Evaluation of antioxidant enzyme activity in doxorubicin treated breast cancer patients in Iraq: A molecular and cytotoxic study

Cytotoxic and chemomodulatory effects of Phyllanthus niruri in MCF-7 and MCF-7ADR 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 (CH₂Cl₂) showed the most cytotoxic activity among all tested fractions. Interestingly, the CH₂Cl₂-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 (IC₅₀ 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 (IC₅₀ 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 CH₂Cl₂ 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 CH₂Cl₂ fraction and elucidate their mechanism(s) of action.

In Vitro Binding and Release Mechanisms of Doxorubicin from Nanoclays

Nanoclays have been developed as drug delivery systems, but their mechanisms of DOX delivery are unclear. Herein, unmodified nanoclays (halloysite, kaolinite, montmorillonite) were comprehensively studied on their in vitro binding and release mechanisms of DOX from both experimental and theoretical aspects. These nanoclays with high loading capacity (>50%) and encapsulation efficiency capacity (>90%) of DOX are attributed to the exposed hydroxyl groups and the Lewis base sites on the surfaces. Density functional theory calculations also confirmed that DOX is preferentially adsorbed on the Al-OH surfaces while adsorption on Si-O surfaces is limited. Besides this, the pH-responsive profiles of DOX release from nanoclays are related to the protonation of negatively charged nanoclays in weakly acidic solutions that makes it easier to dissociate with positively charged DOX. The in-depth mechanistic method in this work is widely applicable and demonstrates that nanoclays can be used as efficient nanocarriers for more biomedical applications.