Variability in Essential Oil Composition and Antioxidant Activity of Twelve Wild-Growing Salvia Species From Türkiye

Abstract

The objective of this study was to examine the antioxidant capacity, chemical composition, essential oil content, and total phenolic content of 12 Salvia species that grow naturally in Karaman, Türkiye's Ermenek district. Essential oil yields varied markedly among species, ranging from 0.66% to 2.02%, with Salvia tomentosa exhibiting the highest yield. Major volatile constituents varied among species and included β-pinene (3.91%–41.92%), α-pinene (9.57%–34.14%), germacrene D (5.85%–24.22%), limonene (10.02%–21.40%), and camphor (5.06%–12.55%). Marked variation was also observed in antioxidant potential and phenolic accumulation. Salvia heldreichiana showed the strongest antioxidant activity (DPPH scavenging up to 99.03%) and the highest total phenolic content (13.90 mg GAE/100 mL), highlighting its phytochemical richness. Soil samples from the root zones of each species were analysed for physicochemical properties, including pH, electrical conductivity, organic matter content, and macroelements, to assess their influence on the chemical profiles of the plants. Soil–plant relationship analysis demonstrated that higher soil organic matter and iron content were positively associated with increased total phenolic content and antioxidant activity in Salvia heldreichiana and Salvia hypargeia. In contrast, elevated soil pH and calcium carbonate levels were linked to reduced phenolic accumulation and weaker antioxidant capacity in Salvia candidissima subsp. occidentalis and Salvia cyanescens. Additionally, available phosphorus showed a positive association with essential oil yield in Salvia tomentosa. Statistical analyses, including one-way ANOVA and principal component analysis (PCA), were performed to evaluate differences between species. The findings indicate that both species identity and edaphic factors play a decisive role in shaping the chemical composition and bioactivity of Salvia species. This study provides a new perspective on soil–plant–secondary metabolite interactions within the Salvia genus and highlights the medicinal and industrial potential of wild-growing taxa from the Ermenek flora.