A new approach to the synthesis of novel bifunctional dinuclear platinum complexes with linear coordinating spermidine and spermine is reported. The synthetic pathway involves first the three-step selective protection of the polyamines, giving bis(trifluoroacetyl)polyamines (1, 4), (tert-butoxycarbonyl)bis(trifluoroacetyl)polyamines (2, 5), and (tert-butoxycarbonyl)polyamines (3, 6), respectively. The platination at desired sites with activated species of cis- or trans-[PtCl2(NH3)2] (CDDP or TDDP, respectively) produces the BOC-protected dinuclear species [{cis- or trans-PtCl(NH3)2}2(μ-L)]X (7, L = BOC-spermidine, X = (NO3)0.75Cl1.25; 9, L = (BOC)2-spermine, X = Cl2; cis spermine species not isolated). Through final deprotection, three different complexes were obtained and further investigated:  [{trans-PtCl(NH3)2}2{μ-spermidine-N 1,N 8}]Cl3 (8), [{trans-PtCl(NH3)2}2{μ-spermine-N 1,N 12}]Cl4 (10), and [{cis-PtCl(NH3)2}2{μ-spermine-N 1,N 12}]Cl4 (11). One- and two-dimensional NMR solution studies provided evidence that 11, at physiological pH, forms an inert bis((tetraamine)platinum) species in which each Pt is chelated by a central and a terminal amino group. In contrast, complexes 8 and 10 retain their reactivity, showing only reversible formation of hydroxo bridges. The comparison of in vitro cytotoxicity data for 8, 10, and 11 with data for previously described bifunctional dinuclear complexes shows the enhanced activity particularly of complex 8 in the CDDP-resistant L1210 cell line. The binding of 8 and 10 to poly(dG-dC)·poly(dG-dC) is further increased and also reflected by B → Z conformational changes at lower doses.

The synthesis and antitumor evaluation of 2, 5-disubstituted-indazolo[4,3-gh]isoquinolin-6(2H)-ones (9-aza-APs) are described. The key intermediates in the synthesis are benz[g]isoquinoline-5,10-diones which are substituted at positions 6 and 9 with groups of different nucleofugacity for SNAr displacements. The initial displacement of fluoride by a substituted hydrazine leads to the pyrazole analogues. Substitution of the remaining leaving group by an amine or BOC-protected amines leads to the 9-aza-APs 12. These analogues were converted into their maleate or hydrochloride salts 13. In two cases, namely, 13x and 13z, sidearm buildup was also employed in the synthetic pathway. In vitro evaluation of 9-aza-APs against the human colon tumor cell line LoVo uncovered for most of the compounds a cytotoxic potency lower than that of DuP-941 or mitoxantrone and comparable to that of doxorubicin. Only analogues 13c, 13n, and 13ff were as cytotoxic as DuP-941. Interestingly, while DuP-941 was highly cross-resistant in the LoVo cell line resistant to doxorubicin (LoVo/Dx), the 9-aza-APs carrying a distal lipophilic tertiary amine moiety in both chains were capable of overcoming the MDR resistance induced in this cell line. The 9-aza-APs show outstanding in vivo antitumor activity against both systemic P388 murine leukemia and MX-1 human mammary carcinoma transplanted in nude mice. At their optimal dosages, congeners 13a-c, 13f, 13n, 13q, 13x, and 13dd were highly effective against P388 leukemia with T/C% of 200-381, while the T/C% value of DuP-941 was 147. In the MX-1 tumor model, 24 compounds elicited percentages of tumor weight inhibitions (TWI) ranging from 50% to 99%. Congeners 13d, 13k, 13l, 13x, 13z, and 13ee emerged as the most effective ones, with TWI% 96, simliar to that of DuP-941 (TWI% = 95). On the basis of their efficacy profile in additional experimental tumors and lack of cardiotoxicity in preclinical models, two congeners have surfaced as potential clinical candidates.

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Synthetic routes have been developed which lead to ring‐hydroxylated aza‐analogues of antitumor anthrapyrazoles, namely, 2,5‐bis[(aminoalkyI)amino] substituted 10‐hydroxymdazolo[3,4‐fg]isoquinolin‐6(2H)‐ones 1 and 7‐hydroxyindazolo[4,3‐gh]isoquinolin‐6(2H)‐ones 2. The regiospecific synthesis of 6,9‐dihalo‐4‐hydroxybenz[g]isoquinolines 3 and 4 has been accomplished. Intermediate 3 was constructed in a multistep process involving Diels‐Alder chemistry of benzoylacrylates whereas 4 was assembled using Ni(II) mediated coupling of methyl 3‐chloro‐5‐methoxyisonicotinate (15b) with the organic zinc reagent 18 derived from 2‐fluoro‐5‐chlorobenzyl bromide (17). After protection of the hydroxy group with a p‐methoxybenzyl moiety, the different nucleofugacities of the leaving groups present in 10 and 20 allowed sequential displacements by substituted hydrazines and amines, respectively, to lead to the desired p‐methoxybenzyl protected analogues 12 and 22. Deprotection led to the side arm modified compounds 1 and 2. The displacements of 21a and 21b with N,N‐dimethylethylenediamine also led to the tri[(aminoalkyl)amino]substituted analogues 23a and 23b, respectively, which arose from further SNAr substitutions of the p‐methoxybenzyloxy group.

A novel approach based on molecular thermodynamics and the information theory is proposed to quantify the influence of water-miscible additives on protein stability. According to the two-state mechanism of inactivation, solvent effects are described in terms of perturbation of the equilibrium between the folded and unfolded protein forms. The model provides the dependence of the protein's melting temperature on the additive concentration. Effects of the latter are accounted for by an empirical parameter related to the free energy of transfer of the protein from the pure to the mixed solvent. The model was tested using experimental data relative to the influence of hydroxylic and aminoacidic additives on the thermal unfolding of hen egg lysozyme and erythrocyte carbonic anhydrase. Fitting parameters were correlated in terms of a theoretic information index characterizing the additive's molecule and incorporating an atomic-composition term and a topological contribution. Model calculations agreed very well with experimental data, suggesting that the molecular information content of the additive can be used effectively to correlate solvent-induced perturbations of stability. The procedure was also used to predict melting temperatures in systems containing binary mixtures of additives and to reconstruct thermal unfolding curves in the different media