In this study, we investigated the cytotoxic effect of perezone, a constituent isolated from the roots of Perezia spp.
Keywords: Perezone Isoperezone Cytotoxic Sesquiterpenes Cell death
Perezone (2-(l,5-dimethyl-4-hexenyl)-3-hydroxymethyl-p-benzoquinone), a sesquiterpene quinone, is recognized as the first secondary metabolite isolated in crystalline form in the New World, by Rio de la Loza in 1852 from roots of plants of the genus Perezia (Rio de la Loza, 1852).
Perezone and isoperezone were dissolved in a minimum concentration of dimethylsulfoxide (DMSO, Sigma) and added to the culture medium at final concentrations of 6.25, 12.5, 25, 50 and 100 [micro]M for 24 h.
To evaluate if the induced cell death on K562 cells altered the mitochondrial membrane potential, cells were treated with perezone or isoperezone for 24 h.
In order to evaluate if the AIF factor was involved in the cell death induced by perezone or isoperezone, a PE-labeled anti-AIF antibody was used.
Perezone had a higher cytotoxic activity than its isomer as it can see clearly at 50 [micro]M.
3 clearly shows the modification induced by both perezone and isoperezone in their light-scattering properties.
To investigate whether the compound-induced decrease in cell viability was accompanied with phosphatidylserine exposure, we measured Annexin V-FITC/PI positive cells after incubation with or without perezone or isoperezone at varying concentrations (6.25, 12.5, 25, 50 and 100 [micro]M).
5 shows that perezone and isoperezone produced a reduction in the mitochondria membrane potential in a dose-dependent manner that correlate with the cytotoxic activity.
In order to evaluate if the cell death process induced by perezone or isoperezone involved a caspase-dependent pathway, we determined by cytometry the percentage of cell with cytoplasmic active caspase-3, since this enzyme is a key executioner of apoptosis and it is activated both in the intrinsic and in the extrinsic pathway of apoptosis.
Perezone showed greater cytotoxic effect than isoperezone but both compounds induce the cell death trough caspase-dependent and caspase-independent mechanisms.