Chemical composition of the essential oil of Salvia bracteata Banks and the biological activity of its extracts: antioxidant, total phenolic, total flavonoid, antifungal and allelopathic effects

The present study was conducted with the aim of determining biological activities of the Salvia bracteata plant, activities such as its antioxidant, total phenolic, total flavonoid, allelopathic and antifungal effects. To this end, aboveground parts (flowers + shoots + leaves) of S. bracteata plants were collected in the province of Kirsehir, Turkey, during the flowering stage in 2018. As a result of GC-MS analysis, 23 constituents were identified, representing 96.21% of the essential oil. The major compounds of essential oil were identified as ledol (24.12%), camphor (15.54%) and valencene (5.64%). In ethyl acetate, methanol and hexane extracts of S. bracteata, total phenolic content was found to be 104.63, 121.66 and 20.97 mg of GAE/g of extract, respectively, while flavonoid content was 12.89, 10.85 and 1.13 mg of QE/g of extract, respectively. In addition to this, DPPII radical removal activity was identified and found to be at its highest in the methanol and ethyl acetate extracts. The TEAC (cation radical removal activity), FRAP (iron reduction power) and CUPRAC (copper reduction power) reduction activities of these plant extracts were also determined. The methanol extract of S. bracteata was found to have an allelopathic effect on Rumex crispus and Taraxacum officinale. This extract had a weak effect on development of the mycelium of Alternaria solani Sorauer, one of the most significant of plant-pathogenic fungi, but it was found to be ineffective on the Sderotinia sclerotiorum pathogen.