Indole alkaloids from the bark of Acacia confusa and their potential antinociceptive and anti-inflammatory activities

Abstract

A pair of novel trimeric indole alkaloid enantiomers [(±)-8], five new bisindole alkaloids [4–7 and (±)-9], and three pairs of new monomeric indole alkaloid enantiomers [(±)-1–(±)-3], together with seven known alkaloids (10–16), were isolated from the bark of Acacia confusa. Their structures were determined on the basis of spectroscopic methods, especially by NMR data analyses combined with single-crystal X-ray diffraction and electronic circular dichroism analyses. Compounds 4 and 11–16 exhibited significant antinociceptive activities in an acetic acid-induced writhing test. Compounds (+)-9 and (−)-9 displayed anti-inflammatory activities through the inhibition of the NF-κB pathway, with inhibitory rates of 68.9% and 59.5%, respectively, at a concentration of 10 µM.

Graphical Abstract

Keywords:

• Acacia confusa Merr.
• indole alkaloids
• analgesic activities
• anti-inflammatory

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by grants from the National Natural Science Foundation of China (No. 21732008). The authors are grateful to the Department of Instrumental Analysis at our institute for the spectroscopic measurements.