Inhibition of human dihydrofolate reductase by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazine s. A quantitative structure-activity relationship analysis.

The inhibitory activity of 101 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines against purified dihydrofolate reductase from human lymphoblastoid cell (WIL 2) has been studied. From the obtained Kiapp values, quantitative structure-activity relationships (QSAR) have been derived. The QSAR from human dihydrofolate reductase are compared with QSAR for triazines inhibiting bovine and murine tumor DHFR, as well with QSAR for their inhibitory action on murine tumor cell culture.

Crystallography, quantitative structure-activity relationships, and molecular graphics in a comparative analysis of the inhibition of dihydrofolate reductase from chicken liver and Lactobacillus casei by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazine s.

The inhibition of dihydrofolate reductase from chicken liver and from Lactobacillus casei has been studied with 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines. It was found that for the chicken enzyme, inhibitor potency for 101 triazines was correlated by the following equation: log 1/Kiapp = 0.85 sigma tau' - 1.04 log (beta X 10 sigma tau' + 1) + 0.57 sigma + 6.36. The parameter tau' indicates that for certain substituents, tau = 0. In the case of the L. casei DHFR results, meta and para derivatives could not be included in the same equation. For 38 meta-substituted compounds, it was found that log 1/Kiapp = 0.38 tau'3-0.91 log (beta X 10 tau'3 + 1) + 0.71I + 4.60 and for 32 para-substituted phenyltriazines log 1/Kiapp = 0.44 tau'4-0.65 log (beta tau'4 + 1') - 0.90 upsilon + 0.69I + 4.67. In the L. casei equation, I is an indicator variable for substituents of the type CH2ZC6H4-Y and ZCH2C6H4-Y, where Z = O, NH, S, or Se. The parameter upsilon is Charton's steric parameter, which is similar to Taft's Es. The mathematical models obtained from correlation analysis are compared with stereo color graphics models.

A new, potent, conformationally restricted analogue of amphetamine: 2-amino-1,2-dihydronaphthalene.

A new stimulant compound, 1,2-dihydro-2-naphthalenamine (2-amino-1,2-dihydronaphthalene, 2-ADN), was prepared as an analogue of amphetamine and of 2-aminotetralin. The optical isomers of 2-ADN were obtained by chemical resolution, and the absolute configuration was determined to be R-(+) and S-(-). Preliminary pharmacological evaluation revealed that racemic 2-ADN is approximately one-fourth as potent as (+)-amphetamine as a stimulant in mice. The S-(-) isomer of 2-ADN was found to be solely responsible for the stimulant effects of the racemate. Both reserpine and alpha-methyl-p-tyrosine antagonized the stimulation produced by 2-ADN.

Comparison of solution conformational preferences for the hallucinogens bufotenin and psilocin using 360-MHz proton NMR spectroscopy.

The 360-MHz 1H NMR spectra of bufotenin and psilocin were obtained, both as the free bases in CDCl3 and as protonated salts in D2O. Coupling constants for the side-chain methylenes were derived using the LAOCN3 program. These time-averaged coupling constants indicate that the trans and gauche rotamers of both compounds have about equal energy in D2O. There is a slight excess of the trans rotamer of bufotenin in CDCl3. For psilocin, in contrast, the gauche form is highly favored in CDCl3. The magnitude of this stabilization was estimated at about 1 kcal/mol using rotamer populations and free energy of transfer from published partitioning studies. It is suggested that this could result from a very weak hydrogen bond. On the other hand, the difference in partitioning between bufotenin and psilocin, which seems to be a major determinant of biological activity, is largely due to a difference in the basicity of the two compounds. The pKa values for the amino group of psilocin and bufotenin were determined to be 8.47 and 9.67, respectively.

Resolution and absolute configuration of trans-2-(2,5-dimethoxy-4-methylphenyl)cyclopropylamine, a potent hallucinogen analogue.

An hallucinogen analogue, trans-2-(2,5-dimethoxy-4-methylphenyl)cyclopropylamine (DMCPA), was resolved into ints two enantiomers by fractional crystallization of salts with d- or l-O,O-dibenzoyltartaric acid. A comparison of the ORD and CD curves of the N-5-bromosalicylidene derivatives of trans-2-phenylcyclopropylamine of known absolute configuration and of the title compound established the stereochemistry of the latter to be (1R,2S)-(-) and (1s,2r)-(+). We have earlier shown that the (-) isomer shows selective behavioral effects in cats and mice. In present study it was found that the (-) isomer selectively elicits rabbit hyperthermia when compared with the (+) isomer. In view of the stereoselective ability of the (-) isomer to elicit hallucinogen-like behavioral profiles in these animal models, the proof of absolute configuration lends further support to a new model which interrelates the active binding, conformation of phenethylamine hallucinogens to that of serotonin and tryptamines.