Combined modality treatment with ternary Cu(II) complexes and X rays.

Ternary Cu(II) complexes with bidentate malonato- and heterocyclic amine ligands were tested with regard to cytotoxicity and potentiation of x-ray induced cell killing in V79 cells. Two lead complexes were also tested in a tumor assay using the MTG-B murine adenocarcinoma model growing in the flanks of female C3H/HeJ mice. One complex, [2,2'-bipyridyl malonatoCu(II)] (RL-5077), produced sensitizer enhancement ratios (SER's) of 1.8 (hypoxic conditions) and 1.0 (oxic conditions) in vitro when irradiation followed 1 hr exposure to the drug at 100 microM. When RL-5077 was administered at doses of 1/2 (11.65 mg/kg) or 1/4 (5.25 mg/kg) the maximum tolerated dose (MTD), 15 min prior to a locally delivered dose of 20 Gy, enhancement ratios (ER's) of 1.6 and 2, respectively, resulted. The second lead complex, [1,10 phenanthroline (malonato)Cu(II)hydrate] (RL-5027), produced SER's of 1.8 and 1.2 under hypoxic and oxic conditions, respectively, at a concentration of 25 microM. Injection of RL-5027 (5 mg/kg) resulted in toxicity without enhancement in combination with radiation. Analogues of these two complexes have been synthesized in an effort to optimize the potentiation of radiation effects while minimizing toxicity to drug alone and increasing water solubility of the drug. Further studies of the structure-activity relationship of Cu(II) ternary complexes using in vitro radiosensitization as the endpoint have identified four classes of ligands with varying biological activity and have supplied information about the effects of group substitution on solubility, toxicity, and radiation potentiation. This group of complexes represents a new class of radiopotentiators that deserves further investigation into its potential for clinical use.

Antiarthritic and suppressor cell inducing activity of azaspiranes: structure-function relationships of a novel class of immunomodulatory agents.

Spirogermanium (1; 8,8-diethyl-N,N-dimethyl-2-aza-8- germaspiro[4.5]decane-2-propanamine dihydrochloride) is a potent cytotoxic agent in vitro which has demonstrated limited activity in experimental animal tumor models. Subsequently, it has been reported that spirogermanium has antiarthritic and suppressor cell-inducing activity. We have synthesized a series of substituted 8-hetero-2-azaspiro[4.5]decane and 9-hetero-3-azaspiro[5.5]undecane analogues of spirogermanium to identify the heteroatom requirements for in vivo antiarthritic and suppressor cell-inducing activity. This structure-activity relationship study has identified that appropriately substituted silicon and carbon analogues of spirogermanium retain both antiarthritic and immunosuppressive activity, with the 8,8-dipropyl (carbon) analogue being among the most active. Following the identification of N,N-dimethyl-8,8-dipropyl-2-azaspiro[4.5]decane-2-propanamine++ + dihydrochloride (9) as a more active analogue than spirogermanium, a series of 8,8-dipropyl analogues with various amine substituents were synthesized. A number of these analogues had activity similar to that of 9. A correlation between activity in the adjuvant arthritic rat and the ability to induce suppressor cells (r = 0.894, p less than 0.001) suggests an association between the two pharmacologic effects. While the precise biochemical mechanism(s) for the pharmacological activity is unclear, these data suggest that compounds within this series, e.g., N,N-dimethyl-8,8-dipropyl-2-azaspiro[4.5]decane-2-propanamine++ + dihydrochloride, may provide effective therapy in diseases of autoimmune origin and/or the prevention of rejection in tissue transplantation.

4-Hydroxyphenylpyruvate dioxygenase is an iron-tyrosinate protein.

A resonance Raman investigation into the blue chromophore of 4-hydroxyphenylpyruvate dioxygenase, a non-heme iron enzyme from Pseudomonas P. J. 874, reveals the presence of enhanced vibrations characteristic of tyrosinate coordination to the iron center. The excitation profiles for these features show that they are associated with the 595 nm absorption feature. EPR studies of this enzyme indicate the presence of a high-spin ferric center in a rhombic environment, as evidenced by a signal at g = 4.3 with the correct intensity for the measured iron content. This enzyme thus belongs to the emerging class of iron-tyrosinate proteins.