S-phase cell cycle arrest, and apoptotic potential of Echium arabicum phenolic fraction in hepatocellular carcinoma HepG2 cells

Abstract

Plants have been used in the treatment of many diseases. The aim of the present investigation was to assess the cytotoxic potential of Echium arabicum extracts against liver and colon cancer cells. The plant was extracted using Soxhlet apparats and ultrasound-assisted hydrolysis. The phenol and antioxidant activity was assessed using Folin–Ciocalteu and DPPH method respectively. The cytotoxicity was determined using MTT and lactate dehydrogenase release assay. The apoptosis study was conducted using DAPI, and Acridine orange/ethidium bromide and confirmed by Caspase 3/7 Fluorescence reagent, and the Cell cycle analysis was carried out using Muse Cell Analyzer. E. arabicum had cytotoxic properties with half inhibitory concentration (IC50) values of 61.6 ± 0.6, 66.4 ± 0.9, 71.9 ± 0.8, and 38.3 ± 0.3 μg/mL against LoVo, HCT116, HuH-7 and HepG2 respectively using MTT assay. Interestingly, the phenolic fraction showed less cytotoxicity at the highest concentration tested on normal human liver (Chang) cells. Staining of HepG2 cells with DAPI and AO/EB post treatment with phenolic fraction (40 and 60 µg/mL) decreased the number of viable cells and exhibited typical features of apoptosis like blebbing of plasma membrane with an increase in the Caspase-3/7 activity. Furthermore, cell cycle study revealed that E. arabicum induced a S-phase arrest in HepG2 cells. The coefficient of determination (R2 = 0.997) and the Pearson’s correlation coefficient (r = 0.998) between DPPH activity and total phenolic content was highly correlated. These results demonstrate that phenolic fraction from E. arabicum might have a strong potential as chemopreventive agent in liver cancer.