Physiological changes, phenolic content and antioxidant activity of Salvia officinalis L. grown under saline conditions.

Background: Hydroponic culture was used to investigate the effect of NaCl concentrations on the growth, nutrient uptake, phenolic content and antioxidant activity of Salvia officinalis L. leaves. The antioxidant capacity of the methanolic extract of S. officinalis was evaluated by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging test and β-carotene-linoleic acid bleaching assay. Physiological and biochemical parameters of S. officinalis were assessed after 4 weeks of salt treatment with 0, 25, 50, 75 and 100 mmol L(-1) NaCl.

Results: Plant growth exhibited a reduction of 61% at 100 mmol L(-1) NaCl. Assessment of Na(+), K(+) and Ca(2+) and water contents of shoots and roots showed that S. officinalis is able to regulate Na(+) concentration by active compartmentation in vacuoles. Salvia officinalis phenolics were increased in response to salinity at the threshold of 75 mmol L(-1) NaCl. This herb was also found to be able to achieve important DPPH(•) quenching activity and to inhibit the β-carotene-linoleic acid bleaching notably enhanced by salt treatment. It is interesting to highlight the correlation between the phenolic and antioxidant activity, suggesting the involvement of these compounds in this activity.

Conclusion: Salvia officinalis treated with 75 mmol L(-1) NaCl constitutes a potential source for production of secondary metabolites useful in several applications.