In vitro assays on the susceptibility of four species of nematophagous fungi to anthelmintics and chemical fungicides/antifungal drug

Abstract

Using nematophagous fungi for the biological control of animal parasitic nematodes will become one of the most promising strategies in the search for alternative chemical drugs. The purpose of this study was to check the in vitro activity of four anthelmintics, four chemical fungicides and two antifungal drugs on the spore germination of nematophagous fungi: Duddingtonia flagrans (SF170), Arthrobotrys oligospora (447), Arthrobotrys superba (435) and Arthrobotrys sp. (PS011). A modified 24-well cell culture plate assay was conducted to evaluate the susceptibility of nematophagous fungi against drugs tested by calculating the effective middle concentrations (EC 50 ) of each tested drug to inhibit the germination of fungal spores. EC 50 ranged between 0Á7 and 47Á2 μg ml −1 for fenbendazole, thiabendazole and ivermectin, except levamisole (546Á5-4057Á8 μg ml −1 ). EC 50 of tested fungicides was 0Á6-2Á3 μg ml −1 for carbendazim, 55Á9-247Á4 μg ml −1 for metalaxyl, 24Á4-45Á2 μg ml −1 for difenoconazole, and 555Á9-1438Á3 μg ml −1 for pentachloronitrobenzene (PCNB). EC 50 of two antifungal drugs was 0Á03-3Á4 μg ml −1 for amphotericin B and 0Á3-10Á9 μg ml −1 for ketoconazole. The results showed that 10 tested drugs, except for levamisole and PCNB, had in vitro inhibitory effects on nematophagous fungi. The chlamydospores of D. flagrans had the highest sensitivity to nine tested drugs, except for ketoconazole.

Design, synthesis, and antifungal activity of novel dithiin tetracarboximide derivatives as potential succinate dehydrogenase inhibitors

“…This suggests a remarkable difference in antifungal activity between the various substituent compounds. Compounds with promising antifungal activity were selected for calculation of the EC 50 value using a linear regression method 37 . As shown in Table 2, compound 18 displayed the lowest EC 50 of 1.37 μg ml −1 against S. sclerotiorum , the most powerful inhibitory effect on this pathogen among the selected compounds.…”

“…Compounds with promising antifungal activity were selected for calculation of the EC 50 value using a linear regression method. 37 As shown in Table 2, compound 18 displayed the lowest EC 50 of 1.37 μg ml −1 against S. sclerotiorum, the most powerful inhibitory effect on this pathogen among the selected compounds. Compounds 1, 2, and 18 possessed potent activity against the mycelial growth of B. cinerea with an approximate EC 50 value of 5.1 μg ml −1 , which was stronger than those of compounds 12 and 13, with EC 50 values of 7.04 and 10.78 μg ml −1 , respectively.…”

Individual and Combined Application of Nematophagous Fungi as Biological Control Agents against Gastrointestinal Nematodes in Domestic Animals

“…Although resistance is quickly developed to chemical drugs, they are more effective at killing nematodes than fungi, so the combination of the two could also reduce resistance and enhance nematicidal efficiency. Further studies are still needed to establish the pattern of combining NF with chemical drugs, such as the compatibility, appropriate dose, and time [104,106].…”

“…[107]. D. flagrans has been found to have high susceptibility to tested drugs, including fenbendazole, thiabendazole and ivermectin, carbendazim, and difenoconazole [106]. In vivo tests also confirmed that chemical drugs inhibited the activity of D. flagrans spores when used in combination with albendazole [108].…”

“…Vilela et al reported that the combination of D. flagrans and levamisole hydrochloride was feasible, with a significantly lower EPG recorded for their combination than for exclusive administration of the chemical drug [105]. In this regard, Wang et al similarly noted that D. flagrans had strong tolerance to levamisole hydrochloride [106]. Nevertheless, most studies suggest an antagonistic effect between chemical drugs and NF.…”