In vitro neuropharmacological evaluation of piperovatine, an isobutylamide from Piper piscatorum (Piperaceae).

Piperovatine, a sialogogic, piscicidal, and buccal local anesthesia producing isobutyl amide from the amazonian piscicidal and toothache-relieving plant, Piper piscatorum Trelease et Yuncker (Piperaceae), was evaluated for its ability to induce changes in neuronal intracellular calcium concentration. Ratiometric calcium imaging of Periplaneta americana neuronal cell cultures upon piperovatine application revealed that this compound induced dramatic increases in intracellular calcium concentration. Calcium flux was not affected by co-application of the muscarinic acetylcholine receptor antagonist, atropine, indicating that the parasympathomimetic system was not involved in piperovatine's sialogogic actions. Calcium flux was, however, totally eliminated by co-application of the voltage-gated sodium channel blocker, tetrodotoxin (TTX). This, in conjunction with the repetitive calcium spikes observed in the assay and previous radioligand binding studies on the chemical class, strongly suggest that activation of voltage-gated sodium channels characterizes piperovatine's mode of action