Research and References

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The complex chemical composition of propolis depends on the plant origin, geographical location and the collection seasons 2. Propolis contains various phytochemicals in different concentrations, such as phenolics, flavonoids, and alkaloids, which are responsible for its biological and pharmaceutical properties. Asian, African, and European propolis contains predominantly phenolics and flavonoids such as naringenin, galangin, pinocembrin, apigenin, pinobanksin, quercetin, cinnamic acid and its esters, kaempferol, chrysin, cinnamyl caffeate, cinnamylidene acetic acid, caffeic acid, rutin, ferulic acid, gallic acid, p-coumaric acid, aromatic acids and their esters 1,3.

Anti-inflammatory and immunomodulation

Propolis extract has the ability to modulate both pro-inflammatory and anti-inflammatory cytokines 3. Therefore, propolis may assist in the treatment and/or prevention of inflammatory diseases by acting as a natural anti-inflammatory agent by modulating the production of immune mediators 3.

In several studies, it has been shown that propolis has immunological activities. For example, Brazilian green propolis
exhibited antioxidant and anti-inflammatory activities in LPS-stimulated macrophage cell line J774A.1 by inhibiting the
production of reactive oxygen species, nitric oxide, and the pro-inflammatory cytokines TNF-α, IL-1, and IL-6 3.

Propolis also exhibits anti-inflammatory effects through the affecting of Toll-like receptors (TLRs), which recognise various
microbial receptors called pathogen-associated molecular patterns (PAMPs). Consequently, pro-inflammatory cytokines are released through the activation of NF-kB and other transcriptional factors. This response is mediated by B and T cells and results in pathogen-specific adaptive immunity. In an in vivo study, propolis administration to C57BL/6 mice for 14 days led to reduced production of IL-1, IL-6, IL-2, IL-10 and IFN-c from spleen cells. Furthermore, ethanolic propolis extract reduced the expression of IL-17 in collagen-induced arthritis in mice, indicating its benefits in autoimmunity. Propolis extracts also suppressed TNF-α and IL-6 production in a dose-dependent manner in LPS-stimulated human peripheral blood mononuclear cells. Propolis also increased the production of anti-inflammatory IL-10 in a dose-dependent manner. The cytokine IL-10 is a potent anti-inflammatory mediator; it reduces and terminates the ongoing inflammatory process 3.
Therefore, propolis and its constituents can be considered as potent natural anti-inflammatory agents that act by modulating immune responses.

Antimicrobial properties

Determination of the zone inhibitions of propolis in different bacteria strains showed that Gram-positive strains are more
sensitive than Gram-negative bacteria. Touzani et al. found that in the disc diffusion method, S. faecalis and S. aureus were the most sensitive and P. aeruginosa was the most resistant to propolis 3. Research showed that Bacillus subtilis and Streptococcus pyogenes were highly sensitive Gram-positive microorganisms to ethanol propolis extracts. In contrast, the aqueous extract of propolis showed low bactericidal activity against Gram-negative bacteria 1.
However, it has been reported to have antibacterial activity against both Gram-positive and Gram-negative microorganisms, including multidrug-resistant bacteria such as Methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, it was found that Turkish propolis has anti-tuberculosis activity against different types of mycobacteria 1.
It is documented to have different antibacterial mechanisms, including inhibition of cell division, collapsing cell membranes and cell walls, inhibition of bacterial motility, enzyme inactivation, bacteriolysis, and protein synthesis. These multi-target effects encouraged researchers to employ propolis to overcome the potential in drug resistance in microorganisms by combining propolis with antibiotics. Propolis extracts synergistically enhanced the efficacy of antibiotics, especially those that act on cell wall synthesis, such as vancomycin and oxacillin 1.

In addition, many studies have documented the remarkable action of propolis against many types of microorganisms,
including yeast, viruses, bacteria, and parasites. Al-ani et al. demonstrated antifungal activity against reference strains and clinical isolates. Candida glabrata, Candida parapsilosis, and Candida tropicalis were the most sensitive Candida species 1. Antiparasitic activity has been demonstrated against Trichomonas and amoebic infections.
 

Anticancer effect

Many reports have indicated that different types of honey and propolis extracts significantly inhibit cell growth and reduce the differentiation or proliferation of cells from various tumour cell lines. It was found that 50 g / ml of ethanolic extract of propolis from southern Poland exhibited 25% cytotoxicity in prostate cancer cells. An ethanolic extract of propolis at a concentration of 125 g/mL was cytotoxic in a MCF-7 cell line. Compared to these results, water-extracted propolis exhibited relatively low grade of cytotoxic effects 3.

References

1. Al-Ani I, Zimmermann S, Reichling J, Wink M. Antimicrobial Activities of European Propolis Collected from Various Geographic Origins Alone and in Combination with Antibiotics. Medicines (Basel). Jan 3 2018;5(1)doi:10.3390/medicines5010002
2. Zhang T, Omar R, Siheri W, et al. Chromatographic analysis with different detectors in the chemical characterisation
and dereplication of African propolis. Talanta. Mar 2014;120:181-90. doi:10.1016/j.talanta.2013.11.094
3. Touzani S, Embaslat W, Imtara H, et al. In Vitro Evaluation of the Potential Use of Propolis as a Multitarget Therapeutic Product: Physicochemical Properties, Chemical Composition, and Immunomodulatory, Antibacterial, and
Anticancer Properties. Biomed Res Int. 2019;2019:4836378. doi:10.1155/2019/4836378

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