Banisteriopsis caapi (B. caapi) contains
harmine,
harmaline, and
tetrahydroharmine, has
monoamine oxidase inhibitory activity, and has reported antiparkinsonian activity in humans when imbibed as a
tea; however, its effects are poorly documented. For this reason, motor function was assessed in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated common marmosets following administration of B. caapi extract (28.4-113.6 mg/kg; po),
harmine (0.1 and 0.3 mg/kg; sc), and
selegiline (10 mg/kg; sc), alone or with a submaximal dose of
L-3,4-dihydroxyphenylalanine (
L-DOPA; 4-7 mg/kg).
L-DOPA reversed motor disability, increased locomotor activity, and induced moderate
dyskinesia. B. caapi did not increase locomotor activity or induce
dyskinesia but at 56.8 and 113.6 mg/kg improved motor disability. The
L-DOPA response was unaltered by co-administration of B. caapi.
Harmine (0.1 and 0.3 mg/kg) produced a mild improvement in motor disability without affecting locomotor activity or
dyskinesia but had no effect on the
L-DOPA-induced antiparkinsonian response.
Selegiline (10 mg/kg) alone improved motor function to the same extent as
L-DOPA, but with only mild
dyskinesia, and did not alter the response to
L-DOPA, although
dyskinesia was reduced. The findings suggest that B. caapi alone has a mild antiparkinsonian effect but does not enhance the
L-DOPA response or reduce
dyskinesia.