Background: Nerium oleander leaves extract preparations have been used for
centuries against sores, abscesses and solid tumors.
Objective: The aim of this study was to identify active compound(s) responsible for the antiproliferative
activity of N. oleander leaves against MCF-7 breast cancer cell line and to explore
their mechanisms of action.
Methods: The methanolic extract and fractions were screened against four human cancer cell
lines: HT-144, MCF-7, NCI-H460 and SF-268 using sulforhodamine B assay. The most active
ethyl acetate soluble fraction led to the isolation of eleven pure compounds viz adynerigenin,
adynerin, odoroside A, odoroside B, 5-O-kaempferobinoside, β-neriursate, oleanderocioic
acid, oleandiginoside, oleandrin, 5-O-quercetibinoside and ursolic acid. The methanolic
extract and the ethyl acetate soluble fraction exhibited significant growth inhibition (TGI:
0.14 to 3.3 μg/ml) against HT-144, MCF-7, NCI-H460 and SF-268 cell lines. The effects of
the methanolic extract, ethyl acetate soluble fraction, odoroside A and oleandrin on the cytoskeleton
and nuclei of MCF-7 cells were evaluated using immunofluorescence microscopy.
Significant reduction in the mitotic index of MCF-7 cells were exhibited by the
methanolic extract, ethyl acetate soluble fraction, odoroside A and oleandrin accompanied
by morphological changes such as band-like arrangement of cells, reduction in F-actin processes,
disruption of interphase microtubule network and condensation of nuclei.
Results: These results support that the N. oleander leaves possess antiproliferative activity
against the aforementioned cell lines particularly estrogen receptor positive MCF-7 cells,
thereby justifying its traditional use against tumors. Moreover, the antiproliferative effects
induced by the methanolic extract, ethyl acetate soluble fraction, odoroside A and oleandrin
were possibly related to skeletal and nuclear morphological changes.