Characterizing the Antimicrobial and Anticancer Activities and Several Associated Bioactive Compounds of Argemone mexicana

Abstract

Commonly called the Mexican prickly poppy, Argemone mexicana is a stress-resistant member of the Papaveraceae family of plants that has been used in traditional medicine for centuries by indigenous communities in Mexico and Western parts of the USA. This plant has been used to treat a wide variety of ailments, including skin diseases and intestinal infections, with reported antimicrobial and anticancer properties. However, these properties are poorly understood, with no associated bioactive compounds yet identified. Herein, we describe the germination conditions of A. mexicana and preliminarily characterize the antimicrobial and anticancer activities of different parts (seeds, leaves, inner vs. outer roots) of the plant. We show that when comparing 1 mg of each sample normalized to background solvent alone, the A. mexicana methanol outer root and leaf extracts possess the strongest antimicrobial activity, with greatest effects against gram-positive bacteria tested, and less activity against gram-negative bacteria and fungi tested. Additionally, we report that when using the MTT colorimetric assay, the outer root and leaf methanol extracts and the seed hexane extract have pronounced inhibitory effects against T84 human colon cancer cells. Using normal-phase column chromatography and subsequent mass spectrometry analysis of the outer root and leaf methanol fractions, we have begun to chemically characterize several candidate antibacterial compounds. These preliminary results warrant further research into defining the bioactive chemicals produced in the roots, leaves and seeds of A. mexicana and are especially significant given the growing global concern of antibiotic-resistant ‘superbugs’ and lack of new antimicrobial and anticancer drug discovery