Cytotoxic and chemomodulatory effects of Phyllanthus niruri in MCF-7 and MCF-7(ADR) breast cancer cells

The members of the genus Phyllanthus have long been used in the treatment of a broad spectrum of diseases. They exhibited antiproliferative activity against various human cancer cell lines. Breast cancer is the most diagnosed cancer and a leading cause of cancer death among women. Doxorubicin (DOX) is an anticancer agent used to treat breast cancer despite its significant cardiotoxicity along with resistance development. Therefore, this study was designed to assess the potential cytotoxicity of P. niruri extracts (and fractions) alone and in combination with DOX against naïve (MCF-7) and doxorubicin-resistant breast cancer cell lines (MCF-7(ADR)). The methylene chloride fraction (CH(2)Cl(2)) showed the most cytotoxic activity among all tested fractions. Interestingly, the CH(2)Cl(2)-fraction was more cytotoxic against MCF-7(ADR) than MCF-7 at 100 µg/mL. At sub-cytotoxic concentrations, this fraction enhanced the cytotoxic effect of DOX against the both cell lines under investigation (IC(50) values of 0.054 µg/mL and 0.14 µg/mL vs. 0.2 µg/mL for DOX alone against MCF-7) and (1.2 µg/mL and 0.23 µg/mL vs. 9.9 µg/mL for DOX alone against MCF-7(ADR)), respectively. Further, TLC fractionation showed that B2 subfraction in equitoxic combination with DOX exerted a powerful synergism (IC(50) values of 0.03 µg/mL vs. 9.9 µg/mL for DOX alone) within MCF-7(ADR). Untargeted metabolite profiling of the crude methanolic extract (MeOH) and CH(2)Cl(2) fraction exhibiting potential cytotoxicity was conducted using liquid chromatography diode array detector-quadrupole time-of-flight mass spectrometry (LC-DAD-QTOF). Further studies are needed to separate the active compounds from the CH(2)Cl(2) fraction and elucidate their mechanism(s) of action.