Antioxidant properties of coumarin derivatives and their antifungal activity against most relevant mycotoxigenic food molds

U ovom radu je izvršena sinteza derivata kumarina s potencijalnom antifungalnom i antioksidacijskom aktivnošću. Naime, prema dosadašnjim istraživanjima, pretpostavlja se da se sintetskom modifikacijom polaznog spoja 7-hidroksi-4-metilkumarina mogu poboljšati njegova antifungalna i antioksidacijska svojstva. Sintetskim putem dobivena je serija Schiffovih baza s različitim supstituentima, kao i tiosemikarbazida i tiazolidinona. Antioksidacijska aktivnost je ispitana DPPH metodom spektrofotometrijski, EPR-om (DPPH i galvinoksil radikal) i fosfomolibden metodom. Rezultati su pokazali da se supstitucijom hidroksilne skupine 7-hidroksi-4-metilkumarina može značajno povećati antioksidacijska aktivnost polaznog kumarina, osobito prisutnošću supstituenata koji sadrže dihidroksifenilnu skupinu i tiosemikarbazidnu skupinu. Derivati kumarina su ispitani i na antifungalno djelovanje prema najčešćim plijesnima namirnica, Aspergillus flavus, A. ochraceus, Fusarium graminearum i F. verticillioides. Novosintetizirani derivati kumarina su se pokazali i kao izvrsna antifungalna sredstva, osobito Schiffove baze s hidroksilnim skupinama, te su, ovisno o primijenjenoj plijesni, pokazali i 100% inhibiciju rasta pojedine plijesni. Supstitucijom 7-hidroksi-4-metilkumarina u položaju 7 antifungalna aktivnost prema ispitanim plijesnima, osobito prema F. verticillioides, se povećala u odnosu na polazni kumarin. Spojevi koji u isto vrijeme posjeduju izvrsnu antioksidacijsku i antifungalnu aktivnost su Schiffove baze s dihidroksifenilnom skupinom i tiosemikarbazidi s fenilnom skupinom (supstituiranom ili ne).In this work synthesis of coumarin derivatives with potential antifungal and antioxidant activity was performed. According to recent research work, synthethic modification of 7-hydroxy-4-methylcoumarin can improve its antifungal and antioxidant activity. A series of new coumarin derivatives, Schiff bases, thiosemicarbazides and thaizolidinones was prepared by conventional synthetic routes. Antioxidant activity of the compounds was evaluated using DPPH radical scavenging method, which was performed spectrophotometrically, by EPR spectroscopy (DPPH radical and galvinoxyl radical) and phosphomolybdenum method. The results indicated that the substitution of hydroxyl group of 7-hydroxy-4-methylcoumarin with dihidroxyphenyl or thiosemicarbazide group can increase an antioxidant activity of the starting compound. Antifungal investigation of coumarin derivatives against most relevant mycotoxigenic food molds, Aspergillus flavus, A. ochraceus, Fusarium graminearum and F. verticillioides, was also performed. The results revealed strong antifungal properties of the derivatives, Schiff bases especially. Several compounds effected a 100% inhibition against selected fungi, especially Schiff bases containing hydroxyl groups. Substitution of 7-hydroxy-4-methylcoumarin in position 7 can increase antifungal activity of the starting compound, especially against F. verticillioides. Compounds showing potent antioxidant and antifungal activity were Schiff bases with dihydroxyphenyl substituents and thiosemicarbazides with unsubstituted or substituted phenyl groups