Phenolic profile, antioxidant properties and brine shrimp toxicity of a hydroalcoholic extract obtained from the aerial parts of Matthiola incana (L.) R. Br. (Brassicaceae).

The spontaneous flora of Sicily (Italy) includes several species belonging to the Brassicaceae family, potential source of bioactive compounds. Matthiola incana (L.) R. Br. is a plant native to the Mediterranean region in Southern and Western Europe, North Africa and the Middle East. It is a biennial, short-lived perennial or annual herb (10-80 cm), often rather shrubby, almost hairless to densely hairy; the leaves (1-3 x 5-12 cm) are linear to oblong-lanceolate or obovate, entire or sometimes slightly sinuous-pinnatifid, obtuse or almost acute. The cruciform flowers, single or double, are gathered in terminal racemes with violet, purple, red, pink or white petals (1,2). M. incana is commonly used for ornamental purposes, due to its colourful flowers, and has become an economically important floral crop. Literature data report the use of this species in the traditional medicine of different countries for the treatment of various ailments, including inflammations and cancer; nonetheless, very few researches have been performed to investigate the phytochemistry and the biological activities of M. incana aerial parts. Thus, in continuation of our studies on species of the Brassicaceae family growing in Sicily, the present work was undertaken to characterize the phenolic profile and to evaluate the antioxidant properties and the toxicity of a hydroalcoholic extract (80% methanol) obtained from the aerial parts (leaves and flower buds) of M. incana grown wild around Capo d’Orlando (Messina). The quali-quantitative characterization of the phenolic compounds contained in M. incana extract was attained by HPLC-PDA-ESI-MS. The analysis led to the identification of 12 compounds, 2 out of them belonging to the group of phenolic acids (5.46 mg/g extract) and 10 to flavonoids (155.85 mg/g extract). Among the detected compounds luteolin-glucoside turned out to be the most abundant one (57.07 mg/g ± 0.87% RSD), followed by dihydrokaempferol (40.46 mg/g ± 1.01% RSD) and naringenin-glucoside (30.92 mg/g ± 0.98% RSD). Antioxidant activity, especially of phytocomplexes, cannot be evaluated satisfactorily by a simple antioxidant test, but it is strongly suggested the use of various methods in order to acquire a more complete antioxidant profile. In order to extensively characterise the antioxidant potential of M. incana extract, three “in vitro” systems based on fundamentally different approaches and mechanisms were utilized: the primary antioxidant activity was examined by DPPH and reducing power assays; the secondary antioxidant properties were determined by ferrous ions chelating activity assay (3,4). Butylated hydroxytoluene (BHT) and ethylenediaminetetraacetic acid (EDTA) were used as reference standards. M. incana extract exhibited mild activity both in the DPPH test (IC50 = 2.32 ± 0.24 mg/mL) and in the reducing power assay (ASE/mL = 12.29 ± 0.42). By contrast, the extract exhibited good chelating properties, reaching nearly 80% activity at the dose of 1 mg/mL. Finally, the extract resulted non-toxic in the Artemia salina Leach (brine shrimp) lethality bioassay (LC50 > 1000 μg/mL) (3,4). Our findings contribute to an increase in knowledge about Matthiola incana, also supporting the traditional use of this species. Acknowledgments: The authors wish to thank the Foundation “Prof. Antonio Imbesi” for financial support. 1) T. G. Tutin, V. H. Heywood, N. A. Burges, D. H. Valentine, S. M. Walters, D. A. Webb (1964) Flora Europea, Vol. I, 279-280 2) J. Cullen, J. C. M. Alexander, A. Brady, C. D. Brickell, P. S. Green, V. H. Heywood, J. P. M. Jӧrgensen, S. L. Jury, S. G. Knees, A. C. Leslie, V. A. Matthews, N. K. B. Robson, S. M. Walters, D. O. Wijnands, P. F. Yeo (2002) The European Garden Flora, Vol. IV, 138-139 3) M. F. Taviano, A. Filocamo, S. Ragusa, F. Cacciola, P. Dugo, L. Mondello, G. Paterniti Mastrazzo, R. F. De Rose, M. Celano, G. E. Lombardo, A. Melchini, N. Miceli (2018) Plant Biosystems, 152, 795-803 4) N. Miceli, A. Filocamo, S. Ragusa, F. Cacciola, P. Dugo, L. Mondello, M. Celano, V. Maggisano, M.F. Taviano (2017) Chemistry and Biodiversity, 14, 1-11