Potential of propolis antifungal activity for clinical applications

Identification of potential markers of elevated anticandidal activity of propolis extracts

ETHNOPHARMACOLOGICAL RELEVANCE

For centuries, propolis has been one of the most important and popular antimicrobial (antibacterial and antifungal) agents used in traditional medicine worldwide, including Central and Eastern Europe. Despite centuries of use of this product, the molecular mechanisms of its activity remain not fully recognized, and the components that determine its biological activity have not been identified.

AIM OF THE STUDY

Hence, the main goal of the present study was to identify propolis ingredients that are crucial for the antifungal activity of this product.

MATERIALS AND METHODS

A serial two-fold microdilution method was applied to evaluate the activity of 83 ethanolic extracts of propolis (EEP) samples collected in different regions of Poland. The chemical composition of all EEPs was determined using UHPLC-DAD and UHPLC-QqTOF-MS methods. Advanced chemometric analysis of the correlation between antifungal activity and chemical composition was performed to identify the components related to the increased antifungal potential of propolis. Subsequently, the antifungal activities of pure "active ingredients" and their combinations were determined.

RESULTS

Only seven extracts (8.4 %) exhibited high anticandidal potential with MIC (Minimum Inhibitory Concentration) values between 32 and 256 μg/mL. The identified most important potential markers related to increased antifungal activity of propolis collected in East Europe are: pinocembrin, pinobanksin-3-acetate, chrysin, galangin, pinobanksin, techtochrysin, genkwanin, pinostrobin and sakuranetin isomer. However, the pure compounds did not inhibit the growth of Candida spp. up to a concentration of 256 μg/mL (MIC >256 μg/mL). Much better activity was observed for combinations of these ingredients. The highest activity was observed for a mixture of five compounds: chrysin, galangin, pinocembrin, pinobanksin, and pinobanksin-3-acetate, with MIC and MFC (Minimal Fungicidal Concentration) values 64 and 128 μg/mL (summary concentration of all compounds - 12.8 or 25.6 of each μg/mL), respectively.

CONCLUSIONS

The relatively low number of propolis samples collected in Poland exhibit considerable activity against Candida spp. Markers of elevated antifungal potential have been identified. Moreover, it has been proved, that only the composition of these compounds (not pure ingredients alone) is effective in the treatment of Candida spp. Mixtures of these ingredients can be considered as potential antifungal agents (artificial propolis). Moreover, UHPLC-DAD and UHPLC-QqTOF-MS methods of determining the chemical composition of EEPs have been optimized.

Brazilian Green Propolis Extract-Loaded Poly(Ε-Caprolactone) Nanoparticles Coated with Hyaluronic Acid: Antifungal Activity in a Murine Model of Vulvovaginal Candidiasis

Brazilian green propolis extract-loaded poly(ε-caprolactone) nanoparticles coated with hyaluronic acid (PE-NPsHA) were developed as a therapeutic strategy to treat vulvovaginal candidiasis (VVC) and combat the growing issue of fungal resistance. The chemical composition of PE was analyzed using UHPLC-MS/MS, revealing the presence of various bioactive compounds, such as phenolic acids, flavonoids, coumarins, and quinones. These compounds were encapsulated into the polymeric matrix of NPs, as indicated by FTIR and DSC. In addition, PE-NPsHA were characterized by DLS, AFM, encapsulation efficiency (EE), and in vitro release study. They displayed a spherical morphology with a hydrodynamic diameter of 170 nm, a low polydispersity index of 0.1, a zeta potential of -28.5 mV, and an EE of 78%. The in vitro release study indicated a controlled and sustained release of PE over a period of 96 h. The in vitro and in vivo PE-NPsHA biocompatibility were investigated as well as their antifungal activity in a murine model of VVC. PE-NPsHA did not impact the HaCaT cell viability and demonstrated no signs of in vivo vaginal toxicity. PE-NPsHA exhibited in vivo antifungal efficacy, effectively eliminating Candida albicans infection. PE-NPsHA could expand the available treatment options for VVC and counteract Candida resistance to antifungal drugs.

A novel black poplar propolis extract with promising health-promoting properties: focus on its chemical composition, antioxidant, anti-inflammatory, and anti-genotoxic activities

Propolis is a resinous mixture produced by honeybees which has been used since ancient times for its useful properties. However, its chemical composition and bioactivity may vary, depending on the geographical area of origin and the type of tree bees use for collecting pollen. In this context, this research aimed to investigate the total phenolic content (using the Folin-Ciocalteu assay) and the total antioxidant capacity (using the FRAP, DPPH, and ABTS assays) of three black poplar (Populus nigra L.) propolis (BPP) solutions (S1, S2, and S3), as well as the chemical composition (HPLC-ESI-MSn) and biological activities (effect on cell viability, genotoxic/antigenotoxic properties, and anti-inflammatory activity, and effect on ROS production) of the one which showed the highest antioxidant activity (S1). The hydroalcoholic BPP solution S1 was a prototype of an innovative, research-type product by an Italian nutraceutical manufacturer. In contrast, hydroalcoholic BPP solutions S2 and S3 were conventional products purchased from local pharmacy stores. For the three extracts, 50 phenolic compounds, encompassing phenolic acids and flavonoids, were identified. In summary, the results showed an interesting chemical profile and the remarkable antioxidant, antigenotoxic, anti-inflammatory and ROS-modulating activities of the innovative BPP extract S1, paving the way for future research. In vivo investigations will be a possible line to take, which may help corroborate the hypothesis of the potential health benefits of this product, and even stimulate further ameliorations of the new prototype.

Antifungal Activity of Mexican Propolis on Clinical Isolates of Candida Species

Infections caused by micro-organisms of the genus Candida are becoming a growing health problem worldwide. These fungi are opportunistic commensals that can produce infections—clinically known as candidiasis—in immunocompromised individuals. The indiscriminate use of different anti-fungal treatments has triggered the resistance of Candida species to currently used therapies. In this sense, propolis has been shown to have potent antimicrobial properties and thus can be used as an approach for the inhibition of Candida species. Therefore, this work aims to evaluate the anti-Candida effects of a propolis extract obtained from the north of Mexico on clinical isolates of Candida species. Candida species were specifically identified from oral lesions, and both the qualitative and quantitative anti-Candida effects of the Mexican propolis were evaluated, as well as its inhibitory effect on C. albicans isolate’s germ tube growth and chemical composition. Three Candida species were identified, and our results indicated that the inhibition halos of the propolis ranged from 7.6 to 21.43 mm, while that of the MFC and FC₅₀ ranged from 0.312 to 1.25 and 0.014 to 0.244 mg/mL, respectively. Moreover, the propolis was found to inhibit germ tube formation (IC₅₀ ranging from 0.030 to 1.291 mg/mL). Chemical composition analysis indicated the presence of flavonoids, including pinocembrin, baicalein, pinobanksin chalcone, rhamnetin, and biochanin A, in the Mexican propolis extract. In summary, our work shows that Mexican propolis presents significant anti-Candida effects related to its chemical composition, and also inhibits germ tube growth. Other Candida species virulence factors should be investigated in future research in order to determine the mechanisms associated with antifungal effects against them.