Phenolic profile and cytotoxic properties of polar extracts from basal leaves and flowers of Isatis tinctoria L.

Isatis tinctoria L. (Brassicaceae) is an ancient European dye and medicinal plant. Historically, I. tinctoria has been cultivated for the production of indigo dye (blue colour) in Europe, and traditionally used for the treatment of wounds, ulcers and tumours, haemorrhoids, snake bites and various inflammatory ailments (Hamburger, 2002). Although I. tinctoria is not considered as an edible vegetable worldwide, rural people living around Vulcan Etna (Sicily, Italy) consume boiled flower buds of this plant as ingredients for salads and omelets (Galletti et al., 2008). Many authors have reported the anti-inflammatory and anti-cancer properties of lipophilic extracts and isolated compounds from I. tinctoria, whereas only a few studies have been carried out to investigate the biological activities of polar constituents present in this species. In continuation of our researches, this work was designed to characterize the phenolic profile and to evaluate the cytotoxic properties of the polar extracts from basal leaves (It-B) and flowers (It-F). of I. tinctoria grown wild around Acireale (Catania, Sicily, Italy). Method Plant material was lyophilized and sequentially extracted with dichloromethane and 70% methanol at a temperature of 50 °C. Characterization of the phenolic profile of the hydroalcoholic extracts was attained by HPLC-PDA-ESI-MS analysis. Artemia salina lethality bioassay was carried out to investigate the potential cytotoxicity of It-B and It-F (Miceli et al., 2016). To test in vitro the anti-proliferative effects of the extracts, a human acute monocytic leukemia (AML-M5a) cell line (MOLM-13) was used. After 24 and 48 hours of treatment, cells were stained with Annexin V and 7-amino-actinomycin D and fluorescence was evaluated by flow cytometry. Results / Discussion / Conclusion By HPLC-PDA-ESI-MS analysis 13 and 8 compounds were successfully separated and identified for It-B and It-F, respectively. I tinctoria extracts have shown a pretty similar phenolic fingerprint; the total amount of the identified phenolics was higher in It-F (19.95 mg/g extract) than It-B (10.13 mg/g extract). Flavonoids represented the main class of compounds, with luteolin-glucuronide and stellarin-2 being present in the greatest amount in It-B and It-F, respectively. Cinnamic acids were more abundant in It-B than in It-F. In the A. salina lethality bioassay both extracts resulted non-toxic to brine shrimp larvae (LC50 > 1000 µg/ml). It-B extract demonstrated good cytotoxic effect against MOLM-13 cells at both time points; particularly, after 48 h exposure, a reduction of viability close to 100% was observed at the highest tested concentration (1 mg/ml). It-F extract showed lower activity, causing about 40% growth inhibition. Further investigations are needed to better explore the promising cytotoxic properties of the polar extract from I. tinctoria basal leaves and to determine its active components. Acknowledgments The authors wish to thank the “University of Messina” within the “Research and Mobility” Project. Bibliographic References - Hamburger M, 2002. Phytochemistry Reviews, 1, 333-344. - Galletti S, Righetti L, Bagatta M, 2008. First European Food Congress. Ljubljana (Slovenia). 3-9 November. - N. Miceli, L.P. Buongiorno, M.G. Celi, et al., 2016. Natural Product Research, 30(11), 1229-1239.