Activity-guided fractionation of Sarracenia purpurea leaf extract. In the first phase the crude leaf extract was fractionated based on solubility in hexane, methanol and water. (A) Each of the solvent fractions was evaluated in the glucose toxicity cell viability assay using WST and the methanol-water fraction was selected for further fractionation by Sephadex LH-20 column chromatography. (B) Each of the subsequent fractions was similarly evaluated with four of ten demonstrating significant cytoprotection. Fractions #1 and #10 were selected for further fractionation by semi-preparative HPLC. (C) Upon evaluation of resulting subfractions using the WST assay, only subfractions #1A and #10C, significantly reduced cell loss. (D) The concentration dependent protective activities of pure morroniside (>95%), the predominant metabolite in fraction #1, and hyperoside (>95%), the predominant metabolite in subfraction #10C, were confirmed using the Live/Dead cell survival assay. In left panels, ** denotes a significant difference (p < 0.01) relative to normal glucose control (Student’s t-test, n = 8-12). In right panels, # and ## denote significant differences (p < 0.05 and ## p < 0.01, respectively) relative to corresponding high glucose control (ANOVA, post-hoc Dunnett’s t-test, n = 8-12.