Composition of propolis

The composition of propolis will vary from hive to hive, 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, and will gather what they need from available sources, and detailed analyses show that propolis chemical composition varies considerably from region to region, along with the vegetation. In northern temperate climates, for example, bees collect resins from trees, such as poplars and conifers (the biological role of resin in trees is to seal wounds and defend against bacteria, fungi and insects). Poplar resin is rich in flavanoids. "Typical" northern temperate propolis has approximately 50 constituents, primarily resins and vegetable balsams (50%), waxes (30%), essential oils (10%), and pollen (5%). In neotropical regions, in additional 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[2]. Clusia resin contains polyprenylated benzophenones.[3][4][5] In some areas of Chile, propolis contains viscidone, a terpene from Baccharis shrubs[6], and in Brazil, naphthoquinone epoxide has recently isolated from red propolis[7], and prenylated acids such as 4-hydroxy-3,5-diprenyl cinnamic acid have been documented[8]. An analysis of propolis from Henan, China found sinapic acid, isoferulic acid, caffeic acid and chrysin, with the first three compounds demonstrating anti-bacterial properties[9]. Occasionally worker bees will even gather various caulking compounds of human manufacture, when the usual sources are more difficult to obtain. The properties of the propolis depend on the exact sources used by each individual hive, therefore any potential medicinal properties that may be present in one hive's propolis may be absent from another's, and the distributors of propolis products cannot control such factors. This may account for the many and varied claims regarding medicinal properties, and the difficulty in replicating previous scientific studies investigating these claims. Even propolis samples taken from within a single colony can vary, making controlled clinical tests difficult, and the results of any given study cannot be reliably extrapolated to propolis samples from other areas.

Propolis knowledge

Propolis is a resinous mixture that bees collect from tree buds, sap flows, or other botanical sources. It is used as a sealant for unwanted open spaces in the hive. Propolis is used for small gaps (approximately 6.35 millimeters (0.3 in) or less), while larger spaces are usually filled with beeswax. Its color varies depending on its botanical source, the most common being dark brown. Propolis is sticky at and above room temperature. At lower temperatures it becomes hard and very brittle.
For centuries, beekeepers assumed [1]that bees sealed the beehive with propolis to protect the colony from the elements, such as rain and cold winter drafts. However, 20th century research has revealed that bees not only survive, but also thrive, with increased ventilation during the winter months throughout most temperate regions of the world.
propolis as hive sealingPropolis is now believed to:
reinforce the structural stability of the hive reduce vibration make the hive more defensible by sealing alternate entrances prevent diseases and parasites from entering the hive prevent putrefaction within the hive. Bees usually carry waste out of and away from the hive. However if a small lizard or mouse, for example, found its way into the hive and died 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.