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Candida albicans is a commensal fungus that naturally inhabits the vagina. However, overgrowth of C. albicans can result in vulvovaginal candidiasis (VVC), one of the most prevalent fungal infections affecting women. The rapid emergence of azole resistance in C. albicans, in addition to the limited available antifungal agents, complicates the treatment and emphasizes the urgent need for novel therapeutic options. Efflux-mediated azole resistance is a common resistance mechanism in fluconazole (FLZ)-resistant C. albicans. Combination therapy using natural compounds is a potential approach that can restore fluconazole's antifungal activity in azole-resistant isolates via efflux pump inhibition. This study aimed to evaluate the ability of celastrol, a natural triterpene, to retrieve FLZ antifungal activity against azole-resistant C. albicans in vitro and in vivo. Celastrol did not exhibit antifungal activity against the tested clinical isolates; however, the sub-MIC of celastrol inhibited rhodamine 6G (R6G) efflux and increased R6G accumulation inside celastrol-treated C. albicans cells. Synergy was spotted between celastrol and FLZ via a checkerboard assay. Quantification of m-RNA levels of efflux-mediated azole resistance genes within azole-resistant C. albicans demonstrated CDR1 overexpression. Upon celastrol treatment, a significant decline in ABC transporters transcript levels were detected. Moreover, molecular docking demonstrated that celastrol is a potential ABC efflux transporters blocker that successfully fits into target binding pockets. A negligible hemolytic effect of celastrol against human erythrocytes was observed. In the in vivo model of VVC, the combination of FLZ and celastrol in vaginal gel revealed a drastic reduction in the fungal burden with apparently normal vaginal tissue. Celastrol promising in vitro and in vivo findings strengthen its future use for the treatment of azole-resistant C. albicans. [ABSTRACT FROM AUTHOR]

A mutual prodrug of sertraline-methylpropyphenazone (SER-MP) was prepared and characterized using a spectral method. The yield of the prepared SER-MP was 90%, and its purity reached 98.8%. The metabolic fate of the prepared SER-MP versus sertraline (SER) was investigated in the plasma and brain tissues of rats. A solid-phase extraction procedure was developed and validated for the optimal recovery of SER, 3-hydroxymethylpropyphenazone (3-OHMP), and SER-MP from plasma and brain tissues. The extraction efficiency for the targeted analytes was improved from 93.5% to 98.0% using Chromabond® C8-100 mg solid-phase extraction columns. A high-performance liquid chromatography-triple-quad-mass spectrometric method was developed and validated to quantify the SER, SER-MP, and potential metabolites. The pharmacokinetic parameters showed that the time to reach the maximum plasma concentration ( t max ) for both SER and SER-MP was 6 hours, and the maximum plasma concentration of SER-MP reached 192 ng mL -1 with an elimination half-life time of 50 hours. The plasma level of SER, which was released as a metabolite of orally administered SER-MP, was increased by 2.4 times compared to SER HCl administered at equimolar doses. The concentration of SER-MP in the rat brains remained approximately stable at 100 ng g -1 for 0.5 to 192 hours. The serotonin level in the rat brain homogenate was 50 to 90 ng g -1 for both the group receiving SER and that receiving an equal molar dose of SER-MP. This observation was consistent during a time range of 1 to 192 h from oral administration. Thus, this approach could lead to the development of more efficient antidepressant therapies with reduced side effects. The findings indicate that SER-MP could minimize serotonin syndrome risks by maintaining steady serotonin levels in the brain, thus improving patient safety and compliance., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)