Cytotoxicity of Anchusa arvensis Against HepG-2 Cell Lines: Mechanistic and Computational Approaches

Abstract

Background: Liver cancer is a devastating cancer with increasing incidence and mortality rates worldwide. Plants possess numerous therapeutic properties, therefore the search for novel, naturally occurring cytotoxic compounds is urgently needed.

Methods: The anticancer activity of plant extracts and isolated compounds from Anchusa arvensis (A. arvensis) were studied against the cell culture of HepG-2 (human hepatocellular carcinoma cell lines) using 3-(4,5-Dimethylthiazol-yl)-diphenyl tetrazoliumbromide (MTT) assay. Apoptosis was investigated by performing Acridine orange -ethidium bromide staining, styox green assay and DNA interaction study. We also used tools for computational chemistry studies of isolated compounds with the tyrosine kinase.

Results: In MTT assay, the crude extract caused a significant cytotoxic effect with IC50 of 34.14 ± 0.9 μg/ml against HepG-2 cell lines. Upon fractionation, chloroform fraction (Aa.Chm) exhibited the highest antiproliferative activity with IC50 6.55 ± 1.2 μg/ml followed by ethyl acetate (Aa.Et) fraction (IC50, 24.59 ± 0.85 μg/ml) and n-hexane (Aa.Hex) fraction (IC50 29.53 ± 1.5μg/ml). However, the aqueous (Aa.Aq) fraction did not show any anti-proliferative activity. Bioactivity-guided isolation led to the isolation of two compounds which were characterized as para-methoxycatechol (1) and decane (2) through various spectroscopic techniques. Against HepG-2 cells, compound 1 showed marked potency with IC50 6.03 ± 0.75 μg/ml followed by 2 with IC50 18.52 ± 1.9 μg/ml. DMSO was used as a negative control and doxorubicin as a reference standard (IC50 1.3 ± 0.21 μg/ml). It was observed that compounds 1-2 caused apoptotic cell death evaluated by Acridine orange -ethidium bromide staining, styox green assay and DNA interaction study, therefore both compounds were tested for molecular docking studies against tyrosine kinase to support cytotoxic activity.

Conclusion: This study revealed that the plant extracts and isolated compounds possess promising antiproliferative activity against HepG-2 cell lines via apoptotic cell death.

Keywords: 3-(4,5-Dimethylthiazol-yl)-diphenyl tetrazoliumbromide; Anchusa arvensis; Anticancer activity; Cytotoxicity; Decane; HepG-2 cell lines; Para–methoxycatechol..