Holothuria leucospilota extract induces apoptosis in Leishmania major promastigotes

The present study aimed to survey antileishmanial activity of
methanolic Holothuria leucospilota extract against Leishmania major promastigotes in
vitro.
Methods: Promastigotes were cultured in RPMI 1640 and after reaching the
stationary phase, the study was conducted with different concentrations of the
extract. Afterwards, MTT colorimetric assay for the obtaining of 50% inhibitory
concentration (IC50) was utilized. Furthermore, in order to determine the possible
induction of apoptosis in L. major promastigotes, flow cytometry and DNA
fragmentation methods were employed using annexin-V FLUOS staining kit
and DNA ladder kit, respectively.
Results: The IC50 value of H. leucospilota extract at three time points of 24, 48,
and 72 h was estimated 2000, 300 and 85 μg/ml, respectively. In addition, the
extract revealed a dose and time-dependent antileishmanial activity. Furthermore,
various characteristics of apoptosis appeared after L. major promastigotes
treatment, which included cell shrinkage, formation of apoptotic bodies,
blebbing of the cell membrane, and externalization of phosphatidylserine, although
no laddering pattern was observed.
Conclusion: The methanolic extract of H. leucospilota possesses lethal effect on
L. major promastigotes and induces the apoptosis in parasites. Further studies
are required to address the apoptosis mechanism in vivo.