Discovery of Natural Products With Antifungal Potential Through Combinatorial Synergy

Baicalein combined with azoles against fungi in vitro

Background

Invasive fungal infections (IFIs) constitute a significant health challenge, particularly among immunocompromised individuals, characterized by a high prevalence and associated mortality rates. The synergistic administration of Baicalein (BE) with azole antifungal agents could potentially herald a novel therapeutic paradigm.

Materials and methods

54 Aspergillus strains and 23 strains of dematiaceous fungi were selected. The standard M38-A2 microbroth dilution method was used to test the minimum inhibitory concentration (MIC) and the fractional inhibitory concentration index (FICI) of fungi when BE combined with itraconazole (ITC), voriconazole (VRC), posaconazole (POS) and Isavuconazole (ISV).

Results

BE shows synergistic effects with POS and ITC, with 89.61% and 25.97% of fungal strains. The BE/POS regimen exerted synergistic effects in 87.04% of Aspergillus and an impressive 95.65% of dematiaceous fungi. In comparison, the BE/ITC combination showed significantly lower synergy, affecting 33.33% of Aspergillus and a mere 8.70% of dematiaceous strains. Antagonistic interactions were sporadically observed with BE in combination with ITC, VRC, POS and ISV. Within the azole class, the BE/POS pairing stood out for its frequent synergistic activity, in contrast to the absence of such effects when BE was paired with VRC or ISV. Highlighting the potential of BE/POS as a notably effective antifungal strategy.

Conclusion

In vitro, BE/POS combination emerged as the most effective antifungal strategy, exhibiting synergistic effects in the majority of Aspergillus and dematiaceous fungi strains, whereas BE/ITC showed significantly less synergy, and BE with VRC or ISV displayed no synergistic activity.

The Neosartorya (Aspergillus) fischeri antifungal protein NFAP2 has low potential to trigger resistance development in Candida albicans in vitro

Due to the increase in the number of drug-resistant Candida albicans strains, new antifungal compounds with limited potential for the development of resistance are urgently needed. NFAP2, an antifungal protein (AFP) secreted by Neosartorya (Aspergillus) fischeri, is a promising candidate. We investigated the ability of C. albicans to develop resistance to NFAP2 in a microevolution experiment compared with generic fluconazole (FLC). C. albicans adapted to only 1× minimum inhibitory concentration (MIC) of NFAP2, which can be considered tolerance rather than resistance, compared with 32× MIC of FLC. Genome analysis revealed non-silent mutations in only two genes in NFAP2-tolerant strains and in several genes in FLC-resistant strains. Tolerance development to NFAP2 did not influence cell morphology. The susceptibility of NFAP2-tolerant strains did not change to FLC, amphotericin B, micafungin, and terbinafine. These strains did not show altered susceptibility to AFPs from Penicillium chrysogenum, except one which had less susceptibility to Penicillium chrysogenum antifungal protein B. FLC-resistant strains had decreased susceptibility to terbinafine and NFAP2, but not to other drugs and AFPs from P. chrysogenum. NFAP2-tolerant and FLC-resistant strains showed decreased and increased NFAP2 binding and uptake, respectively. The development of tolerance to NFAP2 decreased tolerance to cell wall, heat, and UV stresses. The development of FLC resistance increased tolerance to cell wall stress and decreased tolerance to heat and UV stresses. Tolerance to NFAP2 did not have significant metabolic fitness cost and could not increase virulence, compared with resistance to FLC.IMPORTANCEDue to the increasing number of (multi)drug-resistant strains, only a few effective antifungal drugs are available to treat infections caused by opportunistic Candida species. Therefore, the incidence of hard-to-treat candidiasis has increased dramatically in the past decade, and the demand to identify antifungal compounds with minimal potential to trigger resistance is substantial. The features of NFAP2 make it a promising candidate for the topical treatment of Candida infection. Data on the development of resistance to antifungal proteins in Candida albicans are lacking. In this study, we provide evidence that NFAP2 has a low potential to trigger resistance in C. albicans in vitro, and the developed tolerance to NFAP2 is not associated with severe phenotypic changes compared with development of resistance to generic fluconazole. These results suggest the slow emergence of NFAP2-resistant Candida strains, and NFAP2 can reliably be used long-term in the clinic.

Inhibitory effects of berberine on fungal growth, biofilm formation, virulence, and drug resistance as an antifungal drug and adjuvant with prospects for future applications

Berberine (BBR), an isoquinoline alkaloid found in medicinal plants such as Coptidis rhizoma, Berberis sp., and Hydrastis canadensis, is a distinctive compound known for its dual ability to exhibit broad-spectrum antifungal activity while offering beneficial effects to the host. These attributes make it a highly valuable candidate for antifungal therapy and as an antibiotic adjuvant. This review provides a comprehensive evaluation of BBR's antifungal properties, focusing on its in vitro and in vivo activity, underlying mechanisms, and its influence on fungal pathogenicity, including virulence, biofilm formation, and resistance. Additionally, the antifungal potential of BBR extracts, derivatives, and nanoformulations is examined in detail. BBR demonstrates fungicidal effects through multiple mechanisms. It targets critical fungal components such as mitochondria, cell membranes, and cell walls, while also inhibiting enzymatic activity and transcription processes. Furthermore, it suppresses the expression of virulence factors, effectively diminishing fungal pathogenicity. Beyond its direct antifungal activity, BBR exerts beneficial effects on the host by modulating gut microbiota, thereby bolstering host defenses against fungal infections and reducing potential adverse effects. BBR's interaction with conventional antifungal drugs presents a unique complexity, particularly in the context of resistance mechanisms. When used in combination therapies, conventional antifungal drugs enhance the intracellular accumulation of BBR, thereby amplifying its antifungal potency as the primary active agent. These synergistic effects position BBR as a promising candidate for combination strategies, especially in addressing drug-resistant fungal infections and persistent biofilms. As antifungal resistance and biofilm-associated infections continue to rise, the multifaceted properties of BBR and its advanced formulations highlight their significant therapeutic potential. However, the scarcity of robust in vivo and clinical studies limits a full understanding of its efficacy and safety profile. To bridge this gap, future investigations should prioritize well-designed in vivo and clinical trials to thoroughly evaluate the therapeutic effectiveness and safety of BBR in diverse clinical settings. This approach could pave the way for its broader application in combating fungal infections.

Hemisynthesis and cytotoxic evaluation of manoyl oxide analogs from sclareol: effect of two tertiary hydroxyls & Heck coupling on cytotoxicity

Sclareol, a bioactive diterpene alcohol isolated from Salvia sclarea, was subjected to structural modification and cytotoxic evaluation. Boron-Heck-coupled analogs of manoyl oxide were prepared from sclareol in a two-step reaction scheme. In the first step manoyl oxide was prepared from sclareol using cerium (IV) ammonium nitrate. Further the structural modification of manoyl oxide via Palladium (II) catalysed Boron-Heck coupling reaction produced a new series of compounds. All the synthesised compounds were screened for in vitro cytotoxic evaluation against four cancer cell lines HCT-116, MCF-7, MDA-MB231and MDA-MB468. The results showed that manoyl oxide is less active than sclareol. Sclareol shows an IC50 of 2.0 µM compared to manoyl oxide with an IC50 of 50 µM against the MCF-7 cell line. From the results it was inferred that the presence of two tertiary hydroxyls in sclareol are necessary for its cytotoxic activity and Heck coupled analogs are more active than sclareol and manoyl oxide.

Network Pharmacology, Molecular Docking, and Molecular Dynamics Simulation to Elucidate the Molecular Targets and Potential Mechanism of Phoenix dactylifera (Ajwa Dates) against Candidiasis

Candidiasis, caused by opportunistic fungal pathogens of the Candida genus, poses a significant threat to immunocompromised individuals. Natural compounds derived from medicinal plants have gained attention as potential sources of anti-fungal agents. Ajwa dates (Phoenix dactylifera L.) have been recognized for their diverse phytochemical composition and therapeutic potential. In this study, we employed a multi-faceted approach to explore the anti-candidiasis potential of Ajwa dates' phytochemicals. Utilizing network pharmacology, we constructed an interaction network to elucidate the intricate relationships between Ajwa dates phytoconstituents and the Candida-associated molecular targets of humans. Our analysis revealed key nodes in the network (STAT3, IL-2, PTPRC, STAT1, CASP1, ALB, TP53, TLR4, TNF and PPARG), suggesting the potential modulation of several crucial processes (the regulation of the response to a cytokine stimulus, regulation of the inflammatory response, positive regulation of cytokine production, cellular response to external stimulus, etc.) and fungal pathways (Th17 cell differentiation, the Toll-like receptor signaling pathway, the C-type lectin receptor signaling pathway and necroptosis). To validate these findings, molecular docking studies were conducted, revealing the binding affinities of the phytochemicals towards selected Candida protein targets of humans (ALB-rutin (-9.7 kJ/mol), STAT1-rutin (-9.2 kJ/mol), STAT3-isoquercetin (-8.7 kJ/mol), IL2-β-carotene (-8.5 kJ/mol), CASP1-β-carotene (-8.2 kJ/mol), TP53-isoquercetin (-8.8 kJ/mol), PPARG-luteolin (-8.3 kJ/mol), TNF-βcarotene (-7.7 kJ/mol), TLR4-rutin (-7.4 kJ/mol) and PTPRC-rutin (-7.0 kJ/mol)). Furthermore, molecular dynamics simulations of rutin-ALB and rutin-STAT1 complex were performed to gain insights into the stability and dynamics of the identified ligand-target complexes over time. Overall, the results not only contribute to the understanding of the molecular interactions underlying the anti-fungal potential of specific phytochemicals of Ajwa dates in humans but also provide a rational basis for the development of novel therapeutic strategies against candidiasis in humans. This study underscores the significance of network pharmacology, molecular docking and dynamics simulations in accelerating the discovery of natural products as effective anti-fungal agents. However, further experimental validation of the identified compounds is warranted to translate these findings into practical therapeutic applications.

Medicinal plant Miconia albicans synergizes with ampicillin and ciprofloxacin against multi-drug resistant Acinetobacter baumannii and Staphylococcus aureus

BACKGROUND

Given the rising occurrence of antibiotic resistance due to the existence and ongoing development of resistant bacteria and phenotypes, the identification of new treatments and sources of antimicrobial agents is of utmost urgency. An important strategy for tackling bacterial resistance involves the utilization of drug combinations, and natural products derived from plants hold significant potential as a rich source of bioactive compounds that can act as effective adjuvants. This study, therefore, aimed to assess the antibacterial potential and the chemical composition of Miconia albicans, a Brazilian medicinal plant used to treat various diseases.

METHODS

Ethanolic extracts from leaves and stems of M. albicans were obtained and subsequently partitioned to give the corresponding hexane, chloroform, ethyl acetate, and hydromethanolic phases. All extracts and phases had their chemical constitution investigated by HPLC-DAD-MS/MS and GC-MS and were assessed for their antibiofilm and antimicrobial efficacy against Staphylococcus aureus. Furthermore, their individual effects and synergistic potential in combination with antibiotics were examined against clinical strains of both S. aureus and Acinetobacter baumannii. In addition, 10 isolated compounds were obtained from the leaves phases and used for confirmation of the chemical profiles and for antibacterial assays.

RESULTS

Based on the chemical profile analysis, 32 compounds were successfully or tentatively identified, including gallic and ellagic acid derivatives, flavonol glycosides, triterpenes and pheophorbides. Extracts and phases obtained from the medicinal plant M. albicans demonstrated synergistic effects when combined with the commercial antibiotics ampicillin and ciprofloxacin, against multi-drug resistant bacteria S. aureus and A. baumannii, restoring their antibacterial efficacy. Extracts and phases also exhibited antibiofilm property against S. aureus. Three key compounds commonly found in the samples, namely gallic acid, quercitrin, and corosolic acid, did not exhibit significant antibacterial activity when assessed individually or in combination with antibiotics against clinical bacterial strains.

CONCLUSIONS

Our findings reveal that M. albicans exhibits remarkable adjuvant potential for enhancing the effectiveness of antimicrobial drugs against resistant bacteria.

Melatonin targets MoIcl1 and works synergistically with fungicide isoprothiolane in rice blast control

Melatonina natural harmless molecule-displays versatile roles in human health and crop disease control such as for rice blast. Rice blast, caused by the filamentous fungus Magnaporthe oryzae, is one devastating disease of rice. Application of fungicides is one of the major measures in the control of various crop diseases. However, fungicide resistance in the pathogen and relevant environmental pollution are becoming serious problems. By screening for possible synergistic combinations, here, we discovered an eco-friendly combination for rice blast control, melatonin, and the fungicide isoprothiolane. These compounds together exhibited significant synergistic inhibitory effects on vegetative growth, conidial germination, appressorium formation, penetration, and plant infection by M. oryzae. The combination of melatonin and isoprothiolane reduced the effective concentration of isoprothiolane by over 10-fold as well as residual levels of isoprothiolane. Transcriptomics and lipidomics revealed that melatonin and isoprothiolane synergistically interfered with lipid metabolism by regulating many common targets, including the predicted isocitrate lyase-encoding gene MoICL1. Furthermore, using different techniques, we show that melatonin and isoprothiolane interact with MoIcl1. This study demonstrates that melatonin and isoprothiolane function synergistically and can be used to reduce the dosage and residual level of isoprothiolane, potentially contributing to the environment-friendly and sustainable control of crop diseases.

Curcumin and curcumin nanoparticles counteract the biological and managemental stressors in poultry production: An updated review

Antibiotics have the potential to have both direct and indirect detrimental impacts on animal and human health. For instance, antibiotic residues and pathogenic resistance against the drug are very common in poultry because of antibiotics used in their feed. It is necessary to use natural feed additives as effective alternatives instead of synthetic antibiotics. Curcumin, a polyphenol compound one of the natural compounds from the rhizomes of turmeric (Curcuma spp.) and has been suggested to have several therapeutic benefits in the treatment of human diseases. Curcumin exhibited some positive responses such as growth promoter, antioxidant, antibacterial, antiviral, anticoccidial, anti-stress, and immune modulator activities. Curcumin played a pivotal role in regulating the structure of the intestinal microbiome for health promotion and the treatment of intestinal dysbiosis. It is suggested that curcumin alone or a combination with other feed additives could be a dietary strategy to improve poultry health and productivity.

The IV International Symposium on Fungal Stress and the XIII International Fungal Biology Conference

For the first time, the International Symposium on Fungal Stress was joined by the XIII International Fungal Biology Conference. The International Symposium on Fungal Stress (ISFUS), always held in Brazil, is now in its fourth edition, as an event of recognized quality in the international community of mycological research. The event held in São José dos Campos, SP, Brazil, in September 2022, featured 33 renowned speakers from 12 countries, including: Austria, Brazil, France, Germany, Ghana, Hungary, México, Pakistan, Spain, Slovenia, USA, and UK. In addition to the scientific contribution of the event in bringing together national and international researchers and their work in a strategic area, it helps maintain and strengthen international cooperation for scientific development in Brazil.

Evaluating the potential of natural product combinations with sorbic acid for improving preservative action against food-spoilage yeasts

Fungal control methods commonly involve the use of antifungals or preservatives, which can raise concerns about broader effects of these stressors on non-target organisms, spread of resistance and regulatory hurdles. Consequently, control methods enabling lower usage of such stressors are highly sought, for example chemical combinations that synergistically inhibit target-organisms. Here, we investigated how well such a principle extends to improving efficacy of an existing but tightly controlled food preservative, sorbic acid. A screen of ∼200 natural products for synergistic fungal inhibition in combinations with sorbic acid, in either 2% or 0.1% (w/v) glucose to simulate high or reduced-sugar foods, did not reveal reproducible synergies in either of the spoilage yeast species Saccharomyces cerevisiae or Zygosaccharomyces bailii. Potentially promising screen candidates (e.g. lactone parthenolide, ethyl maltol) or a small additional panel of rationally-selected compounds (e.g. benzoic acid) all gave Fractional Inhibitory Concentration Indices (FICI) ≥ 0.5 in combinations with sorbic acid, corroborating absence of synergy in either glucose condition (although FICI values did differ between the glucose conditions). Synergies were not achieved either in a tripartite combination with screen candidates or in a soft-drink formulation as matrix. In previous work with other stressors synergy 'hits' have been comparatively frequent, suggesting that sorbic acid could be unusually resistant to forming synergies with other potential inhibitors and this may relate to the weak acid's known multifactorial inhibitory-actions on cells. The study highlights a challenge in developing appropriate natural product or other chemical combinations applicable to food and beverage preservation.

Escin's Multifaceted Therapeutic Profile in Treatment and Post-Treatment of Various Cancers: A Comprehensive Review

Although modern medicine is advancing at an unprecedented rate, basic challenges in cancer treatment and drug resistance remain. Exploiting natural-product-based drugs is a strategy that has been proven over time to provide diverse and efficient approaches in patient care during treatment and post-treatment periods of various diseases, including cancer. Escin-a plant-derived triterpenoid saponin-is one example of natural products with a broad therapeutic scope. Initially, escin was proven to manifest potent anti-inflammatory and anti-oedematous effects. However, in the last two decades, other novel activities of escin relevant to cancer treatment have been reported. Recent studies demonstrated escin's efficacy in compositions with other approved drugs to accomplish synergy and increased bioavailability to broaden their apoptotic, anti-metastasis, and anti-angiogenetic effects. Here, we comprehensively discuss and present an overview of escin's chemistry and bioavailability, and highlight its biological activities against various cancer types. We conclude the review by presenting possible future directions of research involving escin for medical and pharmaceutical applications as well as for basic research.

The impact of curcumin on livestock and poultry animal's performance and management of insect pests

Plant-based natural products are alternative to antibiotics that can be employed as growth promoters in livestock and poultry production and attractive alternatives to synthetic chemical insecticides for insect pest management. Curcumin is a natural polyphenol compound from the rhizomes of turmeric (Curcuma spp.) and has been suggested to have a number of therapeutic benefits in the treatment of human diseases. It is also credited for its nutritional and pesticide properties improving livestock and poultry production performances and controlling insect pests. Recent studies reported that curcumin is an excellent feed additive contributing to poultry and livestock animal growth and disease resistance. Also, they detailed the curcumin's growth-inhibiting and insecticidal activity for reducing agricultural insect pests and insect vector-borne human diseases. This review aims to highlight the role of curcumin in increasing the growth and development of poultry and livestock animals and in controlling insect pests. We also discuss the challenges and knowledge gaps concerning curcumin use and commercialization as a feed additive and insect repellent.

The bioactivities of sclareol: A mini review

Sclareol, a diterpene alcohol isolated from the herbal and flavor plant clary sage (Salvia sclarea L.), is far-famed as the predominant ingredient in the refined oil of Salvia sclarea (L.). The empirical medicine of Salvia sclarea L. focused on various diseases, such as arthritis, oral inflammation, digestive system diseases, whereas the sclareol possessed more extensive and characteristic bioactivities, including anti-tumor, anti-inflammation and anti-pathogenic microbes, even anti-diabetes and hypertension. However, there is a deficiency of literature to integrate and illuminate the pharmacological attributes of sclareol based on well-documented investigations. Interestingly, sclareol has been recently considered as the potential candidate against COVID-19 and Parkinson’s disease. Accordingly, the bioactive attributes of sclareol in cancer, inflammation, even pharmacochemistry and delivery systems are reviewed for comprehensively dissecting its potential application in medicine.