Synthesis and antifungal activity of 2-azetidinonyl-5-(2-benzoylphenoxy)methyl-1,3,4-oxadiazoles against seed-borne pathogens of Eleusine coracana (L.) Gaertn.

BACKGROUND

Finger millet is a major food crop as well as feed and fodder for livestock, especially in regions of southern India. A sturdy crop to fluctuating environmental conditions, it can be cultivated in all seasons of the year. Leaf, neck and finger blast caused by Pyricularia grisea Sacc. and Bipolaris setariae (Saw.) Shoem, as well as leaf spot disease, Bipolaris nodulosa (Berk & M.A.Curtis) Shoem, are major production constraints in southern India. Apart from environmental conditions, the use of harvested seeds by farmers is a major reason for disease prevalence. Benzophenone analogues have been investigated for controlling phytopathogenic fungi. In addition, the most important applications of azetidin-2-ones are as antibiotics. Based on this information, the present study was conducted to explore the antifungal activity of integrated 2-azetidinonyl and 1,3,4-oxadiazoles moieties into a benzophenone framework.

RESULTS

A simple high-yielding method for the integration of heterocyclic rings, namely 2-azetidinonyl, at the benzophenone nucleus has been achieved, starting from substituted 2-hydroxybenzophenones under mild conditions on a wet solid surface using microwave irradiation. In the present study, an array of newly synthesised compounds, 2-azetidinonyl-5-(2-benzoylphenoxy)methyl-1,3,4-oxadiazoles, were screened for their antifungal property against blast and leaf spot causing fungi associated with the seeds of finger millet, cv. Indof-9.

CONCLUSIONS

Two of the newly synthesised compounds showed promising effects in depleting the incidence of seed-borne pathogenic fungi of finger millet. The suppression of Pyricularia grisea and Bipolaris setariae resulted in enhanced seed germination and seedling growth.