Mass spectral studies on steroidal compounds-3 6-aza compounds in the cholestane series (ring B -lactams).
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The hepatic microsomal metabolites of the highly carcinogenic dimethylbenzacridines, 7,9-dimethylbenz[c]acridine (7,9-DMBAC), and 7,10-dimethylbenz[c]acridine (7,10-DMBAC) were obtained with preparations from 3-methylcholanthrene-pretreated rats. Metabolites were separated by reversed-phase HPLC and characterized using UV spectral data and chemical ionization-mass spectrometry after trimethylsilylation and GC. Comparisons with products formed in the presence of the epoxide hydrolase inhibitor, 1,1,1-trichloropropane 2,3-oxide and with those formed from the three synthetic alcohol derivatives of each parent compound, aided the assignment of firm or tentative structures to 16 products from 7,9-DMBAC found in 22 reversed-phase chromatographic peaks, and for 17 products of 7,10-DMBAC found in 19 chromatographic peaks. The more abundant metabolites were derived from oxidation of the methyl groups. Other metabolites were dihydrodiols, epoxides, phenols and secondary metabolites. The 9-methyl group prevented dihydrodiol formation at the 8,9-position from 7,9-DMBAC, and for each carcinogen, the 3,4-dihydrodiol was formed. As well, 3,4-dihydrodiols of methyl oxidized compounds were found.
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Reduction of half-wave potentials and the mechanism of reduction of 20 polycyclic nitrogen compounds were studied on a dropping-mercury electrode in anhydrous dimethylformamide using tetrabuthylammonium perchlorate as the supporting electrolyte. The measured values of the reducing half-wave potentials of the polycyclic aza-compounds were compared in view of their carcinogenic activity with parental carcinogenic polycyclic hydrocarbons. Electrochemical measurements have confirmed that the size of the shift in reducing potentials towards the more positive values and the decline of the carcinogenic activity generally depend on the number and position of the nitrogen atoms in the molecule of the polycyclic nitrogen compound under study. At the same time, the experimental electrochemical measurements were matched with the results of the quantum-chemical calculations of the molecular orbitals and this showed a good agreement to exist between the values of reducing half-wave potentials obtained by experimental measurement and by calculation.
Geranylgeranyl diphosphate synthase from rat liver was separated from farnesyl diphosphate synthase, the most abundant and widely occurring prenyltransferase, by DEAE-Toyopearl column chromatography. The enzyme catalyzed the formation of E,E,E-geranylgeranyl diphosphate (V) from isopentenyl diphosphate (II) and dimethylallyl diphosphate (I), geranyl diphosphate (III), or farnesyl diphosphate (IV) with relative velocities of 0.09:0.15:1. 3-Azageranylgeranyl diphosphate (VII), designed as a transition-state analog for the geranylgeranyl diphosphate synthase reaction, was synthesized and found to act as a specific inhibitor for this synthase, but not for farnesyl diphosphate synthase. Diphosphate V and its Z,E,E-isomer (VI) also inhibited geranylgeranyl diphosphate synthase, but the effect was not as striking as that of the aza analog VII. Specific inhibition of geranylgeranyl diphosphate synthase by VII was also observed in experiments with 100,000g supernatants of rat brain and liver homogenates which contained isopentenyl diphosphate isomerase and prenyltransferases including farnesyl diphosphate synthase as well as geranylgeranyl diphosphate synthase. For farnesyl:protein transferase from rat brain, however, the aza compound did not show a stronger inhibitory effect than E,E,E-geranylgeranyl diphosphate.
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Doxorubicin and mitoxantrone are carboxyclic anti-cancer drugs that interact with DNA through intercalation. Our laboratory has synthesized a new series of anti-tumor agents, the aza-anthracenediones, which are structurally related to mitoxantrone but contain a heterocyclic, rather than a carbocyclic, chromophore. Both the in vivo and in vitro anti-tumor activities of these compounds were exquisitely sensitive to the positioning of the nitrogen atom within the heterocyclic backbone. Compounds having a 2-aza were 30- to 100-fold more potent than the 1-aza or the di-aza compounds against L1210 cells in vitro. When tested in vivo, the 2-aza-anthracenediones had marked anti-tumor activity, in some cases curative, whereas the 1-aza-anthracenediones had but minimal antitumor activity. To define the importance of the aza positioning on DNA reactivity, spectral shift and gel mobility assays were used. The spectral shift assay suggested that the 2-aza compounds reacted with DNA solely through intercalation whereas the 1-aza-anthracenediones, and mitoxantrone all reacted with DNA through intercalative and non-intercalative processes. The affinity of DNA binding was five to seven times greater for the 2-aza compounds compared to the 1-aza or the di-aza derivatives. The retardation of supercoiled pBR322 DNA mobility in agarose gel electrophoresis further suggested an intercalative type of DNA interaction. Differences in DNA interaction appear related to but can not completely account for differences in cytotoxicity of the aza anthracenediones.
Two compounds, theophylline and 8-aza-9-furfuryl-adenine (SQ 4665), were found to maximally stimulate lipolysis in preparations of rat epididymal fat cells in the absence of exogenous hormones. Cyclic AMP levels in lipocytes maximally stimulated by either agent alone were unchanged from control levels. In contrast, lipolysis stimulated by either epinephrine alone or in combination with several cyclic nucleotide phosphodiesterase inhibitors correlated well with increases in the levels of cyclic AMP observed. These results suggest the presence of a non-cyclic AMP dependent pathway for the stimulation of lipolysis in rat epididymal fat cells.
The relation between polarographic reduction, values of half-wave potentials, and the parameter of potential carcinogenicity (tg alpha) was studied in a series of synthetic analogs of natural nucleic acid components modified by different substituents at position 5 of the base. The series included pyrimidine nucleobases (5-cyanouracil, 5-carboxycytosine, 5-azacytosine), ribofuranosyl nucleosides (5-cyanouridine, 5-carboxycytidine, 5-azacytidine) as well as 2'-deoxy-5-azacytidine and 5-carboxy-1-beta-D-arabinosylcytosine. No direct correlation was found between the reducibility of the studied compounds and the parameter of potential carcinogenicity tg alpha since event a slight alteration in the structure of these molecules markedly affected the properties of these compounds.
The synthesis of the 2,3-dihydro-pyrrolo[1,2,3-de]-1,4-benzothiazine 1a and 11b, 12-dihydro-isoquino[1,2-c]-1,4-benzothiazine 8 has been accomplished by using a Bischler type cyclization of the N-(2,2-diethoxyethyl)-3,4-dihydro-2H-1,4-benzothiazines 3a and 3d, respectively. The new compounds 1a and 8 together with the known pyrrolobenzothiazines 1b,c and some their derivatives and intermediates of preparation were tested in vitro for their antimicrobial activity. Compound 1b was the most active against the Gram-positive Bacillus subtilis. Compound 7b showed interesting antifungal activity when tested against Saccharomyces cerevisiae.
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A series of analogs based on a novel template, 11-aza-(20S)-camptothecin, were obtained from total synthesis and tested as potential anticancer drugs in the topoisomerase I enzyme cleavable complex assay. The parent compound 11-aza-(20S)-camptothecin (8) was derived from a Friedlander condensation between the known aminopyridine derivative 3-(3-amino-4-picolylidene)-p-toluidine and optically active tricyclic ketone 7. Compound 8 had activity approximately twice that of (20S)-camptothecin in the calf thymus topoisomerase I cleavable complex assay. Compounds were prepared wherein the 11-aza nitrogen atom was quaternized as either the corresponding N-oxide or methyl iodide. Compounds with quaternized N-11 showed improved water solubility and were equipotent to the clinically investigated camptothecin analog topotecan in the cleavable complex assay. These compounds were evaluated in vivo in nude mice bearing HT-29 human colon carcinoma xenografts. The analog 11-aza-(20S)-camptothecin 11-N-oxide was found to significantly retard tumor growth when compared to untreated controls. Finally, 7,10-disubstituted 11-azacamptothecin analogs were synthesized using Pd(0) coupling reactions of 10-bromo-7-alkyl-11-aza-(20S)-camptothecins 19 and 20, which in turn were available from a Friedlander condensation of the novel bromopyridine derivatives 17a and 17b with 7. Among the 10-substituted series, a number of analogs displayed extremely high in vitro potency against topoisomerase I and improved aqueous solubility. A significant number of the compounds were found to be active in whole cell cytotoxicity assays and several were evaluated in nude mice bearing the HT-29 tumor xenografts. The most effective of these proved to be (S)-11-aza-7-ethyl-10-(aminohydroximinomethyl)camptothecin trifluoracetic acid salt (27), a potent topoisomerase I inhibitor which demonstrated excellent efficacy in both short term and in extended in vivo assays. A comparison between in vitro enzyme data and in vivo data from nude mouse studies in other compounds in this series revealed a poor overall correlation between topoisomerase inhibition in vitro and antitumor efficacy in vivo.