Antioxidant properties and phenolic profile of a hydroalcoholic extract obtained from the leaves of Ficus vasta Forssk. (Moraceae).

Ficus vasta Forssk. (Moraceae) is a very large tree growing over 25 m tall, with spreading rounded crown. Leaves are alternate, quite stiff, rough to the touch, almost circular (8-25 x 4-23 cm), margin entire, tip rounded but often with a blunt point, base rounded, heart shaped; usually glabrescent above, glabrescent, puberulous, hirsute or velutinous below (1). This species is widespread throughout the dry north and eastern Africa, Sudan, Ethiopia, Saudi Arabia and Tanzania. The leaves of F. vasta are traditionally used for the treatment of rheumatism, pains and intestinal worms (2). F. vasta has been poorly studied to date; very few researches have been performed to investigate the phytochemistry and the biological activities of the leaves of this species (2-5). The aim of this work was to evaluate the antioxidant properties and to characterize the phenolic profile of a hydroalcoholic extract (80% methanol) obtained from the leaves of F. vasta collected in Egypt. In this study, three in vitro methods based on fundamentally different approaches and mechanisms were used to screen the antioxidant potential of F. vasta extract: DPPH, reducing power, and ferrous ions chelating activity assays (6). Butylated hydroxytoluene (BHT) and ethylenediaminetetraacetic acid (EDTA) were used as reference standards. In the DPPH test the extract exhibited strong radical scavenging activity, higher than BHT (IC50 = 0.0672 ± 0.0038 mg/mL and 0.0821 ± 0.0009 mg/mL, respectively). The extract showed reducing power (3.65 ± 0.48 ASE/mL) and chelating activity (IC50 = 0.801 ± 0.007 mg/mL), too; nonetheless, the effects were lower than the standards. In order to establish the antioxidant efficacy of F. vasta extract in a more complex biological setting, the ability to protect bacterial growth from the oxidative stress induced by hydrogen peroxide (H2O2) was evaluated on Escherichia coli (7). The extract displayed noticeable protective effects on E. coli under oxidative stress; compared to H2O2 treated control, a total protection against H2O2-induced damage was observed. The activity of the extract was higher than quercetin, used as reference standard. The quali-quantitative characterization of the phenolic compounds contained in the extract was attained by HPLC-PDA-ESI-MS. The analysis led to the identification of 11 compounds belonging to the groups of phenolic acids and flavonoids; particularly, quercetin-3-galactoside turned out to be the most abundant (81.75 mg/g ± 0.88% RSD), followed by gallic acid (76.36 mg/g ± 2.70% RSD) and isoquercitrin (22.5 mg/g ± 2.02% RSD). The obtained results suggest that F. vasta leaves represent a potential source of natural antioxidants. Further investigations need to be carried out to isolate and identify the individual phenolic compounds responsible for the antioxidant activity. Acknowledgements The authors wish to thank the “University of Messina” within the “Research and Mobility” Project. 1) N.J. Raju, E.A. Yesuf, M. Bekele, N.T. Wabe (2011) Asian J. Pharm. Biol. Res., 1(4), 454-458 2) K. Rashed, R. Anthonissen, D. Cappoen, L. Verschaeve (2015) Phcog. Commn., 5(3), 207-216 3) N.J. Raju, E.A. Yesuf, M. Bekele, N.T. Wabe (2011) Asian J. Pharm. Biol Res., 1(4), 454-458 4) K. Rashed, L. Ono (2013). Int. Curr. Pharm. J., 3(1), 211-218 5) M.E. Osman, H.H. Yassen, J.D. Deng, R.O. Mustafa, S.M. Hussein (2014) J. Forest Prod. Ind., 3(6), 292-295 6) S. Habibatni, N. Miceli, G. Ginestra, Z. Maameri, C. Bisignano, F. Cacciola, M. Utczas, L. Mondello, S. Anwar, S. Benayache, D. Atrouz, F. Benayache, M. F. Taviano (2016) Int. J. Phytomed., 8, 37-46 7) G.V. Smirnova, Z. Y. Samoylova, N. G. Muzyka, O.N. Oktyabrsky (2009) Free Rad. Biol. Med., 46, 759-768