A Withanolide-rich Fraction of Athenaea velutina Induces Apoptosis and Cell Cycle Arrest in Melanoma B16F10 Cells

Abstract

Athenaea velutina is a promising Brazilian shrub with cytotoxic and antimigratory properties against cancer cells. However, the mechanism of induction of cancer cell death and the compounds involved remain unknown. To ascertain these bioactive compounds, bioassay-guided fractionation was performed, alongside the appropriate in vitro tests. A withanolide-rich fraction (FAv_5) from the dichloromethane extract increased cytotoxic activity by 1.5-fold (IC50 = 2.1 µg/mL). Fourteen withanolide steroids were tentatively identified for the first time for this species by mass spectrometry coupled to liquid chromatography (LC MS/MS), including withanolide A, aurelianolide A, and aurelianolide B. FAv_5 significantly decreased cell proliferation, migration, and invasion with a selectivity index greater than 8 for B16F10 cells. Furthermore, flow cytometry with annexin V fluorescein isothiocyanate/propidium iodide (V-FITC/PI) staining showed FAv_5 to promote cell cycle arrest at the G0/G1-phase as well as apoptotic cell death. Overall, these findings highlight A. velutina as a source of withanolide-steroids that inhibit cancer cell proliferation through apoptosis and cell cycle blockade mechanisms. Details on the geographic distribution of A. velutina and species conservation strategies have also been highlighted.

Withaferin A: A Pleiotropic Anticancer Agent from the Indian Medicinal Plant Withania somnifera (L.) Dunal

“…Previously, withaferin A-mediated reactive oxygen species (ROS) initiation was noticed in MCF-7 and MDA-MB-231 cell lines that inhibited the effect of withaferin A on cell death, ER-related proteins, paraptotic vacuole formation, X-box-binding protein-1, and mRNA splicing [ 85 ]. In another research, withaferin A suppressed cell proliferation in prostate, ovarian, breast, gastric, leukemic, and melanoma cancer cells and osteosarcomas by stimulating the inhibition of the cell cycle at several stages, including G0/G1 [ 86 ], G2, and M phase [ 87 , 88 , 89 , 90 , 91 ].…”

Molecular bioprospecting of plant extracts: Experience report of the BIOPROS/UFV group in the search for antitumor compounds

“…Among the withanolides identified in A. velutina, we highlight aurelianolide A, aurelianolide B and withanolide A (FIGURE 4). These compounds induced cancer cell death by apoptosis and promoted cell cycle arres t [21] .…”