Characterization and quantification of phenolic compounds and antioxidant properties of Salvia species growing in different habitats

- Salvia species constitute a source of natural antioxidants.
- Rosmarinic acid was the most abundant phenolic compound in all analyzed methanolic extracts.
- Salvia officinalis showed the strongest antioxidant activity.
- The collection site showed a significant effect on phenolic contents and antioxidant capacities.

Few literature data are available on the antioxidants of Salvia verbenaca, Salvia aegyptiaca and Salvia argentea. Such lack of information prevents exploitation of these potential pool of compounds with strong antioxidant activity. So, in the present study, phenolic contents and compositions and antioxidant activities of methanolic extracts of four Salvia species, growing in various habitats, were determined. The total phenolic contents estimated spectrophotometrically ranged from (67.67-72.02 mg GAE/g DW) for S. argentea extracts to (112.93-161.37 mg GAE/g DW) for Salvia officinalis samples. The HPLC analysis detected the presence of several phenolic acids, particularly the caffeic acid derivatives along with flavonoids and phenolic diterpenes. Rosmarinic acid was found to be the most abundant compound in all analyzed extracts and showed its highest values in S. officinalis samples (13,680.22-18,378.00 μg/g DW). Varying degrees of antioxidant and radical-scavenging efficacity of different sage extracts were illustrated. S. officinalis methanolic extracts had the strongest antioxidant capacity as evaluated by DPPH (10.08-3.37 μg/mL), ABTS (644.85-766.30 μM TE/mg) and FRAP (178.65-197.33 mM Fe(II)/mg) assays. Significant correlations between total phenolics, the most representative phenolic compounds, particularly rosmarinic acid and the antioxidant assays were verified. Variations of total phenolic contents and compositions and antioxidant activities between Salvia samples grown at different regions were significant. Salvias aerial part extracts could be valuable as an effective and safe source of functional food materials such as natural antioxidants.