Cytotoxic and antioxidant activities of selected Lamiales species from Mexico

Context: Methanol extracts obtained from eight species belonging to four families of the Lamiales order native to Mexico were investigated for biological action.

Objective: Cytotoxicity and antioxidant activity of methanol extracts have been investigated.

Materials and methods: Cytotoxic activity was evaluated by the sulphorhodamine B protein staining assay against KB (nasopharyngeal), HEp-2 (larynx), HF-6 (colon), MCF7 (breast), PC-3 (prostate), and Ca Ski (cervix) carcinoma cell lines. To analyze the antioxidant activity, common stable radicals chromogens, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS^·+) and DPPH (1,1-diphenyl-2-picrylhydrazyl) were used. The ferric reducing antioxidant power (FRAP) and the total phenolic content of the samples were also determined.

Results: Some of the extracts, such as Limosella aquatica L. (Scrophulariaceae), Mimulus glabratus Kunth. (Phrymaceae), Pedicularis mexicana Zucc. ex Benth. (Orobanchaceae), and Penstemon campanulatus (Cav.) Willd. (Plantaginaceae) displayed remarkably selective cytotoxic activity. However, the extract from Veronica americana (Raf.) Schwein (Plantaginaceae) showed the highest activity with IC₅₀ values of 1.46 and 0.169 μg/mL on PC-3 and HF-6 cells, respectively. With the exception of M. glabratus, all the extracts showed different degrees of antioxidant activity with IC₅₀ values from 0.89 up to 1.8 in the ABTS assay; from 0.49 up to 1.25?mg/mL in the DPPH assay and with the FRAP evaluation, 36 to 68 equivalents in mM of FeSO₄. V. americana also showed the highest antoxidant activity with IC₅₀ values from 0.491 and 0.892?mg/mL, on DPPH and ABTS assays, respectively.

Discussion and conclusion: These findings demonstrated that the species studied have great potential cytotoxic and antioxidant activity.