Chemical profile and biological activity of Crinum americanum L. (Amaryllidaceae)

Two different alkaloid-guided extraction approaches were used to obtain extracts and fractions of leaves and bulbs from Crinum americanum L. (Amaryllidaceae). Samples were analyzed by gas chromatography-mass spectrometry (GC-MS) and acetylcholinesterase (AChE) inhibition activity, and evaluated for antioxidant capacity and cytotoxicity in human neuroblastoma cells (SH-SY5Y). Crinine (1), 1,2-didehydrocrinan-3-one (2), flexinine (3), lycorine (4), 1-O-acetyl-lycorine (5), caranine (6), acetyl-caranine (7), 11,12-didehydro-anhydrolycorine (8), hippadine (9), crinamine (10), 6-oxo-isocrinamine (11), macronine (12), and epipowelline (13) were identified in different extracts and fractions. Additionally, four steroids were identified: stigmasterol (14), beta-sitosterol (15), cycloartenol acetate (16), and cycloeucalenol acetate (17). Lycorine and crinine were isolated, and their structures were confirmed by nuclear magnetic resonance (NMR) spectroscopy. All extracts and fractions inhibited AChE activity, but with IC50 values ranging from 1–290 µg/mL. One fraction (L_EE2) from the ethanol extract of C. americanum leaves achieved the highest AChE inhibitory activity (IC50 = 1.21 µg/mL), when compared to other extracts or fractions. The extracts did not exhibit significant antioxidant activity. After 24 h of treatment, ethanol extracts of leaves and bulbs showed cytotoxic effects on SH-SY5Y cells in a dose-dependent manner from 25 µg/mL. In this study, we highlighted that, after organic extraction, the remaining plant material still presented secondary metabolites, which is interesting for a better understanding of the chemical composition of C. americanum. To the best of our knowledge, this is the first report of in vitro AChE inhibition and cytotoxicity in SH-SY5Y cells using extracts and fractions from C. americanum. Furthermore, among the 17 compounds, ten were identified for the first time in this species