Cytotoxicity and Preliminary Analysis of the Pro-apoptotic and Cell Cycle Arrest Effects of Lantana ukambensis Against Colorectal Cancer Cells

Lantana ukambensis (Vatke) Verdc. (Verbenaceae) is a seasonal herb widely spread in the West African region. The whole plant is used for the treatment of wounds, infections, and inflammatory pathologies. The purpose of this research is to evaluate the cytotoxicity and to analyze the probable pro-apototic, and cell cycle arrest effects of L. ukambensis methylene chloride extract and its fractions against HCT-116 and HT-29 colorectal cancer cells using preliminary tests in order to highlight the interest of this plant in the search of new anticancer molecules. The dried powder of the whole plant was extracted by methylene chloride maceration for 24 hours and the extract was divided into five fractions. The cytotoxicity of the crude extract and fractions were evaluated by the MTS assay. The most active fractions were subjected to some preliminary assays including crystal violet, Hoechst staining, cell cycle arrest, and annexin V/PI assays on the cancer cells to highlight the probable mechanism of action of these fractions. The methylene chloride, ethyl acetate, and 1-butanol fractions of L. ukambensis crude extract demonstrated significant antiproliferative effects on HCT-116 and HT-29 cell growth with IC₅₀ values ranging between 2 to 15 μg/mL. 1-butanol and ethyl acetate fractions decreased the G1 phase by 20.53% and 28.47% and increased the G2/M by 23.47% and 25.90% respectively on HCT-116. Moreover, 1-butanol fraction increased the cumulative value of apoptotic cells by 49.77% on HCT-116 and ethyl acetate fraction increased this value by 53.37% at 15 μg/mL after 48 hours of exposure. The outcome of this study suggests the potential of 1-butanol and ethyl acetate fractions for the isolation of anticancer molecules against colorectal cancer.

Keywords: Apoptosis; Cancer; Cell cycle arrest; Cytotoxicity; Medicinal plants.