In Vitro Antifungal Activity and Mechanism of Ag3PW12O40 Composites against Candida Species

Vidarabine as a novel antifungal agent against Candida albicans: insights on mechanism of action

Around 1.5 million mortality cases due to fungal infection are reported annually, posing a massive threat to global health. However, the effectiveness of current antifungal therapies in the treatment of invasive fungal infections is limited. Repurposing existing antifungal drugs is an advisable alternative approach for enhancing their effectiveness. This study evaluated the antifungal efficacy of the antiviral drug vidarabine against Candida albicans ATCC 90028. Antifungal susceptibility testing was performed by microbroth dilution assay and further processed to find the minimum fungicidal concentration. Investigation on probable mode of vidarabine action against C. albicans was assessed by using the ergosterol reduction assay, reactive oxygen species (ROS) accumulation, nuclear condensation, and apoptosis assay. Results revealed that C. albicans was susceptible to vidarabine action and exhibited minimum inhibitory concentration at 150 µg/ml. At a concentration of 300 µg/ml, vidarabine had fungicidal activity against C. albicans. 300 µg/ml vidarabine-treated C. albicans cells demonstrated 91% reduced ergosterol content. Annexin/FITC/PI assay showed that vidarabine (150 µg/ml) had increased late apoptotic cells up to 31%. As per the fractional inhibitory concentration index, vidarabine had synergistic activity with fluconazole and caspofungin against this fungus. The mechanism underlying fungicidal action of vidarabine was evaluated at the intracellular level, and probably because of increased nuclear condensation, enhanced ROS generation, and cell cycle arrest. In conclusion, this data is the first to report that vidarabine has potential to be used as a repurposed antifungal agent alone or in combination with standard antifungal drugs, and could be a quick and safe addition to existing therapies for treating fungal infections.

Lindqvist-type Polyoxometalates Act as Anti-breast Cancer Drugs via Mitophagy-induced Apoptosis

OBJECTIVE

Lindqvist-type polyoxometalates (POMs) exhibit potential antitumor activities. This study aimed to examine the effects of Lindqvist-type POMs against breast cancer and the underlying mechanism.

METHODS

Using different cancer cell lines, the present study evaluated the antitumor activities of POM analogues that were modified at the body skeleton based on molybdenum-vanadium-centered negative oxygen ion polycondensations with different side strains. Cell colony formation assay, autophagy detection, mitochondrial observation, qRT-PCR, Western blotting, and animal model were used to evaluate the antitumor activities of POMs against breast cancer cells and the related mechanism.

RESULTS

MO-4, a Lindqvist-type POM linking a proline at its side strain, was selected for subsequent experiments due to its low half maximal inhibitory concentration in the inhibition of proliferation of breast cancer cells. It was found that MO-4 induced the apoptosis of multiple types of breast cancer cells. Mechanistically, MO-4 activated intracellular mitophagy by elevating mitochondrial reactive oxygen species (ROS) levels and resulting in apoptosis. In vivo, breast tumor growth and distant metastasis were significantly reduced following MO-4 treatment.

CONCLUSION

Collectively, the results of the present study demonstrated that the novel Lindqvist-type POM MO-4 may exhibit potential in the treatment of breast cancer.

Tris-Functionalized Polyoxotungstovanadate-Mediated Antitumor Efficacy Involves Multiple Cell Death Pathways

Polyoxometalates (POMs) are promising inorganic drug candidates for cancer chemotherapy. They are becoming attractive because of their easy accessibility and low cost. Herein, we report the synthesis and antitumor activity studies of four Lindqvist-type POMs with mixed-addenda atoms Na2[V4W2O16{(OCH2)3CR}] (R=-CH2OH, -CH3, -CH2CH3) and (Bu4N)2[V3W3{(OCH2)3CH2OOCCH2CH3}]. Compared with the current clinical applied antitumor drug 5-fluorouracil (5-FU) or Gemcitabine, analysis of MTT/CCK-8 assay, colony formation and wound healing assay revealed that the {V4W2} POMs had acceptable cytotoxicity in normal cells (293T) and significant inhibitory effects on cell proliferation and migration in three human tumor cell lines: human lung carcinoma cells (A549), human cervical carcinoma cells (HeLa), and human breast cancer cells (MCF-7). Interestingly, among the POMs analyzed, the therapeutic index (TI) of the {V4W2} POM with R= -CH2OH was relatively the most satisfactory. Thus, it was subsequently used for further studies. Flow cytometry analysis showed it prompted cellular apoptosis rate. qRT-PCR and Western blotting analysis indicated that multiple cell death pathways were activated including apoptosis, autophagy, necroptosis and pyroptosis during the POM-mediated antitumor process. In conclusion, our study shows that the polyoxotungstovanadate has great potential to be developed into a broad-spectrum antitumor chemotherapeutic drug.

Transcriptional Reprogramming of Candida tropicalis in Response to Isoespintanol Treatment

Candida tropicalis, an opportunistic pathogen, ranks among the primary culprits of invasive candidiasis, a condition notorious for its resistance to conventional antifungal drugs. The urgency to combat these drug-resistant infections has spurred the quest for novel therapeutic compounds, with a particular focus on those of natural origin. In this study, we set out to evaluate the impact of isoespintanol (ISO), a monoterpene derived from Oxandra xylopioides, on the transcriptome of C. tropicalis. Leveraging transcriptomics, our research aimed to unravel the intricate transcriptional changes induced by ISO within this pathogen. Our differential gene expression analysis unveiled 186 differentially expressed genes (DEGs) in response to ISO, with a striking 85% of these genes experiencing upregulation. These findings shed light on the multifaceted nature of ISO's influence on C. tropicalis, spanning a spectrum of physiological, structural, and metabolic adaptations. The upregulated DEGs predominantly pertained to crucial processes, including ergosterol biosynthesis, protein folding, response to DNA damage, cell wall integrity, mitochondrial activity modulation, and cellular responses to organic compounds. Simultaneously, 27 genes were observed to be repressed, affecting functions such as cytoplasmic translation, DNA damage checkpoints, membrane proteins, and metabolic pathways like trans-methylation, trans-sulfuration, and trans-propylamine. These results underscore the complexity of ISO's antifungal mechanism, suggesting that it targets multiple vital pathways within C. tropicalis. Such complexity potentially reduces the likelihood of the pathogen developing rapid resistance to ISO, making it an attractive candidate for further exploration as a therapeutic agent. In conclusion, our study provides a comprehensive overview of the transcriptional responses of C. tropicalis to ISO exposure. The identified molecular targets and pathways offer promising avenues for future research and the development of innovative antifungal therapies to combat infections caused by this pathogenic yeast.

Antifungal potential of isoespintanol extracted from Oxandra xylopioides diels (Annonaceae) against intrahospital isolations of Candida SPP

The aim of this study was to evaluate the antifungal activity of isoespintanol (ISO) extracted from Oxandra xylopioides Diels (Annonaceae) against clinical isolates of Candida spp. Isoespintanol was obtained from the petroleum benzine extract of the leaves and was identified by nuclear magnetic resonance (NMR) and mass spectrometry (MS). For antifungal activity experiments, the broth microdilution method was used. The results show an inhibitory effect against Candida spp., with minimum inhibitory concentration (MIC) values between 450.4-503.3 μg/mL. Furthermore, the inhibitory effect of ISO against fungal biofilms is highlighted, even in some cases, greater than the effect shown by amphotericin B (AFB) and in others, where AFB showed no effect. Assays with fluorescent staining with acridine orange (AO) and ethidium bromide (EB), transmission electron microscopy (TEM), Evans blue, measurement of extracellular pH and leakage of intracellular material, evidenced damage at the level of fungal membranes and general cell damage, when cells were exposed to ISO, compared to untreated cells. The results of this research, serve as the basis for future studies in the establishment of the mechanisms of antifungal action of ISO, which could serve as an adjunct in the treatment of infections by these yeasts.

Mechanism of Antifungal Action of Monoterpene Isoespintanol against Clinical Isolates of Candida tropicalis

The growing increase in infections by Candida spp., non-albicans, coupled with expressed drug resistance and high mortality, especially in immunocompromised patients, have made candidemia a great challenge. The efficacy of compounds of plant origin with antifungal potential has recently been reported as an alternative to be used. Our objective was to evaluate the mechanism of the antifungal action of isoespintanol (ISO) against clinical isolates of Candida tropicalis. Microdilution assays revealed fungal growth inhibition, showing minimum inhibitory concentration (MIC) values between 326.6 and 500 µg/mL. The eradication of mature biofilms by ISO was between 20.3 and 25.8% after 1 h of exposure, being in all cases higher than the effect caused by amphotericin B (AFB), with values between 7.2 and 12.4%. Flow cytometry showed changes in the permeability of the plasma membrane, causing loss of intracellular material and osmotic balance; transmission electron microscopy (TEM) confirmed the damage to the integrity of the plasma membrane. Furthermore, ISO induced the production of intracellular reactive oxygen species (iROS). This indicates that the antifungal action of ISO is associated with damage to membrane integrity and the induction of iROS production, causing cell death.

25th Anniversary of Molecules-Recent Advances in Inorganic Chemistry

Celebrating the "25th Anniversary of Molecules" with a Special Issue dedicated to "Recent Advances in Inorganic Chemistry" strengthens the renewed role that inorganic chemistry, one of the oldest chemistry divisions, has lately earned thanks to cutting-edge perspectives and interdisciplinary applications, eventually receiving the veneration and respect which its age might require [...].