Primary
amoebic meningoencephalitis (PAM), caused by the pathogenic
free-living amoeba Naegleria fowleri, is a rare but
fatal disease. Nowadays, no fully effective therapy is available to
erradicate or prevent this disease. Natural products could constitute
a promising source of useful bioactive compounds in drug discovery.
The present study is a characterization of main active compounds from
the ethanolic extract of Inula viscosa (Asteraceae)
leaves against N. fowleri trophozoites. Four compounds
(1–4) were successfully identified
by spectroscopic techniques, but only inuloxin A displayed a potential
antiamoebic activity with an IC50 of 21.27 μM. The
specificity of this compound toward the studied strain leads us to
analyze the insight into its mechanism of action by performing in vitro assays of programmed cell death markers and to
discuss the structure–activity relationship (SAR). The obtained
results demonstrated that inuloxin A interferes with various processes
leading to membrane damage, mitochondria alteration, chromatin condensation,
and ROS accumulation, which highlight features specific to apoptosis.
The current findings could be a promising step for developing new
effective drugs against PAM.