Search

Secretory phospholipase B1 (PLB1) and biofilms act as microbial virulence factors and play an important role in pulmonary cryptococcosis. This study aims to formulate the ethanolic extract of propolis-loaded niosomes (Nio-EEP) and evaluate the biological activities occurring during PLB1 production and biofilm formation of Cryptococcus neoformans. Some physicochemical characterizations of niosomes include a mean diameter of 270 nm in a spherical shape, a zeta-potential of −10.54 ± 1.37 mV, and 88.13 ± 0.01% entrapment efficiency. Nio-EEP can release EEP in a sustained manner and retains consistent physicochemical properties for a month. Nio-EEP has the capability to permeate the cellular membranes of C. neoformans, causing a significant decrease in the mRNA expression level of PLB1. Interestingly, biofilm formation, biofilm thickness, and the expression level of biofilm-related genes (UGD1 and UXS1) were also significantly reduced. Pre-treating with Nio-EEP prior to yeast infection reduced the intracellular replication of C. neoformans in alveolar macrophages by 47%. In conclusion, Nio-EEP mediates as an anti-virulence agent to inhibit PLB1 and biofilm production for preventing fungal colonization on lung epithelial cells and also decreases the intracellular replication of phagocytosed cryptococci. This nano-based EEP delivery might be a potential therapeutic strategy in the prophylaxis and treatment of pulmonary cryptococcosis in the future.

Herpes simplex type 2 (HSV-2) infection causes a significant life-long disease. Long-term side effects of antiviral drugs can lead to the emergence of drug resistance. Thus, propolis, a natural product derived from beehives, has been proposed to prevent or treat HSV-2 infections. Unfortunately, therapeutic applications of propolis are still limited due its poor solubility. To overcome this, a nanoparticle-based drug delivery system was employed. An ethanolic extract of propolis (EEP) was encapsulated in nanoparticles composed of poly(lactic-co-glycolic acid) and chitosan using a modified oil-in-water single emulsion by using the solvent evaporation method. The produced nanoparticles (EEP-NPs) had a spherical shape with a size of ~450 nm and presented satisfactory physicochemical properties, including positively charged surface (38.05 ± 7.65 mV), high entrapment efficiency (79.89 ± 13.92%), and sustained release profile. Moreover, EEP-NPs were less cytotoxic on Vero cells and exhibited anti-HSV-2 activity. EEP-NPs had a direct effect on the inactivation of viral particles, and also disrupted the virion entry and release from the host cells. A significant decrease in the expression levels of the HSV-2 replication-related genes (ICP4, ICP27, and gB) was also observed. Our study suggests that EEP-NPs provide a strong anti-HSV-2 activity and serve as a promising platform for the treatment of HSV-2 infections.