STUDIES ON THE MUSCLE-PARALYZING COMPONENTS OF THE JUICE OF THE BANANA PLANT

The stem juice of the banana plant (Musa species) has been used as an arrow poison by African tribesmen. Lyophilized, partially purified ext racts of the juice augment and then block both directly and indirectly evoked contractions of the mouse diaphragm. We have isolated, purifie d and determined the chemical composition of the active ingredients, a nd characterized their pharmacological activity. The lyophilized sampl e was extracted with a methanol-water (MeOH-H2O) (50/50) mixture and v acuum filtered. The filtrate was rotary evaporated and crystallized in a MeOH-H2O mixture to yield potassium nitrate crystals (melting point 332-334-degrees-C). The filtrate was concentrated and chromatographed over Sephadex LH-20 gel using MeOH-H2O (40/60) as the eluent. The act ive component was found to be magnesium nitrate crystals (melting poin t 87-89-degrees-C). In the mouse isolated phrenic nerve-hemidiaphragm preparation, the pharmacological profile of the first component was si milar to that for authentic potassium nitrate which augments in low co ncentrations, and in higher concentrations augments, and then blocks b oth directly evoked muscle contraction and neuromuscular transmission. The second component had a profile of activity similar to that for au thentic magnesium nitrate which only blocks neuromuscular transmission . It can be concluded that the two major active principles in the bana na stem juice are potassium nitrate and magnesium nitrate.