Bee Propolis And Its Medicinal Uses

Mrs. Lakshmi Sivasubramaniam

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 (see Fig) 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. The use of propolis thus reduces
the chance of infection in the developing brood and the growth of decomposing
bacteria in dead animal tissue.

Foraging for propolis is only known with the Western honeybee Apis mellifera. The Asian species of Apis do not collect propolis. Only Meliponine or sting less bees is known to collect similarly sticky resinous substances, for sealing hives and constructing honey and pollen pots for storage.

Fig: Honeybees frequently use propolis to reduce the size of the entrance
for better defence.

However, propolis shall refer only to resins collected by honeybees, since almost all of the research has been done on it. There may well be similar traditional uses for resins collected by Meliponids.

Physical characteristics of propolis

The colour of propolis ranges from yellow to dark brown depending on the origin of the resins. But, even transparent propolis has been reported.

At temperatures of 250 to 45 C 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 C it will become increasingly sticky and gummy. Typically propolis will become liquid at 60 to 70C, but for some samples the melting point may be as high as 100C.

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.

The composition of propolis

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.

In one recent analysis of propolis from England, 150 compounds were identified in only one sample, 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. The presence of sugars also suggests some metabolization by bees, i.e. as a result of adding saliva during both scraping and chewing.

A list of the major classes of chemicals occurring in propolis is given below (Table 1). 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.

Table 1: The major compounds of propolis as analyzed

The Physiological Effects Of Propolis

Unconfirmed circumstantial evidence

The following uses of propolis or its extracts have been found in literature,
but no substantiating evidence or reference to scientific studies:



§ Anti-asthmatic treatment in mouth sprays

§ Support of pulmonary system

§ Anti-rheumatic inhibition of melanoma and carcinoma tumour cells

§ Tissue regeneration

§ Strengthening of capillaries

§ Anti-diabetic activity

§ Phytoinhibitor

§ Inhibiting plant and seed germination, in general and potato and leaf salad seed germination in particular

Scientific evidence

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. 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. In all cases, the specific conditions and extracts have to be closely considered. Proven effects of propolis on microorganisms are listed in Table 2.

Table 2: A list of microorganisms against which propolis or its extracts have been shown to have a positive effect.

Uses of Propolis

Though there are 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 (Table 3). 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.

Traditional use

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. 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.

In cosmetics

Dermatological and cosmetic applications are at this time probably the most common uses for propolis and its extracts. 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.

In medicine

General medicinal uses of propolis include treatment of the cardiovascular and blood systems (anemia), respiratory apparatus (for various infections), dental care, dermatology (tissue regeneration, ulcers, eczema, 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.

Table 3: Medicinal and other effects described for propolis or its extracts.

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.

Food technology

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.

Formulation and application methods for human and animal use

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.

4. Injection

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

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 10C-12C 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.

Quality control

Since propolis comes in many colours, odours and composition, it is very difficult to give precise guidelines. Most fresh propolis has a pleasant resinous odour. Wax content and visual contamination should obviously be as low as possible. Old propolis becomes very hard and brittle and may also be very dark. However, frozen or recently frozen propolis is also very brittle.

Official quality standards exist for propolis in various East European countries, but most standards refer to the cleanliness or adulteration of the raw product and sometimes, its extracts. Maximum and minimum limits for certain chemical groups are set, but few standardized tests are available to determine the biological activities of various components. Tikhonov et al., (1978) describe the average contents of the principal ingredients as possible standards for raw propolis (Table 4). Official quality standards exist in Romania and the former USSR (Crane, 1990).

Because of its recent manipulation and harvesting by bees, fresh trap-collected propolis is of the highest quality and the least contaminated, if collected on a regular basis. Plant origin however, may be important for certain applications and therefore propolis collected in a certain region or during a certain season may be preferred.

Table 4: Quality standards for propolis as suggested by Tikhonov et al (1978) and upperand lower limits as established by Russian Regional Standards (RSFSR, 1977).

After incorporation into other products, testing for propolis becomes even more complicated and overall product quality becomes important.  Since there is a wide variety of products in which propolis can be included, the standards for each type of product need to be considered.

One easy way to determine a different kind of quality, particularly poor quality as a defect, is the homogeneity of products containing propolis extracts. Without good equipment, a good and stable emulsion is difficult to obtain. Hand-mixed emulsions tend to be stable for shorter periods of time only. Separation after brief or inappropriate storage is unacceptable to consumers and also affects performance of the product. Thus special care needs to be taken to ensure the compatibility of the extraction method and ingredients of the end product. Suitable emulsifiers and better mixing techniques, i.e. higher speed, longer time, warmer temperatures and different mixing sequences would have to be determined by testing.

References:

1. Andrich, G., Fiorentini, R. and Consiglieri, A. 1987. [Characteristics of some samples of propolis from the Ligurian Coast] Caratteristiche di alcuni tipi di propoli della Riviera Ligure. Citta delle Api, (28): 30-31, 34, 35, 37, 38.

2. Apimondia 1975a. A valuable product of beekeeping: propolis. Researches and views on its composition, properties and therapeutic value. Apimondia Publishing House, Bucharest, Rumania, 167 pp.

3. Apimondia 1975b. The hive products: food health and beauty. Proc. of Intern. Symp. on Apitherapy. Apimondia Publishing House, Bucharest, Romania, 154 pp.

4. Apimondia 1978 A remarkable hive product: propolis. Apimondia Publishing House, Bucharest, 250 pp.

5. Anon 1965. Productions du docteur Anon. French Patent No.1,396,582. In: Chem. Abstr. 63: 6782g (1965).

6. Asis, M. 1989. [Propolis: the purple gold of honeybees.] Centro de Informaci6n y Documentaci6n Agropecuano, Havana, Cuba, 255 pp.

7. Ask-Upmark, E. 1967. Prostatitis and its treatment. Acta Med. Scand., 181: 355-357

8. Bankova, V. and 7 others. 1988. [On the chemical composition of some propolis fractions with antiviral action.] Acta Microbiologica Bulgarica, 23: 52-57

9. Bankova, V. and 4 others. 1991. A study on the origin of Bulgarian propolis. Apiacta, 26(1): 13-17

10. Bankova, V., Dyulgerov, A., Popov, S., Evstatieva, L. Kuleva L., Purb 0. and Zamjansan, Z. 1992. Propolis produced in Bulgaria and Mongolia: Phenolic compounds and plant origin. Apidologie, 23 :79-85

11. Bankova, V. Dyalgerov, A., Popov, S. and Marekov, N.L. 1987. [A GC/MS study of the propolis phenolic constituents.] Z. f. Naturforschung, 42:147-151

12. Bansal, R.D., Ghosh, B.N., Bhardwaj

13. Benkova, M., Boroskova', Z., Dubaj, J. and Sze'chenyi, S. 1989. The immunomodulative effect of propolis preparations on guinea pigs with experimental ascaridosis. Helminthologia 26(2): 163-172

14. Brumfitt, W., Hamilton-Miller, J.M.T. and Franklin, 1.1990. Antibiotic activity of natural products: 1. Propolis. Microbios 62:19-22

15. Budavari, S. (ed.) 1989. The Merck Index. Merck & Co., Rahway, NJ.

16. Chernyak, N.F. 1973. On synergistic effect of propolis and some anti-bacterial drugs. Antibiotiki, 18 : 259-261

17. Ghisalberti, E.L. 1979. Propolis: a review. Bee World, 60 (2): 59-84.

About Authors

Madhumathi Seshadri^b and Mrs. Lakshmi Sivasubramaniam
^a, *

Mrs. Lakshmi Sivasubramaniam

^a Lecturer, Department of Pharmaceutical Analysis, College of Pharmacy,
SRM Institute of Science and Technology, Deemed University, Katangulathur, Chennai,
India.

* ^aAuthor for Correspondence: Lakshmi Sivasubramaniam, Lecturer,
Department of Pharmaceutical Analysis, College of Pharmacy, SRM Institute of
Science and Technology, Deemed University, Katangulathur, Chennai, India. E
mail: laxmisiva@rediffmail.com.

Madhumathi Seshadri

^b Department of Chemistry, Pharmaceutical Chemistry unit, Vellore
Institute of Technology, Vellore - 632 014, India.

Madhumathi Seshadri successfully completed M. Tech. in Pharmaceutical Chemistry
at Vellore Institute of Technology, Vellore (a deemed university) in I Class
with Distinction.