BEE PRODUCTS: Bee Propolis
Bee Pollen | Royal Jelly | Bee Propolis
Overview of bee Propolis
Bee Propolis is a waxy substance collected by honey bees, which contains phytotonizides. Phytotnzides are believed to contain immunity factors, which when used internally, stimulates the body and gives it a natural resistance to diseases ( a natural antibiotic).
Bee Propolis is a mixture of various amounts of beeswax and resins collected by the honeybee from plants, particularly from flowers and leaf buds. Since it is difficult to observe bees on their foraging trips the exact sources of the resins are usually not known. Bees have been observed scraping the protective resins of flower and leaf buds with their mandibles and then carrying them to the hive like pollen pellets on their hind legs. It can be assumed that in the process of collecting and modelling the resins, they are mixed with some saliva and other secretions of the bees as well as with wax.
These resins are used by worker bees to line the inside of nest cavities and all brood combs, repair combs, seal small cracks in the hive, reduce the size of hive entrances, seal off inside the hive any dead animals or insects which are too large to be carried out and perhaps most important of all, to mix small quantities of Propolis with wax to seal brood cells. These uses are significant because they take advantage of the antibacterial and antifungal effects of Propolis in protecting the colony against diseases. Propolis has been shown to kill the bee's most ardent bacterial foe, Bacillus larvae - the cause of American Foul Brood (Mlagan and Sulimanovic, 1982; Meresta and Meresta, 1988). The use of Propolis thus reduces the chance of infection in the developing brood and the growth of decomposing bacteria in dead animal tissue.
The composition of Propolis depends on the type of plants accessible to the bees. Propolis changes in colour, odour and probably medicinal characteristics, according to source and the season of the year. Moreover, some bees and some colonies are more avid collectors-generally to the dismay of the beekeeper, since Propolis is a very sticky substance which, in abundance, can make it difficult to remove frames from the boxes.
Physical characteristics of Propolis:
The color of Propolis ranges from yellow to dark brown depending on the origin of the resins. But, even transparent Propolis has been reported by Coggshall and Morse (1984).
At temperatures of 250 to 45 0C Propolis is a soft, pliable and very sticky substance. At less than 150 C, and particularly when frozen or at near freezing, it becomes hard and brittle. It will remain brittle after such treatment even at higher temperatures. Above 45 0C it will become increasingly sticky and gummy. Typically Propolis will become liquid at 60 to 700C, but for some samples the melting point may be as high as 1000C.
The most common solvents used for commercial extraction are ethanol (ethyl alcohol) ether, glycol and water. For chemical analysis a large variety of solvents may be used in order to extract the various fractions. Many of the bactericidal components are soluble in water or alcohol.
Composition of Propolis
In one recent analysis of Propolis from England, 150 compounds were identified in only one sample (Greenaway, et al., 1990), but in total more than 180 have been isolated so far. It appears that with every new analysis, new compounds are found.
Propolis resins are collected from a large variety of trees and shrubs. Each region and colony seems to have its own preferred resin sources, which results in the large variation of colour, odour and composition. Comparisons with tree resins in Europe suggest that, wherever Populus species are present, honeybees preferably collect the resins from leaf buds of these trees.
A Cuban study suggests that the plant resins collected are at least partially metabolized by bees (Cuellar et al., 1990). The presence of sugars (Greenaway et al., 1987) also suggests some metabolization by bees, i.e. because of adding saliva during both scraping and chewing.
A list of the major classes of chemicals occurring in Propolis is given below with references to some recent reviews and analyses from different countries. The major compounds are resins composed of flavonoids and phenolic acids or their esters, which often form up to 50% of all ingredients. The variation in beeswax content also influences the chemical analysis. In addition it must be said that most studies do not attempt to determine all components, but limit themselves to a class of chemicals or a method of extraction. The selection of the studies presented here is based on the most recent publications with preference given to the most complete studies or to studies from countries where these are the only references.
Physiological effects of Propolis
One of the most widely known and extensively tested properties of Propolis is its antibacterial activity. Many scientific tests have been conducted with a variety of bacteria, fungi, viruses and other microorganisms. Many of the tests have shown positive control of the organisms by various extracts and concentrations of Propolis. A synergistic effect has been reported for Propolis extract used together with antibiotics (Chernyak, 1971). Whether Propolis exhibits bactericidal or bacteriostatic characteristics often depends on its concentration in the applied extract. Sometimes, Propolis extracts are more effective than commercially available drugs (Millet-Clerc, et al., 1987). In all cases, the specific conditions and extracts have to be closely considered.
Though there is a large variety of effects attributed to Propolis, many of the reports are based on preliminary studies. If clinical trials were conducted, they were rarely based on large numbers of patients or rigorous test designs such as the double-blind placebo test. The majority of the studies were conducted in East European countries. Much practical work and research is also being done in China, but information is difficult to obtain, not least because of the language barrier. Western European and North American medical research has largely ignored this source of milder and widely beneficial material. More detailed studies are warranted to determine the potential benefits from the medicinal use of Propolis, particularly for intestinal, dermatological and dental applications.
Clinical uses of bee propolis
Dermatological and cosmetic applications are at this time probably the most common uses for Propolis and its extracts (Lejeune, et al., 1988). Its effects on tissue regeneration and renovation have been well studied. Together with its bactericidal and fungicidal characteristics it provides many benefits in various applications in cosmetics. For some recent specific references on scientific studies, the reader should refer to the section on the effects of Propolis.
As a medicine
General medicinal uses of Propolis include treatment of the cardiovascular and blood systems (anaemia), respiratory apparatus (for various infections), dental care, dermatology (tissue regeneration, ulcers, excema, wound healing - particularly burn wounds, mycosis, mucous membrane infections and lesions), cancer treatment, immune system support and improvement, digestive tracts (ulcers and infections), liver protection and support and many others.
Direct external application of ethanol extracts or concentrated ointments (with up to 33% Propolis) have given good results in veterinary use for wound healing and sores. Plastic surgery too, is using Propolis extracts for improved wound healing and reduced scar tissue development.
In Europe and North Africa, the special wound healing properties of Propolis were already known to the Egyptians, Greeks and Romans and in ancient times. In records of the 12th century, medicinal preparations with Propolis are described for treating mouth and throat infections, as well as caries. Propolis probably has been more commonly used in wood preservatives or varnishes than may be suggested by the single, frequently cited reference to Stradivarius (Jolly, 1978).
In sub-Saharan Africa, Propolis is still used today in herbal medicines and the more mundane applications mentioned earlier such as waterproofing containers and wood, adhesive, bow string preparation and for tuning drums.
The antioxidant, antimicrobial and antifungal activities of Propolis offer scope for applications in food technology. One special advantage is that, unlike some conventional preservatives, the residues of Propolis seem to have a generally beneficial effect on human health. However, only very few studies have been done on the possible side-effects of increased consumption of Propolis. Individually, some of the components identified in Propolis can be very damaging to human health.
Mizuno (1989), registered a patent which includes Propolis as a preservative in food packing material.
Extension of frozen storage life of fish by 2-3 times is cited including Donadieu (1979), but without reference to original studies. Propolis is permitted as a preservative for frozen fish. by various authors, In Japan, the use of Addition of only 30 ppm (parts per million) of Propolis to the rations of laying hens increased egg production, food conversion and hen weight by S to 6% (Bonomi, et al., 1976). Ghisalberti (1979) reports additional weight gains for broiler chicken of up to 20% when 500 ppm of Propolis was added to their diets.
The search for new uses of Propolis continues. Sangalli (1990) mentioned use of Propolis for post-harvest treatment and conservation of fruits. Applications in pesticides and fungicides are still in the testing phase. However, for many of its traditional uses Propolis is being replaced by more readily available, sometimes more effective but often also more toxic alternatives.
Beekeepers use Propolis, melted together with wax or in an ammonia solution (Anon, 1982) to apply to the inside of hives or swarm traps to attract swarms. Adequate ventilation and aeration after painting with the ammonia solution are both necessary. Rubbing Propolis or painting it (after melting with wax from old combs) works as well or better and avoids the use of noxious and toxic ammonia.
The current trend to return to environmentally safer and less energy intensive production methods in many developed countries, the increased buying power of consumers and growing markets for more expensive products may lead to considerable growth in the use and new applications of Propolis, particularly in cosmetics and food technology.
Administration of propolis
1- Raw Propolis
Unprocessed Propolis can be used in chunks, or it may be frozen and broken or ground to fine powder. Large pieces of pure Propolis can be chewed, but it should only be consumed in small quantities, since it may cause stomach upsets. Smaller pieces and powders can be taken in capsules or mixed with food or drinks.
2- Liquid extracts
Most commercial uses of Propolis are based on preparations made from primary liquid extracts. The raw material is rarely suited for direct inclusion in final products. Similarly, for most private or small scale uses, raw Propolis is usually treated with a solvent and only the resulting extract is used.
A large variety of organic solvents might be applied but only a few are non-toxic and can be used safely for internal and external applications with humans and animals. The most commonly used is ethanol. A knowledgeable pharmacist or cosmetic chemist can select a few other non-toxic solvents for special applications. In some instances, reduction or elimination of the solvent is necessary and either (on an industrial scale) by lyophilization, (freeze drying) or vacuum distillation and (in small-scale production) by evaporation or distillation.
3- Additives and tablets
Propolis or its extracts can be taken with, or be used as an additive to other medicinal, dietetic and cosmetic preparations. Ethanol extracts can be directly mixed with most foods, medicines or cosmetics. Less frequently, aqueous (water) or glycol extracts are used. Propolis extract paste can easily be included in tablets or sweets.
For experimental purposes with animals, special extracts of Propolis were injected subcutaneously or intramuscularly. Results were positive and injectable extracts for humans may become feasible in the near future.
Storage of propolis
In general, Propolis is fairly stable, but proper storage is important. Propolis and its extracts should be stored in airtight containers in the dark, preferably at less than 100C-120C and away from excessive and direct heat. For similar reasons, very old Propolis from the hive should not be mixed with fresher Propolis. Over 12 months of proper storage, Propolis will lose very little or none of its antibacterial activities. Alcohol extracts may be stored even longer.
Lyophilization (freeze drying) of extracts has been described as a method which preserves the antibacterial characteristics, but nothing has been written about effects of long-term storage of such materials. This method may gain importance for larger scale use and certain formulations, but it is possible that some of the synergistic characteristics of Propolis may be lost during lyophilisation.
The shelf-life of Propolis containing products depends very much on their composition and has to be determined for each case. The more the other components of a product are susceptible to decomposition, the shorter will be the shelf-life of that product. This is the reason for compromises that are necessary in the selection of artificial and/or natural and traditional ingredients, preservatives and larger production for extended markets. However, Propolis and its extracts function as a mild preservative due to their antioxidant and antimicrobial activities and thus may actually prolong the shelf live of some products.
Toxicity of propolis
Hausen et al., (1987) cited almost 200 cases in which people have shown allergic reactions to Propolis. In some cases of direct contact with Propolis, this may have also been a result of contamination by other bee products such as pollen or bee hairs. However, extracts and products containing Propolis extracts have been shown to cause allergic reactions as well (Hausen, et al., 1987, Hausen and Wollenweber, 1987 and Ko~nlg, 1988) mostly in the form of contact dermatitis. Hashimoto et al., (1988) identified caffeic acid and its derivatives as the major allergenic agents.
Therefore, with all preparations intended for human or animal use, small quantities should be tried during the first days, slowly increasing to the full dosage (half for children) in order to test for the compatibility of the preparatino or allergic reactions. Equally, termination of medical treatments prescribed by a physician should be gradual, slowly reducing the daily dosage.
Prolonged chewing of large amounts of raw Propolis may lead to nausea and stomach upsets. Donadieu (1979) recommended chewing one gram at a time, three times a day.
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