Chemistry and antifungal potential of Alantolides from Inula racemosa H

Abstract

Alantolactone and isoalantolactone were isolated from powdered roots of Inula racemosa H. using Soxhlet extraction followed by the column chromatography. Pyrazolines of alantolactone and isoalantolactone were synthesized using diazomethane, diazoethane and diazopropane. The structure elucidation of the compounds were carried out using IR and 1H NMR spectroscopic techniques. All the compounds were screened in vitro for their antifungal potential at various concentrations against Alternaria brassicae and Penicillium italicum using spore germination inhibition technique and against Rhizoctonia solani by poisoned food technique. All the compounds exhibited fairly good fungitoxicity against the test fungi with ED50 values of less than 500 μg mL − 1. Alantolactone (1) and isoalantolactone were treated with diazomethane, diazoethane and diazopropane to give products in good yield. Alantolactone, isoalantolactone and their derivatives prepared showed fairly good fungicidal activity against Alternaria brassicae, Rhizoctonia solani and Penicillium italicum.