Abstract
The use and search for antibiotics and dietary supplements derived from plants have accelerated in recent years. Three plants, used traditionally as medicine and as food additive in Saudi Arabia, were collected and extracted with either methanol or n-butanol. The used plants were Rheum palmatum, Curcuma longa and Alpinia officinarum. The plant extracts were screened for their inhibitory effects on seven bacterial and five fungal genera using agar well diffusion method. It was shown that methanol extract was more effective as compared to n-butanol extracts. The minimum inhibitory concentrations (MIC) of the methanol extracts of the used plants ranged from 50 to 175 mu g/ml. No toxicity was found using Artimia salina as test organism. Antitumor activity against Ehrlich ascites carcinoma was recorded only for C. longa extract.