Leaf glandular trichomes, chemical composition, antioxidant activity, and α-glucosidase inhibitory activity of the essential oil of Salvia taraxacifolia Coss. & Balansa, an endemic Moroccan species

This study investigated the glandular structures of the leaves, the chemical composition, the antioxidant activity (DPPH and FRAP assays), and the α-glucosidase inhibitory potential of the essential oil (EO) of Salvia taraxacifolia, an endemic Moroccan species of the Lamiaceae family. Histological observations revealed the presence of capitate and peltate glandular trichomes responsible for the secretion and accumulation of essential oil. GC–MS analysis identified 57 constituents, representing 99.37% of the total EO, with sesquiterpene hydrocarbons as the predominant chemical class, particularly germacrene D (22.01%). The EO exhibited moderate antioxidant activity, with IC50 values of 350 ± 0.01 µg/mL in the DPPH assay and 368 ± 0.02 µg/mL in the FRAP assay, compared with quercetin and BHT used as reference antioxidants. This activity may be attributed to the combined and potentially synergistic effects of multiple volatile constituents, as commonly reported for essential oils. In addition, the EO showed notable α-glucosidase inhibitory activity, with 91.16% inhibition at 1000 µg/mL and an IC50 value of 619.1 ± 0.21 µg/mL, exceeding that of the reference inhibitor acarbose under the experimental conditions employed. Overall, these findings suggest that the essential oil of S. taraxacifolia may represent a promising natural source of bioactive compounds with potential applications in the management of oxidative stress and postprandial hyperglycemia.