Pharmacological Properties of Magnolol and Hōnokiol Extracted from Magnolia officinalis: Central Depressant Effects

Abstract

The pharmacological properties of magnolol and hõnokiol, neolignane derivatives, extracted from Magnolia officinalis, used in Chinese and Japanese traditional medicine, for neurosis and gastrointestinal complaints, were investigated. Magnolol and hõnokiol produced sedation, ataxia, muscle relaxation and a loss of the righting reflex with an increase in dose of 50 to 500 mg/kg i.p. Magnolol and hõnokiol at a dose of 50 mg/kg suppressed spinal reflexes in young chicks in a similar manner, but with a much longer duration of action than mephenesin. Pretreatment of mice with magnolol 100 mg/kg inhibited tonic extensor convulsions and death produced by an intracerebroventricular injection of penicillin G potassium 50 µg. In rats, after an intraventricular injection of penicillin G 400 µg, magnolol suppressed the incidence of spike discharge, but not seizure discharge. Magnolol produced spindle discharges in sensory and motor cortex electroencephalograms and inhibited mid brain reticular formation- and hypothalamus-stimulated responses in the neo- and palaeo-cortex electroencephalograms, respectively. These results suggest that magnolol causes a depression of the ascending activating systems as well as of the spinal cord.

Key Word Index

Magnolia officinalis - Magnoliaceae - Magnolol - 5,5′-Diallyl-2,2′-dihydroxydiphenyl - Hōnokiol - Central depression - Muscle relaxation - Neolignane derivatives