Cytotoxicity, Anticancer Potentials and Anticancer Phytochemicals Present in Viscum continuum E. Mey. Ex Sprague Extracts

Abstract

Background: Cancer describes a vast category of diseases our body suffers from. The total global oncology spending was USD186bn as of 2021 and was estimated to rise to USD208.9bn in 2022. The adverse effects of managing cancer with orthodox medications includes death among other dire consequences. Several Viscum species including Viscum album L, Viscum angulatum, and Viscum articulatum Burm f. from other countries have been reported for their anticancer potentials. Methods: Four (n = 4) mistletoe extracts namely n-hexane, dichloromethane, acetone, and methanol were tested for their anti-cancer potemtials against Vero (African green monkey, kidney, non-cancerous), BJ-5ta (Human skin fibroblast), A549 (Human non-small cell lung carcinoma), Michigan Cancer Foundation (MCF7) human breast cancer cell lines. The percentage cancer cells survival rate and selectivity index for each extract were calculated against positive controls (untreated cells) and blank dimethyl sulfoside (DMSO) solutions, and the compounds with anticancer potentials were identified to be present in the extracts using gas chromatography-mass spectrometry analysis. Results: All four extracts showed concentration dependent anti-cancer activity as measured from the percentage average cell viability or cytotoxicity. The cytotoxicity to the lung (A549) was recorded as 1.25, 10, 0.5, 1.25 mg/mL for the hexane, dichloromethane, acetone and methanol extracts respectively. Those for the breast (MCF7) cancer cell lines appeared as as 1.25, 0.5, 0.5 and 10 mg/mL for the hexane, dichloromethane, acetone and methanol extracts in that order. In terms of the selectivity index (SI), that is, which extracts is cytotoxic to a specific cancer cell line, all the extracts were highly selective (SI >2). However, the methanol extract was selectively more toxic to the lung cancer cell (A459) with SI of 6.08 and Half maximal Inhibitory Concentration (IC₅₀) value of 0.251 ± 3.96. The other three extracts were highly selective against breast cancer cell (MCF7) with SI of 5.90 (IC₅₀ = 0.38), 9.06 (IC₅₀ = 0.04) and 8.15 (IC₅₀ = 0.02) for n-hexane, dichloromethane (DCM), and acetone extracts, respectively. Conclusions: Eucalyptol, 9(E),11(E)-conjugated linoleic acid, ester and 9, 12, 15-octadecatrienoic acid detected in South African mistletoe by gas chromatoghraphy-mass spectrometry (GC-MS) analysis is proposed to be responsible for the anticancer potentials of the extracts.