West African stimulant

Voacanga thouarsii (Apocynaceae) iboga West African stimulant aphrodisiac... 

This "psychedelic stimulant" is derived primarily from the bark of a West African tree called Pausinystalia or Corynantheyohimbe, although it is also present in other species of Corynanthe and in Aspidosperma quebran-choblanco and Mitragyna stipulosa. When this alkaloid is brewed as a tea and then drunk, its effects come on within forty-five minutes to an hour. The action is reportedly swifter if taken with 500 mg. vitamin C... 

A number of studies have speculated on diazotroph response to mineral dust Fe fertilization in the Atlantic (Mahaffey et al, 2003), and Pacific Oceans (Johnson et al, 2003). Circumstantial evidence for dust stimulation of marine diazotrophic biomass has recently been reported. A 1999 Saharan dust event coincided with increases in dissolved Fe concentrations on the west Florida shelf and a 100-fold increase in Trichodesmium biomass. N2 fixation rates were not measured, but DON concentrations doubled, presumably due to exudation by N2 fixers (Lenes et al, 2001). A recent Saharan dust addition experiment to surface water samples collected along a west African cruise transect (35°W-17°W), found a minimal increase in CO2 fixation and a large stimulation in N2 fixation, suggesting that diazotrophs were co-limited by both P and Fe (Mills et al, 2004). Note however, analysis of aerosol dust shows that while providing Fe, it also supplies P and combined N (Baker et al, 2003 Mills et al, 2004 Ridame and Guieu, 2002). 

The physiological activity of acetylcholine relies on local release, stimulation of the receptor, then rapid hydrolysis (deacetylation) by acetylcholinesterase, which results in deactivation. The indole alkaloid physostigmine, from the West African calabar bean, and the relatively simple synthetic compound pyridostigmine, which has a more obvious relationship to choline, are reversible inhibitors of acetylcholinesterase. Controlled inhibition of the enzyme by such drugs, which results in a build-up of ACh, is useful in conditions such as myasthenia gravis, a muscle weakness, which is caused by insufficient production of ACh. 

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