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Catechol Tetrahydroisoquinolines: Synthesis, Biological Activity, and Natural Occurrence in Portulaca oleracea as Analyzed by UPLC-Q-TOF-ESI-MS/MS

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Catechol tetrahydroisoquinolines (THIQs) with structural novelty have been sporadically reported in Portulaca oleracea L., an edible vegetable and also a medicinal plant. However, their natural occurrence and biological activities are largely unknown. Using dopamine hydrochloride and aliphatic or aromatic aldehydes as substrates, 20 catechol THIQs with varied C1 side chains ( A1 – A20 ) were synthesized via an optimized mild phosphate-mediated Pictet–Spengler (P–S) reaction. Besides our previously developed AB-8 macroporous resin for the purification of hydrophilic THIQs, silica gel column chromatography employing ethyl acetate–methanol–ammonia or dichloromethane–methanol–85% formic acid as the eluent was optimized for the purification of lipophilic THIQs. Except for A1, A3, and A11, all compounds were synthesized for the first time using a mild phosphate-mediated P–S reaction, and A5, A10, A19, and A20 were novel compounds. Using UPLC-Q-TOF-ESI-MS/MS analysis and some synthesized compounds as reference, real-virtual-combined target screening of catechol THIQs was performed. A total of 29 catechol THIQs were simultaneously detected in P . oleracea for the first time, including 11 fatty alkane-connected ones (containing 3 new natural products and 5 new compounds), 9 fatty acid-connected ones (containing 7 new compounds), 1 amide-connected one, and 8 aryl ring-connected ones (containing 1 new compound and 1 new natural product). In vitro assay indicated that two catechol THIQs (6,7-dihydroxy-1- n -undecyl-1,2,3,4-tetrahydroisoquinoline and ethyl 5-(6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline)- n -valerate) exhibited antibacterial activity, and most of them displayed potent antioxidant, Fe 2+ -chelation, and α-glucosidase inhibition activities. This study demonstrated that catechol THIQs made up a group of bioactive alkaloids in P . oleracea .

Source: ACS Omega

DOI: 10.1021/acsomega.5c07408