Seasonal variation in chemical composition and antioxidant activity of essential oils of four Salvia species from Baja California, Mexico: Salvia apiana, Salvia clevelandii, Salvia munzii and Salvia pachyphylla

The present work investigates the seasonal variation in the chemical composition and antioxidant activity of essential oils of the leaves of four Salvia species natives of Baja California, Mexico: Salvia apiana, Salvia clevelandii, Salvia munzii, and Salvia pachyphylla. Camphor and 1,8-cineole were the secondary metabolites with the highest concentrations in the four species throughout the four seasons. In general, the monoterpenoid percentage was greater than that of sesquiterpenoids in the oil composition. The antioxidant activity was measured by various methods: 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH•), 2,2-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+) and β-carotene/linoleic acid bleaching assay. This antioxidant evaluation revealed that this activity depended on the type of metabolites present in the oil and their concentrations, which varied during the four seasons. These results suggest that the essential oil from these Salvias could represent a source of new products with potential use within the food preservation, pharmaceutical, and cosmetic industries.