<i>Butea monosperma</i> (Lam.) Taub. Bark fractions protect against free radicals and induce apoptosis in MCF-7 breast cancer cells <i>via</i> cell-cycle arrest and ROS-mediated pathway

Abstract

<i>Butea monosperma</i> (Lam.) Taub. is an ethnomedicinal tree of remedial value in the treatment of diabetes, bone fractures, and liver and neurological disorders. However, the information available on DNA-protective and anti-proliferative potential of bark of this tree is scarce. In the present study, the extract/fractions obtained from bark of <i>B. monosperma</i> were evaluated for antioxidant, DNA-protective, and anti-proliferative activities, along with their phytochemical profiling for identifying major constituents present in them. Different extract/fractions, namely, <i>Bmth</i> (methanol), <i>Bhex</i> (hexane), <i>Bchl</i> (chloroform), and <i>Beac</i> (ethyl acetate), were prepared and evaluated for antioxidant activity using <i>in vitro</i> assays. Extract/fractions were also evaluated for anti-proliferative and apoptotic activity in human breast carcinoma cell line MCF-7, using <i>in vitro</i> assays, namely, MTT, clonogenic, and neutral comet assay, along with confocal microscopy and flow cytometry. Among all extract/fractions, a pronounced antioxidant activity was exhibited by <i>Bchl</i> and <i>Beac</i> fractions, in DPPH<b>·</b> (EC₅₀ 213.2 and 161.5 µg/mL, respectively), ABTS⁺<b>·</b> (EC₅₀ 139.3 and 44.1 µg/mL, respectively), and reducing power assay (EC₅₀ 86.7 and 84.5 µg/mL, respectively). Both fractions protected plasmid DNA against hydroxyl radical induced damage in plasmid nicking assay. <i>Bchl</i> and <i>Beac</i> were also observed to inhibit the growth of MCF-7 cells (GI₅₀ 203.7 and 246.5 µg/mL, respectively). Both fractions induced apoptosis in MCF-7 cells, by arresting the cell cycle in G1 and sub-G1 phase, respectively, enhancing ROS levels, decreasing mitochondrial membrane potential, and inducing double-strand DNA breaks. HPLC analysis revealed high kaempferol content in <i>Bchl</i>, and catechin, epicatechin, and gallic acid in <i>Beac</i>.