HR-LC/MS Guided Separation and Identification of Acyl-Migrated Sucrose Esters From Physalis Calyx seu Fructus

Physalis Calyx seu Fructus is a commonly used traditional Chinese medicine with recognized effects of clearing heat, detoxifying, soothing the throat, and resolving phlegm. Previous studies have identified it as a rich source of sucrose fatty acid esters (SEs).

The aim of this study was to isolate structurally novel SEs with biological activity.

HR-LC/MS guided isolation was conducted, followed by unequivocal structural characterization of all compounds through comprehensive spectroscopic analysis. All compounds were evaluated for anti-inflammatory activity using an LPS-stimulated RAW 264.7 macrophage model, and their antibacterial activity was assessed against three clinically relevant bacterial strains. Simultaneously, isotope labeling experiments were conducted to elucidate the role of H₂O in the acyl migration process of the SEs.

Ten new SEs, designated Phyalkfranose A-J (1-10), were isolated; six of them were unstable and underwent intramolecular acyl migration. Experimental results demonstrated that these 6 SEs underwent slow intramolecular acyl migration in aqueous solution, a process that was significantly accelerated under conditions of elevated temperature and high water content. Isotope labeling studies confirmed that H₂O facilitates, but does not participate in the migration. Compounds 8 and 10 inhibited the production of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α). All compounds exhibited negligible antimicrobial activity.

This study represents the first report on the acyl migration phenomenon of naturally occurring SEs from the plant source. These findings not only enrich the structural diversity of SEs but also offer novel strategies and methodologies for the isolation of such components.