Journal of Plant Pathology & Microbiology

Abstract

Antifungal Activity of the Stinkwort (Inula graveolens) Extracts

Barakat E Abu Irmaileh, Nida’ M Salem, Amal MF Al Aboudi, Musa H Abu Zarqa and Amany O Abdeen

Bioactive guided fractionation was carried out to determine the antifungal activity of the stinkwort weed, Inula graveolens, on various phytopathogenic fungi species. Dried shoots were extracted and partitioned in various solvent systems. The aqueous methanol extract (AqMeOH) inhibited the growth of several soil-borne fungi; Alternaria sp., Fusarium spp. and Rhizoctonia sp. in in-vitro plate assay. Fractionation of AqMeOH extract by column chromatography in dichloromethane/AqMeOH yielded twenty-two fractions of which Fraction #2, 3 and 4 showed antifungal activity. Further fractionation of the combined Fractions #2, 3 and 4 by column chromatography in solvent system benzene/ethyl acetate on fine silica columns, yielded seven sub fractions of which sub fraction #2 has the most antifungal activity on all fungi in the experiment. The fungitoxicity of sub fraction #2 in terms of percentage inhibition of mycelia growth of all tested-fusaria strains after seven days of incubation was higher compared to that obtained by the fungicide hymexazol (Tachigaren ® 70 WP). The AqMeOH extract significantly reduced browning length at the crown area, a Fusarium-known symptom in in-vivo experiments. Furthermore, the growth of Fusarium-treated cucumber plants was enhanced by drenching with AqMeOH extract. The activity of the extract was comparable to the activity of the fungicide hymexazol in improving plant health, and surpassed the fungicide activity in preventing the discoloration of the crown vascular tissue of cucumber at comparable concentrations.