Antioxidant and neuroprotective properties of an aqueous dry extract from the S. officinale aerial parts

Sisymbrium officinale (L.) Scop. (syn. Erysimum officinale L., hedge mustard; Fam. Brassicaceae), is a medicinal plant used traditionally to relief respiratory system’s disorders, hence its “singers’ plant” name [1]. It has been found endowed with myorelaxant, antimicrobial, antimutagenic, antinflammatory and antioxidant activities, likely ascribed to the presence of glucosinolates (mainly glucoputranjivin and isopropyl isothiocyanate) and polyphenolic compounds [1,2]. Glucosinolates are also shown to possess promising chemopreventive and neuroprotective properties [3]. In line with this evidence, in the present study, we investigated the potential neuroprotective and antioxidant properties of an aqueous dry extract of the S. officinale aerial parts (EPO S.r.l.; standardized to contain 0.50% w/w glucosinolates), in brain cell models. To this end, murine Neuro-2a neuroblasts and human neuroblastoma SHSY-5Y cells were used. The protective effects were assessed towards the oxidative damage induced by hydrogen peroxide (H2O2), tert-butyl hydroperoxide (tBOOH) and amyloid beta peptide (Aβ). Preliminarily, the cytotoxicity of the extract (24 h exposure) was assayed by the MTT assay, to select the nontoxic concentrations to be tested for the cytoprotection; the intracellular concentration of the free peroxide and hydroxyl radicals was measured too [4,5]. Antioxidant in vitro assays, including FRAP (Ferric Reducing Antioxidant Potential), ORAC (Oxygen Radical Antioxidant Capacity), DPPH, xanthine/xanthine oxidase, along with the inhibition of central nervous system (CNS) enzymes (monoaminoxidase A, acetylcholinesterase, tyrosinase), known to be involved in neurodegenerative diseases have been also performed [4]. The extract’s tolerability was confirmed in the Artemia invertebrate model. A chemical characterization of the extract was obtained by derivatization followed by GC-MS (gas chromatography-mass spectrometry) analysis. The obtained results highlighted that the extract was able to prevent the oxidative stress induced by hydroperoxides in Neuro-2a neuroblasts and by Aβ protein in SHSY-5Y cells. However, mitochondrial activity and cell viability of Neuro2a cells were not affected by the treatments. The S. officinale extract has also shown an antioxidant capacity against the free radical DPPH and superoxide anions generated by xanthine/xanthine oxidase (X/X.O.) system, almost reaching and overcoming, respectively, the percentage of inhibition exerted by the standard antioxidant compounds. 1° Congresso intersocietà sui prodotti vegetali per la salute: Il ruolo delle piante medicinali nella medicina moderna PADOVA, 15-17 Giugno 2023 Dipartimento di Scienze del Farmaco, Via Marzolo, 5 Conversely, weak, or null inhibitory effects were highlighted against CNS enzymes, compared to the reference compounds. At last, the extract showed to be well tolerated up to the concentration of 500 μg/ml in the Artemia invertebrate assay. At the phytochemical analysis, the extract revealed the presence of a rich phytocomplex, characterized by alcohols, sugars, fatty acids and carboxylic acids. Altogether, the obtained results highlighted the tested S. officinale extract is a source of bioactive compounds with potential neuroprotective properties. Further studies could allow to clarify the role of phenolic compounds and glucosinolates in S. officinale bioactivities, to develop improved standardized extracts to be exploit for neuroprotective purposes and to confirm these activities in vivo. References 1. Di Sotto et al. Journal of Ethnopharmacology 2010, 127, 731–736. 2. Di Sotto et al. Phytotherapy research 2016, 30, 829–834. 3. Borgonovo et al. Molecules 2019, 24(24). 4. Cásedas et al. Food and Chemical Toxicology