Mulungu Erythrina mulungu, Brazilian coral tree bark

Botany — the coral tree of the dry season

Erythrina mulungu is a majestic tree that can reach some fifteen metres, native to the cerrado and caatinga ecoregions of Brazil and Bolivia. It belongs to the Fabaceae family (legumes), to the genus Erythrina — the coral trees, so named for the coral-red colour of their flowers (Schultes, Hofmann & Rätsch, Plants of the Gods, pp. 42-43). The genus name comes from the Greek erythros, "red."

Its signature is seasonal: at the end of the dry season, the tree sheds its leaves and covers itself in masses of coral-orange flowers shaped like a claw or a beak, pollinated by hummingbirds. When mulungu blooms in the sertão, it is said that rain is on its way — hence its reputation as a calendar-plant, almost a prophet-plant, in the Brazilian Nordeste.

Descriptive phytochemistry

The bark contains a family of Erythrina alkaloids specific to the genus Erythrina, which make up its pharmacological signature. Among the compounds identified are erysothrine, erysovine and erysodine, along with (+)-erythravine — isolated in 2006 and described as the principal anxiolytic agent — and (+)-11-α-hydroxy-erythravine. A minor indole alkaloid, hypaphorine, is also found. Naming these compounds is a matter of botanical description, not a promise of effect.

It should be noted that the seeds of Erythrina trees are reputed to be toxic, with a hypnotic or hallucinogenic effect reported for certain species (Rätsch & Müller-Ebeling, The Encyclopedia of Aphrodisiacs, pp. 457-458). INFUSE uses only the bark, never the seeds.

Mechanisms — what the studies report

The scientific literature describes a mode of action distinct from that of classic GABAergic anxiolytics (benzodiazepines, kava): studies suggest that mulungu's alkaloids may act chiefly by inhibiting nicotinic acetylcholine receptors, in particular the alpha4-beta2 subtype. Work in animals (the so-called elevated plus-maze and forced-swim tests) reports an anxiolytic-like effect without marked alteration of motor coordination at the doses studied, as well as an anticonvulsant effect for certain alkaloids in experimental models.

These results explain the research interest in mulungu as a lead toward a possible new class of non-benzodiazepine anxiolytics. These are research leads, not clinical effects established in humans — and nothing here constitutes medical advice.

History & long lineage

Mulungu bark belongs to Brazilian folk medicine: the raizeiros and benzedeiras prepare it as an evening decoction. For the shamans of the Amazon, it is a teacher of surrender.

Notes on safety & use

Mulungu is traditionally held to be hypotensive: use caution if you have low blood pressure or take antihypertensive medication. Its sedative effect makes driving inadvisable after intake and calls for caution with sedatives, anxiolytics, antidepressants (notably MAOIs) and alcohol. It is to be avoided during pregnancy and breastfeeding, and stopped about two weeks before surgery. Tolerance can develop with prolonged use, and a slight flattening of mood is sometimes reported after several weeks — hence the rule of courses of 4 to 6 weeks maximum followed by a break. As the bark is hard, only a long decoction (15-20 minutes) releases its constituents — a simple infusion is not enough.