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B F Cain

Publications and source records attributed to B F Cain.

At least 19 recordsLinked to original sources
PubMed1984

Potential antitumor agents. 41. Analogues of amsacrine with electron-donor substituents in the anilino ring.

The preparation and antitumor activity of a series of 3'-alkylamino and 3'-dialkylamino analogues of amsacrine are reported. The results support previous work suggesting that the presence of electron-donating groups in the 3'-position of the anilino ring substantially enhance the antitumor activity of amsacrine analogues, possibly by the provision of high levels of electron density at the 6'-position. The alkylamino derivatives generally possess tighter DNA binding, higher levels of in vitro and in vivo antileukemic activity, and greater aqueous solubility than the corresponding amsacrine analogues.

Aminoacridines↗
PubMed1984

Potential antitumor agents. 43. Synthesis and biological activity of dibasic 9-aminoacridine-4-carboxamides, a new class of antitumor agent.

The synthesis and biological activities of representatives of a new class of antitumor agent, the N-[2-(dialkylamino)ethyl ]-9-aminoacridine-4-carboxamides, are reported. Members of this class are stable and very water soluble with high levels of in vitro and in vivo antitumor activity. The compounds bind tightly to double-stranded DNA by intercalation, but the requirements for antitumor activity are more restrictive. They depend critically on the separation distance, positioning, and pKa values of the two cationic centers. For in vivo activity, significant bulk tolerance exists for lipophilic but not hydrophilic groups about the C-9 acridine position and for both lipophilic and hydrophilic groups on the side-chain cationic moiety. Significant attenuation of the pKa of the side-chain cationic center abolishes activity, as does alteration of either the disposition or separation distance of the side-chain charge with respect to the chromophore.

Adenocarcinoma↗
PubMed1982

Potential antitumor agents. 36. Quantitative relationships between experimental antitumor activity, toxicity, and structure for the general class of 9-anilinoacridine antitumor agents.

Quantitative relationships (QSAR) have been derived between antileukemic (L1210) activity and agent physicochemical properties for 509 tumor-active members of the general class of 9-anilinoacridines. One member of this class is the clinical agent m-AMSA (NSC 249992). Agent hydrophobicity proved a significant but not a dominant influence on in vivo potency. The electronic properties of substituent groups proved important, but the most significant effects on drug potency were shown by the steric influence of groups placed at various positions on the 9-anilinoacridine skeleton. The results are entirely consistent with the physiologically important step in the action of these compounds being their binding to double-stranded DNA by intercalation of the acridine chromophore between the base pairs and positioning of the anilino group in the minor groove, as previously suggested. An equation was also derived for the acute toxicities of 643 derivatives of 9-anilinoacridine. This equation took a somewhat similar form to the one modeling antileukemia potency, emphasizing the usual fairly close relationship between potency and acute toxicity for antitumor agents in general. This study demonstrated the power of QSAR techniques to structure very large amounts of biological data and to allow the extraction of useful information from them bearing on the possible site of action of the compounds concerned.

Aminoacridines↗
PubMed1982

Potential antitumor agents. 37. Organophosphorus derivatives of 9-anilinoacridine.

A series of 9-anilinoacridine derivatives substituted in the anilino ring with a variety of phosphoramide and related substitutents has been prepared, and the antitumor activity has been evaluated both in vivo and in vitro against the L1210 or P-388 mouse leukemia systems. The DNA-binding properties were measured using the ethidium displacement method, and the structural requirements for strong binding were found to differ from those for antileukemic activity. For high biological activity a marked preference for oxygen-containing substituents on the phosphorus atom was noted, while for high DNA binding a requirement for nitrogen-containing or cyclized substituents was observed. The most active congeners, as assayed in both in vitro and in vivo systems, were comparable in activity to the clinically utilized anilinoacridine derivative N-[4'-(9-acridinylamino)-3'-methoxyphenyl]methanesulfonamide (m-AMSA, amsacrine).

Aminoacridines↗
PubMed1982

Comparison of the in vivo and in vitro antileukemic activity of monosubstituted derivatives of 4'-(9-acridinylamino)methanesulfon-m-anisidide.

The growth-inhibitory activity of 4'-(9-acridinylamino)methanesulfon-m-anisidide and 47 acridine-monosubstituted derivatives has been measured using cultures of L1210 murine leukemia cells grown for 3 days in the presence of each drug. The results have been compared with previously published in vivo antitumor activity and physicochemical properties related to DNA binding, acridine base strength, stability to chemical attack by thiols, and lipophilicity. Multiple-parameter regression equations show that both dose potency and host toxicity in mice are related to a combination of in vitro activity and a nonlinear (quadratic) term in lipophilicity. The in vitro activity can in turn be modeled as a combination of terms representing DNA binding, ability to quench the fluorescence of DNA-bound ethidium stability to thiolysis, and lipophilicity. It is hypothesized that the terms for thiolytic stability and lipophilic-hydrophilic balance describe the availability of the drug to the cell, and that the DNA binding constant determines what proportion of the available drug is bound to DNA, the proposed target site. The remaining terms could reflect changes in the geometry of drug-DNA binding, which in turn affect the intrinsic activity of these drugs when bound at their site of action.

Aminoacridines↗
PubMed1981

Potential antitumor agents. 34. Quantitative relationships between DNA binding and molecular structure for 9-anilinoacridines substituted in the anilino ring.

In an investigation of the structure-activity relationships in the 4'-(9-acridinylamino)methanesulfonanilide (AMSA) tumor inhibitory analogues, the DNA-binding properties of a series of simple 9-anilinoacridines were examined. Positional numbering as in the AMSA series has been employed. DNA binding was determined by drug competition with the fluorochrome ethidium for available sites. The decrease in fluorescence of a DNA-ethidium complex by the addition of drug is due to both drug displacement of bound ethidium and quenching of the fluorescence of bound ethidium by bound drug; measurement of both factors allows drug-DNA association constants (K) to be determined. DNA binding is augmented by 1' or 2' electron donor substituents, and significant correlation equations have been derived with Hammett's sigma p or sigma m constants. Group molar refractivity (MR) for 1'-substituents is an additional significant regression equation term for binding, while the values for 2' and 3' groups play no significant role. Most 3'-substituents decrease binding, presumably as a result of steric inhibition of entry of the acridine nucleus into intercalation sites. A 3'-NHSO2CH3 and 3'-NHCOCH3 substituent confer selectivity of binding to poly[d(G-C)] and poly[d(A-T)], respectively. It is suggested that a combination of H-bond formation and stereochemical features, coupled with steric hindrance, provides the selectivity observed. Binding data are consistent with a model in which the acridine nucleus occupies an intercalation site and the noncoplanar 9-anilino ring resides in the DNA minor groove.

Acridines↗
PubMed1981

Potential antitumor agents. 35. Quantitative relationships between antitumor (L1210) potency and DNA binding for 4'-(9-acridinylamino)methanesulfon-m-anisidide analogues.

Factors influencing dose potency of 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA) analogues in L1210 assays have been investigated by multiple regression analysis. The dependent variable was D40, the dose to provide 40% life extension in L1210 tests. Independent variables examined were chromatographic Rm values, as a measure of agent lipophilic-hydrophilic balance; Rm2; log K, where K is the agent-DNA association constant for poly[d(A-T)]; log T1/2, the half-life for congener thiolytic cleavage; and agent pKa values. A regression equation containing terms in Rm2 and log K was derived with the latter term accepting the greater proportion of the biological variance. DNA binding, of acridine substituted m-AMSA variants, is the most important factor influencing dose potency. Modeling of log K for 3-substituted derivatives provided an equation in substituent R constants and molar refractivities (MR).

Aminoacridines↗
PubMed1979

Potential antitumor agents. 29. Quantitative structure-activity relationships for the antileukemic bisquaternary ammonium heterocycles.

Quantitative relationships between physicochemical drug properties and antileukemic (L1210) efficacy have been examined for a series of bisquaternary ammonium heterocycles employing multiple variable regression analysis. Three measures of biologic response were examined: ILSmax, the percentage increase in mean life span of leukemic animals at the LD10 dose; D40, the drug dose necessary to provide 40% increase in life span; and CI (=LD 10/D40), the chemotherapeutic index. A cross correlation matrix between these three measures and the LD10 values demonstrates ILSmax and CI to be independent of toxicity. D40 is highly inversely correlated with LD10 and positively correlated with ILSmax, suggesting that this parameter measures a composite of both drug selectivity and toxicity. Superior regression equations resulted at all stages employing ILSmax as a measure of antitumor selectivity. Acceptable equations modeling LD10 could not be obtained. There was a parabolic relationship between agent lipophilic-hydrophilic balance, measured as chromatographic Rm values, and ILSmax. To reduce residual variance in the L1210 screening data, not accepted by this parabolic equation, measures of agent-DNA interaction were investigated as possible indices of site fit. Relative levels of drug-DNA interaction were obtained by spectrofluorimetric quantitation of drug displacement of DNA-bound ethidium. Addition to regression equations of agent C50 values for calf thymus DNA, those micromolar drug concentrations necessary to displace 50% of the ethidium bound to that DNA, provided a significant reduction in the screening data variance. C50 values for drug interactions with poly[d(A-T)] and poly[d(G-C)] were also investigated as possible indicators of drug selectivity towards different DNA sites. Marked differences were observed in the C50 values for the two synthetic nucleic acids, with those for calf thymus DNA and poly[d(G-C)] proving highly covariant. A regression equation containing a positive term in C50[poly[d(G-C)]] and a negative term in C50-[poly[d(A-T)]] provided the greatest acceptance of the variation in the biologic data. The term in C50[poly[d(A-T)]] is the single most important equation term, alone accounting for 35% of the variance in the data. This best equation provides both an adequate summary of the L1210 screening data for the 174 active compounds considered and a physical explanation for the antitumor selectivity for these agents. The major factor influencing antitumor selectivity in these drugs is their ability to distinguish alternating adenine-thymine sequences in DNA.

Animals↗
PubMed1979

Potential antitumor agents. 31. Quantitative structure-activity relationships for the antileukemic bis(guanylhydrazones).

Certain L1210-active bis(guanylhydrazones) have structural and biological properties in common with the DNA minor groove binding, antileukemic, bisquaternary ammonium heterocycles. Monitoring of the DNA binding of the bis(guanylhydrazones), by fluorimetric quantitation of drug displacement of DNA-bound ethidium, shows that, like the bisquaternary salts, these agents bind more strongly to poly[d(A-T)] than poly[d(G-C)]. The drug concentrations necessary to inhibit L1210 DNA-dependent DNA polymerase in vitro by 50% (IC50) are linearly related to measures of drug-DNA binding with no preference for a particular primary sequence of DNA being evident. Mammalian toxicity of the bis(guanylhydrazones) is effectively modeled by a regression equation containing binomial terms in Rm values, used as a measure of agent lipophilic-hydrophilic balance, and the logarithms of the IC50 values.

Animals↗
PubMed1979

Radiosensitization of E. coli B/r by 9-anilinoacridines.

Six anilinoacridine derivatives have been tested for the ability to act as radiosensitizers. Two gave good sensitization at concentrations of 100 microM or less. Both of these are known to possess significant activity against experimental tumours, and one (m-AMSA) is in Phase II clinical trial as a chemotherapeutic drug. Anilinoacridines may have potential as drugs with both a chemotherapeutic and radiosensitizing role. In spite of their structural similarity, the 2 derivatives which sensitize do so by different mechanisms. Compound VI behaves like a typical hypoxic cell sensitizer but Compound I (m-AMSA) interferes with the accumulation of sublethal damage in either the presence or absence of O2. The latter also displays a post-irradiation sensitizing effect. Differences in mechanism may be related to the relative DNA-binding abilities and electronic differences between the 2 drugs.

Aminoacridines↗
PubMed1978

Potential antitumor agents. 26. Anionic congeners of the 9-anilinoacridines.

To investigate the possible importance of small levels of sulfonamide anion in the antileukemia (L1210) 4'-(9-acridinylamino)methanesulfonanilides, an anionic derivative was prepared, in which -COOH replaced -NHSO2CH3, and shown to have experimental antitumor activity. Analogue synthesis and evaluation show that acceptable placement of the carboxylate function on the 9-anilino ring is restricted to the 1'-position. While the 1'-COOH and 1'-(CH2)2COOH analogues proved active, the intermediate acetate variant (1'-CH2COOH) was inactive. There were marked differences in the effects of added acridine ring substituents, on biologic activity, depending on the function attached to the 9-anilino ring (1'-NHSO2CH3 or 1'-COOH). Consideration of the vector components of possible drug-binding forces, acting on a DNA-intercalated agent, suggests that there may be low-energy barriers to two-dimensional reorientation of a planar, intercalated chromophore in relation to the neighboring purine-pyrimidine base pairs. It is proposed that site forces from an added substituent could lead to modified DNA-binding orientations. Observed acridine-ring substituent effects on biologic activity would then depend on the 9-anilino ring function (1'-NHSO2CH3, 1'-COOH) employed.

Acridines↗
PubMed1978

Potential antitumor agents. 27. Quantitative structure--antileukemic (L1210) activity relationships for the omega-[4-(9-acridinylamino)phenyl]alkanoic acids.

Simple carboxylic acid derivatives of 9-anilinoacridine (e.g., 1,R=-COOH) provide high experimental antileukemic (L1210) activity. The homologous 1'-(CH2)nCOOH congeners also prove active, and there is a parabolic interrelationship between maximum increase in life span in L1210 tests and Rm values used as a measure of agent lipophilic--hydrophilic balance. The corresponding carboxamides [1'-(CH2)nCONH2] provide a similar parabolic relationship, which has an optimum Rm value displaced from that of the acids. Earlier examined 1'-NHSO2(CH2)nCH3 variants, the 3-NHCOCH3 congeners of these, and the carboxamide [1'-(CH2)nCONH2] and sulfonamide [1'-(CH2)nSO2NH2] homologues can be treated as one group and a correlation equation derived that is identical with that for the carboxamide variants alone. The optimum Rm value for this group is displaced from that of the acids by the equivalent of 1.8 log P units on the octanol--water scale. In this drug series a carboxylic acid residue acts as an acceptable hydrophilic unit, providing a log P contribution intermediate between that of the un-ionized acid and the totally ionized carboxylate anion. Quantitative effects of acridine ring substituents on L1210 activity differ in analogues containing either carboxylic acid or alkanesulfonanilde side chains, supporting the view that different site-binding orientations may be involved with these two drug classes.

Acridines↗
PubMed1977

Potential antitumor agents. 21. Dialkanolamine dialkanesulfonic esters.

Homologous dialkanesulfonic esters of 2,2'-iminodiethanol, 3,3'-iminodi-1-propanol, N-(2-hydroxyethyl)-6-amino-1-hexanol, and N-(3-hydroxypropyl)-6-amino-1-hexanol were prepared via the N-trityl derivatives and screened for L1210 activity. For each active agent significant increases in life-span in L1210 tests (ILS) were correlated by linear least-squares regression with the corresponding log doses. The maximum ILS, taken from this regression line at the determined LD10, was used as a quantitative measure of antileukemic effectivenss. Within each homologoud series log ILSmax could be correlated with a binomial expression in lipophilic-hydrophilic balance, as measured by Rm values, but all active members from the four series could not be successfully included in a single correlation. By modification of Rm values with an ionization factor, log (H+/H+ + Ka), all active compounds could then be included in a significant correlation equation.

Alkanesulfonates↗
PubMed1977

Potential antitumor agents. 22. Latentiated congeners of the 4'-(9-acridinylamino)methanesulfonanilides.

N1-Acyl derivatives of the tumor inhibitory 4'-(9-acridinylamino)methanesulfonanilide agents act as prodrugs undergoing deacylation to liberate the core agents on incubation with pH 7.5 buffer or mouse blood. Against L1210 tumor implanted remotely from the drug administration site, lower acyl derivatives often provide enhanced effects over that obtained with nonacylated precursor alone. In certain homologous series of acyl derivatives, toxicity first increased with increasing lipophilic character, until greater than that of the core agent alone, and then at higher lipophilic levels decreased. Tumor inhibitory properties of the acyl derivatives in such series appeared inversely related to their toxicity. Several 3-(3,3-dialkyl-1-triazeno)acridine-substituted congeners provided excellent L1210 activity. Contrasting with most other tumor-active triazenes, one alkyl group need not be a methyl group of antileukemic activity to be observed. 3-Methyl-3-propyl-1-triazene and 3,3-diethyl-1-trazene analogues had comparable lipophilic-hydrophilic balance, toxicity, and antileukemic effectiveness; usual metabolic activation of the triazene N-methyl group may make little contribution to antitumor properties in the examples presented. Prepared as a nonalkylated triazene analogue, a 3-azidoacridine congener had high L1210 activity.

Anilides↗