GC/MS and LC-MS/MS phytochemical evaluation of the essential oil and selected secondary metabolites of Ajuga orientalis from Jordan and its antioxidant activity

The current investigation aimed to shed light in the volatile and non-volatile secondary metabolites of Ajuga orientalis L. from Jordan. GC/MS and GC/FID analysis of the hydrodistilled essential oil obtained from aerial parts of the plant revealed tiglic acid (18.90 %) as main constituent. Each of the methanol and butanol fractions of A. orientalis were screened for their total phenol content (TPC), total flavonoid content (TFC), and antioxidant activity determined by DDPH and ABTS methods. The extracts were then analyzed by LC-ESI-MS/MS to unveil their chemical constituents, especially phenols and flavonoids. Results showed that the AO-B extract had the highest TPC (217.63 ± 2.65 mg gallic acid/g dry extract), TFC (944.41 ± 4.77 mg quercetin /g dry extract), highest DPPH and ABTS antioxidant activity ((4.00 ± 0.20) × 10-2; (3.00 ± 0.20) × 10-2 mg/mL, respectively) as compared to the AO-M extract. LC-ESI-MS/MS analysis of both extracts revealed the presence of several phenolics, flavonoids and nonphenolic acids.