In Vitro Antifungal Activity of ZJ-522, a New Triazole Restructured from Fluconazole and Butenafine, against Clinically Important Fungi in Comparison with Fluconazole and Butenafine

Inhibitory effect of Shikonin on Candida albicans growth

Our study showed that Shikonin (SK) could provide an action against almost all Candida albicans isolates tested. More importantly, to some Fluconazole (FCZ)-resistant Candida albicans, the action of SK (MIC(80) value 4 µg/mL) was shown to be >16 times higher than that of FCZ (MIC(80) >64 µg/mL). To clarify the mechanism underlying this action, we performed a comparative study in untreated control C. albicans and C. albicans treated with SK. In this study, we found that SK treatment increased generation of endogenous reactive oxygen species (ROS) and decreased mitochondrial membrane potential. Furthermore, anti-oxidants N-acetylcysteine (NAC) and glutathione (GSH) could reduce the antifungal activity of SK significantly in C. albicans. Our analyses also identified 9 differentially expressed genes, which were related to glycolysis-related genes (CDC19 and HXK2), fermentation-related genes (ALD5 and ADH1), antioxidant defense-related genes (SOD2 and SOD5), thioredoxin reductase-related gene (TRR1), mitochondrial respiratory electron transport chain-related gene (MRF1) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidoreductase-related gene (EBP1). These results suggest that mitochondrial aerobic respiration shift and endogenous ROS augmentation contribute to the action of SK against C. albicans.

A novel polyamide SL-A92 as a potential fungal resistance blocker: synthesis and bioactivities in Candida albicans

AIM

To synthesize a novel polyamide SL-A92 and evaluate its bioactivity against drug resistance in Candida albicans.

METHODS

SL-A92 was synthesized using N-hydroxybenzotriazole (HOBT)/N,N'-dicyclohexylcarbodiimide (DCC) in solution phase. Its antifungal activities and effects on strain growth were tested using the micro-broth dilution method and growth curves, respectively. Induced drug resistance in the C. albicans collection strain SC5314 was obtained by incubation with fluconazole (12 microg/mL) for 21 passages. Meanwhile, incubations with SL-A92 plus fluconazole were also carried out in SC5314 strains, and the MIC(80)s were used to evaluate the inhibitory effects of SL-A92 on drug resistance during the induction process. Real time RT-PCR was performed to investigate the CDR1 and CDR2 mRNA levels in induced SC5314 strains.

RESULTS

SC5314 strain induced by the combination of fluconazole and SL-A92 (200 microg/mL) did not develop drug resistance. On day 24, the CDR1 and CDR2 mRNA levels in SC5314 strain co-treated with fluconazole and SL-A92 relative to fluconazole alone were 26% and 24%, respectively, and on day 30 the CDR1 and CDR2 mRNA levels were 43% and 31%, respectively.

CONCLUSION

SL-A92 can block the development of drug resistance during the fluconazole induction process, which partially results from the down-regulation of CDR1 and CDR2.

In vitro and in vivo activities of HQQ-3, a new triazole antifungal agent

The activity of HQQ-3, a new triazole antifungal agent, was evaluated and compared with those of fluconazole, ketoconazole and terbinafine in vitro and with fluconazole in vivo. HQQ-3 exhibited potent in vitro activity against clinically important fungi. The activity of HQQ-3 against Candida spp. was superior to those of fluconazole and terbinafine and comparable or superior to that of ketoconazole. HQQ-3 retained potent activity against Candida albicans strains with low levels of susceptibility to fluconazole (fluconazole MIC80s range, 4 to >64 microg/ml). Against Cryptococcus neoformans and filamentous fungi, the activity of HQQ-3 was superior to that of fluconazole. HQQ-3 also exhibited potent in vivo activity against murine systemic infections caused by C. albicns and C. krusei. The 50% effective doses against these infections were 0.12 to 1.9 mg/kg of body weight. These result suggest that HQQ-3 may be useful in the treatment of candidiasis.