The Synthesis,Antifungal Activity And Fluorescent Property Of Furanocoumarin Derivatives

Coumarins(or benzopyrones)occur commonly in many plants,and act as the plant's own pesticide,they displayed broad pharmacological activities,including antibacterial,cycloxygenase inhibiton,antimutagenic,antiinflammatory,anticoagulant,antithrombotic,vasodilatory,and anticancer activity.In addtion,several investigations prove that coumarin can depresse the development of insects and their larvae,and inhibit the growth of fungi colonies.Therefore,various researches of coumarin derivatives have attracted considerable interest.In recent years,the use of the pesticidesled led to environment pollution and fungicide-resistance.Therefore,there is a need for novel antifungal compounds with new mechanism of action and lower application dosage.Coumarins as natural products,which are considered to be environment friendly,can be used as ideal lead structures to develop fungicides.For that,we modified the structures of umbelliferone and psoralen,geting a series of 7-hydroxycoumarin derivatives and linear furanocoumarins derivatives.In this paper,we synthesized 27 7-hydroxycoumarin derivatives via Pechmann reaction,from commercially available substituted resorcinol and ?-keto ester catalysised by sulfuric acid.And then Williamson etherification of 19 of the 7-hydroxycoumarin derivatives and different a-halo ketones were taken,after that make it cyclization in concentrated sodium hydroxide solution,getting 47 linear furanocoumarins.We identified the structure of all the synthesized compounds by 1H NMR,13C NMR,HRMS,and IR.Then the synthesized compounds were evaluated for their in vitro antifungal activities against six plants Pathogenic fungi,Botrytis cinerea,Colletotrichu mcapsici,Alternaria solani,Gibberella zeae,Rhizoctonia solani,Alternaria mali,which are often encountered in plants,using the mycelium growth rate method.The bioassay results showed that the synthesized compounds are potential antifungal agents.For instance,compounds I-1f,I-2f,I-3f,and I-4f which with a trifluoromethyl on C-4 position,and compound I-3e with chloro on C-3 and C-6 position always show outstanding inhibition rate against the six plants Pathogenic fungi in thepreliminary bioassay.Besides,compounds I-4c and I-4e which with chloro on C-8 position also showed excellent inhibitory activity against Rhizoctonia solani.However,these furanocoumarins need further evaluation of their antifungal activity against other fungi strains to ascertain their broad spectrum antifungal activity.In addition,coumarins always show good fluorescence properties and with potential application value in the field of molecular marker.Therefore,we measured the fluorescence properties of several representative synthesized compounds,and the effects of different substituent groups on the fluorescence properties were analyzed.Fluorescence detection results show that when electron with drawing group(such as Cl atom)on C-6 or C-8 position of the 7-hydroxycoumarin will reduce the fluorescence quantum yield of the coumarin compounds,and when trifluoromethyl exists on C-4 position,the emission of the compounds will shift to red and stokes shift will increase,when expend the ring the emission shift to red and stokes shift also increase.While,the fluorescence quantum yield of the compounds will not be improved.