Phytochemical study on the corks of Euonymus alatus resulted in the isolation of a novel 3-hydroxycoumarinflavanol (23), along with ten triterpenoids (1-10), ten phenolic derivatives (11-20), and two flavonoid glycosides (21 and 22). Their structures were determined by extensive 1D and 2D-nuclear magnetic resonance spectroscopic and mass spectrometry data analysis. Furthermore, their inhibitory effects against the protein tyrosine phosphatases 1B (PTP1B) and α-glucosidase enzyme activity were evaluated. Compounds 6, 7, 9, 15, 19, and 23 were non-competitive inhibitors, exhibiting most potency with IC50 values ranging from 5.6 ± 0.9 to 18.4 ± 0.3 µm, against PTP1B. Compound 3 (competitive), compounds 5 and 15 (mixed-competitive) displayed potent inhibition with IC50 values of 15.1 ± 0.7, 23.6 ± 0.6 and 14.8 ± 0.9 µm, respectively. Moreover, compounds 15, 20, and 23 exhibited potent inhibition on α-glucosidase with IC50 values of 10.5 ± 0.8, 9.5 ± 0.6, and 9.1 ± 0.5 µm, respectively. Thus, these active ingredients may have value as new lead compounds for the development of new antidiabetic agents.
Keywords: Euonymus alatus; PTP1B inhibitors; flavanol; triterpenoids; α-glucosidase.
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