In vitro cultures of Argemone mexicana (Papaveraceae) were induced from leaves of mature plants. Sanguinarine, a benzophenanthridine, was the main alkaloid in the cultures, even in the absence of inducers of secondary metabolism. The accumulation of this metabolite was increased by adding methyl jasmonate and fungal elicitors, although in a limited fashion in comparison to other sanguinarine-producing species. Evidence of a transport mechanism, which may be related to the magnitude of the response, was obtained based on the fluorescent properties of bezophenathridines in the elicited cultures.

The effects of the sequential application of methyl jasmonate (MeJa), salicylic acid (SA) and yeast extract (YE) to Argemone mexicana cell cultures were compared to either the sole application of each elicitor, or to the three-partite mixture. The highest sanguinarine accumulation occurred using the sequential treatment (ninefold over unexposed control cultures), followed by the single application of YE (fivefold). The elicitor mixture produced less sanguinarine than sole exposure to YE but higher than MeJa alone. SA did not produce any effect. Transcripts corresponding to tyrosine decarboxylase and berberine bridge enzyme accumulated in treated cells, but did not correlate with alkaloid accumulation. Discrete epifluorescence foci, surrounding the nucleus and scattered throughout the cytoplasm of elicited cells, suggested the presence of alkaloid-accumulating vesicles which could participate in a mechanism to avoid sanguinarine toxicity.

Alkaloid contents in <em>Argemone mexicana</em> cell line AMMiF were analyzed during a 36-day culture cycle. The benzophenanthridine sanguinarine (SA) represented the main alkaloid. Dihydrosanguinarine (DHSA), a SA biosynthetic precursor and a less toxic benzophenanthridine, was also identified, based on chromatographic properties and further confirmed by gas chromatography coupled to mass spectrometry. Along the culture cycle, SA contents increased simultaneously while DHSA decrease, suggesting their biosynthetic conversion. Upon exposure to yeast extract as an inducer of secondary metabolism, there was an increase in SA content, which was preceded by DHS accumulation. However, after a long exposure (72 h), contents of both SA and DHSA were noticeable elevated, with close to 20% of the total alkaloid produced being recovered from the external medium. These results suggest the operation of a cell mechanism to avoid damage inflicted by the excessive accumulation of SA.

A protocol for the induction of a cell suspension culture of Argemone mexicana is described. This suspension has been kept for over 3 years producing sanguinarine, a benzophenanthridine-type alkaloid. Sanguinarine levels can be increased by exposing these cultures to yeast or fungal elicitation.