Antifungal activity of cercosporamide produced by Phaeosphaeriaceae GV-1 against pathogenic fungi.

Fungal infections affect millions of people worldwide, and the several cases are related to invasive infections, which is a problem mainly for immunocompromised people, such as transplant and cancer patients with high mortality and morbidity rates. In addition, the number of emerging and multidrug-resistant fungal species has increased in the last decade. The search for new antifungal compounds is necessary, due to the increase in cases of resistance and the toxicity of drugs used in fungal infection treatment. This work aimed to study the antifungal activity of cercosporamide produced by Phaeosphaeriaceae GV-1. Cercosporamide was tested against pathogenic fungi by determining the minimum inhibitory (MIC) and minimum fungicidal (MFC) concentrations, using the broth microdilution method. Cercosporamide showed antifungal activity in vitro against 13 of 16 strains of medical importance tested, with the most susceptible species being Candida tropicalis, with MIC and MFC of 15.6 µg/mL. Thus, cercosporamide might be considered a promising therapeutic antifungal agent.

Besifloxacin Nanocrystal: Towards an Innovative Ophthalmic Preparation.

Bacterial conjunctivitis significantly impacts public health, including more than one-third of eye diseases reported worldwide. It is an infection caused by various aerobic and anaerobic bacteria and is highly contagious. Therefore, it has a high incidence of bacterial resistance to the antibiotics commonly used for treatment. Among the most recent antibiotics, besifloxacin is a fourth-generation fluoroquinolone antibiotic indicated exclusively for topical ophthalmic use. Due to its importance in treating bacterial conjunctivitis and its low solubility in water, limiting its efficacy, a nanotechnology-based drug delivery preparation was developed to overcome this hurdle. Besifloxacin nanocrystals were prepared by small-scale wet milling and response surface methodology, using Povacoat® as a stabilizer. The particle's average hydrodynamic diameter (Z-ave) was approximately 550 nm (17 times smaller than raw material), with a polydispersity index (PdI) of less than 0.2. The saturation solubility increased about two times compared to the raw material, making it possible to increase the dissolution rate of this drug substance, potentially improving its bioavailability and safety. The optimized preparation was stable under an accelerated stability study (90 days). The Z-ave, PZ, PdI, and content did not alter significantly during this period. Furthermore, the 0.6% m/m besifloxacin nanocrystals at the maximum dose and the Povacoat® stabilizer did not show toxicity in Galleria mellonella larvae. The innovative ophthalmic preparation minimum inhibitory concentration (MIC) was 0.0960 µg/mL and 1.60 µg/mL against Staphylococcus aureus and Pseudomonas aeruginosa, respectively, confirming in vitro efficacy. Therefore, besifloxacin nanocrystals revealed the potential for reduced dosing of the drug substance, with a minor occurrence of adverse effects and greater patient adherence to treatment.

Ketoconazole/calix[n]arenes-based compounds improve the antifungal activity against azole-resistant Candida isolates.

Ketoconazole (KTZ) is an antifungal agent; however, its bioavailability and therapeutic efficacy are reduced by the low aqueous solubility of the drug. Aiming at providing to improve the biopharmaceutical properties of KTZ, we studied the water-soluble different calix[n]arenes as carrier systems for KTZ. All calix[n]arene-KTZ tested showed in vitro antifungal activity superior or similar to free KTZ against Candida spp. The CX6Na/KTZ obtained by physical mixture and freeze-drying methods were the most active, decreasing KTZ concentrations required for growth inhibition against azole-resistant isolates (e.g., C. auris). Moreover, CX6Na/KTZ showed no toxic effect on Galleria mellonella larvae and the treatment of infected larvae with C. albicans and C. auris was effective at a lower dose compared with free KTZ. Thus, CX6Na/KTZ may have a potential approach to treat mycosis, especially by improvement of KTZ inhibitory activity against azole-resistant Candida.

In Vitro and In Vivo Antifungal Activity of Buparvaquone against Sporothrix brasiliensis.

Sporotrichosis has become an important zoonosis in Brazil, and Sporothrix brasiliensis is the primary species transmitted by cats. Improvement of animal treatment will help control and limit the spread and geographic expansion of sporotrichosis. Accordingly, buparvaquone, an antiprotozoal hydroxynaphthoquinone agent marketed as Butalex, was evaluated in vitro and in vivo against feline-borne isolates of S. brasiliensis. Buparvaquone inhibited in vitro fungal growth at concentrations 4-fold lower than itraconazole (the first-choice antifungal used for sporotrichosis) and was 408 times more selective for S. brasiliensis than mammalian cells. Yeasts treated with a subinhibitory concentration of buparvaquone exhibited mitochondrial dysfunction, reactive oxygen species and neutral lipid accumulation, and impaired plasma membranes. Scanning electron microscopy images also revealed buparvaquone altered cell wall integrity and induced cell disruption. In vivo experiments in a Galleria mellonella model revealed that buparvaquone (single dose of 5 mg/kg of body weight) is more effective than itraconazole against infections with S. brasiliensis yeasts. Combined, our results indicate that buparvaquone has a great in vitro and in vivo antifungal activity against S. brasiliensis, revealing the potential application of this drug as an alternative treatment for feline sporotrichosis.

Miltefosine as an alternative strategy in the treatment of the emerging fungus Candida auris.

OBJECTIVES: Candida auris (C. auris) is an emerging fungal species that is able to develop multidrug resistance and outbreaks of invasive infections worldwide with high mortality rates. To increase the treatment options for C. auris infection this study assessed the efficacy of miltefosine (MFS), that has demonstrated a broad-spectrum antifungal action in vitro. This study aimed to: (i) evaluate the in vitro antifungal activity of MFS against C. auris clinical isolates in the planktonic and biofilm lifestyles; and (ii) compare the activity of MFS in its free form and encapsulated in alginate nanoparticles (MFS-AN) in Galleria mellonella larvae infected by C. auris. METHODS: The antifungal susceptibility test was performed using broth microdilution method and the in vivo treatment in Galleria mellonella larval infection model. RESULTS: MFS exhibited in vitro inhibitory effects at MICs ranging 1-4 µg/mL and fungicidal activity against planktonic cells of C. auris clinical isolates. MFS antibiofilm activity was observed during biofilm formation (0.25-4 µg/mL) and on pre-formed biofilms (16-32 µg/mL). Moreover, the dispersed cells from C. auris biofilms had a similar susceptibility to those obtained for planktonic cells. Treatment with free MFS or MFS-AN resulted in significant improvements in the survival and morbidity rates of Galleria mellonella larvae infected by C. auris. In addition, reduction of fungal burden (0.5-1 log CFU/g) and granuloma formation were observed when compared with the untreated group. CONCLUSIONS: The findings suggest that both the free MFS and MFS-AN have potential for the treatment of fungal infections caused by the emerging C. auris.