Methanol elicits the accumulation of bioactive steviol glycosides and phenolics in Stevia rebaudiana shoot cultures

• Accumulation of bioactive compounds in Stevia shows different sensitivity to methanol.
• Low methanol concentration (0.1%) increases the levels of steviol glycosides in Stevia.
• A methanol concentration of 1.5% maximizes the accumulation of phenolics in Stevia.
• Antioxidant capacity in Stevia shoots is closely-related to phenolic content.

Stevia rebaudiana Bertoni is a plant that generates interest mainly due to the presence in their leaves of steviol glycosides that can be used as non-caloric sweetener agents. But S. rebaudiana is also interesting for its medicinal properties related to the accumulation in leaves of steviol glycosides and other bioactive compounds, such as phenolics. In order to find ways to increase the production of secondary metabolites with commercial interest, S. rebaudiana in vitro shoot cultures were elicited with methanol at different concentrations. Analysis of the extracts obtained from plant materials revealed that the addition of 1.5% (v/v) methanol to culture media resulted in the highest antioxidant capacity determined. Similar trends were observed when levels of total soluble phenols, flavonoids, and hydroxycinnamic acids were assessed pointing to a close association between these compounds and antioxidant capacity in S. rebaudiana shoots. Regarding steviol glycosides, incubation of shoots in the presence of 0.1% (v/v) methanol led to the maximum levels with an increase of approximately 2-fold over control values. Taken together, these results seem to indicate a differential sensitivity to methanol of metabolic pathways leading to the accumulation of steviol glycosides and phenolics in S. rebaudiana leaves. Moreover, from this study methanol emerges as a potential, concentration-dependent, selective elicitor that opens up new opportunities for the production of valuable natural bioactive compounds.

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