Preliminary screening of some Egyptian weeds for antimicrobial activity.

Eleven Egyptian weeds collected from the Menoufeya district were screened for phytochemical compounds effective against several representatives of bacteria and yeasts. It was found that Soxhlet benzene extracts, especially those of Capsella bursa-pastoris (L.) Medik., were the most effective. Alkaloids and flavonoids of Capsella gave the highest antibiotic potencies and had the broadest antimicrobial spectra. It is suggested that these alkaloids might consist of yohimbine and ergocristine and the flavonoids included the flavone diosmin.