Novel P450(17alpha) inhibitors: 17-(2'-oxazolyl)- and 17-(2'-thiazolyl)-androstene derivatives

Twelve 17-(2'-oxazolyl)- and 17-(2'-thiazolyl)-androsta-5,16-diene derivatives were designed and synthesized from 3 beta-acetoxy-pregna-5,16-dien-20-one (1b) as inhibitors of 17 alpha-hydroxylase-C(17,20)-lyase (P450(17 alpha)). Potent inhibitors of this enzyme could be of value as treatment of prostate cancer. Two substituents (methyl and phenyl) were introduced either at their 4'- or 5'-position in order to investigate their structure-activity relationship. Due to the 16,17-double bond, 17-thiazoles were generally obtained in low yield. The pharmacological results showed that the compounds containing 17-(2'-oxazolyl) (14c) and 17-(2'-thiazolyl) (8c) (41.5%) demonstrated reasonable inhibition against P450(17 alpha). Their 3-acetate (13c and 7c) were less potent than their 3-OH counterparts. The introduction of a phenyl or methyl group generally decreased inhibitory activity. Surprisingly, 17-(5'-methyl-2'-thiazolyl) (12a) was the most potent compound in this series and was almost as potent as L-39, which has good antitumor activity.     

Utility of 17-(allylamino)-17-demethoxygeldanamycin treatment for skeletal muscle injury

Repeated eccentric contractions can injure skeletal muscle and result in functional deficits that take several weeks to fully recover. The 70-kDa heat shock protein (Hsp70) is a stress-inducible molecular chaperone that maintains protein quality and plays an integral role in the muscle’s repair processes following injury. Here, we attempted to hasten this recovery by pharmacologically inducing Hsp70 expression in mouse skeletal muscle with 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) (40 mg/kg) both prior to and throughout the first 7 days after an injurious bout of 150 maximal eccentric contractions. Hsp70 content in the injured skeletal muscle was strongly induced following the eccentric contractions and remained elevated over the next 7 days as the muscle underwent repair. Treatment with 17-AAG increased Hsp70 content ～fivefold; however, this was significantly less than that induced by the injury. Moreover, 17-AAG treatment did not recover the decrements to in vivo isometric torque production following the bout of eccentric contractions. Together, these findings demonstrate that although Hsp70 content was induced in the uninjured skeletal muscle, treatment of 17-AAG (40 mg/kg) was not a preventive measure to either reduce the severity of skeletal muscle damage or enhance functional recovery following a bout of maximal eccentric contractions.     

Synthesis of 11beta-(4-dimethylaminophenyl)-17beta-hydroxy-17alpha- (3-methyl-1-butynyl)-4, 9-estradien-3-one and 11beta-(4-acetophenyl)- 17beta-hydroxy-17alpha-(3-methyl-1-butynyl)-4, 9-estradien-3-one: two new analogs of mifepristone (RU-486)

From the structure activity relationship, two new analogs, 2 and 3, of the potent progesterone antagonist mifepristone 1 have been designed. The syntheses of these two analogs have been achieved in eleven steps through modified synthetic sequences and improved procedures starting from (+)-estrone. In comparison with mifepristone 1, the relative binding affinities of compound 2 for the progesterone receptor was found to be more, whereas that of compound 3 was less.     

Development and validation of a rapid and sensitive high-performance liquid chromatography-mass spectroscopy assay for determination of 17-(allylamino)-17-demethoxygeldanamycin and 17-(amino)-17-demethoxygeldanamycin in human plasma

A sensitive method was developed and validated for the measurement of 17-(allylamino)-17-demethoxygeldanamycin (17AAG) and its active metabolite 17-amino-17-demethoxygeldanamycin (17AG) in human plasma using 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17DMAG) as an internal standard. After the addition of internal standard, 200 microL of plasma was extracted using ice cold acetonitrile followed by analysis on a Thermo Finnigan triple-quadruple mass spectrometer coupled to an Agilent 1100 HPLC system. Chromatography was carried out on a 50 mm x 2.1 mm Agilent Zorbax SB-phenyl 5 microm column coupled to a 3mm Varian metaguard diphenyl pre-column using glacial acetic acid 0.1% and a gradient of acetonitrile and water at a flow rate of 500 microL/min. Atmospheric pressure chemical ionization and detection of 17AAG, 17AG and 17DMAG were accomplished using selected reaction monitoring of m/z 584.3>541.3, 544.2>501.2, and 615.3>572.3, respectively in negative ion mode. Retention times for 17AAG, 17AG, and 17DMAG were 4.1, 3.5, and 2.9 min, respectively, with a total run time of 7 min. The assay was linear over the range 0.5-3000 ng/mL for 17AAG and 17AG. Replicate sample analysis indicated within- and between-run accuracy and precision within 15%. The recovery of 17AAG and 17AG from 200 microL of plasma containing 1, 25, 300, and 2500 ng/mL was 93% or greater. This high-performance liquid chromatographic tandem mass spectroscopy (HPLC/MS/MS) method is superior to previous methods. It is the first analytical method reported to date for the quantitation of both 17AAG and its metabolite 17AG and can reliably quantitate concentrations of both compounds as low as 0.5 ng/mL.     

17 beta-(cyclopropylamino)-androst-5-en-3 beta-ol, a selective mechanism-based inhibitor of cytochrome P450(17 alpha) (steroid 17 alpha-hydroxylase/C17-20 lyase)

A new compound, 17 beta-(cyclopropylamino)-androst-5-en-3 beta-ol, MDL 27,302, has been designed and synthesized as a mechanism-based inhibitor of cytochrome P450(17 alpha). The time-dependent inactivation of human testicular P450(17 alpha) is irreversible by dialysis and requires the cofactor, NADPH; Kiapp. 90 nM (determined on cynomolgous monkey testis enzyme). Inactivation was not affected by the nucleophile DTT, suggesting retention of the inhibitor in the enzyme active site during the inactivation process. Inhibition is specific to the cyclopropylamino compound, since the isopropylamino- and cyclobutylamino-analogs were not inhibitory. Enzymatic specificity of MDL 27,302 for P450(17 alpha) was demonstrated by its failure to inhibit steroid 21-hydroxylase and the cholesterol side chain cleavage enzyme (P450scc). Both the 17 alpha-hydroxylase and C17-20 lyase activities of cytochrome P450(17 alpha) of human testis microsomes were inhibited by MDL 27,302.     

Solid-phase synthesis of sauvagine-(17-40)

The solid-phase synthesis of the tetracosapeptide corresponding to the C-terminal amino acid sequence of sauvagine is described. After purification by gel filtration, the polypeptide appeared to possess an acceptable degree of homogeneity, as judged by different kinds of electrophoresis and chromatography, and by automated Edman degradation analysis. Preliminary pharmacological results indicate that the fragment-(17-40) is practically devoid of any sauvagine activity on the circulatory system and endocrine glands; a weak effect on gastric emptying delay has been demonstrated (1% of the natural product).     

Meeting report: Guanosines and quadruplexes (London, September 15-17, 2010)

The meeting entitled “Guanosines and quadruplexes” was held in London on September 2010. It attracted over 80 participants from all over the world, combining researchers interested in nucleoside/nucleotide self-assembly and nucleic acids structures, working in fields ranging from chemistry, biology, physics, theory to material sciences and nanotechnology.     

Synthesis of (5alpha)-17-azaandrostan-3-ols and (5alpha)-17-aza-D-homoandrostan-3-ols and their N-acylated derivatives.

Two groups of N-acylated D-azasteroids (4 and 5) were synthesized to explore structure-activity relationships for steroid modulation of GABA(A) receptor function. The target compounds were prepared conveniently from (5alpha)-3-hydroxyandrostan-17-ones (6 and 7) via the intermediate (5alpha)-17-aza-D-homoandrostan-3-ols (14 and 15) or (5alpha)-17-azaandrostan-3-ols (18 and 19) precursors in high overall yields. A Beckmann rearrangement and a Hofmann rearrangement were employed as two key steps in the synthetic sequences.     

Effects of 17β-estradiol on galanin(1-29)- and galanin(1-16)-like immunoreactivities

There are reasons to believe that the galanin neuropeptide family could include more than the two hitherto known members (galanin(1-29) and galanin-like peptide), such as the existence of at least three galanin receptors and the fact that synthetic short-chain homologues have effects and binding sites that are distinct from those of galanin(1-29). The current study uses a radioimmunoassay based on a polyclonal rabbit antiserum raised against galanin(1-16) to study the concentrations of galanin(1-16) like immunoreactivity (LI) in the various parts of the brain and gut of ovariectomized female rats, and investigates the effects of different concentrations of estradiol on these concentrations in relation to galanin(1-29)-LI. Galanin(1-29) concentrations were increased by 17β-estradiol administration in almost all examined tissues whereas galanin(1-16)-LI was increased by 17β-estradiol treatment in most of the gut, but only in the pituitary of the brain. Furthermore, the relation between galanin(1-29)-LI and galanin(1-16)-LI varied substantially from tissue to tissue. The main hypothesis, that galanin(1-16)-LI would be affected by 17β-estradiol in brain and/or gut, was confirmed in addition to the secondary hypothesis, stating that the pattern of galanin(1-16)-LI changes would differ from that of galanin(1-29). The study indicates that galanin(1-16)-LI is estrogen-responsive but that its concentrations are regulated differently from that of galanin(1-29). This is strongly indicative of a biological relevance of this potentially new member of the galanin neuropeptide family.     

Measurement of the novel antitumor agent 17-(allylamino)-17-demethoxygeldanamycin in human plasma by high-performance liquid chromatography

A sensitive HPLC assay has been developed to determine the concentration of 17-(allylamino)-17-demethoxygeldanamycin (AAG) in human plasma over the concentration range of 12.5 to 2500 nM (7.33 to 1465 ng/mL). After the addition of 1000 nM geldanamycin as the internal standard, 1 mL samples of human plasma were subjected to solid-phase extraction, via Bond-Elut C₁₈ cartridges, followed by analysis using an isocratic reversed-phase HPLC assay with UV detection. A Phenomenex Kingsorb, 3 micron, C18, 150×4.60 mm column and a Phenomenex Security Guard pre-column, C₁₈ (ODS, Octadecyl), were used to achieve separation. AAG and GM were monitored at 334 and 308 nm, respectively, on a Hewlett-Packard 1050 Diode-Array Detector. The mobile phase, run at a flow-rate of 1 mL/min, was composed of 50% (v/v) 25 mM sodium phosphate (pH 3.00) with 10 mM triethylamine and 50% acetonitrile. HPLC effectively resolved AAG with retention times of 14.60 0.54 min and the internal standard geldanamycin at 10.72±0.38 min (n=15). This assay was able to measure plasma concentrations of AAG, the lower limit of quantitation being 12.5 nM, at a starting dose of 10 mg/m² infused intravenously over 1 h in a Phase I clinical trial in adult patients with solid tumors.     

Efficient synthesis of 17-acetyl-13-(p-bromophenyl)-3-methoxy-11,11-bis(methoxycarbonyl)gona-1,3,5(10)-trienes

We described an efficient synthesis of (8β,9β,14β)-17β-acetyl-13β-p-bromophenyl-11,11-di(methoxycarbonyl)-3-methoxygona-1,3,5(10)-triene, (8β,9α,14β)-17β-acetyl-13β-p-bromophenyl-11,11-di(methoxycarbonyl)-3-methoxygona-1,3,5(10)-triene, (8β,9β,14β)-13 β-p-bromophenyl-11,11-di(methoxycarbonyl)-17β-(2-hydroxyethyl)-3-methoxygona-1,3,5(10)-triene, and (8β,9β,14β)-13β-p-bromophenyl-11,11-di(methoxycarbonyl)-17β-(2-oxoxyethyl)-3-methoxygona-1,3,5(10)-triene in five or six steps from 1-iodo-4-methoxybenzocyclobutene and readily available materials.     

Separation of 17 DL-amino acids and chiral sequential analysis of peptides by reversed-phase liquid chromatography after labeling with R(-)-4- (3-isothiocyanatopyrrolidin-1-yl)-7-(N, N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole

Seventeen DL-amino acids labeled with a fluorescent chiral labeling reagent, R(-)-4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N, N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole (R(-)-DBD-PyNCS), were separated by reversed-phase chromatography and detected fluorometrically at 550 nm (excitation at 460 nm). The reagent reacted with amino functional group in dl-amino acids under basic medium. The thiocarbamoyl derivatives were converted to thiohydantoin via thiazolinone in trifluoroacetic acid (TFA) solution. The epimerization ratios during the reaction of the cyclization were less than 37% in all dl-amino acids tested. The resulting thiohydantoin derivatives of individual dl-amino acids were completely separated with isocratic elutions using acidic mobile phase involving 0.1% TFA. The separations of the thiohydantoins yielded from acidic, basic, neutral, hydroxyl, and aromatic amino acids were good enough for the identification of dl-amino acid. The method using the reagent was adopted to identification of dl-amino acid sequences in eight peptides. The separation and identification of the thiohydantoin derivatives liberated from the peptides labeled were performed by the isocratic elutions. The applicability of the proposed procedure to sequential analysis of peptide was demonstrated with [D-Ala(2)]-leucine enkephalin, [D-Ala(2)]-deltorphin II, d-Phe-Met-Arg-Phe-amide, and Phe-D-Met-Arg-Phe-amide. D-Ala, D-Phe, and D-Met in the peptides were positively identified with the proposed procedures. [L-Ala(2)]-leucine enkephalin, beta-lipotropin, Asp-Ser-Asp-Pro-Arg, and Pro-Asp-Val-Asp-His-Val-Phe-Leu-Arg-Phe-amide were also analyzed as the references without D-amino acid.     

“远古生命与现代途径”研究的盛大聚会——我国成功举办第二届国际古生物学大会

(一)倍受国内外注目、被誉为国际古生物学界“奥林匹克盛会”的“第二届国际古生物学大会”于2006年6月17至21日在北京大学成功举行。中国科协名誉主席周光召院士、中国科协党组书记、中国科协副主席、书记处第一书记邓楠、国家自然科学基金委员会主任陈宜瑜院士、中国科学院副