Isolation of antifungal compounds from someZygophyllum species and their bioassay against two soil-borne plant pathogens

Roots and aerial shoots ofZygophyllum coccineum L.,Z. album L. andZ. dumosum Boiss were extracted with solvents of increasing polarity and tested against spore germination ofVerticellium albo-atrum andFusarium oxysporum f.sp.lycopersici. The effectiveness of each extract depends on the solvent, plant species, organ and test fungus. Petroleum ether extracts were ineffective as fungistatics while the methanol extracts possessed a high inhibitory effect toward spore germination suppression, depending on the fungus and plant species. Water or ethyl acetate root extracts ofZ. album caused a marked suppression of spore germination of the test fungi. Six saponins were isolated from the effective extracts on silica gel and Sephadex columns. They were identified by acid hydrolysis, alkaline saponification, IR and FAB MS. Quinovic acid was the dominant aglycone. Kaempferol was isolated from the flavonoid fraction ofZ. dumosum for the first time. Some of the isolated saponins and kaempferol provided successful control against the test plant pathogens under greenhouse experiment when used as seed treatment.