Improvement of Tool Steel Powder Cold Sprayability Via Softening and Agglomeration Heat Treatments

Cold spray can produce deposits from a broad range of materials but reports on cold spray of steels are still limited to the few steel families demonstrating high ductility and medium strength. Softening and agglomeration of steel powders via heat treatment in a rotary tube furnace were investigated as promising ways to improve H13 tool steel powder cold sprayability. By adjusting starting powder size, as well as heat treatment conditions (maximum temperature, cooling rate and heat treatment atmosphere), cold spray of H13 powder improved from virtually no deposition to the production of dense, sound and thick deposits with a powder deposition efficiency of 70%. Powder agglomeration, surface state, microstructure evolution and softening are identified as key factors determining the powder deposition efficiency and resulting deposit microstructure. The developed powder modification method has the potential to facilitate the cold spray of all steels subjected to martensitic transformation.

Evaluation of hydrogen peroxide and ozone residue levels on N95 masks following chemical decontamination

Background

Hydrogen peroxide and ozone have been used as chemical decontamination agents for N95 masks during supply shortages. If left behind on the masks, the residues of both chemicals represent a potential health hazard by skin contact and respiratory exposure.

Aim

Characterization of hydrogen peroxide and ozone residues on mask surfaces after chemical decontamination.

Methods

Various N95 masks were decontaminated using two commercial systems employing either aerosol spray or vaporization of hydrogen peroxide in the presence of ozone. Following the decontamination, the masks were aired out to eliminate moisture and potential chemical residues. The residual hydrogen peroxide and ozone were monitored in the gas phase above the mask surface, and hydrogen peroxide residue directly on mask surfaces using a colorimetric assay.

Findings

After decontamination, hydrogen peroxide and ozone were detectable in the gas phase in the vicinity of masks even after 5 h of aeration. Hydrogen peroxide was also detected on all studied masks, and levels up to 56 mg per mask were observed after 0.5 h of aeration. All residues gradually decreased with aeration, likely due to decomposition and vaporization.

Conclusion

Hydrogen peroxide and ozone were present on N95 masks after decontamination. With appropriate aeration, the gaseous residue levels in the vicinity of the masks decreased to permissible levels as defined by the US Occupational Safety and Health Administration. Reliable assays to monitor these residues are necessary to ensure the safety of the mask users.

Importance of the vegetation-groundwater-stream continuum to understand transformation of biogenic carbon in aquatic systems - A case study based on a pine-maize comparison in a lowland sandy watershed (Landes de Gascogne, SW France)

During land-aquatic transfer, carbon (C) and inorganic nutrients (IN) are transformed in soils, groundwater, and at the groundwater-surface water interface as well as in stream channels and stream sediments. However, processes and factors controlling these transfers and transformations are not well constrained, particularly with respect to land use effect. We compared C and IN concentrations in shallow groundwater and first-order streams of a sandy lowland catchment dominated by two types of land use: pine forest and maize cropland. Contrary to forest groundwater, crop groundwater exhibited oxic conditions all-year round as a result of higher evapotranspiration and better lateral drainage that decreased the water table below the organic-rich soil horizon, prevented the leaching of soil-generated dissolved organic carbon (DOC) in groundwater, and thus limited consumption of dissolved oxygen (O₂). In crop groundwater, oxic conditions inhibited denitrification and methanogenesis resulting in high nitrate (NO₃^-; on average 1140 ± 485 μmol L^-1) and low methane (CH₄; 40 ± 25 nmol L^-1) concentrations. Conversely, anoxic conditions in forest groundwater led to lower NO₃^- (25 ± 40 μmol L^-1) and higher CH₄ (1770 ± 1830 nmol L^-1) concentrations. The partial pressure of carbon dioxide (pCO₂; 30,650 ± 11,590 ppmv) in crop groundwater was significantly lower than in forest groundwater (50,630 ± 26,070 ppmv), and was apparently caused by the deeper water table delaying downward diffusion of soil CO₂ to the water table. In contrast, pCO₂ was not significantly different in crop (4480 ± 2680 ppmv) and forest (4900 ± 4500 ppmv) streams, suggesting faster degassing in forest streams resulting from greater water turbulence. Although NO₃^-concentrations indicated that denitrification occurred in riparian-forest groundwater, crop streams nevertheless exhibited important signs of spring and summer eutrophication such as the development of macrophytes. Stream eutrophication favored development of anaerobic conditions in crop stream sediments, as evidenced by increased ammonia (NH₄⁺) and CH₄ in stream waters and concomitant decreased in NO₃^- concentrations as a result of sediment denitrification. In crop streams, dredging and erosion of streambed sediments during winter sustained high concentration of particulate organic C, NH₄⁺ and CH₄. In forest streams, dissolved iron (Fe²⁺), NH₄⁺ and CH₄ were negatively correlated with O₂ reflecting the gradual oxygenation of stream water and associated oxidations of Fe²⁺, NH₄⁺ and CH₄. The results overall showed that forest groundwater behaved as source of CO₂ and CH₄ to streams, the intensity depending on the hydrological connectivity among soils, groundwater, and streams. CH₄ production was prevented in cropland in soils and groundwater, however crop groundwater acted as a source of CO₂ to streams (but less so than forest groundwater). Conversely, in streams, pCO₂ was not significantly affected by land use while CH₄ production was enhanced by cropland. At the catchment scale, this study found substantial biogeochemical heterogeneity in C and IN concentrations between forest and crop waters, demonstrating the importance of including the full vegetation-groundwater-stream continuum when estimating land-water fluxes of C (and nitrogen) and attempting to understand their spatial and temporal dynamics.

Aragonite saturation state in a tropical coastal embayment dominated by phytoplankton blooms (Guanabara Bay - Brazil)

The dynamics of the aragonite saturation state (Ω_arag) were investigated in the eutrophic coastal waters of Guanabara Bay (RJ-Brazil). Large phytoplankton blooms stimulated by a high nutrient enrichment promoted the production of organic matter with strong uptake of dissolved inorganic carbon (DIC) in surface waters, lowering the concentrations of dissolved carbon dioxide (CO_2aq), and increasing the pH, Ω_arag and carbonate ion (CO₃^2-), especially during summer. The increase of Ω_arag related to biological activity was also evident comparing the negative relationship between the Ω_arag and the apparent utilization of oxygen (AOU), with a very close behavior between the slopes of the linear regression and the Redfield ratio. The lowest values of Ω_arag were found at low-buffered waters in regions that receive direct discharges from domestic effluents and polluted rivers, with episodic evidences of corrosive waters (Ω_arag<1). This study showed that the eutrophication controlled the variations of Ω_arag in Guanabara Bay.

Assessing the toxicity of sediments using the medaka embryo-larval assay and 2 other bioassays

Sediments are sinks for aquatic pollutants, and analyzing toxicity in such complex matrices is still challenging. To evaluate the toxicity of bioavailable pollutants accumulated in sediments from the Bizerte lagoon (Tunisia), a novel assay, the medaka embryo-larval assay by sediment contact, was applied. Japanese medaka (Oryzias latipes) embryos were incubated in direct contact with sediment samples up to hatching. Lethal and sublethal adverse effects were recorded in embryos and larvae up to 20 d postfertilization. Results from medaka embryo-larval assay were compared with cytotoxicity (Microtox®), genotoxicity (SOS chromotest), and pollutant content of sediments. The results highlight differences in the contamination profile and toxicity pattern between the different studied sediments. A significant correlation was shown between medaka embryo-larval assay by sediment contact and SOS chromotest responses and concentrations of most organic pollutants studied. No correlation was shown between pollutant levels and Microtox. According to the number of sediment samples detected as toxic, medaka embryo-larval assay by sediment contact was more sensitive than Microtox, which in turn was more sensitive than the SOS chromotest; and medaka embryo-larval assay by sediment contact allowed sediment toxicity assessment of moderately polluted sediments without pollutant extraction and using an ecologically realistic exposure scenario. Although medaka embryo-larval assay by sediment contact should be tested on a larger sample set, the results show that it is sensitive and convenient enough to monitor the toxicity of natural sediments. Environ Toxicol Chem 2016;35:2270-2280. © 2016 SETAC.

Bioaccumulation of perfluorinated carboxylates and sulfonates and polychlorinated biphenyls in laboratory-cultured Hexagenia spp., Lumbriculus variegatus and Pimephales promelas from field-collected sediments

Polychlorinated biphenyls (PCBs) and perfluorinated carboxylates and sulfonates (PFASs) are persistent pollutants in sediment that can potentially bioaccumulate in aquatic organisms. The current study investigates variation in the accumulation of PCBs and PFASs in laboratory-cultured Hexagenia spp., Lumbriculus variegatus and Pimephales promelas from contaminated field-collected sediment using 28-day tests. BSAF(lipid) (lipid-normalized biota-sediment accumulation factor) values for total concentration of PCBs were greater in Hexagenia spp. relative to L. variegatus and P. promelas. The distribution of congeners contributing to the total concentration of PCBs in tissue varied among the three species. Trichlorobiphenyl congeners composed the greatest proportion of the total concentration of PCBs in L. variegatus while tetra- and pentabiphenyl congeners dominated in Hexagenia spp. and P. promelas. Perfluorooctane sulfonate (PFOS) was present in all three species at concentrations greater than all other PFASs analyzed. Hexagenia spp. also produced the greatest BSAF(lipid) and BSAF(ww) (non-lipid-normalized biota-sediment accumulation factor) values for PFOS relative to the other two species. However, this was not the case for all PFASs. The trend of BSAF values and number of carbon atoms in the perfluoroalkyl chain of perfluorinated carboxylates varied among the three species but was similar for perfluorinated sulfonates. Differences in the dominant pathways of exposure (e.g., water, sediment ingestion) likely explain a large proportion of the variation in accumulation observed across the three species.

Salmonella Surrogate Reduction Using Industrial Peanut Dry Roasting Parameters

Studies were conducted to evaluate the effectiveness of industrial peanut dry roasting parameters in Salmonella reduction using a Salmonella surrogate, Enterococcus faecium, which is slightly more heat tolerant than Salmonella. Runner-type peanuts were inoculated with E. faecium and roasted in a laboratory scale roaster simulator in which temperature, airflow, airflow direction and bed depth were highly controlled, allowing for conditions that duplicate industrial dry roasting. Temperature data were collected at the top, middle and bottom of the roasting bed in addition to internal peanut temperature via thermocouples in the bed of peanuts and embedded in a peanut. Regardless of roast conditions, peanuts in the middle of the roasting bed received the least amount of heat and hence, represent the worst case scenario for microbial reduction. E. faecium reductions, reported as the logarithm of colony forming units/g (log CFU/g), followed a linear trend with increasing roasting time when peanuts were roasted at 149, 163, and 177 C, with &gt; 5-log CFU/g reductions occurring at the middle of the peanut bed after 21, 15 and 11 min, respectively, at a bed depth of 75 mm and an air flow of 1.3 m/s. Increased air flow increased E. faecium reduction. At 16 min roast time and a 75 mm bed depth, reduction at the middle of the bed was ≤ 3-log CFU/g at 1 m/s and &gt; 5-log CFU/g at 1.3 m/s. When all other roast parameters were held constant, decreasing bed depth also increased reduction of E. faecium in the middle of the bed. Comparing various samples roasted at 149, 163 and 177 C over a range of times, roast color (Hunter L-value) was positively correlated (R2  =  0.73) with the log reduction of E. faecium. Most peanuts with an L-value darker than 53, a common threshold for light roast had ≥ 5-log CFU/g reductions; however, further study is required, including roasting peanuts from different origins and maturity, to fully understand the implications of roast color development and microbial reduction. This work provides valuable practical information for manufacturers of roasted peanuts when validating Salmonella reductions under a particular set of roasting parameters.

X-ray microanalysis of porous materials using Monte Carlo simulations

Quantitative X-ray microanalysis models, such as ZAF or φ(ρz) methods, are normally based on solid, flat-polished specimens. This limits their use in various domains where porous materials are studied, such as powder metallurgy, catalysts, foams, etc. Previous experimental studies have shown that an increase in porosity leads to a deficit in X-ray emission for various materials, such as graphite, Cr(2) O(3) , CuO, ZnS (Ichinokawa et al., '69), Al(2) O(3) , and Ag (Lakis et al., '92). However, the mechanisms responsible for this decrease are unclear. The porosity by itself does not explain the loss in intensity, other mechanisms have therefore been proposed, such as extra energy loss by the diffusion of electrons by surface plasmons generated at the pores-solid interfaces, surface roughness, extra charging at the pores-solid interface, or carbon diffusion in the pores. However, the exact mechanism is still unclear. In order to better understand the effects of porosity on quantitative microanalysis, a new approach using Monte Carlo simulations was developed by Gauvin (2005) using a constant pore size. In this new study, the X-ray emissions model was modified to include a random log normal distribution of pores size in the simulated materials. This article presents, after a literature review of the previous works performed about X-ray microanalysis of porous materials, some of the results obtained with Gauvin's modified model. They are then compared with experimental results.

Impact of solid waste disposal on nutrient dynamics in a sandy catchment

Groundwaters impacted by mature landfill leachate are generally enriched in ammonium. In order to assess the dynamics of ammonium exchanges between leachates and the water system inside a sandy permeable catchment we measured ammonium, nitrate and chloride concentrations in the stream and in sediment pore waters of the streambed of a landfill impacted aquifer. Geophysical investigation methods complemented the biogeochemical survey. The studied zone is a 23 km(2) catchment located in a coastal lagoon area sensitive to eutrophication risk. Ammonium concentrations in the river were up to 800 micromol l(-1) during low water period in summer. Three surveys of the river chemistry showed a regular increase in ammonium, nitrate and chloride concentrations along a 1 km section of the watercourse, downstream the landfill, implying that the leachate plume exfiltrates along this section. Sediment cores collected within this section showed all an increase in ammonium concentrations with depth in pore waters as a consequence of the landfill leachate dispersion, as attested by a simultaneous increase in chloride concentrations. Nitrate enrichment in the river water was due to nitrification of ammonium at the interface between groundwater and streamwater. The apparent nitrification rate obtained was within values reported for turbid estuaries, although the river contained very little suspended particulate matter. Actually, pore water chemistry suggests that nitrification occurred for the most part in subsurface permeable sediments, rather than in stream water. The overall topographic, hydrological, geochemical, and geoelectrical data set permit to estimate the extension of the chloride and ammonium plume. The estimation of the apparent ammonium plume velocity is 23 m year(-1) whereas the chloride plume velocity should be 50 m year(-1). The river is the outlet of the impacted groundwaters. Considering that the input of ammonium from the landfill is balanced by the present day output via the river, the residence time of ammonium in the aquifer is between 7 and 18 years.

Design and synthesis of bisubstrate inhibitors of type 1 17beta-hydroxysteroid dehydrogenase: overview and perspectives

Type 1 17beta-hydroxysteroid dehydrogenase (17beta-HSD1) is a key steroidogenic enzyme that catalyses the reduction of steroid estrone into the most potent endogenous estrogen estradiol using the cofactor NAD(P)H. Bisubstrate inhibition is a good way to enhance the potency of inhibitors of cofactor-assisted enzymes. The design of a bisubstrate inhibitor of 17beta-HSD1, the estradiol/adenosine hybrid EM-1745, is reviewed and strategies for future designs of inhibitors are proposed.

Validated, Stability-Indicated Quantitative Purity Test for Triethylenetetramine Tetrachlorhydrate by Automated Multiple Development

There is a monography of Triethylenetetramine dichlorhydrate (Trientine) in the United States Pharmacopeia. But neither the base nor the salts di- or tetra-chlorhydrate are in the European Pharmacopeia. Triethylène tetramine tetrachlorhydrate, used by AGEPS now as matural, is more soluble then triethylene tetramine dichlorhydrate. It is administred to patients with Wilson's disease, which results from a congenital lack of the copper metabolism. A quantitative purity test of this drug by automated multiple development high-performance thin-layer chromatography is developed and validated. The validation parameters tested are specifically characterized by retention factor, linearity, limits of detection and quantitation of several nanograms, reliability, and accuracy. To determine impurities, the monography of triethylenetetramine dichlorhydrate in the American Pharmacopeia is tested. This method in classic developing tank requires two mobile phases and is not quantitative. Assays in high-performance liquid chromatography with a different column and mobile phase did not give good results for the separation of impurities. Thus, it is not possible to perform comparative validation of the separation of the impurities. Only the assay of triethylenetetramine with potentiometer detection has been validated.

Parallel solid-phase synthesis of 3beta-peptido-3alpha-hydroxy-5alpha-androstan-17-one derivatives for inhibition of type 3 17beta-hydroxysteroid dehydrogenase

Type 3 17beta-hydroxysteroid dehydrogenase (17beta-HSD), a key steroidogenic enzyme, transforms 4-androstene-3,17-dione (Delta(4)-dione) into testosterone. In order to produce potential inhibitors, we performed solid-phase synthesis of model libraries of 3beta-peptido-3alpha-hydroxy-5alpha-androstan-17-ones with 1, 2, or 3 levels of molecular diversity, obtaining good overall yields (23-58%) and a high average purity (86%, without any purification steps) using the Leznoff's acetal linker. The libraries were rapidly synthesized in a parallel format and the generated compounds were tested as inhibitors of type 3 17beta-HSD. Potent inhibitors were identified from these model libraries, especially six members of the level 3 library having at least one phenyl group. One of them, the 3beta-(N-heptanoyl-L-phenylalanine-L-leucine-aminomethyl)-3alpha-hydroxy-5alpha-androstan-17-one (42) inhibited the enzyme with an IC(50) value of 227nM, which is twice as potent as the natural substrate Delta(4)-dione when used itself as an inhibitor. Using the proliferation of androgen-sensitive (AR(+)) Shionogi cells as model of androgenicity, the compound 42 induced only a slight proliferation at 1 microM (less than previously reported type 3 17beta-HSD inhibitors) and, interestingly, no proliferation at 0.1 microM.

Chemical synthesis of 16beta-propylaminoacyl derivatives of estradiol and their inhibitory potency on type 1 17beta-hydroxysteroid dehydrogenase and binding affinity on steroid receptors

The 17beta-hydroxysteroid dehydrogenases (17beta-HSDs) are members of a family of enzymes that catalyze the interconversion of weakly active sexual hormones (ketosteroids) and potent hormones (17beta-hydroxysteroids). Among the known isoforms of 17beta-HSD, the type 1 catalyzes the NAD(P)H-mediated reduction of estrone (E(1)) to estradiol (E(2)), a predominant mitogen for the breast cancer cells. Therefore, the inhibition of this particular enzyme is a logical approach to reduce the concentration of estradiol in breast tumors. To develop inhibitors of type 1 17beta-HSD activity, we hypothesized that molecules containing both hydrophobic and hydrophilic components should be interesting candidates for interacting with both the steroid binding domain and some amino acid residues of the cofactor binding domain of the enzyme. Firstly, a conveniently protected 16beta-(3-aminopropyl)-E(2) derivative was synthesized from commercially available E(1). Then, a representative of all class of NHBoc-protected amino acids (basic, acid, aromatic, aliphatic, hydroxylated) were coupled using standard procedures to the amino group of the precursor. Finally, cleavage of all protecting groups was performed in a single step to generate a series of 16beta-propylaminoacyl derivatives of E(2). The enzymatic screening revealed that none of the novel compounds can inhibit the reductive activity of type 1 17beta-HSD. On the other hand, all of these E(2) derivatives did not show any significant binding affinity on four steroid receptors including the estrogen receptor. Additional efforts aimed at improving the inhibitory potency of these steroidal derivatives on type 1 17beta-HSD without providing estrogenic activities is under investigation using a combinatorial chemistry approach.

Synthesis and steroid sulphatase inhibitory activity of C19- and C21-steroidal derivatives bearing a benzyl-inhibiting group

Two series of compounds, benzyl alkylated at position 17alpha and 20 of androstane and pregnane, respectively, were synthesised and tested for steroid sulphatase inhibition. We compared the ability of the compounds to inhibit steroid sulphatase obtained from two different sources (homogenates of transfected HEK-293 cells and Jeg-3 cells) and with two types of substrate (DHEAS or E(1)S). The inhibitory activity of 17alpha-benzyl-5alpha-androstane-3beta,17beta-diol (7), 17alpha-benzyl-5-androstene-3beta,17beta-diol (9), 17alpha-benzyl-4,17beta-dihydroxy-4-androsten-3-one (15) and 20-benzyl-5-pregnene-3beta,20alpha-diol (16) has proven to be superior to that of danazol, the first steroid sulphatase inhibitor to be reported, but still lower than that of the potent inhibitor estrone-3-O-sulphamate. The inhibitory activity of compound 7 was as potent as that of its previously reported estrane analogue, 17alpha-benzyl estradiol. Benzyl alkylated compounds with no OH group on the A-ring (with a 4-OCH(3), 4-Cl, or 4-H and their precursor epoxides), as well as a series of basic steroids without a benzyl group (ADT, epi-ADT, 3alpha-diol, 3beta-diol, DHEA, Delta(5)-diol, DHT, T, Preg and Prog), did not show steroid sulphatase inhibition. We have thus demonstrated that the steroid sulphatase inhibitory effect of a benzyl group, previously observed for an estrane nucleus, can be extended to certain androstane and pregnane nuclei bearing a 3beta-OH or a 4-OH group. Inhibitors 7, 9, 15 and 16 did not induce any proliferative effect on androgen-sensitive Shionogi cells. However, when tested on oestrogen-sensitive ZR-75-1 cells, a proliferative effect was observed for 7 and 9, but not for 15 and 16.

Inhibitors of type II 17beta-hydroxysteroid dehydrogenase

The 17beta-hydroxysteroid dehydrogenases (17beta-HSDs) are involved in the last step of the biosynthesis of sex steroids from cholesterol. This family of steroidogenic enzymes constitutes an interesting target in the control of the concentration of estrogens and androgens. Among the isoforms of 17beta-HSD, type II preferentially catalyzes the oxidation of estradiol (E(2)), testosterone (T), dihydrotestosterone (DHT), and 20alpha-dihydroprogesterone (20alpha-DHP). Based on structure-activity relationship studies, we have developed steroidal spirolactones as inhibitors of type II 17beta-HSD using different steroid nuclei: a C18-steroid (lactones 1 and 10), an antiestrogenic nucleus (lactone 2), and a C19-steroid (lactone 28). We know these inhibitors are selective for type II 17beta-HSD as no or only weak inhibition was observed for types I and III. They also have no proliferative (androgenic) activity on androgen sensitive (AR(+)) Shionogi cells whereas their proliferative (estrogenic) activity on estrogen sensitive (ER(+)) ZR-75-1 cells depends on the nature of the steroid nucleus. Lactones 1 and 10 are weak estrogens, while lactones 2 and 28 do not exert estrogenic activity, in fact lactone 2 is an antiestrogen. Lactones 1, 2, 10 and 28 were also tested in an identical assay with a series of enzyme substrates, C19-steroid diols, and known inhibitors, for the oxidation of testosterone and estradiol into androstenedione and estrone, respectively. From this comparative study, the best inhibitors of type II 17beta-HSD (oxidase activity) were identified, but none of them were clearly more potent than the hydroxylated (reduced) forms of enzyme substrates, E2, T, and DHT. Such inhibitors remain, however, useful tools to, (1) further elucidate the role of type II 17beta-HSD, and (2) regulate the level of active estrogens, androgens and progesterone.

Androsterone 3beta-substituted derivatives as inhibitors of type 3 17beta-hydroxysteroid dehydrogenase

Androsterone derivatives substituted at position 3 were synthesized starting from dihydrotestosterone in a short sequence of reactions. They proved to be potent inhibitors (IC50 = 57-147 nM) of type 3 17beta-hydroxysteroid dehydrogenase, a key enzyme of steroidogenesis, which catalyzes the transformation of androstenedione to steroid active androgen testosterone.

Structure-activity relationships of 17alpha-derivatives of estradiol as inhibitors of steroid sulfatase

The steroid sulfatase or steryl sulfatase is a microsomal enzyme widely distributed in human tissues that catalyzes the hydrolysis of sulfated 3-hydroxy steroids to the corresponding free active 3-hydroxy steroids. Since androgens and estrogens may be synthesized inside the cancerous cells starting from dehydroepiandrosterone sulfate (DHEAS) and estrone sulfate (E(1)S) available in blood circulation, the use of therapeutic agents that inhibit steroid sulfatase activity may be a rewarding approach to the treatment of androgeno-sensitive and estrogeno-sensitive diseases. In the present study, we report the chemical synthesis and biological evaluation of a new family of steroid sulfatase inhibitors. The inhibitors were designed by adding an alkyl, a phenyl, a benzyl, or a benzyl substituted at position 17alpha of estradiol (E(2)), a C18-steroid, and enzymatic assays were performed using the steroid sulfatase of homogenized JEG-3 cells or transfected in HEK-293 cells. We observed that a hydrophobic substituent induces powerful inhibition of steroid sulfatase while a hydrophilic one was weak. Although a hydrophobic group at the 17alpha-position increased the inhibitory activity, the steric factors contribute to the opposite effect. As exemplified by 17alpha-decyl-E(2) and 17alpha-dodecyl-E(2), a long flexible side chain prevents adequate fitting into the enzyme catalytic site, thus decreasing capacity to inhibit the steroid sulfatase activity. In the alkyl series, the best compromise between hydrophobicity and steric hindrance was obtained with the octyl group (IC(50) = 440 nM), but judicious branching of side chain could improve this further. Benzyl substituted derivatives of estradiol were better inhibitors than alkyl analogues. Among the series of 17alpha-(benzyl substituted)-E(2) derivatives studied, the 3'-bromobenzyl, 4'-tert-butylbenzyl, 4'-butylbenzyl, and 4'-benzyloxybenzyl groups provided the most potent inhibition of steroid sulfatase transformation of E(1)S into E(1) (IC(50) = 24, 28, 25, and 22 nM, respectively). As an example, the tert-butylbenzyl group increases the ability of the E(2) nucleus to inhibit the steroid sulfatase by 3000-fold, and it also inhibits similarly the steroid sulfatase transformations of both natural substrates, E(1)S and DHEAS. Interestingly, the newly reported family of steroid sulfatase inhibitors acts by a reversible mechanism of action that is different from the irreversible mechanism of the known inhibitor estrone sulfamate (EMATE).

Solid-phase synthesis of hydroxysteroid derivatives using the diethylsilyloxy linker

Four different types of hydroxysteroids (primary alcohol, secondary alcohols, and phenol), bearing either an oxirane or an azide as a precursor of molecular diversity, were linked in good yields to solid support using the butyldiethylsilane polystyrene (PS-DES) resin. These molecules were then used as scaffolds to generate hydroxysteroid derivatives containing two levels of diversity. The proposed libraries were tested by running steroidal alcohols through a model sequence of reactions (solid-phase coupling, aminolysis of oxirane or reduction of azide, amidation, and final cleavage). As a result, two linked secondary alcohols (17beta-hydroxy-spiro-3(R)-oxirane-5alpha-androstane and 3beta-hydroxy-spiro- 17(S)-oxirane-5alpha-androstane) and a primary alcohol (spiro-17(S)-oxirane-3-(hydroxymethyl)-1,3,5(10)-estratriene) afforded good overall yields (>45%) and high HPLC purities (>90%) of hydroxysteroids derivatized as alkylamides without purification. One limitation was noted for the fourth library: the phenolic steroid linked by the diethylsilyloxy linker gave a poor overall yield of 8% of the desired model compound. Finally, the diethylsilyloxy linker was used successfully for a rapid solid-phase synthesis of a model library of twenty C19-steroid derivatives (3beta-amido-3alpha-hydroxy-5alpha-androstane-17-ones), with an average yield of 53% and average HPLC purity of 97% without purification steps.

N-Butyl-N-methyl-11-(3'-hydroxy-21', 17'-carbolactone-19'-nor-17'alpha-pregna-1',3', 5'(10')-trien-7'alpha-yl)-undecanamide: an inhibitor of type 2 17beta-hydroxysteroid dehydrogenase that does not have oestrogenic or androgenic activity

It is well known that 17beta-hydroxysteroid dehydrogenases (17beta-HSDs) play a key role in the formation and inactivation, from circulating precursors, of several active androgens and oestrogens. These enzymes can thus regulate tumoural cell proliferation in androgen- and oestrogen-dependent cancers. Recently, we discovered that adding a spiro-gamma-lactone to the oestradiol nucleus results in a novel inhibitor of type 2 17beta-HSD, an enzyme that catalyses the interconversions between 4-androstene-3,17-dione and testosterone, and between oestrone and oestradiol. This finding motivated our introducing the spiro-gamma-lactone moiety onto an anti-oestrogenic nucleus. The N-butyl-N-methyl-11-(3'-hydroxy-21', 17'-carbolactone-19'-nor-17'alpha-pregna-1',3', 5'(10')-trien-7'alpha-yl)-undecanamide (4) was then efficiently synthesized and its biological activity was assessed in vitro. Despite the presence of a bulky alkylamide side chain, the spiro-gamma-lactone function conserved its ability to inhibit type 2 17beta-HSD (IC(50) = 0.35 and 0.25 microM, with and without side chain, respectively). Furthermore, the selective inhibition by lactone 4 toward type 2 17beta-HSD (microsomal fraction of human placenta) was demonstrated by the absence of inhibitory activity toward type 1 17beta-HSD (cytosolic fraction of human placenta). Cell proliferation assays indicated that compound 4 had no oestrogenic activity but did show anti-oestrogenic activity on ER(+) cell line ZR-75-1. No androgenic activity could be detected when assayed on the AR(+) cell line Shionogi either. Based on these facts, we report the synthesis of a new steroidal derivative, one that inhibits type 2 17beta-HSD while possessing anti-oestrogenic activity.

Solid-phase synthesis of phenolic steroids: from optimization studies to a convenient procedure for combinatorial synthesis of biologically relevant estradiol derivatives

During the course of our studies on therapeutic agents for the treatment of breast cancer, we became interested in the solid-phase combinatorial synthesis of estradiol derivatives that contain a functionalized side chain at either position 16 beta or 7 alpha. Both types of compounds have already demonstrated inhibitory activity toward both biosynthesis and action of estradiol. As a first step, two versatile precursors bearing an azidoalkyl side chain at either position 16 beta or 7 alpha of estradiol were synthesized using standard solution-phase methods. Afterward, the effectiveness of five linkers to attach the phenolic function of these estradiol derivatives to a polystyrene resin was investigated; they were benzylic ether (Merrifield), 4-alkoxy-benzylic ethers (Wang, Sheppard), tetrahydropyranyl ether (Ellman), benzoic ester, and o-nitrobenzyl ether. To test the linker in a synthetic context, a short sequence of reactions, including reduction of the azide and acylation of the corresponding amine, was performed on the polymer-bound estradiol derivative. While all of the tested linkers proved effective in attaching the phenol functionality of the precursor, only the o-nitrobenzyl ether photolabile linker enabled the release of the final products in acceptable purities. Consequently, this linker was used to perform successfully the solid-phase synthesis of four different classes of estradiol derivatives in acceptable yields and excellent purities. This study was preliminary to the combinatorial synthesis of larger libraries of biologically relevant estradiol derivatives.

Transmission of calicivirus by a foodhandler in the pre-symptomatic phase of illness

After a Christmas party in a restaurant, 48 (68%) of the 82 guests contracted calicivirus gastroenteritis. The epidemiological investigation showed that salad was strongly associated with the disease episode (RR = 2.43, P = 0.0005). Similar symptoms occurred among other customers who had had a meal at the same restaurant on the same evening. A foodhandler who had only prepared salad and appetizers became sick about 30 min after the end of his shift. He had been free of symptoms while preparing food. Few outbreak investigations have shown calicivirus transmission by foodhandlers some hours before becoming symptomatic.

17Alpha-alkan (or alkyn) amide derivatives of estradiol as inhibitors of steroid-sulfatase activity

To develop inhibitors of steroid sulfatase without residual estrogenic activity, we have designed a series of estradiol (E2) derivatives bearing an alkan (or alkyn) amide side chain at position 17alpha. A hydrophobic alkyl group was selected from our previous study where 17alpha-octyl-E2 was found to inhibit strongly the steroid-sulfatase activity. Furthermore, it is known that an alkylamide side chain blocks the estrogen-receptor activation. Starting from ethynylestradiol, the chemical synthesis of target compounds was short and efficient with overall yields of 22-42% (3 or 4 steps). Among these compounds, N-octyl,N-methyl-3-(3',17'beta-dihydroxy-1',3',5'(10')-estratrien- 17'alpha-yl)-propanamide (15) was the most potent inhibitor, with an IC50 value of 0.08 microM for the transformation of estrone sulfate (E1S) to estrone (E1) by homogenated JEG-3 cells. N-butyl, N-hexyl, and N,N-dioctyl propanamide derivatives of E2 (IC50 values of 6.4, 2.8, and >20 microM, respectively) were less potent inhibitors than N-octyl analog 15. Furthermore, the unsaturated propynamide analog of 15 gave lower inhibition (four times) than the saturated compound. Compound 15 is also about 100-fold more effective in interacting with the enzyme than substrate E1S itself. The ability of target compounds to bind the estrogen receptor, to stimulate the proliferation of estrogen-sensitive ZR-75-1 cells, or to inhibit the E2-stimulation of ZR-75-1 cells was also evaluated. Although a mixed estrogenic/anti-estrogenic activity was obtained for tested compounds at 1 microM, no estrogenic activity was observed at 0.03 microM for 15. In conclusion, a promising inhibitor of steroid-sulfatase activity was obtained by introducing a hydrophobic octyl group in a 17alpha-propanamide side chain of E2, but further structure-activity relationships (SAR) studies are necessary to minimize the residual estrogenic activity.

Separation by thin-layer chromatography of the most common androgen-derived C19 steroids formed by mammalian cells

Several methods have been developed in the past for the separation and identification of closely related steroid hormones. Although these methods are effective, most of them use HPLC-derived systems and are expensive, laborious, or time-consuming. In the course of our studies of the metabolism of dehydroepiandrosterone and androstenedione in tissues, we have modified a previously published technique in such a way that in one TLC step we can separate most of the androgen C19 steroid derivatives produced by mammalian cells. We have used this modified technique for the past 2 years with considerable success and reproducible results, and we find it to be rapid and relatively inexpensive.

Parallel solid-phase synthesis of a model library of 7alpha-alkylamide estradiol derivatives as potential estrogen receptor antagonists

The C17-THP derivative of 7alpha-(11-azidoundecanyl)-estradiol (4) was synthesized and coupled to an aminomethyl resin via a photolabile o-nitrobenzyl linker. Reduction of the azide by the Staudinger reaction to its corresponding amine followed by acylation using four activated NFmoc protected amino acids gave a first level of diversity. Subsequent deprotection of the Fmoc followed by a second acylation with five activated carboxylic acids produced, after photocleavage, a model library of twenty antiestrogen-related 7alpha-alkylamide estradiol derivatives in acceptable overall yields and very good purities.

Potent inhibition of steroid sulfatase activity by 3-O-sulfamate 17alpha-benzyl(or 4'-tert-butylbenzyl)estra-1,3,5(10)-trienes: combination of two substituents at positions C3 and c17alpha of estradiol

Steroid sulfates are precursors of hormones that stimulate androgen- and estrogen-dependent cancers. Thus, steroid sulfatase, the enzyme that catalyzes conversion of DHEAS and E1S to the corresponding unconjugated steroids DHEA and E1, appears to be one of the key enzymes regulating the level of active androgenic and estrogenic steroids. Since 17alpha-substituted benzylestradiols and 3-O-sulfamate estrone (EMATE) represent two families of steroid sulfatase inhibitors that probably act through different mechanisms, we synthesized compounds 3-O-sulfamate 17alpha-benzylestradiol (4) and 3-O-sulfamate 17alpha-(tert-butylbenzyl)estradiol (5) that contain two kinds of substituents on the same molecule. In our enzymatic assay using a homogenate of human embryonal (293) cells transfected with steroid sulfatase, compounds 4 and 5 were found to be more potent inhibitors than already known steroid sulfatase inhibitors that have only a C17alpha-substituent or only a C3-sulfamate group (EMATE). The IC50 values of 4 and 5 were, respectively, 0.39 and 0.15 nM for the transformation of E1S to E1 and 4.1 and 1.4 nM for the transformation of DHEAS to DHEA. Compound 5 inhibited the steroid sulfatase activity in intact transfected (293) cell culture assays by inactivating the enzyme activity. Compound 5 also inactivates the steroid sulfatase activity at lower concentration than EMATE in microsomes of transfected (293) cells. In this assay, an excess of natural substrate E1S protects enzyme against inactivation by 5 or EMATE. Furthermore, the unsulfamoylated analogue of 5, compound 3, did not inactivate the steroid sulfatase.

Spironolactone-related inhibitors of type II 17beta-hydroxysteroid dehydrogenase: chemical synthesis, receptor binding affinities, and proliferative/antiproliferative activities

The family of 17beta-hydroxysteroid dehydrogenases (17beta-HSDs) catalyzes the formation and inactivation of testosterone (T), dihydrotestosterone (DHT), and estradiol (E2), thus playing a crucial role in the regulation of active steroid hormones in target tissues. Among the five known 17beta-HSD enzymes, type II catalyzes the oxidation of E2 into estrone (E1), T into androstenedione, DHT into androstanedione, and 20alpha-dihydroprogesterone into progesterone. Specific inhibitors are thus an interesting means to study the regulation and to probe the structure of type II 17beta-HSD. In this context, we have efficiently synthesized a series of 7alpha-thioalkyl and 7alpha-thioaryl derivatives of spironolactone that inhibit type II 17beta-HSD. These new C19-steroidal inhibitors possess two important pharmacophores, namely 17-spiro-gamma-lactone and a bulky side-chain at the 7alpha-position. It was found that a para-substituted benzylthio group at the 7alpha-position enhances the inhibitory potency of spironolactone derivatives on type II 17beta-HSD. In fact, the compound with a para-hydroxy-benzylthio group showed an IC50 value of 0.5 microM against type II 17beta-HSD, whereas the compound with a para-[2-(1-piperidinyl)-ethoxy]-benzylthio group inhibited this enzyme with an IC50 value of 0.7 microM. The latter inhibitor is more selective than the former because it did not show any inhibitory potency against P450 aromatase as well as any affinity towards four steroid receptors (AR, PR, GR, ER). As a result, this inhibitor did not show any proliferative effect on androgen-sensitive Shionogi cells and estrogen-sensitive ZR-75-1 cells. These findings contribute to a better knowledge of the structure of type II 17beta-HSD and offer an interesting tool to study the regulation of this enzyme in several biological systems.

Two non-reactive ternary complexes of estrogenic 17beta-hydroxysteroid dehydrogenase: crystallization and preliminary structural analysis

Human estrogenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD1, EC1.1.1.62) is an important enzyme that catalyses the last step of active estrogen formation. 17Beta-HSD1 plays a key role in the proliferation of breast cancer cells. The three-dimensional structures of this enzyme and of the enzyme-estradiol complex have been solved (Zhu et al., 1993, J. Mol. Biol. 234:242; Ghosh et al., 1995, Structure 3:503; Azzi et al., 1996, Nature Struct. Biol. 3:665). The determination of the non-reactive ternary complex structure, which could mimic the transition state, constitutes a further critical step toward the rational design of inhibitors for this enzyme (Ghosh et al. 1995, Structure 3:503; Penning, 1996, Endocrine-Related Cancer, 3:41). To further study the transition state, two non-reactive ternary complexes, 17beta-HSD1-EM519-NADP+ and 17beta-HSD1-EM553-NADP+ were crystallized using combined methods of soaking and co-crystallization. Although they belong to the same C2 space group, they have different unit cells, with a = 155.59 A, b = 42.82 A, c = 121.15 A, beta = 128.5 degrees for 17beta-HSD1-EM519-NADP+, and a = 124.01 A, b = 45.16 A, c = 61.40 A, beta = 99.2 degrees for 17beta-HSD1-EM553-NADP+, respectively. Our preliminary results revealed that the inhibitors interact differently with the enzyme than do the natural substrates.

Overview of a rational approach to design type I 17beta-hydroxysteroid dehydrogenase inhibitors without estrogenic activity: chemical synthesis and biological evaluation

Hormone-sensitive diseases such as breast cancer are health problems of major importance in North America and Europe. Endocrine therapies using antiestrogens for the treatment and the prevention of breast cancer are presently under clinical trials. Antiestrogens are drugs that compete with estrogens for the estrogen receptor without activating the transcription of estrogen-sensitive genes. However, an optimal blockade of estrogen action could ideally be achieved by a dual-action compound that would antagonize the estrogen receptor and inhibit the biosynthesis of estradiol. Type I 17beta-hydroxysteroid dehydrogenase (17beta-HSD) was chosen as a key steroidogenic target enzyme to inhibit the formation of estradiol, which is the most potent estrogen. This article describes a rational approach that could lead to the development of compounds that exhibit both actions. The chemical syntheses of estradiol derivatives bearing a bromoalkyl and a bromoalkylamide side chain at the 16alpha-position are summarized. Two parameters were studied for biological evaluation of our synthetic inhibitors: (1) the inhibition of estrone reduction into estradiol by type I 17beta-HSD, and (2) the proliferative/antiproliferative cell assays performed on the estrogen-sensitive ZR-75-1 breast tumor cell line. First, the substitution of the 16alpha-position of estradiol by bromoalkyl side chain led to potent inhibitors of type I 17beta-HSD, but the estrogenic activity remained. Secondly, an alkylamide functionality at the 16alpha- or 7alpha-position of estradiol cannot abolish the estrogenic activity without affecting considerably the inhibitory potency on type I 17beta-HSD. In conclusion, the best dual-action inhibitor synthesized showed an IC50 of 13 +/- 1 microM for type I 17beta-HSD, while displaying antiestrogenic activity at 1.0 microM. Despite the fact that we did not obtain an ideal dual-action blocker, we have optimized several structural parameters providing important structure-activity relationship.

17 alpha-alkyl- or 17 alpha-substituted benzyl-17 beta-estradiols: a new family of estrone-sulfatase inhibitors

A series of 17 alpha-derivatives of 17 beta-estradiol was synthesized and tested for their ability to inhibit the estrone-sulfatase activity transforming estrone sulfate to estrone. A strong inhibitory activity was obtained when an alkyl side chain or a substituted benzyl was introduced at position 17 alpha of estradiol. The 17 alpha-(3'-bromobenzyl)-estradiol (26) and 17 alpha-(4'-t-butylbenzyl)-estradiol (30) were the most potent estrone-sulfatase inhibitors obtained in our study with IC50 values of 24 and 28 nM, respectively. They also represent a new family of estrone-sulfatase inhibitors. These compounds are about 300-fold more effective in interacting with the enzyme than the substrate estrone sulfate itself.

C16 and C17 derivatives of estradiol as inhibitors of 17 beta-hydroxysteroid dehydrogenase type 1: chemical synthesis and structure-activity relationships

As a first part of our research focused on the synthesis of 17 beta-HSD type 1 inhibitors without estrogenic activity, we needed to identify a small, easy-to-handle pharmacophore able to block the enzymatic activity. Previous studies on the active site of the enzyme by affinity labeling gave us a basis for the design of steroidal inhibitors derivatives. Several estradiol derivatives bearing a short (three carbons) side chain in position 17 alpha or 16 alpha were synthesized and tested for their ability to inhibit the transformation of estrone into estradiol by 17 beta-HSD type 1 (cytosolic fraction of human placenta). We found that 16 alpha-derivatives of estradiol gave better 17 beta-HSD inhibition than their corresponding 17 alpha analogs. Among several chemical groups used in this study, we conclude that better 17 beta-HSD inhibition was obtained for compounds with a good leaving group at the end of side chain. Thus, an iodopropyl or a bromopropyl side chain at C16 alpha of estradiol (E2) inhibit efficiently the 17 beta-HSD type 1 with IC50 values of 0.42 and 0.46 microM, respectively. Their 17-keto analogs inhibit also the enzyme activity similarly. Since this kind of compounds inhibit the 17 beta-HSD type 1 in time-dependent manner and that enzymatic activity cannot be restored later, we conclude to inhibitor of inactivator type. This conclusion is in accordance with the correlation observed between the ability of leaving group to dissociate and their potency to inhibit 17 beta-HSD type 1. We have also observed that additional addition of untritiated estrone protect the enzyme against the inactivation caused by 16 alpha-bromopropyl-E2 suggesting a competitive inhibitor of 17 beta-HSD. The bromopropyl pharmacophore was then selected to be further added onto an antiestrogenic steroid nucleus.