The Identification of Steroids

Abstract

In this paper the problems of establishing the identity of a compound isolated from biological material with a steroid are outlined and discussed. The nature of evidence required for identification and some techniques for obtaining this are briefly considered. The importance of establishing the specificity of a method for the quantitative measurement of a steroid in a biological extract is emphasized. THE problemThe meaning of the term identification used here is the complete description of the chemical constitution (or structure) of the compound isolated, or the demonstra¬ tion that its chemical and physical properties are indistinguishable from those of a reference sample of a compound of established constitution.The identification of steroids in biological extracts is made difficult by the large number and low concentrations of closely related compounds which may be present.Even when consideration is limited to steroid hormones, their precursors and meta¬ bolites in biological extracts, the number of steroids likely to be present is formidable. The use of synthetic steroids in investigations and therapy adds to the problem. It may sometimes be possible to isolate and purify enough material to enable evidence of identity to be obtained by observation of infrared and mass spectra and, if possible, melting points, optical rotation and molar extinction coefficients. Usually very much smaller amounts of purified substance will be available for examination. The advent, in recent years, of an increasing variety of sensitive physical and chemical procedures for investigating steroids is thus fortunate. The use made of these pro¬ cedures and the criteria for the identification of steroids should be reviewed from time to time. This is the purpose of the present paper.Consideration might be given to three aspects of the problem : (a) the identification of unlabelled steroid-like compounds isolated from biological materials;(b) the identification of isotopically labelled steroids, when such steroids are formed in experiments with labelled precursors ;(c) the specificity of methods intended for quantitative estimation of steroids in biological extracts.

Demethylation of Mestranol to Ethinyloestradiol in Vitro and in Vivo

“…The deviation of the specific activities was less than 5 % in three subsequent crystallizations, as required for identification by Axelrod et al (1965) and Brooks et al (1970). This demonstrates that frac¬ tion III contains ethinyloestradiol as the main metabolite.…”

Effects of Progesterone on Uptake and Retention of ³H-Testosterone in the Neonatal Female Rat

“…Because positive identification of 3H-testosterone levels was desired, the criterion defined by Brooks et al [1970] for identification and accurate quantitation of steroids in mctabolically active tissues was adopted. Adequate purification for the purpose of quantita tion was considered acceptable following TL.C of the -'H extracts in the presence of pure 14C-teslostcronc when the final ratio of 3H/,4C remained constant ( ± 5 % of their mean) for two additional chromatographic runs in different solvent systems.…”