Variation in the volatile phytochemistry of Ageratum conyzoides

Abstract

Ageratum conyzoides, billy-goat weed, is an introduced invasive weed species to Asia, but is used in traditional herbal medicine in Nepal. The essential oil from the aerial parts of A. conyzoides growing wild in Biratnagar, Nepal, was obtained by hydrodistillation and analyzed by gas chromatography – mass spectrometry. A total of forty compounds were identified representing 99.7% of the oil composition. The major components were precocene I (61.7%) and precocene II (23.5%). The essential oil was screened for antimicrobial activity, nematicidal activity, and brine shrimp lethality, but was largely inactive in these bioassays. A hierarchical cluster analysis based on the compositions of this essential oil composition and compositions reported in the literature revealed two distinct clusters based on the relative concentrations of precocene I and precocene II.