Inhibition of Kinase Activity and In Vitro Downregulation of the Protein Kinases in Lung Cancer and Cervical Cancer Cell Lines and the Identified Known Anticancer Compounds of Ziziphus mucronata

Abstract

Plants have long been used as sources of natural compounds with therapeutic benefits, providing molecules capable of inhibiting multiple kinases. Many medicinal plants are recognized for their anticancer properties and may offer ways to mitigate the adverse effects of conventional cancer treatments. In this study, the potential of <i>Ziziphus mucronata</i> methanol extract as a kinase inhibitor was assessed using the MTT assay, a universal kinase assay, and a human phosphokinase antibody array, along with a GC-MS analysis of volatile anticancer compounds. The MTT assay revealed strong cytotoxicity in A549 cells, with an IC₅₀ of 31.25 µg/mL, while HeLa cells showed weaker cytotoxicity with an IC₅₀ of 125 µg/mL. In comparison, paclitaxel exhibited potent inhibitory effects on A549 cells (IC₅₀ of 31.25 µg/mL) and moderate inhibition on HeLa cells (IC₅₀ of 65 µg/mL). Enzyme activity, measured by ADP production in the ADP-Glo assay, indicated that the extract inhibited protein kinase activity in both A549 and HeLa cells after 24 h of treatment. Additionally, the human phosphokinase antibody array, which includes 44 pre-spotted kinases, showed that the extract downregulated multiple phosphorylated kinases in both cell lines. Some of the affected kinases, such as TOR, Fyn, HcK, Fgr, STAT5b, PLC-γ1, p38α, ERK1/2, AMPKA, Akt1/2, GSK-3α/β, MSK1/2, CREB, RSK1/2/3, PLC-γ1, and STAT5a are critical regulators of various cellular processes, including apoptosis, differentiation, and proliferation. The findings of this study suggest that extract from <i>Z. mucronata</i> may have the capacity to regulate protein kinase activity, highlighting their significant potential as growth inhibitors for cancer cells.