Chemistry and antifungal activity of Xyris species (Xyridaceae): a new anthraquinone from Xyris pilosa

• Published in: Biochemical systematics and ecology 2004-04, Vol.32 (4), p.391-397
• Main Authors: Barros Cota, Betânia, Braga de Oliveira, Alaíde, Guilherme Guimarães, Keller, Pimentel Mendonça, Miriam, Dias de Souza Filho, José, Castro Braga, Fernão
• Format: Article
• Language: English
• Subjects: 1,5-dihydroxy-3-methoxy-anthraquinone; 3-methoxychrysazin; Antifungal activity; Aspergillus niger; Flavonoid content; Fusarium oxysporum; Xyridaceae; Xyris pilosa
• ISSN: 0305-1978; 1873-2925
• DOI: 10.1016/j.bse.2003.11.006

Over-harvesting of Xyris spp. in Brazil has resulted in the extinction of some species. The chemistry of Xyris is poorly studied as is its biological activities. In the present study, seven species of Xyris ( X. cipoensis, X. longiscapa, X. peregrina, X. pilosa, X. platystachia, X. pterygoblephara and X. tortula) were assayed for in vitro antifungal activity and their flavonoid content was evaluated. Ethanol extracts from all seven species, except X. cipoensis, inhibited the growth of Fusarium oxysporum, whereas the extracts from X. peregrina, X. platystachia, X. pterygoplephara and X. tortula also inhibited Aspergillus niger. There was no correlation between the antifungal activity and total flavonoid content of aerial parts of Xyris, which ranged from 1.03% to 7.80%. The bioguided study of X. pilosa afforded two anthraquinones active against F. oxysporum. Their structures were assigned by 1D and 2D NMR experiments as 3-methoxychrysazin and 1,5-dihydroxy-3-methoxy-anthraquinone, a new compound. 3-methoxychrysazin was previously isolated from X. semisfuscata but its occurrence is restricted to X. pilosa among the seven species evaluated; it cannot constitute a chemical marker for the genus.