Chemical profile and antioxidant activity of essential oils and polyphenolic compounds of lippia graveolens from different Mexican localities

Extraction of polyphenolic fraction and essential oils (EOs) from Lippia graveolens (Mexican oregano) leaves were explored using innovative and conventional extraction techniques such as ultrasound assisted extraction (UAE) and steam distillation, respectively. The metabolites were further analyzed to evaluate their bioactivity as antioxidants and the identification of the chemical profile was performed using a UPLC-ESI-Q/TOF-MS2 and GC-MS. The antioxidant assays on EOs showed potential as inhibitors of lipid oxidation, and the polyphenolic fraction obtained higher inhibition activity against DPPH• radical. The lower IC50 for DPPH• radical corresponded to the phenolics from “San Pedro” with 545.40 ± 47.2 μg mL-1, and the higher inhibition of lipid oxidation appertained to EOs (99.06 ± 3.91%). Furthermore, the GC-MS tentative characterization identified sixty-one compounds for EOs, and UPLC-ESI-Q/TOF-MS2 showed six identified compounds, the tentative compounds englobe flavonoids, terpenes, sesquiterpenes xanthines, and dicarboxylic acid. The present study demonstrated that Mexican crops of L. graveolens possess essential oils and polyphenolic fractions with strong antioxidant activity, which might be useful in the food and pharmaceutical industries.