Amaryllidaceae plant extracts

Plants were collected and supplied under the framework of the CYTED BIFRENES project network (ref. 416RT0511). Alkaloids are the principal active constituent of Amaryllidaceae, and the extraction procedure explained below was devised to solely keep their alkaloid fraction. Unless otherwise indicated, alkaloid extracts were obtained from aerial parts or bulbs through acid–base extraction. Each species was collected and dried for 7 days at 40 ºC. Samples were ground and the powders macerated with methanol (3 × 100 mL) at room temperature for 3 days. The mash was filtered and the organic solvent was taken to dryness under reduced pressure to obtain the crude extract. These extracts were acidified to pH 3 with sulfuric acid (2%, volume/volume [v/v]) in order to remove the neutral material with diethyl ether. Aqueous solutions were then basified up to pH 10 with ammonium hydroxide (25%, v/v) to obtain the alkaloid extract with ethyl acetate. All alkaloid extracts were dried using reduced pressure. Dried material of each extract was solubilized with 100 µL of dimethyl sulfoxide (DMSO) and used in the experiments. In all cases, the final DMSO percentage per well was below 0.5%. The collection of alkaloid extracts is shown in Additional file 1: Table S1 and Additional file 2: Table S2.