Conformations, DNA binding parameters, and antileukemic activity of certain cytotoxic protoberberine alkaloids.

The tetrahydroprotoberberine alkaloids 5 and 7 possessing a trans-quinolizidine conformation display in vitro KB cytotoxicities in contrast to their corresponding diastereomers 4 and 6 which exist in the cis-quinolizidine conformation and are much less toxic. The DNA-binding parameters of these compounds as well as the protoberberine salts 1, 8, and 9 have been examined by equilibrium dialysis. Only the quaternary salts bind to DNA. The alcohol 5 showed low in vivo activity against leukemia P388 systems, while the quaternary salts 8 and 9 proved to be toxic to the host.

(+/-)-4-Aryl-4,5-dihydro-3H-1,3-benzodiazepines. 3. 2-Phenyl and 2-amino analogues as potential antihypertensive agents.

A series of 2-phenyl- and 2-amino-4-aryl-4,5-dihydro-3H-1,3-benzodiazepines was prepared and submitted for broad biological screening, including evaluation for potential antihypertensive activity. Compound 4a [(+/-)-4,5-dihydro-2,4-diphenyl-3-methyl-3H-1,3-benzodiazepine hydrochloride] was the most active member of the series in the spontaneously hypertensive rat (SHR) model, producing a 56 mmHg decrease in systolic blood pressure at an oral screening dose of 50 mg/kg. The synthesis of 4a analogues containing nuclear substituents in the 4-phenyl moiety resulted in a marked decrease of antihypertensive activity. It was not possible to improve on the antihypertensive properties of 4a through further synthetic modifications.

(+/-)-4-Aryl-4,5-dihydro-3H-1,3-benzodiazepines. 1. Synthesis and evaluation of (+/-)-4,5-dihydro-2,3-dimethyl-4-phenyl-3H-1,3-benzodiazepine and analogues as potential antidepressant agents.

A series of (+/-)-4,5-dihydro-4-phenyl-3H-1,3-benzodiazepines and (+/-)-4,5-dihydro-4-phenyl-1H-1,3-benzodiazepines was synthesized as part of a program to develop novel psychotropics. Of these compounds, (+/-)-4,5-dihydro-2,3-dimethyl-4-phenyl-3H-1,3-benzodiazepine (10a, HRP 543) emerged as a potential antidepressant. In in vivo mouse tests (inhibition of tetrabenazine-induced ptosis and potentiation of yohimbine toxicity) which are predictive of antidepressant-like activity, 10a is comparable to amitriptyline. The similarity is also maintained in vitro, as both 10a and amitriptyline inhibit norepinephrine and serotonin uptake into rat brain synaptosomes. No significant inhibition of rat brain monoamine oxidase A or B was found with 10a, nor did the compound potentiate tryptamine-induced seizures. On chronic administration, the number of cortical beta-adrenergic receptor sites was similarly reduced by 10a and desipramine. The anticholinergic activity of clinically useful antidepressants, such as amitriptyline, is a proposed cause of side effects which reduce patient compliance. In contrast to the tricyclics, 10a apparently lacks anticholinergic activity, as evidenced in vitro by negligible displacement of [3H]quinuclidinyl benzylate from rat brain muscarinic receptors and in vivo by insignificant antagonism of the cholinergic stimulation produced by physostigmine or oxotremorine. These data suggest that 10a may be clinically useful as a novel nontricyclic antidepressant which is devoid of anticholinergic side-effect liability. Further evaluation of 10a in nonrodent species is in progress.