Oleanane triterpenoids with PTP1B and α-glucosidase inhibitory activities from Caulophyllum robustum

Abstract

Eleven oleanane triterpenoids (1–11) including two new ones (1 and 2) were isolated from the roots and stems of Caulophyllum robustum. Their structures were established by extensive spectroscopic analysis, comparison with literature, and NMR calculations. Compounds 1 and 2 represent the first examples of 23-hydroxy-28-nor-oleanane and 21-hydroxy-olean-3-one triterpenoids, respectively. All isolates were evaluated for their PTP1B and α-glucosidase inhibitory activities in vitro. Among them, the triterpene aglycones 1–5 showed almost equivalent PTP1B inhibitory activities to oleanolic acid and ursolic acid, while 1, 2, and the triterpene saponins 6–11 showed significant α-glucosidase inhibitory activities. Furthermore, compounds 1 and 3 were proved to regulate the expression of proteins implicated the PTP1B/IRS-1/pIRS-1 signalling pathway to improve insulin resistance.

Graphical Abstract

Keywords:

• Caulophyllum robustum Maxim (Berberidaceae)
• triterpenoids
• PTP1B inhibitory activities
• α-glucosidase inhibitory activities
• insulin signalling pathway

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Technological Innovation Project of Hubei Province under Grant (No. 2020BGB004); National Key R and D Program of China under Grant (No. 2018YFC1708004).