[The heterozygous effect of X-ray or ENU-induced null-mutant Adh alleles on alcohol tolerance of Drosophila melanogaster].

To study the mechanisms of partial dominance, 12 intragenic alcohol dehydrogenase null mutations (Adhn) in Drosophila melanogaster were used as a model system. These known sequenced mutations, either single base substitutions or small intragenic deletions (9-16 bp) were analyzed for peptide production, dimer formation and enzymatic activity of the heterodimer. Multiple mechanisms leading to partial enzyme expression in heterozygotes and a wide range of dominance varying from almost complete recessive to a high degree of dominance were found. An expression of partial dominance for alcohol tolerance was observed for all 12 Adhn under the high stress of 10% ethanol. The genetic background on which the null mutations are expressed is a major determinant for alcohol tolerance of the heterozygous adult flies. The mutations induced by X-ray had higher average dominance than that of ENU-induced mutations, and the mutations that formed nonfunctional heterodimers had the highest dominance.

N-(cyanomethyl)- and N-(2-methoxy-1-cyanoethyl)anthracyclines and related carboxyl derivatives.

Treatment of doxorubicin with formaldehyde and NaCN afforded the N-(cyanomethyl) derivative as a stable alpha-cyanoamine with but moderate antitumor activity in mice, although it was prototypal to the intensely potent alpha-cyanomorpholine derivative. 2-Methoxyacetaldehyde and NaCN afforded the N-(2-methoxy-1-cyanoethyl) derivative as an open-chain analogue of the cyanomorpholine. This analogue underwent rapid hydrolysis to doxorubicin and appeared to act as a prodrug, giving increased antitumor efficacy although with decreased potency. N-(Carboxymethyl)daunorubicin was a highly water-soluble but inactive analogue, synthesized by N-alkylation with ethyl iodoacetate and saponification. The similar N-alkylation of N-(cyanomethyl) daunorubicin demonstrated the combining of N-alkyl chains having different functional substituents.

N-(2-hydroxyethyl)doxorubicin from hydrolysis of 3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin.

The susceptibility of 3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin to hydrolysis at pH 7, 4, and 2 has been compared with that of the typically stable morpholine analogue. At pH 7, 74% of the cyanomorpholine was unchanged after 24 h at room temperature, but at pH 2 only 10% remained. Products identified were aglycon (8%) and N-(2-hydroxyethyl)doxorubicin (7%). Most of the losses were to unidentified polar products not eluted from HPLC. Authentic hydroxyethyl was synthesized from doxorubicin by reductive alkylation with glycolaldehyde. Antitumor potency was comparable to that of doxorubicin rather than of cyanomorpholine.

New cyanomorpholinyl byproduct of doxorubicin reductive alkylation.

Previously we reported that reductive alkylation of doxorubicin with 2,2'-oxybis[acetaldehyde] and NaBH3CN to form the 4''-morpholinyl derivative also gave the intensely potent 3''-cyano-4''-morpholinyl as a byproduct, by addition of CN- to an iminium intermediate in place of hydride. We now find that sugar 4'-OH is a third nucleophile that can add to the iminium intermediate in this reaction. Bridging of the 4'-OH to the morpholine ring at C.5'' formed a novel byproduct with an oxazolidino ring fused to the sugar and morpholine. The new product was minor at neutral pH but predominant at an acidic pH. When tested against tumors in mice it was 4-6 times more potent than doxorubicin. Hence, in comparison with the 3''-cyano-4''-morpholinyl, potency was reduced up to 100-fold by the O bridge. Analytical HPLC showed the presence of three of the four possible diastereoisomers, and two were isolated. The diastereoisomers appeared to differ in stability. In vitro tests suggested that biological potency varied inversely with stability.

Intensely potent morpholinyl anthracyclines.

3'-Deamino-3'-(3-cyano-4-morpholinyl)doxorubicin is a new analogue that is 100 to 1000 times more potent than doxorubicin against tumors in cell culture or in mice, that is active by intraperitoneal, intravenous, or oral dosing, and that does not produce chronic myocardial lesions in mice. This analogue was encountered in studies on the reductive alkylation of doxorubicin and daunorubicin with 2,2' - oxybis [acetaldehyde], which constructs a morpholino ring incorporating the amino N. The morpholinyl nitrile byproducts are separated by virtue of their nonbasicity from the expected morpholino derivatives. The 13-dihydro and 5-imino derivatives are also described in this important new class of anthracyclines.

Adriamycin analogues. 3. Synthesis of N-alkylated anthracyclines with enhanced efficacy and reduced cardiotoxicity.

Reaction of daunorubicin (1) and adriamycin (2) with aldehydes and ketones in the presence of NaCNBH3 afforded N-alkyl- and N,N-dialkylanthracyclines along with their 13-dihydro derivatives. Product ratios depended upon the nature of the carbonyl reagent and the starting drug. The majority of these analogues retained in vivo antitumor activity comparable to 1 and 2. However, unlike the parent compounds, which inhibit DNA and RNA synthesis at comparable concentrations, several of these analogues inhibit RNA synthesis at markedly lower concentrations than required to inhibit DNA synthesis. In addition, in some cases the ability to bind to DNA in vitro was reduced while antitumor activity was retained. N,N-Dibenzyldaunorubicin was especially notable for increased efficacy (T/C 259, qd 1--9) against P388 leukemia in mice, despite reduction of DNA binding in vitro. It showed almost complete loss of mutagenicity vs S. typhimurium (Ames test) and it was tenfold less cardiotoxic by electrocardiographic measurements (Zbinden test) in the rat.

7-(Aminoethyl) ether and thioether of daunomycinone.

One-step treatment of daunomycinone with excess 2-aminoethanethiol and 2-aminoethanol in trifluoroacetic acid afforded at C-7 the thioether (77% yield) and ether (30% after recycling), respectively. Stereoselectivity for the natural 7S over the 7R configuration was greater for the ether (97:3) than for the thioether (2.5:1). Esterification of daunomycin at C-7 with beta-alanine was accomplished through the mixed anhydride of Z(OMe)-beta-alanine. Preliminary biological tests suggests that the antitumor and DNA interactive properties of the anthracyclines can be retained in such structures.

5-Iminodaunorubicin. Reduced cardiotoxic properties in an antitumor anthracycline.

Treatment of daunorubicin with methanolic ammonia affords 5-iminodaunorubicin, the first quinone-modified analogue of either daunorubicin or adriamycin. This product retains antileukemic activity in mice, is less cardiotoxic by electrocardiographic measurements in rats, and is nonmutagenic in Salmonella typhimurium (Ames test).

Antitumor anthracycline antibiotics. Structure-activity and structure-cardiotoxicity relationships of rubidazone analogues.

A series of rubidazone analogues (4-14) with varying phenyl group substituents was prepared. The effect of these compounds on inhibition of nucleic acid synthesis in cultured cells, on in vivo antitumor properties, and on cardiotoxicity was examined. Substituent effects on drug-DNA binding as indicated by DNA melting temperature measurements were also investigated. Substituent effects were essentially absent among the rubidazone analogues in in vivo and in vitro test systems which measure cytotoxic characteristics; however, the rubidazone analogues varied substantially in their cardiotoxic effects and this variation was closely correlated with the electronic character of the phenyl substituent.

Biotransformation of drugs: quantitative structure-activity relationships for barbiturates, tertiary amines, and substituted imidazoles.

When using free energy-related physicochemical parameters, stimulation of NADPH oxidation by barbiturates and the N-oxidation of tertiary amines was found to be primarily dependent upon the lipophilic character of the substrates as measured by log P, where P is the partition coefficient from either 1-octanol-water or corn oil-water solvent systems. In contrast, the inhibition of epoxidation of aldrin by a series of substituted imidazoles appears to be much more dependent on electronic (sigma) and steric (Es) effects of the inhibitors.