Pain relief represents a critical unresolved medical need. Consequently, the search for new
analgesic agents is intensively studied. Annona crassiflora, a native species of the Brazilian Savanna, represents a potential source for painful treatment. This study aimed to investigate the antinociceptive potential of A. crassiflora fruit peel, focusing on its major
alkaloid,
stephalagine, in animal models of
pain evoked by the activation of transient receptor potential
ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) channels. Male C57BL/6/J mice were submitted to
formalin-,
cinnamaldehyde-, and
capsaicin-induced nociception tests to assess nociceptive behavior, and to the open-field and rotarod tests for motor performance analyses. Moreover, the
stephalagine's effect was tested on
capsaicin- and
cinnamaldehyde-induced Ca2+ influx in spinal cord synaptosomes. In silico assessments of the absorption, distribution, metabolism and central nervous system permeability of
stephalagine were carried out. The
ethanol extract and alkaloidal fraction reduced the nociception induced by
formalin. When administered by oral route (1 mg/kg),
stephalagine reduced the spontaneous nociception and paw
edema induced by TRPV1 agonist,
capsaicin, and by TRPA1 agonists,
cinnamaldehyde- and
formalin, without altering the animals' locomotor activity. The prediction of in silico pharmacokinetic properties of
stephalagine suggests its capacity to cross the blood-brain barrier. Furthermore, this
alkaloid reduces the
capsaicin- and
cinnamaldehyde-mediated Ca2+ influx, indicating a possible modulation of TRPV1 and TRPA1 channels, respectively. Together, our results support the antinociceptive and anti-edematogenic effects of the A. crassiflora fruit peel and suggest that these effects are triggered, at least in part, by TRPV1 and TRPA1 modulation by
stephalagine.