Dihydroxy‐Isosteviol Methyl Ester from Pulsatilla nigricans Induces Apoptosis in HeLa Cells: Its Cytoxicity and Interaction with Calf Thymus DNA

Dihydroxy‐isosteviol methyl ester (DIME), the principal biological compound isolated from the medicinal plant Pulsatilla nigricans (Fam: Ranunculaceae) having the molecular formula of C₂₁H₃₄O₃ (molecular weight 334.25), was administered to cervical cancer cells (HeLa) in vitro to evaluate its possible apoptotic (anti‐cancer) potentials. We analyzed the expression of p53, Bax, Bcl2, Apaf and caspase 3 signal proteins and analyzed the early apoptotic events in HeLa cells induced by DIME using protocols like Annexin V‐FITC and PI staining. DIME caused a significant decrease in cell viability, induced nuclear condensation and inter‐nucleosomal DNA fragmentation. We further studied the interaction of DIME with calf thymus DNA as target through circular‐dichroism spectra. Results showed that DIME interacted with DNA, bringing indiscernible changes in structure and conformation. Thus, DIME showed its capability to induce apoptosis in cancer cells, signifying its utility in drug design as a possible candidate for chemoprevention. Copyright © 2012 John Wiley & Sons, Ltd.