Bioactivity investigation of anti-cancer activities of Elephantorrhiza Elephantina, Dicoma Anomala, Xysmalobium Undulatum and Cussonia Paniculata plant extracts

Abstract

Cancer is the term used to define a group of diseases associated with uncontrollable proliferation of abnormal cells. More than half of the drugs used currently are from natural products and their derivatives. Medicinal plants have been used as a source of medication for many years. Cussonia paniculata, Dicoma anomala, Elephantorrhiza elephantina, and Xysmalobium undulatum are used by traditional healers and herbalists in South Africa and other African countries to treat breast and cervical cancer. The aim of the study was to investigate E. elephantina root, D. anomala root, X. undulatum root, and C. paniculata leaf and root extracts for anti-cancer activities. The four medicinal plants were extracted with distilled water (dH2O), dichloromethane (DCM), methanol (MeOH), and DCM:MeOH (1:1 ratio) solvents using the sequential method of extraction. The MCF7 and Caco2 cell lines were exposed to all extracts with concentrations 10 and 100 μg/mL to determine their toxicity and IC50 values using the Hoechst 33342/Propidium iodide (PI) dual staining method. Thereafter, the effect of cytotoxic extracts on MCF7 and Caco2 cells and their progression through the cell cycle, apoptosis, and mitochondrial membrane potential was investigated using fluorescent staining with annexin V- with a conjugated flurophore flourescein isothioscyanate (FITC), annexin V-FITC/PI and Tetramethylrhodamine ethyl ester (TMRE) staining respectively. An anti-inflammation test was performed on the aqueous extract of each plant using Lipopolysaccharide (LPS) induced nitric oxide production in RAW 264.7 macrophages, and compounds in the X. undulatum extracts were identified and characterised using liquid chromatography-mass spectrometry. Out of the 20 extracts tested, only the D. anomala root, X. undulatum root, and C. paniculata leaf DCM extracts were toxic enough to the two cell lines with IC50 values of 1.8, 26.52, and 7.71 μg/mL for Caco2. For MCF7, the IC50 values were 2.24, 8.99, and 25.74 μg/mL respectively. After 48 hours of treatment with the three extracts, an arrest of early mitosis was evident for the C. paniculata and X. undulatum extracts on both cell lines; however, for the D. anomala extract, the MCF7 cells arrested at the G0/G1 phase, while the Caco2 cells arrested at the early M phase. Annexin V- FITC staining confirmed apoptosis for the X. undulatum extract as a decrease in mitochondrial membrane potential was evident for the Caco2 cells and relative hyperpolarisation was evident for the MCF cells. The Annexin V-FITC / PIassay showed that there were apoptotic cells after 24 hours of treatment with the C. paniculata leaf extract and the D. anomala root for the Caco2 cells, but apoptotic cells were evident in the MCF7 cells only after 48 hours. The aqueous E. elephantina extract exhibited anti-inflammatory activity without inducing cytotoxicity against RAW 264.7 macrophages. The D. anomala extract also showed a reduction in nitric oxide production at 200 μg/mL; however, this was probably as a result of the associated toxicity at that extract concentration. Due to high activity of X. undulantum, its extracts, were selected for identification characterization of present compounds. Chromatographic fingerprinting of the X. undulatum medicinal plant resulted in a total of 24 compounds identified from the DCM, MeOH, dH2O, and DCM:MeOH extracts, and from the 24, five were unknown. This study indicates that C. paniculata, D. anomala, E. elephantina, and X. undulatum medicinal plants could be good candidates for new drug therapies.