Soluble epoxide hydrolase inhibitors from Docynia indica (Wall.) Decne.

Abstract

Nine bioactive compounds, including one new dihydroisocoumarin glycoside, 3S-thunberginol C 6-O-β-D-glucopyranoside (1a/1b), were isolated by chromatographic separation from the fruits of the Vietnamese medicinal plant Docynia indica (Wall.) Decne. 3S-thunberginol C 6-O-β-D-glucopyranoside was determined as a mixture of boat-like conformers based on NMR evidence and density functional theory (DFT) calculations. The in vitro inhibition of soluble epoxide hydrolase (sEH) by the isolated compounds was comparable to that of AUDA (positive control), yielding IC₅₀ values ranging from 10.0 ± 0.6 to 88.4 ± 0.2 µM. Among isolated compounds, 3-methoxy-4-hydroxy-benzoic acid (7) and 2′,6′-dihydroxy 3′,4′-dimethoxychalcone (9) were identified as a potent inhibitor of sEH, with IC₅₀ values of 19.3 ± 2.2 and 10.0 ± 0.6 mM, respectively. These results suggest that the fruits of D. indica may be useful as daily supplements for the prevention of cardiovascular and other sEH-related diseases.

KEYWORDS:

• Docynia indica
• 3S-thunberginol C 6-O-β-D-glucopyranoside
• soluble epoxide hydrolase
• CD spectrum
• 3-aryl dihydroisocoumarin
• boat-like conformer
• DFT

Supplementary material

General experimental procedures, acid hydrolysis and sugar identification, enzymatic assay, HR-ESI, MS, and 1D-2D-NMR spectra of 1a/1b, conformer search by DFT approach.

Disclosure statement

The authors have declared that there is no conflict of interest.