The aim of this study was to assess the antioxidant, antiproliferative, cytotoxic
and apoptotic effects of aqueous and methanol extracts from the Western Mediterranean
species Cistus albidus L. (Cistaceae). Antioxidant activity was evaluated by three different assays: Folin-Ciocalteau,
trolox equivalent antioxidant capacity and oxygen radical antioxidant capacity. Antiproliferative
activity and cytotoxicity were evaluated on HeLa cells by the crystal violet and WST-1
assays, respectively. The distribution of normal and apoptotic cells in the various
phases of cell cycle was analysed by flow cytometry. The data showed that both C. albidus extracts exhibit interesting antioxidant properties, although slightly higher in
methanol. Extracts inhibited cell proliferation and reduced cell viability in a time
and concentration dependent manner. Methanol extract at 136µg ml-1 and aqueous extract at 169µg ml-1 reduced 50% of cell proliferation after 72h. In the cytotoxicity assay, IC50 values increase to 353 and 389µg ml-1, respectively for methanol and aqueous extracts. The sub-G1 population significantly
increased in cells treated with 300µg ml-1 of methanol and aqueous extract, indicating apoptotic-associated chromatin degradation.
Moreover, in the non-apoptotic population the HeLa cells treated with methanol extract
seem to accumulate in the G2/M phase and, on the other hand, the aqueous extract seems to cause the accumulation
of cells in the G0/G1 phase. In conclusion, this study demonstrates the strong antioxidant potential and
anticancer activity, through the inhibition of cell proliferation and induction of
apoptosis on cancer cells, of methanol and aqueous extracts from C. albidus.
S. Gonçalves acknowledges a grant from Portuguese Science and Technology Foundation
(FCT, Grant SFRH/BPD/31534/2006).
