In vitro and In silico Studies on Leonotis nepetifolia (L.) R. Br. Root Extract against Cancer Cells

Abstract

Background: Leonotis nepetifolia (L.) R. Br. (Lamiaceae) is a shrub traditionally used to alleviate inflammatory conditions. Objective: The present study aimed at investigating the biological activity of methanolic nontrans-formed and transformed Rhizobium rhizogenes root extracts from L. nepetifolia against human melanoma cells. Methods: Cytotoxicity and genotoxicity properties, the impact on topoisomerase I activity, and proapoptotic activity were evaluated by the MTT test, comet assay, topoisomerase I assay, and fluorescence-activated cell sorting analysis. Moreover, the expressions of p53 were examined by qPCR and Western blot analysis. Docking studies were conducted to assess the potential interac-tions of the identified phytochemicals with the p53 binding protein Mdm-2, and computational analyses exhibited their antioxidant potential. Results: Both extracts showed cytotoxic potential against human melanoma cells, but generally the activity was more potent for transformed roots than untransformed (IC50 760 μg/mL and 980 μg/mL, respectively). A similar effect was revealed during the evaluation of genotoxic and proapoptotic properties. Moreover, the expression of p53 was also found to be increased after ex-tract treatment. The most dominant identified compounds in both extracts were as follows: (+)-catechin, p-coumaric acid, m-coumaric acid, and (+)-rosmarinic acid. Docking studies and compu-tational analysis showed that (+)-rosmarinic acid possesses the highest binding affinity to the p53 binding protein, Mdm-2, and exhibits the best antioxidant property from the most commonly iden-tified phytochemicals. Conclusion: Our findings revealed the potential of L. nepetifolia transformed root extract as a source of bioactive compounds with cytotoxic, genotoxic, and proapoptotic activity against human melanoma cells as well as antioxidant properties.