Tetrandrine enhances the antifungal activity of fluconazole in a murine model of disseminated candidiasis

Insights into the anti-Candida albicans properties of natural phytochemicals: An in vitro and in vivo investigation

Invasive candidiasis, attributed to Candida albicans, has long been a formidable threat to human health. Despite the advent of effective therapeutics in recent decades, the mortality rate in affected patient populations remains discouraging. This is exacerbated by the emergence of multidrug resistance, significantly limiting the utility of conventional antifungals. Consequently, researchers are compelled to continuously explore novel solutions. Natural phytochemicals present a potential adjunct to the existing arsenal of agents. Previous studies have substantiated the efficacy of phytochemicals against C. albicans. Emerging evidence also underscores the promising application of phytochemicals in the realm of antifungal treatment. This review systematically delineates the inhibitory activity of phytochemicals, both in monotherapy and combination therapy, against C. albicans in both in vivo and in vitro settings. Moreover, it elucidates the mechanisms underpinning the antifungal properties, encompassing (i) cell wall and plasma membrane damage, (ii) inhibition of efflux pumps, (iii) induction of mitochondrial dysfunction, and (iv) inhibition of virulence factors. Subsequently, the review introduces the substantial potential of nanotechnology and photodynamic technology in enhancing the bioavailability of phytochemicals. Lastly, it discusses current limitations and outlines future research priorities, emphasizing the need for high-quality research to comprehensively establish the clinical efficacy and safety of phytochemicals in treating fungal infections. This review aims to inspire further contemplation and recommendations for the effective integration of natural phytochemicals in the development of new medicines for patients afflicted with C. albicans.

Alternative Oxidase - Aid or obstacle to combat the rise of fungal pathogens?

Fungal pathogens present a growing threat to both humans and global health security alike. Increasing evidence of antifungal resistance in fungal populations that infect both humans and plant species has increased reliance on combination therapies and shown the need for new antifungal therapeutic targets to be investigated. Here, we review the roles of mitochondria and fungal respiration in pathogenesis and discuss the role of the Alternative Oxidase enzyme (Aox) in both human fungal pathogens and phytopathogens. Increasing evidence exists for Aox within mechanisms that underpin fungal virulence. Aox also plays important roles in adaptability that may prove useful within dual targeted fungal-specific therapeutic approaches. As improved fungal specific mitochondrial and Aox inhibitors are under development we may see this as an emerging target for future approaches to tackling the growing challenge of fungal infection.

Beyond Ergosterol: Strategies for Combatting Antifungal Resistance in Aspergillus fumigatus and Candida auris

Aspergillus fumigatus and Candida auris are historically problematic fungal pathogens responsible for systemic infections and high mortality rates, especially in immunocompromised populations. The three antifungal classes that comprise our present day armamentarium have facilitated efficacious treatment of these fungal infections in past decades, but their potency has steadily declined over the years as resistance to these compounds has accumulated. Importantly, pan-resistant strains of Candida auris have been observed in clinical settings, leaving affected patients with no treatment options and a death sentence. Many compounds in the ongoing antifungal drug discovery pipeline, similar to those within our aforementioned trinity, are predicated on the binding or inhibition of ergosterol. Recurring accounts of resistance to antifungals targeting this pathway suggest optimization of ergosterol-dependent antifungals is likely not the best solution for the long-term. This review aims to present several natural products with novel or underexplored biological targets, as well as similarly underutilized drug discovery strategies to inspire future biological investigations and medicinal chemistry campaigns.

Alkaloids in genus stephania (Menispermaceae): A comprehensive review of its ethnopharmacology, phytochemistry, pharmacology and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Approximately 60 species of the genus Stephania (Menispermaceae) are distributed worldwide. Among these, 39 species are located in South and Southwest China; in particular, these plants are rich in alkaloids and were used in traditional Chinese medicine (TCM) against numerous ailments.

AIM OF THIS REVIEW

The purpose of this study was to provide organized information on the ethnopharmacological uses as well as the phytochemical, pharmacological, and toxicological evaluation of the alkaloids derived from plant species included in the genus Stephania. In addition, we aimed to provide comprehensive basic knowledge on the medicinal properties of these plants and establish meaningful guidelines for further research.

MATERIALS AND METHODS

Information related to the Stephania genus was collected from scientific databases, such as Web of Science, PubMed, Baidu Scholar, and China Academic Journals (CNKI), within the last 20 years on phytochemistry, pharmacology, and toxicology of the plants in genus Stephania. Furthermore, information was obtained from the Pharmacopoeia of the People's Republic of China. Chinese Pharmacopoeia and Flora of China.

RESULTS

Plant species belonging to the genus Stephania have been mentioned as traditional remedies and various alkaloidal compounds have been identified and isolated, including aporphine, proaporphine, morphinane, hasubanane, protoberberine, benzylisoquinoline, and bisbenzylisoquinoline and among others. The isolated alkaloidal compounds reportedly exhibited promising pharmacological properties, such as antimicrobial, antiviral, antitumor, antioxidant, antihyperglycemic, anti-inflammatory, antinociceptive, anti-multidrug resistance, neuroprotective, and cardioprotective activities.

CONCLUSIONS

The genus Stephania is widely used in TCM. The ethnopharmacological uses, phytochemistry, and pharmacology of the Stephania sp. Described in this review demonstrated that these plants contain numerous alkaloids and active constituents and display myriad pharmacological activities. Typically, research on the plants' pharmacological activity focuses on parts of the plants and the associated compounds. However, many Stephania species have rarely been studied, and the ethnomedicinal potential of those discovered has not been scientifically evaluated and needs to be further elucidated. Furthermore, quality control and toxicology studies are warranted in the future.

Augmenting Azoles with Drug Synergy to Expand the Antifungal Toolbox

Fungal infections impact the lives of at least 12 million people every year, killing over 1.5 million. Wide-spread use of fungicides and prophylactic antifungal therapy have driven resistance in many serious fungal pathogens, and there is an urgent need to expand the current antifungal arsenal. Recent research has focused on improving azoles, our most successful class of antifungals, by looking for synergistic interactions with secondary compounds. Synergists can co-operate with azoles by targeting steps in related pathways, or they may act on mechanisms related to resistance such as active efflux or on totally disparate pathways or processes. A variety of sources of potential synergists have been explored, including pre-existing antimicrobials, pharmaceuticals approved for other uses, bioactive natural compounds and phytochemicals, and novel synthetic compounds. Synergy can successfully widen the antifungal spectrum, decrease inhibitory dosages, reduce toxicity, and prevent the development of resistance. This review highlights the diversity of mechanisms that have been exploited for the purposes of azole synergy and demonstrates that synergy remains a promising approach for meeting the urgent need for novel antifungal strategies.

Tetrandrine, a Potent Antifungal Agent, Inhibits Mycelial Growth and Virulence of Botrytis cinerea

Tetrandrine (TET) is a potent calcium channel blocker used to treat hypertension and inflammation. Currently, TET is predominantly used to treat a variety of human diseases, and there is little information regarding the use of TET against plant pathogens. In this study, we explored the antifungal activity of TET on a plant pathogen, Botrytis cinerea. We show that administration of low concentrations of TET effectively inhibited hyphal growth of fungus grown on potato dextrose agarose and decreased the virulence of B. cinerea in tomato plants. Real-time PCR revealed that the expression of drug efflux pump-related genes (alcohol dehydrogenase 1, multidrug/pheromone exporter, pleiotropic drug resistance protein 1, and synaptic vesicle transporter) were downregulated in the presence of TET. Finally, we show that TET acts synergistically with iprodione, resulting in increased inhibition of B. cinerea both in vitro and in vivo. These results indicate that TET might act as an effective antifungal agent in reducing gray mold disease.

Design, synthesis, and biodistribution studies of new analogues of marine alkaloids: Potent in vitro and in vivo fungicidal agents against Candida spp

Invasive candidiasis, such as intra-abdominal candidiasis (IAC), is a significant cause of morbidity and mortality worldwide. IAC is still poorly understood, and its treatment represents a challenge for public health. In this study, we showed the in vitro anti-Candida activity of four alkaloid synthetic derivatives and their antifungal potential in a murine model of IAC. The biological effects of alkaloids were evaluated against Candida spp. through the determination of the minimum inhibitory concentration (MIC). For the alkaloids that showed antifungal activity, the fungicidal concentration, time-kill curve, synergism with azoles and polyenes, phenotypic effects, and the effect against virulence factors were also determined. The most active alkaloids were selected for in vivo assays. The compounds 6a and 6b were active against C. albicans, C. glabrata, and C. tropicalis (MIC 7.8 μg/mL) and showed promising antifungal activity against C. krusei (MIC 3.9 μg/mL). The compound 6a presented a potent fungicidal effect in vitro, eliminating the yeast C. albicans after 8 h of incubation at MIC. An important in vitro synergistic effect with ketoconazole was observed for these two alkaloids. They also induced the lysis of fungal cells by binding to the ergosterol of the membrane. Besides that, 6a and 6b were able to reduce yeast-to-hyphal transition in C. albicans, as well as inhibit the biofilm formation of this pathogen. In the in vivo assay, the compound 6a did not show acute toxicity and was mainly absorbed by the liver, spleen, and lung after a parenteral administration. Also, this analogue significantly reduced the fungal load of C. albicans on the kidney and spleen of animals with IAC. Therefore, these results showed that the compound 6a is a potent anti-Candida agent in vitro and in vivo.

Braz J, Quintans Junior LJ, Serafini MR. The Patenting and Technological Trends in Candidiasis Treatment: A Systematic Review (2014-2018)

Background:

In the last few decades, mycoses caused by opportunistic fungi namely Candida species has gained significant attention. Such infections are very common and present high mortality rates, especially in immunocompromised patients. Currently, a limited number of antifungal drugs are available for the treatment of these infections and are also often related to severe adverse side effects. Therefore, new drugs and innovative technologies for the treatment of this infection are necessary.

Objective:

The aim of this study was to evaluate the development of new drugs, formulations, as well as patents for the treatment of infections caused by Candida spp.

Methods:

The present patent review was carried out through a specialized search database Espacenet. The patent selection was based on the following inclusion criteria: Recent patents published in English or Spanish containing candidiasis as the keyword in the title, abstract or full text. This survey was conducted in October and November 2018.

Results:

As a result of that, 22 patents were selected to the final selection, the most common routes of application were oral (n = 6), vaginal (n = 6), topical (n = 5) and others (n = 5). This fact is related to the clinical manifestations of candidiasis.

Conclusion:

Through this review, it was possible to identify significant improvements and advances in the area of antifungal therapeutic innovation research. In addition, we demonstrated the growing interest of academic and industrial groups in pharmaceutical development and novel formulations for the treatment of candidiasis. New therapeutic options can contribute to improve the quality of patient’s life, prevent infections and promote the search for an innovative and effective treatment of Candida infections.

Triterpenoids from Ganoderma gibbosum: A Class of Sensitizers of FLC-Resistant Candida albicans to Fluconazole

Fungal drug resistance is a major health threat, and reports of clinical resistance worldwide are becoming increasingly common. In a research program to discover new molecules to help overcome this problem, 14 new lanostane-type triterpenoids, gibbosicolids A-G (2-8) and gibbosic acids I-O (9-15), were isolated from the fruiting bodies of Ganoderma gibbosum, along with seven known triterpenoid derivatives. These compounds featured high levels of oxidation, epimerization, and γ-lactonization. Structures were elucidated by comprehensive spectroscopic analyses and HRMS data. Absolute configurations were assigned based on quantum chemical calculations, including calculated chemical shift with DP4+ analysis, coupling constants, and electronic circular dichroism (ECD) methods. Results show that the calculated NMR with DP4+ analysis could not reliably establish the overall spatial configuration of molecules possessing independent and free-rotational stereoclusters. All these compounds significantly increased the sensitivity of fluconazole (FLC)-resistant C. albicans to FLC. Compounds 2, 5, 9, 12, 16, 17, and 21 exhibited strong antifungal activity against FLC-resistant C. albicans when combined with FLC, with MIC₅₀ values ranging from 3.8 to 8.8 μg/mL.

Antifungal activity of immunosuppressants used alone or in combination with fluconazole

Fungal infections remain a challenge to clinicians due to the limited available antifungals. With the increasing use of antifungals in clinical practice, drug resistance has been emerging continuously, especially to fluconazole (FLC). Thus, a search for new antifungals and approaches to overcome antifungal resistance is needed. However, the development of new antifungals is usually costly and time consuming; discovering the antifungal activity of non-antifungal agents is one way to address these problems. Interestingly, some researchers have demonstrated that several classes of immunosuppressants (calcineurin inhibitors, glucocorticoids, etc) also displayed potent antifungal activity when used alone or in combination with antifungals, especially with FLC. Some of them could increase FLC's susceptibility against resistant Candida albicans significantly reversing fungal resistance to FLC. This article reviews the antifungal activities of immunosuppressants used alone or in combination with antifungals and their potential antifungal mechanisms that have been discovered so far. Although immunosuppressive agents have been identified as risk factors for fungal infection, we believe these findings are very important for overcoming drug resistance and developing new antifungals.