Evaluation of the antifungal properties of nanoliposomes containing rhinacanthin-C isolated from the leaves of Rhinacanthus nasutus.

ABSTRACT

Fungal infections represent a challenging threat to the human health. Microsporum gypseum and Trichophyton rubrum are pathogenic fungi causing various topical mycoses in humans. The globally emerging issue of resistance to fungi demands the development of novel therapeutic strategies. In this context, the application of nanoliposomes as vehicles for carrying active therapeutic agents can be a suitable alternative. In this study, rhinacanthin-C was isolated from Rhinacanthus naustus and encapsulated in nano-liposomal formulations, which were prepared by the modified ethanol injection method. The two best formulations composed of soybean phosphatidylcholine (SPC), cholesterol (CHL), and tween 80 (T80) in a molar ratio of 110 (F1) and 110.5 (F2) were proceeded for experimentation. The physical characteristics and antifungal activities were performed and compared with solutions of rhinacanthin-C. The rhinacanthin-C encapsulating efficiencies in F1 and F2 were 94.69 ± 1.20% and 84.94 ± 1.32%, respectively. The particle sizes were found to be about 221.4 ± 13.76 nm (F1) and 115.8 ± 23.33 nm (F2), and zeta potential values of -38.16 mV (F1) and -40.98 mV (F2). Similarly, the stability studies of rhinacanthin-C in liposomes demonstrated that rhinacanthin-C in both formulations was more stable in mediums with pH of 4.0 and 6.6 than pure rhinacanthin-C when stored at the same conditions. Rhinacanthin-C in F1 was slightly more stable than F2 when stored in mediums with a pH of 10.0 after three months of storage. However, rhinacanthin-C in both formulations was less stable than pure rhinacanthin-C in a basic medium of pH 10.0. The antifungal potential was evaluated against M. gypsum and T. rubrum. The findings revealed a comparatively higher zone of inhibition for F1. In the MIC study, SPC CHL T80 showed higher inhibition against M. gypseum and a slightly higher inhibition against T. rubrum compared to free rhinacanthin-C solution. Moreover, rhinacanthin-C showed significant interaction against 14α-demethylase in in silico study. Overall, this study demonstrates that nanoliposomes containing rhinacanthin-C can improve the stability and antifungal potential of rhinacanthin-C with sustained and prolonged duration of action and could be a promising vehicle for delivery of active ingredients for targeting various fungal infections.