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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Steroids interact with bovine plasma albumin at a binding region that involves tryptophanyl, tyrosyl, arginyl and lysyl residues. The function of the tryptophanyl residues is demonstrated by: (a) the decrease of albumin binding affinity after modification of one tryptophanyl with 2-nitrophenylsulfenyl chloride; (b) steroid quenching of albumin tryptophanyl fluorescence; and (c) steroid quenching of 1-anilinonaphth-alene-8-sulfonate fluorescence, when it is excited by energy transfer from excited tryptophanyls. The function of tyrosyl residues is demonstrated by the decrease of albumin binding affinity after nitration of 30% tyrosyls with tetranitromethane, or deprotonation of tyrosyls by variation of pH. The function of arginyl and lysyl residues is demonstrated by the decrease of binding affinity after modification of these residues with glyoxal, formaldehyde or acetic anhydride. The presence of both apolar (Trp, Tyr and Lys (deprotonated)) and polar (Arg and Lys(protonated)) residues at the steroid binding site fits in well with the site relative apolarity, when expressed on the Kosower scale (Kosower, E.M. (1958) J. Am. Chem. Soc. 80, 3253-3260). 2. The contribution of specific amino acid residues to steroid binding depends to some extent on the steroid structure, as exemplified by the quantitatively different role of arginyl (or lysyl) residues in albumin interaction with testosterone acetate and epitestosterone, respectively, or that of tyrosyl residues in albumin interaction with 11-deoxycorticosterone and epitestosterone, respectively. 3. The concerted action of polar and apolar amino acid residues is an essential requirement for steroid binding, since unfolding of albumin polypeptide chain by guanidine-HC1, urea, or by reduction of disulfide bridges with 2-mercaptoethanol, strongly decreases steroid binding to albumin while, conversely, reoxidation and refolding of the unfolded polypeptide chain restore albumin affinity for steroids. 4. Parallel determinations of steroid binding constants by equilibrium dialysis and fluorimetric titration, as well as the general pattern of the pH and temperature effects on steroid quenching of albumin fluorescence, confirm the validity of the fluorescence quenching titration as an effective method for measuring albumin-steroid molecular interactions.
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PMID:Structural requirements for steroid binding and quenching of albumin fluorescence in bovine plasma albumin. 95 52

The reaction of ethyl magnesium bromide and 17 alpha-ethynylestradiol with formaldehyde in the presence of triethyl phosphate or hexamethylphosphoramide gave the 2- and 4-formyl-17 alpha-ethynylestradiol in high yield. Treatment of the formyl derivatives with an alkaline solution of hydrogen peroxide in tetrahydrofuran afforded the corresponding catechols in almost quantitative yield. This new synthetic method was far superior to other methods, especially concerning simplicity, selectivity, and high yields.
Steroids 1990 Nov
PMID:A new efficient synthetic method for 2- and 4-hydroxy-17 alpha-ethynylestradiol. 207 14

The 'two-step' model proposed by Jensen and his collaborators for explaining estrogen action conceptualized hormone-free estrogen receptors (ER) to be cytoplasmic, and hormone-filled, transformed ER to be nuclear. Applying monoclonal antibodies which recognized epitopes in ER and formaldehyde-fixed tissues, King et al demonstrated exclusively nuclear staining in target tissues utilizing immunoperoxidase technique. Recently these antibodies have become commercially available enabling other investigators to conduct studies. In this report, using these monoclonal antibodies we have demonstrated that a change in the concentration of formaldehyde alters the staining pattern yielding cytoplasmic instead of nuclear staining in calf uterus, MCF-7 cells, and ER(+) human breast cancer. In addition, neutralization of the antibody activity was not achieved with freshly prepared ER(+) cytosols. Formaldehyde-treated cytosols were essential. These results ought to caution investigators in determining in vivo location of antigens based on the staining pattern obtained in fixed tissues. Furthermore, this effect of formaldehyde on estrogen receptors may be applicable to other steroid hormone receptors.
Steroids
PMID:Nuclear location of hormone-free estrogen receptors by monoclonal antibodies could be a tissue-fixation dependent artifact. 324 69

The commercial anti-inflammatory drug triamcinolone has been shown to rearrange by similar, but distinct pathways when exposed to certain trace metal ions or to dilute aqueous base. In the presence of aqueous base, the 16-hydroxy-20-keto system undergoes reverse aldol cleavage of the 16,17-bond, followed by aldol cyclization linking C-16 to C-20. This base-catalyzed rearrangement gives a 16 beta,17 alpha-dihydroxy product and a corresponding 16 alpha,17 alpha-dihydroxy product in roughly 4 to 1 ratio. Metal-catalyzed rearrangement provides the 16 alpha,17 alpha-dihydroxy product with extremely high stereoselectivity. Mechanistic models are proposed that help explain the ratio of products isolated from each route. The studies presented suggest that similar forms of rearrangement could be of preparative value in syntheses requiring specific stereochemistry of appropriately substituted bicyclic alpha,beta-dihydroxyketones. Under more vigorous conditions of aqueous base treatment these rearrangement products undergo further decomposition with loss of formaldehyde from the hydroxymethyl group, followed by beta-elimination of water. Reaction of the beta-elimination product with formaldehyde results in the formation of a dimeric species linked by a methylene group.
Steroids 1994 Mar
PMID:A reinvestigation of the D-homoannular rearrangement and subsequent degradation pathways of (11 beta,16 alpha)-9-fluoro-11,16,17,21- tetrahydroxypregna-1,4-diene-3,20-dione (triamcinolone). 804 52

We describe the synthesis of 13 beta- and 13 alpha-H-18-nor-androst-4-ene-3,17-dione (1a and 1b) from 18-hydroxyprogesterone (18-->20) hemiketal, via the 18-acetoxy-17 beta-hydroxyandrost-4-en-3-one formed by a modified Baeyer-Villiger reaction. Saponification of 18-acetoxyandrost-4-ene-3,17-dione with sonication, then retroaldolization in the presence of a formaldehyde trap, methone, afforded the mixture of 1a and 1b with 80% yield in a "one-pot" procedure and at room temperature. This yield was greatly improved, compared with the already published procedure.
Steroids 1993 Mar
PMID:An improved synthesis of 18-norandrost-4-ene-3,17-dione. 847 19

In order to determine whether or not a 19-hydroxymethyl group of 19-hydroxyandrosta-1,4-diene-3,17-dione (2, 19-hydroxy ADD), an intermediate of aromatase-catalyzed estrone formation from ADD, a suicide substrate of aromatase, is eliminated as formaldehyde, we examine chemical nature of removal of the 19-hydroxymethyl group. 19-acetate 3 and 19-tert-butyldimethylsiloxy compound 4 are known to convert rapidly to estrone with treatment of NaOH or n-Bu4NF. Since compound 2 was unstable and unobtainable under these conditions, compounds 3 and 4 as equivalents to compound 2 were used in this study. The acetate 3 with 5 mol/l HCl in acetone and 10% KOH in MeOH along with the silyl ether 4 with 5 mol/l HCl in acetone and 1 mol/l n-Bu4NF in THF gave formaldehyde and estrone in which a ratio of the aldehyde to estrone was near 1. This result indicates that the 19-hydroxymethyl groups of compound 3 and 4 are eliminated as formaldehyde along with estrone derived from the steroid skeleton under the acid or base treatment. The findings suggest that a single hydroxylation at the 19 carbon of ADD (1) would be, chemically, all that was required for estrone formation.
Steroids 2009 Feb
PMID:Chemical aromatization of 19-hydroxyandrosta-1,4-diene-3,17-dione with acid or alkaline: elimination of the 19-hydroxymethyl group as formaldehyde. 1902 74