A new alkaloid from Pancratium maritimum - Structure elucidation using computer-assisted structure elucidation (CASE) and evaluation of cytotoxicity and anti-SARS-CoV-2 activity

Pancratium maritimum L. (or ‘sea daffodil’) is one of the most studied plant species in the Amaryllidaceae family. Recently, due to the advancement of new probabilistic methods and spectroscopic techniques, the potential for phytochemical investigations on isomeric compounds has significantly improved. In this study, application of these techniques in combination with conventional phytochemical analysis led to the isolation and identification of a new alkaloid named 2β,10bα-dihydroxy-9-O-demethylhomolycorine from P. maritimum, together with 17 known ones. Assessment of anti-SARS-CoV-2 activity and cytotoxicity on a Vero E6 cell line for all compounds revealed four compounds with weak anti-SARS-CoV-2 potency at non-cytotoxic concentrations, namely of 9-O-demethylhomolycorine (EC50 = 44 µM), galanthamine (EC50 = 70 µM), 1-O-acetyl-norpluviine (EC50 = 80 µM) and 1-O-acetyl-10-O-methylpseudolycorine (EC50 = 47 µM). On the other hand, cytotoxicity was observed for 2β,10bα-dihydroxy-9-O-demethylhomolycorine (CC50 = 13.28 µM), haemanthamine (CC50 = 0.76 µM), 6α- and 6β-haemanthidine (CC50 = 5.43 µM), 11-hydroxyvittatine (CC50 = 10.57 µM) and pseudolycorine (CC50 = 3.41 µM).