Propolis or bee glue is a resinous mixture that honey bees produce by mixing saliva and beeswax with

exudate An exudate is a fluid emitted by an organism through pores or a wound, a process known as exuding or exudation. ''Exudate'' is derived from ''exude'' 'to ooze' from Latin ''exsūdāre'' 'to (ooze out) sweat' (''ex-'' 'out' and ''sūdāre'' 'to ...

gathered from tree buds, sap flows, or other botanical sources. It is used as a sealant for unwanted open spaces in the beehive. Propolis is used for small gaps (approximately or less), while gaps larger than the bee space (approximately ) are usually filled with

burr comb In beekeeping, in a Langstroth hive, burr comb, also known as brace comb and bridge comb, are portions of honeycomb built by the bees in other places than in the intended place in the frames. Burr comb is commonly found on the top of frames, parti ...

. Its color varies depending on its botanical source, with dark brown as the most common. Propolis is sticky at and above , while at lower temperatures it becomes hard and brittle. When foraging, worker bees primarily harvest pollen and nectar, while also collecting water and plant resin necessary for the production of propolis. The chemical composition and nature of propolis depend on environmental conditions and harvested resources.

Types

Mixed types of propolis found in European countries with a moderate climate include two or more sources of plant resins (plant species) identified by composition, such as aspen, Mediterranean, poplar, Pacific, Brazilian green, Brazilian red, and Mangifera types of propolis.

Purpose

Bees seal the beehive with propolis to protect the colony from the elements, such as rain and cold winter drafts. Propolis functions may include: #Reinforce the structural stability and reduce vibration #Provide improved thermal insulation to the hive and reduce water loss #Provides protection from pathogens, via anti-fungal and antibacterial properties #Make the hive more defensible against parasites and predators by narrowing the existing entrance (in wild colonies) to a single "choke point" #Mitigate putrefaction within the hive. Bees usually carry waste out of and away from the hive. However, if a small

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...

mouse A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

, for example, finds its way into the hive and dies there, bees may be unable to carry it out through the hive entrance. In that case, they would attempt instead to seal the carcass in propolis, essentially mummifying it and making it odorless and harmless.

Composition

The composition of propolis varies from hive to hive, from district to district, and from season to season. Normally, it is dark brown in color, but it can be found in green, red, black, and white hues, depending on the sources of resin found in the particular hive area. Honey bees are opportunists, gathering what they need from available sources, and detailed analyses show that the chemical composition of propolis varies considerably from region to region, along with the vegetation. In northern temperate climates, for example, bees collect resins from trees, such as

poplars ''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood. The we ...

and

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

s (the biological role of resin in trees is to seal wounds and defend against bacteria, fungi, and insects). "Typical" northern temperate propolis has approximately 50 constituents, primarily resins and vegetable balsams (50%), waxes (30%),

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

s (10%), and

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...

(5%). An analysis of propolis from Henan,

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

found sinapinic acid,

isoferulic acid Isoferulic acid is a hydroxycinnamic acid, a type of organic compound. It is an isomer of ferulic acid. Occurrence in nature Isoferulic acid can be found, amongst other compounds, in ''Lobelia chinensis''. In food Ferulic acid is found in pin ...

, caffeic acid, and

chrysin Chrysin, also called 5,7-dihydroxyflavone, is a flavone found in honey, propolis, the passion flowers, ''Passiflora caerulea'' and ''Passiflora incarnata'', and in ''Oroxylum indicum''. It is extracted from various plants, such as the blue passion ...

. In neotropical regions, in addition to a large variety of trees, bees may also gather resin from flowers in the genera '' Clusia'' and '' Dalechampia'', which are the only known plant genera that produce floral resins to attract pollinators. ''Clusia'' resin contains polyprenylated benzophenones. In some areas of Chile and Argentina Andean valleys, propolis contains viscidone, a terpene from '' Baccharis'' shrubs, and prenylated acids, such as 4-hydroxy-3,5-diprenyl cinnamic acid. Overall,

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s, phenolic acids, and phenolic aldehydes are common constituents, while coumarins, stilbenes, and lignans are less common.

Traditional medicine

Propolis has been used in traditional medicine, with insufficient evidence to rate its effectiveness in the treatment of any illnesses.

Other uses

Musical instruments

Propolis is used by some string instrument makers (violin, viola, cello, and bass) as a

varnish Varnish is a clear transparent hard protective coating or film. It is not a stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, and is sold commercially in various ...

ingredient. A tincture of propolis may be used to seal the surface of newly made violin family bridges, and may be used in the maintenance of the bores of pan flute tubes. Claims that Antonio Stradivari used propolis in the varnish of his instruments were disproven in 2009.Secret behind the composition of the varnish on Stradivari violins revealed
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References

External links

* {{Authority control Beekeeping Bee products Traditional medicine Xanthine oxidase inhibitors