Variability in Phenolic Compounds, DPPH Scavenging Activity, and Essential Oil Profile of Pulicaria gnaphaloides (Vent.) Boiss. Populations: An Opportunity for Industrial Products

Intra-species diversity is a feature of plant responses to different ecological conditions of the habitat. Due to the lack of reports on the Pulicaria gnaphalodes chemotypes in the literature, in this work, five populations (Mayduk, Koohpayeh, Dalfard, Sarcheshmeh, and Khabr) were evaluated in terms of phenolic compounds, 2,2-diphenyl-1--picrylhydrazyl (DPPH) scavenging activity, and essential oil (EO) quality and quantity in Iran based on a completely randomized design (CRD) in 2018. The results showed EO content ranged from 0.30% to 0.61% (w/w) and DPPH scavenging activity was obtained in a range of 37.1-70.7%. The P. gnaphalodes populations represented different amounts of total phenolic content (5.19-6.48 mg garlic acid g(-1) DW) and total flavonoid content (3.08-3.79 mg rutin g(-1) DW). Gas chromatography/mass spectrometry (GC/MS) analysis represented that the main EO profile of P. gnophalodes populations were 1,8-cineole (11.80-23.98%), terpinen-4-ol (4.84-20.29%), alpha-terpineol (7.94-11.46%), geraniol (1.61-7.51%), and cedr-8(15)-en-9-alpha-ol (2.52-11.05%), which were mainly oxygenated monoterpenes. Different groups of populations were revealed via principal component analysis (PCA) and agglomerative hierarchical clustering (AHC), with Khabr being notably different from the others. Heat map analysis revealed that EO compounds, especially geraniol, cedr-8(15)-en-9-alpha-ol, and terpinen-4-ol possessed higher variability than other phytochemical variables. The findings are beneficial in determining the preferred chemotype for pharmacological and therapeutic purposes based on phenolic content and EO profile.