secondary alcohols to a steroidic conjugated enone and a saturated ketone in the presence of CU/AI2O3 has been investigated. The stereochemical pathway of the reaction has been studied and the results are compared with those obtained by conventional molecular hydrogen addition in the presence of the same catalyst. 

We report here the results obtained by using secondary alcohols as hydrogen donors towards steroidic conjugated enones and saturated ketones in the presence of 7.5% Cu on alumina. 

Reddy S, Iden CR, Brownawell BJ (2005) Analysis of steroid conjugates in sewage influent and effluent by liquid chromatography-tandem mass spectrometry. Anal Chem 77 7032-7038... 

Bean, K.A. and Henion, J.B. (1997) Direct determination of anabolic steroid conjugates in human urine by combined high-performance liquid chromatography and tandem mass spectrometry. J. Chromatogr. B, 690 (1-2), 65-75. 

Addition of the enolate of the hindered 17 - /er/- bu ty Id im e thy I si I y I - pro tec ted testosterone was successfully used by Rubin, Kenyon, and co-workers to prove the efficiency of sequential double Michael-type additions to C6o (cf. Section IV.C.l.d and Scheme 1.20).378 Fullerene-steroid conjugates derived from vitamin D, cholesterol, testosterone, and estrone were, finally, reported by Wilson, Schuster, and co-workers 411... 

S. Bernstein and S. Solomon, eds., Chemical and Biological Aspects of Steroid Conjugates, Springer Verlag, New York, 1970. 

Lee, J., Zylka, M.J., Anderson, D.J., et al. (2005) A steroid-conjugated contrast agent for magnetic resonance imaging of cell signaling. Journal of the American Chemical Society, 127, 13164—13166. 

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