So far, a protective influence of
phytosterols on the human organism and
atherogenesis has been suggested. Most studies have concentrated on the cytotoxic efficacy of
phytosterols on
cancer cells. However, there are only a few reports showing their influence on normal cells. The aim of the present study was to determine whether dietary
plant sterols and their thermal processing products could influence the viability of normal, abdominal endothelial cells that play a crucial role in
atherogenesis. Thus, we studied the effect of
rapeseed oil-extract components,
beta-sitosterol,
cholesterol and their epoxy-derivatives, 5 alpha,6 alpha-epoxy-
beta-sitosterol and 5 alpha,6 alpha-epoxycholesterol, on the proliferation and viability of human abdominal aorta endothelial cells HAAE-2 in vitro. We showed strong cytotoxic properties of
beta-sitosterol in HAAE-2 cells (half maximal inhibitory concentration (IC50) = 1.99 (SEM 0.56) microm) and, interestingly, a weaker cytotoxic effect of 5 alpha,6 alpha-epoxy-
beta-sitosterol (IC50>200 microm). Moreover, we observed a significantly stronger cytotoxic activity of
beta-sitosterol than
cholesterol (IC50 = 8.99 (SEM 2.74) microm). We also revealed that
beta-sitosterol as well as
cholesterol caused apoptosis, inducing
caspase-3 activity in the cells (60 % increase compared with control cells) that corresponded to the DNA fragmentation analysis in a terminal
uridine deoxynucleotidyl transferase-mediated
deoxyuridine triphosphate nick-end labelling (TUNEL) study. Although absorption of
plant sterols is low compared with
cholesterol, they can still influence other physiological functions. Since they effectively reduce serum
LDL-cholesterol and atherosclerotic risk but also decrease the viability of
cancer cells as well as normal cells in a time- and dose-dependent manner in vitro, their influence on other metabolic processes remains to be elucidated.