Yixin Liu,1 Feifei Ren,1 Shan Li,1 Xiangchen Li,1 Dongyan Shi,2 Zhiqing Zhang1 

1Department of Pharmacy, the Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, People’s Republic of China; 2Department of Clinical Laboratory, the Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, People’s Republic of China

Correspondence: Zhiqing Zhang, Department of pharmacy, the Second Hospital of Hebei Medical University, 215, Heping Road, Xinhua District, Shijiazhuang, Hebei, People’s Republic of China, Email 26500007@hebmu.edu.cn Dongyan Shi, Department of clinical laboratory, the Second Hospital of Hebei Medical University, 215, Heping Road, Xinhua District, Shijiazhuang, Hebei, People’s Republic of China, Email shidongyan73@126.com

Objective: To define the antifungal activity of n-butylphthalide alone or in combination with fluconazole in Candida glabrata and Candida tropicalis.
Methods: The antifungal activity of n-butylphthalide alone and in combination with fluconazole was investigated by the classical broth microdilution method and the time-killing curve method. The QRT-PCR method was used to determine gene expressions changes of mitochondrial respiratory chain enzymes, drug efflux pumps and drug target enzymes in Candida glabrata and Candida tropicalis after n-butylphthalide treatment.
Results: The MIC values of n-butylphthalide against Candida glabrata and Candida tropicalis ranged from 16 to 64 μg·mL-1. The FICI value of the combination of n-butylphthalide and fluconazole against drug-resistant Candida glabrata and Candida tropicalis ranged from 0.5001 to 0.5315 with partial synergism. Time-killing curves showed that 256 μg·mL-1 n-butylphthalide significantly inhibited the growth of drug-resistant colonies of Candida glabrata and Candida tropicalis, and 128 μg·mL-1 n-butylphthalide combined with 1 μg·mL-1 fluconazole had an additive effect. N-butylphthalide could alter the expression of mitochondrial respiratory chain enzymes COX1, COX2, COX3, and CYTB genes in Candida glabrata and Candida tropicalis (P< 0.05) and downregulate the expression of the drug efflux pump genes CDR1 and CDR2 in drug-resistant Candida glabrata to 3.36% and 3.65%, respectively (P< 0.001), but did not affect the drug target enzyme ERG11 in drug-resistant Candida tropicalis.
Conclusion: N-butylphthalide had antifungal activity against Candida glabrata and Candida tropicalis. N-butylphthalide improved the activity of fluconazole against drug-resistant Candida glabrata by affecting the expression of mitochondrial respiratory chain enzyme genes and reversing the high expression of drug efflux pump genes CDR1 and CDR2.

Keywords: n-butylphthalide, fluconazole, drug resistance, Candida glabrata, Candida tropicalis, potentiation