Anticancer effect of ethanolic extract of Rheum ribes L. rhizomes: assessment of dose and time-dependent effects in cell-based models

Medicinal plants have been traditionally used in the treatment of various diseases including cancer, however, their IC₅₀ determined in vitro are hardly attained in patients. Rheum ribes L. is an indigenous medicinal plant shown to possess anticancer activity due to high polyphenolic compounds abundance. Our objective was to assess if long-term exposure to plant extract concentrations lower than IC₅₀ may still possess an anticancer potential.

We used the ethanolic extract of rhizomes of Rheum ribes L. (EERR) and assessed its effect on proliferation, clonogenicity, and senescence in cell lines-based models.

Our results showed that EERR has a short-term antiproliferative activity on non-small cell lung carcinoma A549, breast cancer MCF7, and glioblastoma SF268 cell lines with IC₅₀ varying from 100 to 255 µg/mL. Additionally, EERR decreased the population doubling level and the clonogenic ability of the three cancer cell lines at lower concentrations (10 to 100 µg/mL) and with longer treatment protocols. This was accompanied by a significant increase in the senescence-associated β-galactosidase activity, suggesting that EERR induces senescence at these concentrations.

EERR displayed anticancer activity at concentrations 2- to 10-fold lower than the IC₅₀ in three different cancer cell lines and should be further investigated as it may provide novel therapeutic avenues for cancer treatment.