Effect of Nicotinamide Against Candida albicans

Sirtuin E deacetylase is required for full virulence of Aspergillus fumigatus

Aspergillus fumigatus represents a public health problem due to the high mortality rate in immunosuppressed patients and the emergence of antifungal-resistant isolates. Protein acetylation is a crucial post-translational modification that controls gene expression and biological processes. The strategic manipulation of enzymes involved in protein acetylation has emerged as a promising therapeutic approach for addressing fungal infections. Sirtuins, NAD+-dependent lysine deacetylases, regulate protein acetylation and gene expression in eukaryotes. However, their role in the human pathogenic fungus A. fumigatus remains unclear. This study constructs six single knockout strains of A. fumigatus and a strain lacking all predicted sirtuins (SIRTKO). The mutant strains are viable under laboratory conditions, indicating that sirtuins are not essential genes. Phenotypic assays suggest sirtuins' involvement in cell wall integrity, secondary metabolite production, thermotolerance, and virulence. Deletion of sirE attenuates virulence in murine and Galleria mellonella infection models. The absence of SirE alters the acetylation status of proteins, including histones and non-histones, and triggers significant changes in the expression of genes associated with secondary metabolism, cell wall biosynthesis, and virulence factors. These findings encourage testing sirtuin inhibitors as potential therapeutic strategies to combat A. fumigatus infections or in combination therapy with available antifungals.

Candida albicans Infection Disrupts the Metabolism of Vaginal Epithelial Cells and Inhibits Cellular Glycolysis

Vulvovaginal candidiasis (VVC) is a common gynecologic disorder caused by fungal infections of the vaginal mucosa, with the most common pathogen being Candida albicans (C. albicans). Exploring metabolite changes in the disease process facilitates further discovery of targets for disease treatment. However, studies on the metabolic changes caused by C. albicans are still lacking. In this study, we used C. albicans-infected vaginal epithelial cells to construct an in vitro model of VVC, analyzed the metabolites by UHPLC-Q-Exactive MS, and screened the potential metabolites based on metabolomics. The results showed that C. albicans infection resulted in significant up-regulation of D-arabitol, palmitic acid, adenosine, etc.; significant down-regulation of lactic acid, nicotinamide (NAM), nicotinate (NA), etc.; and disruption of amino acid metabolism, and that these significantly altered metabolites might be potential therapeutic targets of VVC. Further experiments showed that C. albicans infection led to a decrease in glycolytic enzymes in damaged cells, inhibiting glycolysis and leading to significant alterations in glycolytic metabolites. The present study explored the potential metabolites of VVC induced by C. albicans infection based on metabolomics and verified the inhibitory effect of C. albicans on vaginal epithelial cell glycolysis, which is valuable for the diagnosis and treatment of VVC.

Antimicrobial Potential of Different Isolates of Chaetomium globosum Combined with Liquid Chromatography Tandem Mass Spectrometry Chemical Profiling

The antimicrobial resistance of pathogenic microorganisms against commercial drugs has become a major problem worldwide. This study is the first of its kind to be carried out in Egypt to produce antimicrobial pharmaceuticals from isolated native taxa of the fungal Chaetomium, followed by a chemical investigation of the existing bioactive metabolites. Here, of the 155 clinical specimens in total, 100 pathogenic microbial isolates were found to be multi-drug resistant (MDR) bacteria. The Chaetomium isolates were recovered from different soil samples, and wild host plants collected from Egypt showed strong inhibitory activity against MDR isolates. Chaetomium isolates displayed broad-spectrum antimicrobial activity against C. albicans, Gram-positive, and Gram-negative bacteria, with inhibition zones of 11.3 to 25.6 mm, 10.4 to 26.0 mm, and 10.5 to 26.5 mm, respectively. As a consecutive result, the minimum inhibitory concentration (MIC) values of Chaetomium isolates ranged from 3.9 to 62.5 µg/mL. Liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) analysis was performed for selected Chaetomium isolates with the most promising antimicrobial potential against MDR bacteria. The LC-MS/MS analysis of Chaetomium species isolated from cultivated soil at Assuit Governate, Upper Egypt (3), and the host plant Zygophyllum album grown in Wadi El-Arbaein, Saint Katherine, South Sinai (5), revealed the presence of alkaloids as the predominant bioactive metabolites. Most detected bioactive metabolites previously displayed antimicrobial activity, confirming the antibacterial potential of selected isolates. Therefore, the Chaetomium isolates recovered from harsh habitats in Egypt are rich sources of antimicrobial metabolites, which will be a possible solution to the multi-drug resistant bacteria tragedy.

Deacetylation by sirtuins is important for Aspergillus fumigatus pathogenesis and virulence

Protein acetylation is a crucial post-translational modification that controls gene expression and a variety of biological processes. Sirtuins, a prominent class of NAD + -dependent lysine deacetylases, serve as key regulators of protein acetylation and gene expression in eukaryotes. In this study, six single knockout strains of fungal pathogen Aspergillus fumigatus were constructed, in addition to a strain lacking all predicted sirtuins (SIRTKO). Phenotypic assays suggest that sirtuins are involved in cell wall integrity, secondary metabolite production, thermotolerance, and virulence. AfsirE deletion resulted in attenuation of virulence, as demonstrated in murine and Galleria infection models. The absence of AfSirE leads to altered acetylation status of proteins, including histones and non-histones, resulting in significant changes in the expression of genes associated with secondary metabolism, cell wall biosynthesis, and virulence factors. These findings encourage testing sirtuin inhibitors as potential therapeutic strategies to combat A. fumigatus infections or in combination therapy with available antifungals.

Guar gum-based multilayer fiber membranes inspired by plant transpiration for enhancing the functionality of dry facial masks

As more eco-friendly and economical choice for wet facial masks, dry facial masks have always had the problem of cumbersome application process and poor water retention property. In this study, based on the mechanism of directional water transport of Janus membrane and plant transpiration, the hydrophobic polylactic acid (PLA) nanofiber layer and the superhydrophilic guar gum (GG) nanofiber layer were prepared on both sides of the silk facial mask (SM) by electrospinning to obtain the guar gum-based bionic Janus directional water transport facial mask (G-DFM). The results showed that the directional water transport function improved the facial mask's water retention by 37 %, and the nicotinamide (NAM) encapsulated in the GG layer gave the facial mask excellent whitening and antibacterial properties. The GG layer could be directed to swell after absorbing water to form the "gel-like", which ensured that the G-DFM could continue to release NAM during its work and would enhance the attachment between the G-DFM and the skin. G-DFM not only retained the advantages of SM but also expanded the functions that SM did not have, providing an idea for designing more practical and ideal facial masks in the future.

3-Hydroxy coumarin demonstrates anti-biofilm and anti-hyphal efficacy against Candida albicans via inhibition of cell-adhesion, morphogenesis, and virulent genes regulation

Candida albicans, a common fungus of human flora, can become an opportunistic pathogen and causes invasive candidiasis in immunocompromised individuals. Biofilm formation is the prime cause of antibiotic resistance during C. albicans infections and treating biofilm-forming cells is challenging due to their intractable and persistent nature. The study intends to explore the therapeutic potential of naturally produced compounds by competitive marine bacteria residing in marine biofilms against C. albicans biofilm. To this end, 3-hydroxy coumarin (3HC), a compound identified from the cell-free culture supernatant of the marine bacterium Brevundimonas abyssalis, was found to exhibit anti-biofilm and anti-hyphal activity against both reference and clinical isolates of C. albicans. The compound demonstrated significant inhibitory effects on biofilms and impaired the yeast-to-hyphal transition, wrinkle, and filament morphology at the minimal biofilm inhibitory concentration (MBIC) of 250 µg mL^-1. Intriguingly, quantitative PCR analysis of 3HC-treated C. albicans biofilm revealed significant downregulation of virulence genes (hst7, ume6, efg1, cph1, ras1, als1) associated with adhesion and morphogenesis. Moreover, 3HC displayed non-fungicidal and non-toxic characteristics against human erythrocytes and buccal cells. In conclusion, this study showed that marine biofilms are a hidden source of diverse therapeutic drugs, and 3HC could be a potent drug to treat C. albicans infections.

The dawn of repurposing vitamins as potential novel antimicrobial agents: A call for global emergency response amidst AMR crisis

Amidst, the global pandemic of antimicrobial resistance (AMR), the rate at which AMR increases overwhelms the increased efforts to discover new effective antimicrobials. There is a persistent need for alternative treatment modalities so as to keep up with the pace. AMR is the leading cause of death in the world and its health and economic consequences suggest the urgent need for sustainable interventions. Vitamins have consistently proven to have antimicrobial activity as well as slowing down the AMR rate by influencing the AMR genes even towards extensive multidrug resistant strains. Evidences suggest that the use of some vitamins on their own or in combination with existing antimicrobial agents could be a breakthrough towards combating AMR. This will widen the antimicrobial agents' options in the treatment arena, preserve the antimicrobial agents susceptible to develop resistant so that they can be used in severe infections only, reduce the tension and burden of the AMR crisis significantly and give enough room for development of new antimicrobial agents. Moreover, almost all viral, fungal, parasitic and bacterial resistant strains of concern as listed by World Health Organization have been found to be sensitive to several vitamins either synergistically with other antimicrobials or independently. Considering their widened spectrum of immunomodulatory and antimicrobial effect, some vitamins can further be repositioned as prophylactic antimicrobial agents in clinical situations like in presurgeries prophylaxis so as to avoid unnecessary use of antimicrobials especially antibiotics. Various relevant AMR stakeholders should invest in clinical trials and systematic reviews with available data to enable quick repositioning of some potential vitamins as antimicrobial agents as an emergency rapid response towards AMR Crisis. This includes the preparation of guidelines containing specificity of which vitamin to be used for treatment of which type of infection.

Design, Synthesis and Structure-Activity Relationship Studies of Nicotinamide Derivatives as Potent Antifungal Agents by Disrupting Cell Wall

Fungal infections pose a serious challenge to human health due to the limited paucity of antifungal treatments. Starting as a hit compound screened from our compound library, a series of nicotinamide derivatives have been successfully synthesized via a facile one-step coupling reaction of aromatic carboxylic acid and amine. The synthesized compounds were evaluated for their antifungal activity against Candida albicans SC5314. Among the 37 nicotinamide derivatives screened, compound 16g was found to be the most active against C. albicans SC5314, with an MIC value of 0.25 μg/mL and without significant cytotoxicity. The rudimentary structure-activity relationships study revealed that the position of the amino and isopropyl groups of 16g was critical for its antifungal activity. In particular, compound 16g showed potent activity against six fluconazole-resistant C. albicans strains with MIC values ranging from 0.125-1 μg/mL and showed moderate activity against the other seven species of Candida, three strains of Cryptococcus neoformans, and three strains of Trichophyton. Furthermore, compound 16g showed fungicidal, anti-hyphal, and anti-biofilm activities in vitro, which were related to its ability to disrupt the cell wall of C. albicans. Taken together, 16g is a promising compound that is fungal-specific by targeting the cell wall and could be used as a lead compound for further investigation.

[Research Progress in Niacinamide in the Prevention and Treatment of Mouth and Systemic Diseases]

Nicotinamide (NAM) is the amide form of niacin and one of the precursors of nicotinamide adenine dinucleotide (NAD +). NAM can be used as a dietary supplement or clinical therapeutic drug to replenish NAD + levels in the human body and participate in key bodily functions such as cellular metabolism and DNA repair. NAM has the advantage of low cost, wide availability, and sound biosafety. It also has multiple biological functions, including antibacterial effect, anti-inflammatory effect, and modulation of cellular immunity, producing significant ameliorative effects on skin and neurodegenerative diseases. However, most studies on NAM are still at the laboratory stage. Herein we reviewed the role and mechanism of NAM in the prevention and treatment of oral and systemic diseases, explored its potential as clinical therapeutic medication, provided some basis and references for the clinical application of nicotinamide in the prevention and treatment of various diseases, and discussed its prospects for future research and application.

Succinylation modification provides new insights for the treatment of immunocompromised individuals with drug-resistant Aspergillus fumigatus infection

Invasive Aspergillus fumigatus infection poses a serious threat to global human health, especially to immunocompromised individuals. Currently, triazole drugs are the most commonly used antifungals for aspergillosis. However, owing to the emergence of drug-resistant strains, the effect of triazole drugs is greatly restricted, resulting in a mortality rate as high as 80%. Succinylation, a novel post-translational modification, is attracting increasing interest, although its biological function in triazole resistance remains unclear. In this study, we initiated the screening of lysine succinylation in A. fumigatus. We discovered that some of the succinylation sites differed significantly among strains with unequal itraconazole (ITR) resistance. Bioinformatics analysis showed that the succinylated proteins are involved in a broad range of cellular functions with diverse subcellular localizations, the most notable of which is cell metabolism. Further antifungal sensitivity tests confirmed the synergistic fungicidal effects of dessuccinylase inhibitor nicotinamide (NAM) on ITR-resistant A. fumigatus. In vivo experiments revealed that treatment with NAM alone or in combination with ITR significantly increased the survival of neutropenic mice infected with A. fumigatus. In vitro experiments showed that NAM enhanced the killing effect of THP-1 macrophages on A. fumigatus conidia. Our results suggest that lysine succinylation plays an indispensable role in ITR resistance of A. fumigatus. Dessuccinylase inhibitor NAM alone or in combination with ITR exerted good effects against A. fumigatus infection in terms of synergistic fungicidal effect and enhancing macrophage killing effect. These results provide mechanistic insights that will aid in the treatment of ITR-resistant fungal infections.

Nicotinamide potentiates amphotericin B activity against Candida albicans

Amphotericin B (AmB) is a widely used antifungal agent especially for the therapy of systemic fungal infections. However, the severe side effects of AmB often leads to the premature termination of the treatment. So it is imperative to find the drugs that can both reduce the dosage and enhance the antifungal efficacy of AmB. Here we demonstrated that Nicotinamide (NAM), a cheap and safe vitamin, could enhance the antifungal activities of AmB. We demonstrated the synergistic interaction of NAM and AmB against Candida albicans as well as other Candida spp. and Cryptococcus neoformans. Moreover, NAM could enhance of the activity of AmB against biofilm. This enhancement was also observed in disseminated candidiasis in vivo. Our further study revealed that AmB could induce oxidative damage through the modification of histone acetylation. AmB could inhibit the expression of HST3, an H3K56 deacetylase in C. albicans. The immunoblotting test revealed excessive H3K56ac in AmB-treated fungal cells. Consistantly, the hst3Δ mutant displayed high sensitivity to AmB, while addition of NAM, an H3K56 deacetylation inhibitor, resulted in an even severe inhibition in the growth of this strain. These results indicated that AmB could execute antifungal activity via boosting H3K56ac which was mediated by HST3, and the mechanism for the synergistic interaction of NAM and AmB was based on exacerbating this process, which led to even excessive H3K56ac and oxidative damage. This finding provided theoretical basis for better understanding the antifungal mechanisms of AmB and clinical application of this drug.

Citrus bergamia: Kinetics of Antimicrobial Activity on Clinical Isolates

Background: The inappropriate use of antibiotics has increased selective pressure and the spread of multi-drug-resistant (MDR) pathogens, which reduces the possibility of effective treatment. A potential alternative therapeutic approach may be represented by essential oils, such as the distilled extract of bergamot (Citrus bergamia Risso et Poiteau). Such natural products exercise numerous biological activities, including antimicrobial effects. Methods: This work aimed to evaluate the kinetics of the bactericidal and fungicidal activity of the distilled extract of bergamot on MDR bacteria and fungi from clinical specimens using the time-kill assay. Furthermore, the antimicrobial activity of the distilled extract of bergamot on the morphology and cellular organization of clinical pathogens was evaluated by confocal laser scanning microscopy. Results: Our results demonstrated that the distilled extract of bergamot exhibited significant antimicrobial activity and a specific bactericidal effect against the bacterial and fungal strains tested. Furthermore, confocal microscope images clearly showed compromised membrane integrity, damage and cell death in bacterial samples treated with the distilled extract of bergamot. In addition, progressive alterations in cell-wall composition, cytoplasmic material and nucleus structure triggered by exposure to the distilled extract of bergamot were identified in the fungal samples considered. Conclusions: Our data suggest that the use of essential oils, such as distilled extract of bergamot (Citrus bergamia Risso et Poiteau), can represent a valid alternative therapeutic strategy to counteract antibiotic resistance of pathogens.

Improving chemical stability of resveratrol in hot melt extrusion based on formation of eutectic with nicotinamide

Hot melt extrusion (HME) is a technique applied in the preparation of pharmaceutical amorphous solid dispersions (ASD). Notably it is important to prevent thermal degradation of heat-sensitive drugs during HME. In this study, we present a new strategy to improve chemical stability of pharmaceutical compounds during HME through the formation of eutectics with small molecules. Resveratrol (RES) was selected as the model compound because it is a heat-liable natural product with a very high melting point of 267 °C. When heated at its melting point for 3 min, it degrades by 40%. RES can co-crystallize with nicotinamide (NIC) in solution, however, it can only form a eutectic with NIC during heating. HPMCAS was selected as the polymer matrix and the drug loading of RES was fixed as 20% (weight ratio). The lowest extrusion temperature that can result to RES-HPMCAS ASD is 215 °C. At this temperature, RES shows 7.36% degradation during extrusion. Replacement of 21.4% HPMCAS with NIC decreased the melting temperature of NIC and thus lowered the minimal extrusion temperature to 155 °C. This effectively prevented thermal degradation of RES without negatively affecting non-sink dissolution. The only extra cost for this method is stricter storage conditions (low temperature and low humidity) due to the low glass transition temperature of NIC. Similar strategy may be applied to other heat-liable drugs in similar ways. This study demonstrates the use of eutectic formation for preventing thermal degradation of drug during extrusion of ASD.

Activation of Deoxyribonuclease I by Nicotinamide as a New Strategy to Attenuate Tetracycline-Resistant Biofilms of Cutibacterium acnes

Biofilms of Cutibacterium (C.) acnes (formerly Propionibacterium acnes) are responsible for the persistence and antibiotic resistance of acne vulgaris. In addition to the standard treatments for acne vulgaris, a common adjunctive treatment is the topical administration of nicotinamide (NAM). However, the effects of NAM on biofilms of C. acnes have never been explored. This study comprehensively investigates the effects of NAM against biofilms of C. acnes using in vitro and in vivo approaches. The results showed that NAM potentiated the efficacy of suboptimal dosing of tetracycline against C. acnes. Moreover, NAM alone decreased the formation and increased the degradation of biofilms in C. acnes. The antibiofilm effect of NAM against C. acnes was further enhanced in combination with deoxyribonuclease (DNase) I, an enzyme with known antibiofilm properties. The computational molecular docking, surface plasmon resonance analysis, and enzymatic kinetic assay demonstrated that NAM binds to DNase I and accelerated its reaction. In conclusion, NAM activates DNase I to attenuate biofilms of C. acnes. This offers valuable insights into the strategies against biofilms that are worth elaborating on in other biofilm-related chronic cutaneous infections in the future.

Cosmeceutical Aptitudes of Niacinamide: A Review

BACKGROUND

The prevalence and scope of dermatological illness differ from region to region. Based upon type and severity, the conditions may vary from superficial to deep systemic skin infections. Niacinamide, an amide analog of vitamin B3 which was conventionally utilized as a food supplement, is now explored for the management of skin disorders. Being a powerhouse on its own, it is not stored inside the body naturally and has to be acquired from external sources. Areas Covered: This review is an attempt to disclose the physiology, pharmacology, and highlight the dermatological potentials of niacinamide, discussing its pharmacological mechanisms, varied commercially available treatments, and novel approaches, i.e., in research and patented formulations.

RESULTS

Niacinamide has been verified in treating almost every skin disorder, viz. aging, hyperpigmentation, acne, psoriasis, pruritus, dermatitis, fungal infections, epidermal melasma, non-melanoma skin cancer, etc. It has been reported to possess numerous properties, for instance, anti-inflammatory, antimicrobial, antioxidant, antipruritic, and anticancer, which makes it an ideal ingredient for varied dermal therapies. Long term use of niacinamide, regardless of the skin type, paves the way for new skin cells, making skin healthier, brighter, and hydrated.

CONCLUSION

Niacinamide possesses a variety of positive characteristics in the field of dermatology. Novel approaches are warranted over current treatments which could bypass the above shortcomings and form an effective and stable system. Hence, niacinamide has the potential to become an individual and a productive component with wide future scope.

In Vitro and In Silico Analysis of Ascorbic Acid Towards Lanosterol 14-α-Demethylase Enzyme of Fluconazole-Resistant Candida albicans

Antibiotic resistance is one of the major concerns and the biggest threats to the world population. The incidents of antibiotic resistance in Candida spp. were frequently recorded. In the present investigation, antifungal potential of ascorbic acid (AA) was evaluated. According to the in vitro analysis, the zone of inhibition of AA (24.75 ± 0.35 mm) against C. albicans was greater as compared to other vitamins tested. AA significantly modulate the growth of C. albicans at 25 mg/ml. The highest percentage (94.67%) of cell viability was observed in untreated cells, and low cell viability (29.36%) was observed in cells treated with 50 mg/ml of AA (2 × MIC). Further, AO/EB (acridine orange/ethidium bromide), propidium iodide staining, and real-time qPCR confirmed the loss of membrane integrity due to membrane lesions that caused cell death. Lanosterol 14-α-demethylase (L-14α-DM) is the product of ERG11 and acted as superior drug target of C. albicans. Molecular docking analysis confirmed that active interaction of ascorbic acid with L-14α-DM. Based on the present investigation, the efficiency of AA was effectively proved through the in vitro and in silico analysis. This finding has evidenced the effectiveness of AA as a potential candidate against C. albicans.

Protein Acetylation/Deacetylation: A Potential Strategy for Fungal Infection Control

Protein acetylation is a universal post-translational modification that fine-tunes the major cellular processes of many life forms. Although the mechanisms regulating protein acetylation have not been fully elucidated, this modification is finely tuned by both enzymatic and non-enzymatic mechanisms. Protein deacetylation is the reverse process of acetylation and is mediated by deacetylases. Together, protein acetylation and deacetylation constitute a reversible regulatory protein acetylation network. The recent application of mass spectrometry-based proteomics has led to accumulating evidence indicating that reversible protein acetylation may be related to fungal virulence because a substantial amount of virulence factors are acetylated. Additionally, the relationship between protein acetylation/deacetylation and fungal drug resistance has also been proven and the potential of deacetylase inhibitors as an anti-infective treatment has attracted attention. This review aimed to summarize the research progress in understanding fungal protein acetylation/deacetylation and discuss the mechanism of its mediation in fungal virulence, providing novel targets for the treatment of fungal infection.

Chromatin Structure and Drug Resistance in Candida spp

Anti-microbial resistance (AMR) is currently one of the most serious threats to global human health and, appropriately, research to tackle AMR garnishes significant investment and extensive attention from the scientific community. However, most of this effort focuses on antibiotics, and research into anti-fungal resistance (AFR) is vastly under-represented in comparison. Given the growing number of vulnerable, immunocompromised individuals, as well as the positive impact global warming has on fungal growth, there is an immediate urgency to tackle fungal disease, and the disturbing rise in AFR. Chromatin structure and gene expression regulation play pivotal roles in the adaptation of fungal species to anti-fungal stress, suggesting a potential therapeutic avenue to tackle AFR. In this review we discuss both the genetic and epigenetic mechanisms by which chromatin structure can dictate AFR mechanisms and will present evidence of how pathogenic yeast, specifically from the Candida genus, modify chromatin structure to promote survival in the presence of anti-fungal drugs. We also discuss the mechanisms by which anti-chromatin therapy, specifically lysine deacetylase inhibitors, influence the acquisition and phenotypic expression of AFR in Candida spp. and their potential as effective adjuvants to mitigate against AFR.

Histone acetylation/deacetylation in Candida albicans and their potential as antifungal targets

Recently, the incidence of invasive fungal infections has significantly increased. Candida albicans (C. albicans) is the most common opportunistic fungal pathogen that infects humans. The limited number of available antifungal agents and the emergence of drug resistance pose difficulties to treatment, thus new antifungals are urgently needed. Through their functions in DNA replication, DNA repair and transcription, histone acetyltransferases (HATs) and histone deacetylases (HDACs) perform essential functions relating to growth, virulence, drug resistance and stress responses of C. albicans. Here, we summarize the physiological and pathological functions of HATs/HDACs, potential antifungal targets and underlying antifungal compounds that impact histone acetylation and deacetylation. We anticipate this review will stimulate the identification of new HAT/HDAC-related antifungal targets and antifungal agents.

Minocycline and Fluconazole Have a Synergistic Effect Against Cryptococcus neoformans Both in vitro and in vivo

In recent decades, the incidence of Cryptococcus neoformans infection, which causes cryptococcosis, has consistently increased. Fluconazole (FLU) is frequently used in the treatment of this disease, mainly in the immunocompromised population, and long-term therapy usually produces drug resistance. Research on antifungal sensitizers has gained attention as a possible means of overcoming this drug resistance. Minocycline (MINO) has an inhibitory effect in vitro on FLU-resistant Candida albicans, and the combination of MINO and FLU has a synergistic effect on FLU-resistant C. albicans. A synergistic effect of MINO/FLU has been reported against C. neoformans, but this effect has not been evaluated on FLU-resistant isolates. This study aimed to investigate the interaction of MINO and FLU against FLU-resistant C. neoformans both in vitro and in vivo. We found that the combination of MINO and FLU had a synergistic effect on FLU-resistant C. neoformans in vitro. For all FLU-resistant strains, the minimum inhibitory concentration (MIC) of FLU decreased significantly when used in combination with MINO, dropping from >128 μg/ml down to 4–8 μg/ml. Additionally, MINO and FLU had a synergistic effect on both susceptible and resistant C. neoformans biofilms, in which the MIC of FLU decreased from >256 μg/ml down to 4–16 μg/ml. Compared with FLU alone, the combination of MINO with FLU prolonged the survival rate of Galleria mellonella larvae infected with FLU-resistant C. neoformans, and also significantly decreased the fungal burden of infected larvae and reduced the tissue damage and destruction caused by FLU-resistant C. neoformans. These findings will contribute to the discovery of antifungal agents and may yield a new approach for the treatment of cryptococcosis caused by FLU-resistant C. neoformans.

Nicotinamide as Independent Variable for Intelligence, Fertility, and Health: Origin of Human Creative Explosions?

Meat and nicotinamide acquisition was a defining force during the 2-million-year evolution of the big brains necessary for, anatomically modern, Homo sapiens to survive. Our next move was down the food chain during the Mesolithic 'broad spectrum', then horticultural, followed by the Neolithic agricultural revolutions and progressively lower average 'doses' of nicotinamide. We speculate that a fertility crisis and population bottleneck around 40 000 years ago, at the time of the Last Glacial Maximum, was overcome by Homo (but not the Neanderthals) by concerted dietary change plus profertility genes and intense sexual selection culminating in behaviourally modern Homo sapiens. Increased reliance on the 'de novo' synthesis of nicotinamide from tryptophan conditioned the immune system to welcome symbionts, such as TB (that excrete nicotinamide), and to increase tolerance of the foetus and thereby fertility. The trade-offs during the warmer Holocene were physical and mental stunting and more infectious diseases and population booms and busts. Higher nicotinamide exposure could be responsible for recent demographic and epidemiological transitions to lower fertility and higher longevity, but with more degenerative and auto-immune disease.