4-Methyl-7-hydroxycoumarin antifungal and antioxidant activity enhancement by substitution with thiosemicarbazide and thiazolidinone moieties.

According to literature data, thiosemicarbazide and thiazolidinone moieties should enhance biological properties of coumarin. Antioxidant, metal-chelating and antifungal activities of all compounds were investigated and compared to the activity of the starting material, 7-hydroxy-4-methylcoumarin, and were proven to possess potent antioxidant and antifungal activity. In general, thiosemicarbazides showed higher scavenging activity towards DPPH and galvinoxyl radicals than did 4-thiazolidinones and some of them had the same or even better activity than had ascorbic acid itself, depending on the free radical used. In antifungal activity tests towards four foodborne mycotoxigenic fungi, Aspergillus flavus, Aspergillus ochraceus. Fusarium graminearum and Fusarium verticillioides, coumarin derivatives were proven to possess a very high activity in terms of growth inhibition, depending on the fungi investigated. In general, 4-thiazolidinones showed better antifungal activity than did thiosemicarbazides. F. graminearum was the most susceptible to the compounds investigated and F. verticillioides was proven to be the most resistant. Two compounds, both coumarinyl thiosemicarbazides, were found to possess both antifungal and antioxidant activity which could be useful for applications in medicine, food industry and agriculture.