Abstract
Background: Several edible plants are used in Kingdom of Saudi Arabia since early time to control microbial
infections. In the present study, twenty-four Saudi Arabian medicinal plants d according to traditionally used were
select and investigated for the antimicrobial activities
Materials and Methods: This study was designed at evaluating the antimicrobial activities of the methanol extracts of
twenty-four species of sixteen plant families used in the traditional medicine by Saudi Arabian people for the treatment
of numerous ailments of the microbial and non-microbial origin against four Gram-positive, four Gram-negative
bacteria and four fungi and yeast using the agar well diffusion method.
Results: Of most of the plants tested were found to be active against two to eight organisms. Five plants were active
against eight organisms. The data appeared that extracts of Echium arabicum (SY-176), Rhantarium epapposum (SY-180), Rumex vesicarus (SY-181), Ziziphus nummularia (SY-188), Caylusea hexagyna (SY-197) and Artemisia
monosperma (SY-198) have anti-microbial activity against the most of tested bacteria, fungi and yeast. Whereas (SY-181), the extracts of Teucrium oliverianum (SY-175), Zilla spinosa (SY-187), and Rhazya stricta (SY-195) have poor
action against the tested bacteria, fungi and yeast.
Conclusion: The antimicrobial activity of plant extracts against bacteria was more effective than against fungi