Opuntia ficus-indica (L.) Mill. Extract: from chemical characterization to inflammatory profiling and its potential effects in a zebrafish model of spinal cord injury—a morphological and molecular study

Natural compounds are increasingly explored for their ability to modulate multiple molec-
ular pathways involved in inflammation and oxidative stress and for their therapeutic
potential. Among these, Opuntia ficus-indica (L.) Mill. has attracted growing interest due to
its rich phytochemical profile; however, the biological properties of unripe fruits remain
largely unexplored. In this study, a hydroalcoholic extract obtained from unripe O. ficus-
indica fruits was characterized for its chemical composition, antioxidant capacity, and
concentration-dependent embryotoxic profile and subsequently investigated in a zebrafish
model of spinal cord injury (SCI). UHPLC-HRMS/MS analysis identified 14 secondary
metabolites, mainly flavonoids and phenylpropanoid acids. Antioxidant activity was con-
firmed by DPPH and ABTS assays. An embryotoxicity assessment conducted according to
OECD Test Guideline 236 revealed no mortality at concentrations below 100 µg mL→1 and
an LC50 of 323.59 µg mL→1 at 96 h post-fertilization, allowing the identification of non-toxic
concentrations for subsequent in vivo experiments. Based on these results, the extract
was tested in a larval zebrafish SCI transection model. Treated larvae showed improved
locomotor recovery, particularly under continuous exposure, accompanied by modulation
of molecular pathways involved in inflammation, neurotrophic support, and neurogenesis,
including reduced pro-inflammatory cytokine expression and increased BDNF and Sonic
Hedgehog signaling markers. Overall, these findings expand current knowledge on unripe O. ficus-indica and highlight its potential to modulate molecular pathways involved in
SCI-induced damage and repair.