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The cellular response of Escherichia coli exposed to alkaloids extracted from a biennial endemic plant, Papaver polychaetum, was explored using proteome analysis. Following determination of the minimum inhibitory concentration of the berberine-containing plant extract as 1,250 μg/mL, E. coli cells were grown in the presence of 750 μg/mL extract. The response of the bacteria to the extract, with berberine found as the major alkaloid, was analyzed on two-dimensional gels. The differentially expressed proteins in the presence of 750 μg/mL extract were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. These proteins included those that play vital roles for maintenance such as protein synthesis (elongation factor-Ts), transport (oligopeptide-binding protein A, uncharacterized amino-acid ABC transporter ATP binding protein YECC), energy metabolism (alpha-subunit of ATP synthase, pyridine nucleotide transhydrogenase STHA) and regulation. These results provide clues for understanding the mechanism of the alkaloid extract-induced stress and cytotoxicity on E. coli. The altered proteins can serve as potential targets for development of innovative therapeutic agents.

Three alkaloids, cheilantifoline, mecambrine, and laudanosine, and two flavonoids, luteoline and tricine, have been isolated from two samples of Papaver macrostomum Boiss. & Huet ex Boiss. (Papaveraceae) of Turkish origin. Antimicrobial tests have been performed on the extracts obtained from these species. It has been found that diethyl ether and acetone extracts of two samples obtained from the aerial parts of the plant have antimicrobial activity against almost all bacteria tested. The existence of flavonoids and the antimicrobial activity of this species are reported for the first time.

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