Isolation and Characterization of Flavones from Artemisia monosperma

Abstract

Background: Artemisia monosperma (Delile) is a green aromatic shrub that grows widely in the deserts of Middle East, Africa and China. This plant is commonly used in folk medicine as a remedy of a wide range of illness including gastrointestinal disorders, inflammation, diabetes and microbial infection. The different categories of the secondary metabolites identified from Artemisia species are recognized for their biological activities as antioxidants, anti-inflammatory and antimicrobial compounds. Objective: This study aims to isolate new flavonoids from A. monosperma that might have potential biological activities thus be translated into pharmaceutical uses. Materials and Methods: Air-dried A. monosperma extraction was done using different organic solvents. The methanolic extract was selected for isolation of flavonoids using column chromatography and thin layer chromatography. The chemical structures of the isolated flavones determined based on spectroscopic analysis of ultraviolet, mass and nuclear magnetic resonance spectra. Results: Nine flavone aglycones were isolated and identified from the methanolic extract; four of which are reported for the first time from A. monosperma. These include: 5-Hydroxy-3',4', 6,7-tetramethoxyflavone; 3',5-dihydroxy-4',6,7-trimethoxyflavone (eupatorin); 5,6-dihydroxy-4',7-dimethoxyflavone(ladanein); and 2',4',5-trihydroxy-5',6,7trimethoxyflavone (arcapillin). The remaining five flavones were previously identified from this plant as : 4',5-Dihydroxy-3',6,7-tri-methoxyflavone(cirsilineol);5,7-dihydroxy-3',4',6-trimethoxyflavone (eupatilin);4',5,7-trihydroxy-3',6-dimethoxyflavone(jaceosidin);4',5-dihydroxy-6,7-dimethoxy-flavone (circimaritin) and 4',5,7-trihydroxy-6-methoxyflavone (hispidulin). In addition, two acetophenone derivatives were isolated from fractions yielded selected flavones and these were identified as 4-hydroxyacetophenone and 3-(2-hydroxymethyl-2-buten-4-yl)-4-hydroxyaceto-phenone. Conclusion: This successful isolation of these natural flavonoids from A. monosperma can contribute further to the evaluation of bioactive compounds against disorders including but not limited to inflammatory associated disorders and microbial infections.