Getting the Jump on the Development of Bullfrog Oil Microemulsions: a Nanocarrier for Amphotericin B Intended for Antifungal Treatment

Abstract

Amphotericin B (AmB), a potent antifungal drug, presents physicochemical characteristics that impair the development of suitable dosage forms. In order to overcome the AmB insolubility, several lipid carriers such as microemulsions have been developed. In this context, the bullfrog oil stands out as an eligible oily phase component, since its cholesterol composition may favor the AmB incorporation. Thus, the aim of this study was to develop a microemulsion based on bullfrog oil containing AmB. Moreover, its thermal stability, antifungal activity, and cytotoxicity in vitro were evaluated. The microemulsion formulation was produced using the pseudo-ternary phase diagram (PTPD) approach and the AmB was incorporated based on the pH variation technique. The antifungal activity was evaluated by determination of minimal inhibitory concentration (MIC) against different species of Candida spp. and Trichosporon asahii. The bullfrog oil microemulsion, stabilized with 16.8% of a surfactant blend, presented an average droplet size of 26.50 ± 0.14 nm and a polydispersity index of 0.167 ± 0.006. This system was able to entrap AmB up to 2 mg mL. The use of bullfrog oil as oily phase allowed an improvement of the thermal stability of the system. The MIC assay results revealed a growth inhibition for different strains of Candida spp. and were able to enhance the activity of AmB against T. asahii. The microemulsion was also able to reduce the AmB toxicity. Finally, the developed microemulsion showed to be a suitable system to incorporate AmB, improving the system's thermal stability, increasing the antifungal activity, and reducing the toxicity of this drug.

Bullfrog Oil Reduces the Carrageenan-induced Edema in Wistar Rats by <i>in vitro</i> Reduction of Inflammatory Mediators

“…The results showed that both BFO and BFO-CV were not able to decrease the cell viability at all tested times and concentrations, suggesting an absence of toxicity of these products against macrophages Raw 264.7 . These data are in accordance to previous literature reports regarding the cytotoxicity evaluation of BFO against an epithelial cell lineage 3T3 and a macrophage cell lineage Raw 264.7 6,29 . These reports revealed that both BFO and its emulsified system, at concentrations up to 100 µg.mL 1 , did not show cytotoxicity up to 72 hours of treatment against these cell lineages.…”

Buccal Bullfrog (Rana catesbeiana Shaw) Oil Emulsion: A Mucoadhesive System Intended for Treatment of Oral Candidiasis

“…The fungal MIC was performed using the biological strains aforementioned (Section 2.1.2). The inocula were diluted in Mueller–Hinton broth (MHB) at the ratio of 1:30 according to an adaptation from the method described by Oliveira et al (2018) [18]. The BBE and the BME were diluted in sterile MHB and bullfrog oil was diluted with DMSO at 1% in sterile MHB in order to obtain an oil concentration of 4 mg·mL −1 for all samples.…”

“…Turk’s solution at 1% and saline solution at 0.9% were used as positive and negative control, respectively. Finally, the hemolytic potential was calculated according to the Equation (1) [18]:Hp(%)=100×As−AnAp where, Hp = Hemolytic potential (in percentage); As = Absorbance of tested sample; An = Absorbance of the Negative Control; Ap = Absorbance of the Positive Control.…”

“…To overcome these drawbacks, the development of an emulsified system to deliver the bullfrog oil and to allow its adherence to the buccal mucosa could be a technological approach that enables its use for treatment of OC. Examples of emulsified systems are microemulsion [18], topical nanoemulsion for external use [17], and oral nanoemulsion [19], already developed by our research group. Indeed, such systems, composed of aqueous and oily phases stabilized by a surfactant blend [20], allow the internalization of bullfrog oil in its droplets and, through the use of pharmaceutical excipients, may increase the adherence of this oil into the buccal mucosa, allowing contact to the microorganisms of the oral cavity, and consequently improving its antimicrobial activity [21].…”

Study on the bacteriostatic action of Chinese herbal medicine on avian Trichosporon

“…Studies of Oliveira et al. have shown that bullfrog oil obtained from adipose tissues of amphibious wood frogs could significantly enhance antifungal activities of AMB and reduce its toxicity ( Oliveira et al., 2018 ). Ludwig et al.…”