Antimicrobial chromenes from Eupatorium toppingianum

The chloroform extract of the air-dried leaves of Eupatorium toppinggianum afforded 6-hydroxy-7, 8-dimethoxy-2, 2-dimethylchromeme (ET6) and 6-(1-hydroxyethyl)-7, 8-dimethoxy-2, 2-dimethylchromene (ET7). The structure of compounds ET6 and ET7 were elucidated by extensive ID and 2D NMR spectroscopy. The structures were confirmed by comparison of their 1H NMR spectral data with those reported in the literature. Antimicrobial tests on ET6 indicated that it is active against Pseudomonas aeruginosa and Trichophyton mentagrophytes with antimicrobial indices of 0.1 and 1.0, respectively. It was inactive against Staphylococcus aureus, Escherichia coli, Bacillus substilia, Candida albicans and Aspergillus niger. Similarly, ET7 is active against Staphylococcus aureus, Pseudomonas aeruginosa and Trichophyto mentagrophytes with antimicrobial indices of 1.5, 0.2 and 0.1, respectively. ET7 is more active than the standard antibiotic chloramphenicol. Thus, ET7 can be used for the treatment of food poisoning and gastroenteritis caused by S. aureus. The antimutagenic potential of ET7 was determined using the Micronucleus test. Results of the study did not show significant reduction in the micronucleated polychromatic erythrocytes (MPCE) induced by Mitomycin C. Thus, ET7 has no anti-mutagenic activity. ET6 was not analyzed for its antimutagenicity due to the limited amount of the isolate