Isolation and characterization of ent-pimarane diterpenoids from Sigesbeckia pubescens

Abstract

Five new ent-pimarane diterpenoids ent-16-nor-2-oxopimar-8(14)-ene-15,19-dial (1), ent-16-nor-2α,19-dihydroxypimar-8-en-15-al (2), 3-O-acetyldarutigenol (3), 19-O-acetylkirenol (4), ent-16-nor-3β,15-dihydroxypimar-8(14)-ene (5) were isolated and characterized from the ethanol extract of Sigesbeckia pubescens. Their structures were elucidated on the basis of spectroscopic analysis. The absolute configuration of C-15 in compounds 3 and 4 was assigned using Snatzke’s method. All these compounds were assessed for their anti-inflammatory potential by measuring the inhibitory effects on NO production in LPS-induced RAW 264.7 macrophage cells and compound 4 showed significantly inhibitory activity with IC₅₀ value of 5.9 μM.

Keywords:

• ent-Pimarane diterpenoids
• Sigesbeckia
• Sigesbeckia pubescens Makino
• Snatzke’s method
• anti-inflammatory
• RAW 264.7 macrophage cells

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This project was supported by the National Science Foundation of China (No. 30973628 , 81773595, and 81903481), the National Science and Technology Project of China (No. 2012ZX09103201-022), and China Postdoctoral Science Foundation (2019M653297).