Characterisation of phenolic antioxidants in Scabiosa arenaria flowers by LC–ESI-MS/MS and NMR Malek Besbes Hlila a , Habib Mosbah b , Nahla Zanina c , Aymen Ben Nejma d , Hichem Ben Jannet d , Mahjoub Aouni a and Boulbaba Selmi b a Laboratory of Transmissible Diseases and Biological Active Substances, Faculty of Pharmacy, University of Monastir, b Laboratory of Bioresources: Integrative Biology and exploiting, Higher Institute of Biotechnology of Monastir, c Laboratory of Biophysics, Faculty of Medicine, Monastir University, and d Laboratory of Heterocyclic Chemistry, Natural Products and Reactivity, Team: Medicinal Chemistry and Natural Products, Faculty of Sciences of Monastir, University of Monastir, Monastir, Tunisia Keywords 1,4-O-dicaffeoylquinic acid; apigenin 7-O- glucoside; DPPH; luteolin-7-O-glucoside; Scabiosa arenaria Correspondence Malek Besbes Hlila, Laboratory of Transmissible Diseases and Biological Active Substances, Faculty of Pharmacy, Avenue Avicenne, University of Monastir, 5000 Monastir, Tunisia. E-mail: angelkm2007@yahoo.fr Received November 23, 2015 Accepted March 29, 2016 doi: 10.1111/jphp.12561 Abstract Objectives This work describes the bioguided fractionation of the flower’s ethyl acetate fraction of Scabiosa arenaria Forssk. (Dipsacaceae). Methods The identification of the pure compound isolated has been studied by mono-dimensional NMR experiments. The mixture of phenolic compounds was analysed by LC–ESI-MS/MS. The antioxidant activity has been evaluated by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Key findings The bioguided fractionation of the flower’s ethyl acetate fraction of Scabiosa arenaria led to the isolation of a pure compound: luteolin. The mixture of three phenolic compounds was identified as: 1, 4-O-dicaffeoylquinic acid, api- genin 7-O-glucoside and luteolin-7-O-glucoside. Two of which are reported here for the first time in Scabiosa genus. Luteolin had the highest antioxidant activity with an IC50 value of 0.02 Æ 0.007 mg/ml, followed by the three phenolic com- pounds with an IC50 value of 0.025 Æ 0.008 mg/ml. Conclusions The results of the present work indicate that S. arenaria flower’s ethyl acetate extract could be used as natural antioxidant agents in food preserva- tion and human health. Introduction Plants such as vegetables, fruits, spices and medicinal herbs have been used to cure many diseases since ancient time. Today in this modern world, even though synthetic drugs are readily available and highly effective in curing various diseases, there are people who still prefer using traditional folk medicines because of their less harmful effects. [1] Antioxidants found in food are a heterogeneous category of molecules. [2] Antioxidants are compounds or systems that can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. They can use several mechanisms: (1) scavenging species that ini- tiate peroxidation, (2) chelating metal ions so that they are unable to generate reactive species or decompose peroxides, (3) quenching radical oxygen preventing formation of per- oxides, (4) breaking the auto-oxidative chain reaction and/ or (5) reducing localised O2 concentrations. [3] The antioxidative effectiveness of these compounds depends on their chemical characteristics and physical loca- tion within a food (proximity to membrane phospholipids, emulsion interfaces or in the aqueous phase). [4] A number of biological and pharmacological activities of antioxidants (e.g. flavonoids, phenolic acids, tannins, vitamin C and vitamin E) have been reported. They are crucial in the pre- vention of pathologies such as cancer, heart diseases, bio- logical damage in living tissues and neurodegenerative diseases, in which ROS (reactive oxygen species) or free radicals are implicated. [5,6] Synthetic antioxidants such as butylated hydroxylanisole (BHA), propyl gallate (PG), butylated hydroxyltoluene (BHT) which have been used to prevent oxidation have been found to cause internal and external bleeding in rats and guinea pigs at high dose. [7,8] Attention is therefore turned to the use of natural antiox- idants such as bioactive flavonoids which are of great © 2016 Royal Pharmaceutical Society, Journal of Pharmacy and Pharmacology, 68 (2016), pp. 932–940 932 Research Paper Downloaded from https://academic.oup.com/jpp/article/68/7/932/6128230 by guest on 05 January 2023