Minimum Fungicidal Concentrations

Aciiviiy expressed as minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and minimum bacteriocidal concentration (MBC) Oig/ml) using two-fold serial broth macrodilution technique. 

To estimate the minimum fungicidal concentration (MFC), a loopful of biomass is taken from respective tubes containing the MIC and higher concentrations of antimicrobial compound and inoculated into tubes containing sterile (autoclaved) broth and incubated at 25 2 °C for 72 h (for fungi). Subsequently a loopful from these tubes is then streaked on to the surface of sterile agar plates and incubated at 25 2 °C for 72 h [29, 30]. 

Tabli 9 Enzyme Inhibition Minimum Fungicidal Concentrations that Inhibited 90% o/ Fungal Growth (MFCgg) of Species of Candida, and Effective Dose Allowing 50% Survival (ED l of C. albicanj-Infected Mice of Three Cationic Pneumocandins. 

According to the results of Fujimura et al. [45], the minimum inhibitory concentrations (MICs) of MBC (12) and diethofencarb (15) for wild-type N. crassa were 0.2 ppm and >100 ppm, whereas for N. crassa F914 they were >100 ppm and 0.1 ppm, respectively. Therefore, an experiment using two combination systems, (1) benzimidazole-resistant strain + diethofencarb + emodin, and (2) benzimidazole-susceptible strain + MBC + emodin was carried out in order to obtain data on whether emodin could exhibit antidote activity in both systems. In this experiment, only emodin was used as an antidote because of the relatively weak activity of other antidotes in the interaction of MBC with wild-type N. crassa [44]. The results are summarized in Table 6, and indicate that emodin (18) can also act as an antidote against diethofencarb (15) in a benzimidazole-resistant strain of N. crassa. These and other results (Tables 4 and 6) are indicative of the versatility of emodin (18) as an antidote to the action of certain types of fungicide which possess an affinity for fungal P-tubulin, and may suggest that the antidote effect of emodin is closely linked to the function of P-tubulin. 

As is shown by the minimum inhibition concentrations in Table 83, dithio-2,2 -bis(benzmethylamide) is a broad spectrum fungicide which is also effective against bacteria. Apparently Trichoderma viride is more resistant to the compound than other fungal species. 

Dichlorobenzoxazolinone is a very potent fungicide which had been used in the past mainly for the protection of textile material against biodeterioration. The minimum inhibition concentrations of the compound for a wide variety of fungal species are in the range of 10-100 mg a.i./ml nutrient agar. However, 5,6-dichlorobenzoxazolinone is no longer of practical importance. 

Table 101. Minimum Inhibition Concentrations (MIC) (mg/litre) of three Azole Fungicides...

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