Antiproliferative Activity and Synergistic Effect of Fractions of Cyrtostachys renda and Doxorubicin Against Human Cancer Cells

The cytotoxic activity of Cyrtostachys renda bioactive substances was recently investigated in vitro. C. renda was macerated with methanol to extract its four groups of fractions (C, E, K, and O), which were then separated using column chromatography. Each component was qualitatively identified in its fraction content and assessed in vitro for its cytotoxic properties in HeLa, MCF-7, T47D, and Vero cells. The most active fraction was further evaluated for its synergistic effect in co-chemotherapy with doxorubicin against HeLa cells. Each fraction dose-dependently inhibited the growth of HeLa, MCF-7, and T47D cells. Fraction O had the highest cytotoxic activity, as indicated by the IC₅₀ value of 112 μg/mL against HeLa cells, with a selectivity index of 7.70. Fraction O, with a concentration of 28 μg/mL, also showed synergistic activity with doxorubicin 2.8 μg/mL in inhibiting the growth of HeLa cells. Fraction O induces cell cycle arrest at the G1 and G2/M phases, as well as apoptosis in HeLa cells. Furthermore, cell necrosis might be reduced by combining the effects of fraction O at 28 μg/mL and doxorubicin at 2.8 μg/mL. Fraction O, a natural chemotherapeutic drug that requires further development for cancer management, was introduced by our findings.