Mechanism of Action of Tetrandrine, a Natural Inhibitor of <i>Candida albicans</i> Drug Efflux Pumps

Abstract

Synergistic eŠects have previously been observed for a natural compound, tetrandrine (TET), with ‰uconazole (FLC) in vitro and in the treatment of Candida albicans-infected mice. To investigate the mechanisms of these synergistic eŠects, 16 strains of C. albicans from the same parent but with diŠerent FLC sensitivities were examined using ‰ow cytometry and ‰uorescent spectrophotometry. Rhodamine 123 (Rh123)-positive cells and intracellular Rh123 ‰uores-cence intensity were determined in accumulation/eOEux experiments involving no or a noncytotoxic dose of TET. Total RNA extracted from each strain was used to compare the expressions of drug eOEux pump genes in FLC-susceptible, -susceptible dose-dependent, and -resistant strains before and 24 h after TET administration. Accumulation experiments determined that mean percentages of Rh123-positive cells were 26.65％ (TET-free) and 70.99％ (TET 30 mg/ml), and mean respective intracellular Rh123 ‰uorescence intensities were 11.34 and 18.00. EOEux experiments showed that percentages of Rh123-positive cells were 1.79％ (TET free) and 42.57％ (TET 30 mg/ml), respectively, and respective mean intracellular Rh123 ‰uorescence intensities were 0.74 and 2.19. DiŠerences in MDR1, FLU1, CDR1, and CDR2 expression levels in the absence of TET were statistically signiˆcant ( p＜0.05) between FLC-susceptible, -susceptible dosedependent, and -resistant strains. Compared with TET-free conditions, 24 h TET-treated strains showed statistically diŠerent ( p＜0.05) expression of MDR1 (FLC-resistant strain), FLU1 (FLC-susceptible dose-dependent and -resistant strains), and CDR1 and CDR2 (FLC-susceptible, -susceptible dose-dependent, and -resistant strains). Thus TET can inhibit the C. albicans drug eOEux system and reduce drug eOEux. Its mechanism of action is related to the inhibition of expression of the drug eOEux pump genes MDR1, FLU1, CDR1, and CDR2.

The Monoamine Oxidase A Inhibitor Clorgyline Is a Broad-Spectrum Inhibitor of Fungal ABC and MFS Transporter Efflux Pump Activities Which Reverses the Azole Resistance of Candida albicans and Candida glabrata Clinical Isolates

“…Screening for chemosensitization in agar diffusion assays or liquid growth assays has been used to identify inhibitors of fungal efflux pumps. The application of these usually non-high-throughput screens, to panels of xenobiotics (23), combinatorial peptide libraries (33), and libraries of natural products (46) has identified tacrolimus (FK506), milbemycins (23), enniatins, beauvericin, unnarmicins (46), ibuprofen (40), tetandrine (52), cerulenin analogs (9), and some octapeptides (33) as specific fungal ABC pump inhibitors. Ideally, such compounds will inhibit a range of clinically important efflux pumps but not human orthologs.…”

In VitroEffect of Malachite Green on Candida albicans Involves Multiple Pathways and Transcriptional RegulatorsUPC2andSTP2

“…Many naturally occurring compounds, such as curcumin, berberine, and tetrandrine, show promising antifungal activity (27,41,47,52). However, these compounds are active at high concentrations, in contrast to established antifungal agents, such as azoles, allylamine, and polyenes.…”

An in vitro and in vivo study on the synergistic effect and mechanism of itraconazole or voriconazole alone and in combination with tetrandrine against Aspergillus fumigatus

“…Furthermore, analysis of R6G efflux revealed that TET could inhibit the drug efflux pump of A. fumigatus. Zhang et al (2009) also demonstrated that the synergistic mechanism of TET with fluconazole against C. albicans was related to inhibition of the drug efflux pump and downregulation of drug efflux pump genes. Guo et al (2014) found that the synergistic mechanism of TET to fluconazole against C. albicans was related to the generation and transport of ATP, resulting in reduced utilization of ATP and inhibition of drug efflux pump activity.…”