LC/MS method development for the determination of the phenolic compounds of Tunisian Ephedra alata hydro-methanolic extract and its fractions and evaluation of their antioxidant activities

Abstract Ephedra alata is a medicinal plant with a long history of traditional use for its bronchodilator, anti-asthmatic and cytotoxic effects. In this work, we develop a sensitive and validate LC-ESI/MS method to simultaneously identify and quantify 33 standard phenolic compounds in E. alata methanol (MeOH) crude extract and its derived fractions (Dichloromethane (DCM), Ethyl acetate (EAc), butanol (BuOH) and water). The antioxidant activities were tested using total antioxidant capacity (TAC), DPPH and FRAP assays. Results showed that the validated and reliable LC-ESI/MS method used unambiguously lead to identify and quantify 24 phenolic compounds most of them are present in all extracts. The major components detected were epicatechin, quinic acid, quercetin-3-o-rhamnoside, catechin, trans -cinnamic acid, naringin and trans -ferulic acid which their amounts vary according to the solvent used for the extraction. The DCM extract showed the highest activity when the TAC test was applied, the BuOH and EAc extracts displayed the highest activities with the DPPH test, whereas the DCM and EAc extracts exhibited the strongest activities with the FRAP method. This difference could be attributed to the nature and amounts of phenolic compounds of the extracts. These realized phytochemical and biological analyses could be helpful for the potential use of this plant in novel medicament products.