New prenylated carbazole alkaloids from Zanthoxylum armatum

Abstract

A phytochemical investigation on the ethyl acetate soluble fraction of Zanthoxylum armatum led in the isolation of two new prenylated alkaloids 2,6,7-trimethoxy-8-(3-methyl-2-butenyl)carbazole-3-carbaldehyde (1) and methyl-2,6,7-trimethoxy-8-(3-methyl-2-butenyl)carbazole-3-carboxylate (2), along with three known lignans cisamin (3), methyl pirpirtol (4), and fargesin (5) and one known alkaloid dictamine (6). Their structures were established on the basis of spectroscopic and crystallographic analysis and by comparison of the data with those in the literature. All the isolated compounds were screened for the DPPH free radical scavenging activity. Compounds 1, 2, and 6 showed profound activity while compounds 3–5 showed moderate activity.

Keywords::

• Zanthoxylum armatum
• Rutaceae
• alkaloids
• DPPH radical scavenging activity

Acknowledgements

The author is thankful to Higher Education Commission, Pakistan for financial support under IRSIP Fellowship Program at University of Sydney, Australia. The author also acknowledges Dr Jane Hanrahan, Faculty of Pharmacy, University of Sydney for her guidance in the spectral and crystal analysis of the compounds.