Microbial Metabolism of Atovaquone and Cytotoxicity of the Produced Phase I Metabolite

Chemical Composition, Antifungal, and Cytotoxic Activities of Essential Oil From Brunfelsia uniflora Leaves

This study aimed to determine the phytochemical composition of the essential oil (EO) from Brunfelsia uniflora leaves and to evaluate its antifungal and cytotoxic activities. The EO was obtained by hydrodistillation and analyzed using GC-MS and GC-FID, leading to the identification of 39 compounds. The composition was predominantly terpenoid (65.7%), followed by non-terpenoid constituents (31.2%). The major compounds identified included phytol (13.2%), oleic acid (10.5%), phenylethyl alcohol (9.2%), and γ-eudesmol acetate (7.0%). The antifungal activity of the EO was evaluated against Candida species using the broth microdilution method. The EO exhibited strong inhibitory effects against C. albicans and C. orthopsilosis (MIC = 62.5 µg/mL), moderate activity against C. glabrata and C. rugosa (MIC = 250 µg/mL), and weak activity against C. tropicalis (MIC = 1000 µg/mL). The cytotoxic effects of the EO were assessed in human tumor cell lines (HeLa, MCF-7) and a nontumor fibroblast line (GM07492A). The EO demonstrated selective cytotoxicity toward HeLa (IC50 = 21.9 µg/mL) and MCF-7 (IC50 = 25.7 µg/mL), while exhibiting lower toxicity to fibroblasts (IC50 = 131.9 µg/mL). The selectivity indices (SI = 6.0 for HeLa, 5.1 for MCF-7) suggest its potential as a promising therapeutic candidate for antifungal and anticancer applications.

Efficacy of azithromycin combined with compounded atovaquone in treating babesiosis in giant pandas

BACKGROUND

Babesia is a tick-borne protozoan blood parasite that can cause hemolytic anemia, thrombocytopenia, lethargy and splenomegaly in giant pandas.

METHODS

We evaluated the efficacy and safety profile of a therapeutic regimen combining atovaquone and zithromycin in the context of babesiosis in giant pandas that have been naturally infected. The examined pandas underwent clinical and laboratory analyses, including hematology, biochemistry and thyroid hormone profiles. Upon diagnosis, the giant pandas were administered a compounded treatment consisting of atovaquone oral suspension (15 mg/kg, PO, q8 h), azithromycin tablets (10 mg/kg, PO, q24 h) and Enteral Nutritional Suspension (TPF) as a fat-rich supplement (0.5 ml/kg, PO, q8 h) for a 10-day period.

RESULTS

The combination treatment increased the red blood cell count, hemoglobin levels and hematocrit in the pandas within a short period, while also reducing parasite levels below the PCR detection threshold.

CONCLUSIONS

Our study suggested that atovaquone and azithromycin combination therapy is highly effective for emergency treatment of Babesia sp. infection in giant pandas.

Biotransformation of hydroxychloroquine to evaluate the cytotoxicity of its metabolites and mimic mammalian metabolism

Hydroxychloroquine (HCQ) displays attractive anti-inflammatory and antiviral effects. Because of that, such a drug made part of some clinical trials for combating Sars-CoV-2 during the COVID-19 pandemic. The present study aimed to conduct the biotransformation of HCQ by filamentous fungi reported as microbial models of mammalian drug metabolism to evaluate its cytotoxic after metabolization. Cunninghamella echinulata var. elegans ATCC 8688a could efficiently biotransform HCQ into one main metabolite identified as the new 4-(1,2,3,4-tetrahydroquinolin-4-ylamino)pentan-1-ol (HCQ-M). The microbial transformation occurred through N-dealkylation, 7-chloro-elimination, and reduction of the two conjugated double-bond from the quinoline system of HCQ. The cytotoxic profiles of HCQ and its metabolite were evaluated using CCD-1059Sk cells (human fibroblasts) through sulforhodamine B, trypan blue, and Live/Dead assays. Both HCQ and HCQ-M displayed cytotoxic activities in human fibroblasts, but HCQ-M was significantly more toxic than HCQ. The reported findings should be considered for further clinical studies of HCQ and will be important for guidance in achieving new derivatives from it.

The Etiology, Incidence, Pathogenesis, Diagnostics, and Treatment of Canine Babesiosis Caused by Babesia gibsoni Infection

Babesia gibsoni is one of the small Babesia species and the infection this pathogen causes is usually asymptomatic, which complicates the capture of potential parasite carriers. In endemic areas, especially in Asia, B. gibsoni occurs quite often due to direct transmission by way of a tick vector. Due to the absence of vectors, its occurrence is described only sporadically in Europe; but, it is increasingly occurring in predisposed, so-called fighting breeds, especially the American pit bull terrier. This review describes the etiology, incidence, clinical signs, pathogenesis, diagnostics, and treatment of B. gibsoni infection, with an emphasis on the clinical and laboratory peculiarities of the disease. As the treated dogs do not eliminate the parasite from the body-only reducing parasitemia and improving clinical signs-the treatment of B. gibsoni infection is a challenge in many cases, and its study therefore deserves great attention.

Ent-hardwickiic acid from C. pubiflora and its microbial metabolites are more potent than fluconazole in vitro against Candida glabrata

The incidence of Candida glabrata infections has rapidly grown and this species is among those responsible for causing invasive candidiasis with a high mortality rate. The diterpene ent-hardwickiic acid is a major constituent in Copaifera pubiflora oleoresin and the ethnopharmacological uses of this oleoresin by people from Brazilian Amazonian region point to a potential use of this major constituent as an antimicrobial. Therefore, the goal of this study was to evaluate the antifungal activity of ent-hardwickiic acid against Candida species and to produce derivatives of this diterpene by using microbial models for simulating the mammalian metabolism. The microbial transformations of ent-hardwickiic acid were carried out by Aspergillus brasiliensis and Cunninghamella elegans and hydroxylated metabolites were isolated and their chemical structures were determined. The antifungal activity of ent-hardwickiic acid and its metabolites was assessed by using the microdilution broth method in 96-well microplates and compared with that of fluconazole. All the diterpenes showed fungistatic effects (ranging from 19·7 to 75·2 µmol l^-1 ) against C. glabrata at lower concentrations than fluconazole (163·2 µmol l^-1 ) and were more potent fungicides (ranging from 39·5 to 150·4 µmol l^-1 ) than fluconazole, which showed fungicidal effect at the concentration of 326·5 µmol l^-1 .

Using Machine Learning Methods and Structural Alerts for Prediction of Mitochondrial Toxicity

Over the last few years more and more organ and idiosyncratic toxicities were linked to mitochondrial toxicity. Despite well-established assays, such as the seahorse and Glucose/Galactose assay, an in silico approach to mitochondrial toxicity is still feasible, particularly when it comes to the assessment of large compound libraries. Therefore, in silico approaches could be very beneficial to indicate hazards early in the drug development pipeline. By combining multiple endpoints, we derived the largest so far published dataset on mitochondrial toxicity. A thorough data analysis shows that molecules causing mitochondrial toxicity can be distinguished by physicochemical properties. Finally, the combination of machine learning and structural alerts highlights the suitability for in silico risk assessment of mitochondrial toxicity.

An Overview of Biotransformation and Toxicity of Diterpenes

Diterpenes have been identified as active compounds in several medicinal plants showing remarkable biological activities, and some isolated diterpenes are produced at commercial scale to be used as medicines, food additives, in the synthesis of fragrances, or in agriculture. There is great interest in developing methods to obtain derivatives of these compounds, and biotransformation processes are interesting tools for the structural modification of natural products with complex chemical structures. Biotransformation processes also have a crucial role in drug development and/or optimization. The understanding of the metabolic pathways for both phase I and II biotransformation of new drug candidates is mandatory for toxicity and efficacy evaluation and part of preclinical studies. This review presents an overview of biotransformation processes of diterpenes carried out by microorganisms, plant cell cultures, animal and human liver microsomes, and rats, chickens, and swine in vivo and highlights the main enzymatic reactions involved in these processes and the role of diterpenes that may be effectively exploited by other fields.

Antiprotozoal treatment of canine babesiosis

Canine babesiosis is a tick-borne disease caused by several Babesia spp. which have different susceptebility to anti-protozoal drugs. A few drugs and drug combinations are used in the treatment of canine babesiosis often without complete parasite elimination leaving treated dogs as carriers which could relapse with clinical disease and also transmit infection further. Although the large form canine babesial species Babesia canis, Babesia vogeli and Babesia rossi are sensitive to the aromatic diamidines imidocarb dipropionate and diminazene aceturate, small form species such as Babesia gibsoni, Babesia conradae and Babesia vulpes (Theileria annae) are relatively resistant to these drugs and are treated with the combination of the hydroxynaphthoquinone atovaquone and the antibiotic azithromycin. Azithromycin and other antibiotics that have anti-protozoal properties target the apicoplast, a relict plastid found in protozoa, and exert a delayed death effect. The triple combination of clindamycin, diminazene aceturate and imidocarb dipropionate is also effective against B. gibsoni and used to treat atovaquone-resistant strains of this species. Novel drugs and the synergistic effects of drug combinations against Babesia infection should be explored further to find new treatments for canine babesiosis.