Biochemical profile, selective cytotoxicity and molecular effects of Calendula officinalis extracts on breast cancer cell lines

Abstract

Calendula officinalis extracts have been known to possess anti-tumor properties, but questions regarding their mechanisms of action still need to be answered. Therefore, the present study aims to investigate the selective cytotoxicity, the biochemical profile and the corresponding molecular effects of two extracts of C. officinalis: flowers and leaves, against several breast cancer cell lines in vitro. Dry flowers and leaves were subjected to ultrasonication assisted extraction in methanol 70%. The phenolic and volatile profiles of the extracts, determined by HPLC-MS and nontargeted GC-MS, revealed high levels of specific phenolic acids, flavonols and coumarin and several volatile compounds, including mono- and sesquiterpenes, ketones, aldehydes and esters. Both extracts proved to possess selective cytotoxic activities against tumor cells in comparison to healthy endothelial cells, according to the MTT assay. The flower extract was superior in terms of both cytotoxicity and selectivity when compared to the leaf extract, in accordance to their biochemical profiles. The gene expression pattern for 10 genes of interest was evaluated by RT-qPCR. The expression level of several genes involved in apoptosis (BCL2, BAX, BBC3, ZMAT3), and cell cycle progression (NFkB, CCND1, STAT3) was modulated by the treatment with both extracts. Therefore, C. officinalis extracts proved to be rich in compounds characterized by cancer-related cytotoxicity and are capable of inducing selective cytotoxicity on breast cancer cell lines.