Metabolite profiles of Pulicaria crispa and P. incisa in relation to their in-vitro/ in-vivo antioxidant activity and hepatoprotective effect: A comparative mass spectrometry-based metabolomics

Plants of the genus Pulicaria (family: Asteraceae) are widely used in central Asia and the Middle East for treatment of different human diseases. Ultra performance liquid chromatography coupled to high resolution mass spectrometry (UPLC/MS) was utilized to establish the metabolic profiles of two Pulicaria species: P. crispa and P. incisa. 122 metabolites were identified including flavonoids (37), phenolic acids (22), sesquiterpenes (17), diterpenes (7), and fatty acids (27), with enrichment in methoxylated flavonoids (20), caffeoylquinic acid conjugates (14) xanthane sesquiterpenes (9) and hydroxylated fatty acids (20) in both Pulicaria species. The metabolite profile of P. incisa was characterized by the presence of tri- and tetra-methoxylated flavonoids while xanthane sesquiterpenes were the main chemical markers of P. crispa. Additionally, a novel sesquiterpene acid (dihydropulicaric acid) was annotated in both species based on its MS fragments. Antioxidant activity for P. crispa and P. incisa methanol extracts was assessed in vitro based on DPPH and ABTS assays and further in vivo using chlorpromazine intoxicated rat model. Results revealed that P. incisa extract was more effective in inhibiting both DPPH and ABTS free radicals (IC₅₀ 0.36 and 0.52 mg/mL, respectively) than P. crispa (IC₅₀ 0.51 and 0.73 mg/mL). In the animal model, antioxidant activity of P. incisa (20 mg/kg/day) was also slightly higher causing a 55 % reduction in MDA levels and 65 % increase in GSH activity compared to untreated animals. Furthermore, both extracts showed a hepatoprotective effect as revealed by improvement in levels of serum biomarkers of liver functions: total bilirubin, alanine transaminase (ALT) and aspartate transaminase (AST) comparable to silymarin at 25 mg/kg/day. These findings were also supported by the preserved integrity of the hepatic tissues of animals receiving either extracts at a dose of 20 mg/kg b.wt. The present study reveals for the potential antioxidant and hepatoprotective effects for Pulicaria in relation to its bioactive metabolites.