HPLC-MS/MS chemical characterization and biological properties of Origanum onites extracts: a recent insight

This study investigated into the phytochemical profile and biological properties of extracts (methanol and aqueous) of Origanum onites based on the antioxidant, enzyme inhibitory, and antibacterial activities. The aqueous extract exhibited higher antioxidant activities in the 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS), ferric reducing antioxidant power, cupric reducing antioxidant capacity, phosphomolybdenum, and metal chelating assays, compared to the methanol extract. In contrast, the methanol extract was the most effective inhibitor of acetylcholinesterase, butyrylcholinesterase, tyrosinase, α-amylase, and α-glucosidase. The methanol extract also showed higher antibacterial activity with highest inhibition against Escherichia coli (MIC = 6.25 mg/mL). The total phenolic content was higher in the aqueous extract while the methanol extract possessed higher total flavonoid content. A total of 28 and 18 compounds (belonging to polyphenols, flavonoids, terpenoids, and ester classes) were identified from the methanol and water extracts, respectively. These findings suggest that O. onites could be helpful in the management of oxidative stress-associated diseases including diabetes and neurodegenerative complications. Abbreviations: ABTS: 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid; ACAE: acarbose equivalent; AChE: acetylcholinesterase; AD: Alzheimer's disease; BChE: butyrylcholinesterase; CUPRAC: cupric reducing antioxidant capacity; DPPH: 1,1-diphenyl-2-picrylhydrazyl; EDTAE: EDTA equivalent; FRAP: ferric reducing antioxidant power; GAE: gallic acid equivalent; GALAE: galatamine equivalent; HPLC: high performance liquid chromatography; KAE: kojic acid equivalent; RE: rutin equivalents; TE: trolox equivalent; TPC: total phenolic content; TFC: total flavonoid content.