Bioactive potential of Origanum elongatum extracts: Focus on phytochemical composition and antioxidant properties of different fractions

Abstract

The variation of phenolic compounds and antioxidant activities of plant extracts is widely influenced by environmental factors, extraction methods and solvent polarity. Therefore, this study aimed to evaluate the phenolic composition and the antioxidant activities in vitro of Origanum elongatum aerial part, a perennial plant endemic to the Rif region of Morocco. It processed into crude, 80% methanolic extracts, and fractions obtained from it using hexane, dichloromethane, and ethyl acetate solvents. Total polyphenolic, flavonoid and proanthocyanidins contents were determined using the Folin-Ciocalteu, Andary, and vanillin methods. The antioxidant activity was assessed by four complementary methods DPPH, ABTS, FRAP and TAC. Preliminary phytochemical screening revealed the presence of saponins, essential oils, sterols, free Quinones, flavonoids, but the alkaloids were absent. Among the fractions, the hexane fraction (213.07 mg GAE.g-1 of extract) and ethyl acetate fraction (193.93 mg GAE.g-1 of extract) exhibited the high total phenolic content. Also, the hydromethanolic extract contained the highest flavonoids concentration (18.83 mg QE.g-1). Notably, the ethyl acetate fraction consistently showed superior antioxidant activity across all assays, with an IC₅₀ of 0.17 ± 0.01 mg/mL for DPPH and 1.6 ± 0.01 μg/mL for ABTS. It also demonstrated the highest TAC 319.00 ± 0.05 mg EAA/g and FRAP values, confirming strong ferric reducing power. These results highlight the ethyl acetate fraction as a rich source of bioactive compounds with strong antioxidant properties, with a potential applications in pharmaceuticals, nutraceuticals, and food preservation. Further research is recommended to characterize its active constituents and investigate its biological efficacy in vivo.