The Effects of Tormentic Acid and Extracts from Callistemon citrinus on Candida albicans and Candida tropicalis Growth and Inhibition of Ergosterol Biosynthesis in Candida albicans

Formulation of a herbal topical cream against Tinea capitis using flavonoids glycosides from Dicerocaryum senecioides and Diospyros mespiliformis

Topical fungal infections including, Tinea capitis with escalating resistance to conventional therapies are a rising concern globally. Studies have shown substantial in vitro efficacy of plant compounds against fungal pathogens. This study utilized flavonoid glycosides from Dicerocaryum senecioides and Diospyros mespiliformis as active compounds to formulate a topical cream against Tinea capitis. The in vitro test utilized disc diffusion assay prepared from fungal isolates obtained from individuals showing resistance to topical miconazole. Clinical trials were performed using volunteers. Both isolated strains exhibited substantial in vitro susceptibility to the cream formulation with inhibition zones ranging between 10 and 18 mm. MIC values for both test organisms ranged between 85 mg/ml and 120 mg/ml. The cream showed stability both physico-chemically and against microbial contamination. Physicochemical parameters evaluated include colour, pH, appearance, particle size, phase separation, phase inversion, creaming, spread-ability, electrical conductivity and in vitro occlusivity test and were within the accepted range. In limited clinical trials using volunteers, Tinea capitis started disappearing as from day 5 by topically applying the cream twice per day. All the patients were completely healed by the 7th day. The results of the study showed that flavonoid glycosides from D. senecioides and D. mespiliformis are good candidates to be utilized as active natural compounds against Tinea capitis resistant strains. Therefore more clinical trials and structural elucidations are recommended.

In silico Prediction and Pharmacokinetic Studies on Glucosinolates as a Potential Drug and Key Inhibitor Molecule for Lanosterol-14α- demethylase: A Fungal Membrane Biosynthesis Enzyme

BACKGROUND

Glucosinolates (β-thioglucoside-N-hydroxysulfates) are a water-soluble organic anion with sulfur- and nitrogen-containing glycosides which are found in abundance in Cruciferous plants. Ergosterol (ERG13) lanosterol-14α-demethylase protein has been targeted for inhibition studies as a key regulator enzyme of fungal membrane biosynthesis.

OBJECTIVES

To understand the molecular mechanism of inhibition of Ergosterol (ERG13) lanosterol- 14α-demethylase by various phytochemicals from brassicales, i.e., glucosinolates and their potential role as putative drug molecules.

METHODS

In this study, in silico analyses were performed to predict the molecular basis of various glucosinolates as a potential inhibitor of lanosterol-14α-demethylase protein, which is a key regulator of fungal membrane biosynthesis and its pharmacodynamics and toxicity profile. 3d structures of various glucosinolates were retrieved from PubChem, and the target protein, lanosterol-14α-demethylase (Pdb ID- 4lxj), was retrieved from the RCSB protein data bank. Molecular docking and interactions were carried out using the PyRx software using the AutoDOCK toolbar with default parameters. Dru- LiTo, ORISIS web servers were used to predict various drug likeliness predictions and Lipinski's Rule of 5, whereas admetSAR was used for prediction of toxicity, and PASS Program was used to study the antifungal and antimicrobial properties of these compounds.

RESULTS

This study shows that among the different compounds screened, gluconasturtiin, Glucotropaeolin, and Indolylmethyl-Glucosinolate showed the highest binding energies of -8.7 kcal/mol, -8.5 kcal/mol, and -8.3 kcal/mol with the lanosterol-14α-demethylase, respectively. Further all the compounds follow the Lipinski's rule as well as they are found to be non-carcinogenic and non-cytotoxic in nature. These compounds also show antifungal properties.

CONCLUSION

This study thus reveals that various glucosinolates interact with the ERG13 enzyme at various amino acid positions, which behaves as a catalytic site, thus indicates the probable mechanism of inactivation, and subsequently, these can be used as potential drug molecules. In vitro studies can be taken to further examine the utility of these compounds as antifungal agents.

Evaluation of the Anti-Histoplasma capsulatum Activity of Indole and Nitrofuran Derivatives and Their Pharmacological Safety in Three-Dimensional Cell Cultures

Histoplasma capsulatum is a fungus that causes histoplasmosis. The increased evolution of microbial resistance and the adverse effects of current antifungals help new drugs to emerge. In this work, fifty-four nitrofurans and indoles were tested against the H. capsulatum EH-315 strain. Compounds with a minimum inhibitory concentration (MIC₉₀) equal to or lower than 7.81 µg/mL were selected to evaluate their MIC₉₀ on ATCC G217-B strain and their minimum fungicide concentration (MFC) on both strains. The quantification of membrane ergosterol, cell wall integrity, the production of reactive oxygen species, and the induction of death by necrosis–apoptosis was performed to investigate the mechanism of action of compounds 7, 11, and 32. These compounds could reduce the extracted sterol and induce necrotic cell death, similarly to itraconazole. Moreover, 7 and 11 damaged the cell wall, causing flaws in the contour (11), or changing the size and shape of the fungal cell wall (7). Furthermore, 7 and 32 induced reactive oxygen species (ROS) formation higher than 11 and control. Finally, the cytotoxicity was measured in two models of cell culture, i.e., monolayers (cells are flat) and a three-dimensional (3D) model, where they present a spheroidal conformation. Cytotoxicity assays in the 3D model showed a lower toxicity in the compounds than those performed on cell monolayers. Overall, these results suggest that derivatives of nitrofurans and indoles are promising compounds for the treatment of histoplasmosis.

Potential Inhibitors of CYP51 Enzyme in Dermatophytes by Red Sea Soft Coral Nephthea sp.: In Silico and Molecular Networking Studies

In this study, the n-hexane fraction of soft coral Nephthea sp. gathered from the Red Sea was evaluated for its antidermatophyte activity. The antidermatophyte activity was performed versus different fungi, including Microsporum canis, Trichophyton gypseum, and Microsporum mentagrophytes, using a broth microdilution method. The n-hexane fraction showed minimum inhibitory concentrations (MICs) against the tested dermatophytes of 104.2 ± 20.8, 125 ± 0.0, and 83.33 ± 20.83 μg/mL respectively. The chemical constitution of the lipoidal matter (n-hexane fraction) was characterized by gas chromatography coupled with a mass spectrometer (GC-MS). The unsaponifiable fraction (USAP) of Nephthea sp. showed relative percentages of hydrocarbons and vitamins of 69.61% and 3.26%, respectively. Moreover, the percentages of saturated and unsaturated fatty acids were 53.67% and 42.05%, respectively. In addition, a molecular networking study (MN) of the GC-MS analysis performed using the Global Natural Products Social Molecular Networking (GNPS) platform was described. The molecular docking study illustrated that the highest binding energy score for spathulenol toward the CYP51 enzyme was -8.3674 kcal/mol, which predicted the mode of action of the antifungal activity, and then the results were confirmed by the inhibitory effect of Nephthea sp. against CYP51 with an IC₅₀ value of 12.23 μg/mL. Our results highlighted the antifungal potential of Nephthea sp. metabolites.

Emerging Antifungal Targets and Strategies

Despite abundant research in the field of antifungal drug discovery, fungal infections remain a significant healthcare burden. There is an emerging need for the development of novel antifungals since those currently available are limited and do not completely provide safe and secure protection. Since the current knowledge regarding the physiology of fungal cells and the infection mechanisms is greater than ever, we have the opportunity to use this for the development of novel generations of antifungals. In this review, we selected and summarized recent studies describing agents employing different antifungal mechanisms. These mechanisms include interference with fungal resistance, including impact on the efflux pumps and heat shock protein 90. Additionally, interference with virulence factors, such as biofilms and hyphae; the impact on fungal enzymes, metabolism, mitochondria, and cell wall; and antifungal vaccines are explored. The agents investigated belong to different classes of natural or synthetic molecules with significant attention given also to plant extracts. The efficacy of these antifungals has been studied mainly in vitro with some in vivo, and clinical studies are needed. Nevertheless, there is a large quantity of products employing novel antifungal mechanisms that can be further explored for the development of new generation of antifungals.