Propolis is a honey-related product with reported health benefits such as improved immunity, lowered blood pressure, treated allergies and skin conditions.
Propolis, referred to as bee glue, is produced by bees in the construction and maintenance of their hives. Bees produce propolis using a combination of beeswax and saliva, where it acts as the defence mechanism for the hive.
To date, propolis has been extensively researched in thousands of scientific papers on its bioactivity and health benefits.
The protective immune defence and antioxidant properties of propolis come from the bioactive phytochemicals’ constituents. Multiple compounds have been identified in propolis and differ based on the location of production. The compounds in propolis include phenolic acids, flavonoids, esters, diterpenes, sesquiterpenes, lignans, aromatic aldehydes, alcohols, amino acids, fatty acids, vitamins and minerals.
The exact composition of a propolis sample will vary between hives, location and seasons. Given that the function of propolis is to support the sterility and health of the beehive, the protective properties of the bioactives found in propolis can provide significant benefits for human health.
Propolis has attracted attention in recent years due to its reported benefits, which make it a potential preventive and therapeutic agent. The sales of propolis products is growing, and in many commercial settings supply cannot keep up with demand. Sales on propolis containing oral health and wound care products appear at the top of the category list.
Oxidative and Inflammatory Effects of Propolis
Free Radicals and Oxidative Stress
The antioxidant activity of propolis and its constituents has been well documented, with the vast majority of outcomes demonstrating a reduction in oxidative stress markers. In order to reduce the oxidative stress-induced tissue damage, endogenous antioxidant systems have developed protective mechanisms including enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT), and antioxidant nutrients ascorbic acid, glutathione and flavonoids.
Malondialdehyde concentrations are commonly being used as potential oxidative stress biomarkers and indicators of oxidative lipid damage. The chemical structure of the constituent polyphenols enable propolis to effectively eliminate free radicals. The flavonoids in propolis are powerful antioxidants, capable of scavenging free radicals and thereby protecting the cell membrane against lipid peroxidation.
The most important organ of the central nervous system, the brain, is more sensitive to free radical-induced damage because of its high use of oxygen, its high concentration of polyunsaturated fatty acids, and its low concentration of antioxidant molecules compared to other tissues
In the brain, oxidative stress results in acute and chronic injury and plays an important role in the pathogenesis of neuronal damage. Propolis and its derivatives appear to prevent oxidative stress in radiation-injured brain tissue by decreasing the formation of lipid peroxidation and increasing the antioxidant enzyme activities, and also by inhibiting free radical generation.
These results suggest an important role of propolis and its constituents as an antioxidant and free radical scavenger on the oxidative stress in the radiation-injured brain tissue. Preclinical studies have also suggested that pinocembrin, a component of propolis, protects rat brain against oxidation and apoptosis induced by ischemia-reperfusion both in vivo and in vitro.
In transgenic mice at risk of Alzheimer’s, those given pinocembrin maintained adequate glutathione content and SOD activity. Administration of brown propolis from Iran ameliorated neuronal damage of permanent cerebral artery occlusion in mice because it restored the antioxidant SOD and GPx activity, and enzyme ratio, as well as reduced lipid peroxidation.
Oxidative stress is a well-known cause of persistent chronic inflammation due to its ability to activate transcription factors such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), activator protein 1, tumour protein, hypoxia-inducible factor 1-alpha, peroxisome proliferator-activated receptor gamma and nuclear factor erythroid 2-related factor 2 (Nrf2).
NF-κB is a protein complex that controls the transcription of DNA and is involved in cellular responses to stimuli such as stress, cytokines, free radicals, ultraviolet irradiation, oxidised low density lipoproteins (LDL) and bacterial or viral antigens. Propolis is able to activate the Nrf2 transcription factor which is a major regulator of antioxidant proteins. The binding of Nrf2 to the antioxidant response element leads to transcription of several antioxidant enzymes, including heme oxygenase-1, the regulatory and catalytic subunits of γ-glutamate-cysteine ligase, GPx, glutathione reductase, CAT, SOD and glutathione-S-transferase.
Inflammation is defined as an interaction between the immune system and injured tissues designed to restore homeostasis via complex signalling pathways.
The anti-inflammatory activity of propolis appear related to its associated constituents: flavonoids, phenolic acids and their esters, terpenoids, steroids and amino acids, with CAPE being the most studied compound.
The main mechanisms underlying the anti-inflammatory activity of propolis include: (1) the inhibition of cyclooxygenase (COX) and consequent inhibition of prostaglandin biosynthesis, (2) free radical scavenging as discussed below; (3) inhibition of nitric oxide synthesis; (4) reduction in the concentration of inflammatory cytokines; and (5) immunosuppressive activity.
COX is an enzyme that is responsible for the formation of prostaglandins, prostacyclin and thromboxane. Pharmacological inhibition of COX can provide relief from the symptoms of inflammation and pain.
CAPE inhibits the activity and expression of COX-2 in human oral epithelial cells and in rat models of inflammation. In transgenic mice at risk of Alzheimer’s, three months of pinocembrin treatment confirms significant reductions in neuronal inflammatory markers (tumour necrosis factor alpha (TNF-α), interleukin-1 (IL-1) and interleukin-6 (IL-6).
Melipona Stingless Raw Honey Propolis with Eucalyptus Biodegradable Jumbo Sticks 20 ml / $5.50 each