sixteen hours, while that of harmine disappeared in about 
eight nours (78). The enzyme MAO functions in the 
breakdown of serotonin, a biologically highly active sub- 
stance found in various tissues, including the central ner- 
vous system; and in the breakdown of norepinephrine, 
a possible neurohumor of the central nervous system and 
known neurotransmitter in the sympathetic nervous sys- 
tem (2). Antidepressant drugs known to inhibit MAO 
have produced a variety of systemic and_ psychoto- 
mimetic effects, but there is little agreement about the 
mechanism underlying these actions (18). 
Pletscher et al. (22) and Zirkle and Kaiser (46) have 
recently prepared extensive reviews on monoamine oxi- 
dase inhibitors. Harmine and harmaline cause hypoten- 
sion and bradycardia when administered intravenously, 
but prevent or reverse the hypotensive and sedative ef- 
fects of reserpine. Small dosages of harmine can slightly 
increase blood pressure. Although harmine blocks or 
depresses ganglionic and myoneural transmission, it 
stimulates intestinal contractions in intact animals. Both 
harmine and harmaline promote uterine contractions. 
Antihelmintic action on parasitic ascarid worms by 
harmine and harmaline has been observed, and various 
harman derivatives are also active against Protozoa 
(trypanosomes, amoebae) in vitro (32). 
V 
The psychotropic effects of the malpighiaceous drugs 
are many and varied, and depend upon the species em- 
ployed, upon the method of preparing the drugs, upon 
the social and physical environment in which they are 
taken, and upon the age, health, personality, expecta- 
tions and mental state of those who take them. I do not 
intend here to summarize these effects, but attention is 
called to the report of Pennes and Hoch (29) on the 
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