Corticotropin-releasing hormone receptor antagonists: framework design and synthesis guided by ligand conformational studies.

As described in the preceding paper (Arvanitis et al. J. Med. Chem. 1999, 42), anilinopyrimidines I were identified as potent antagonists of corticotropin-releasing hormone-1 receptor (CRH1-R, also referred to as corticotropin-releasing factor, CRF1-R). Our next goal was to understand the receptor-bound conformation of the antagonists and to use this information to help guide preclinical optimization of the series and to develop new leads. Since receptor structural information was not available, we assumed that these small, high-affinity antagonists would tend to bind in conformations at or energetically close to their global minima and that rigid analogues that maintained the important stereoelectronic features of the bound anilinopyrimidine would also bind tightly. Conformational preferences and barriers to rotation of the anilinopyrimidines were determined by semiempirical methods, and X-ray and variable-temperature NMR spectroscopy provided experimental results that correlated well with calculated structures. Using these data, a key dihedral angle was constrained to design fused-ring analogues, substituted N-arylpyrrolopyridines II, synthesis of which provided CRH1 receptor antagonists with potency equal to that of the initial congeneric leads (Ki = 1 nM) and which closely matched the conformation held by the original compound, as determined by crystallography. In addition to providing a useful template for further analogue synthesis, the study unequivocally determined the active conformation of the anilinopyrimidines. Theoretical and spectroscopic studies, synthesis, and receptor binding data are presented.

Biochemical markers of malignant melanoma.

The excretion of Thormählen positive melanogens (TPM), zincuria, serum dopaoxidase activity of tyrosinase and serum sialic acid were determined in 60 patients with primary and/or metastatic cutaneous melanoma and in 20 healthy persons. On the basis of our results we can recommend the following of TPM urinary excretion and serum dopaoxidase activity in the course of malignant melanoma as specific markers of the tumor growth. The following of serum sialic acid in the course of malignant melanoma is valuable from the standpoint of prognosis of the disease. The following of zincuria in the course of malignant melanoma is not recommended because of its low value for monitoring melanoma patients.

An evaluation of the effectiveness of azelaic acid as a depigmenting and chemotherapeutic agent.

In the past five years, it has been reported that certain dicarboxylic acids (C8-C13) and azelaic acid (C9) (AZA), in particular, have a remarkable effect in the management of lentigo maligna, human malignant melanoma, and certain disorders of hyperpigmentation. Preclinical trials, therefore, were undertaken in order to evaluate the effectiveness of AZA as a depigmenting agent and as a chemotherapeutic agent. Twenty-seven uniformly black pigmented guinea pigs were given topical applications of various concentrations (3, 5, 10, 15, and 20%) of AZA preparations for 8 weeks, and their effects on the melanocytes of epilated skin of the backs and the nonepilated ears of guinea pigs were compared to the effects of well-known depigmenting agents. Whereas 4-isopropylcatechol, monobenzylether of hydroquinone, monoethylether of hydroquinone, hydroquinone, and 4-hydroxyanisole were found to be selectively cytotoxic to melanocytes in black-skinned guinea pigs, AZA has little or no visually recognizable effect on melanocytes in these animals. The therapeutic effect of local s.c. injections of various concentrations of AZA preparations on the development of s.c. implanted B-16 melanoma tumor was evaluated in 96 C57BL/6J mice. In addition, 31 BDF1 mice, implanted i.p. with B-16 melanoma tumor, were used to assess the effect of 100-500 mg/kg concentrations of AZA administered i.p. In both studies, AZA revealed no significant tumoristatic or tumoricidal effect on the size, color, and growth of melanoma. The effect of AZA was also evaluated on S-91A (melanotic or pigmented) and S-91B (amelanotic) human melanoma cells in culture. Low concentrations (10(-5) and 10(-3) M) of AZA had no inhibitory effect on the growth of these cells. Only at higher concentrations (greater than 10(-3) M) was a cytotoxic effect on cell viability observed. These observations indicate AZA is not selectively cytotoxic to normal and proliferative melanocytes and has no apparent inhibitory effect on the formative process of melanin pigmentation.

Imine analogues of tricyclic antidepressants.

Analogues of tricyclic antidepressants were synthesized in which the alpha-carbon of the side chain was replaced by nitrogen. The antidepressant activity of these imines, as measured by the reversal of the effects of tetrabenazine in mice, showed a structure-activity relationship similar to that of the carbon analogues. The most active imine (19) was six times as potent as amitriptyline. Some of the compounds differed from amitriptyline in that they produced stimulation in mice.