“BIOLOGICAL ACTIVITIES OF PROPOLIS”

Yong Kun Park; Severino Matias de Alencar; Fabiana Fonseca de Moura & Masaharu Ikegaki. 

The origin of the man's knowledge on the nutritious, healing and prophylactic virtues of the products of the bees is plenty of curiosity and interest. 

Practically all the ancient civilizations with their millenarian therapies knew and used the products of the bees as a valuable resource in its medicine. The histories of the medicine of the Chinese, Tibetan, Egyptian and Greco-Roman civilizations are also rich, containing in their old writings, hundreds of recipes based mainly on honey, propolis, bee larvae and sometimes the own bees, to cure or to prevent illnesses. From the Hebraic Civilization, the Holly Bible, in some texts, exalts and ennobles the nutritious and medical properties of the honey. Some other texts refer to the propolis as " The balm of Gileade ", that was used to cure wounds, reaching high prices in the market of that time. In Japan, the use of the propolis took a great pushing in 1985, after the accomplishment of XXX International Congress of APIMONDIA in the city of Nagoya. Nowadays, Japan is the principal consumer of Brazilian propolis. 

In the last two decades it has been observed a major interest on the products of the species Apis Mellifera bees, as honey, royal jelly, apitoxin, pollen and propolis. These products have been of great acceptance, mainly for its therapeutic properties, originating a new ramify of the alternative medicine, denominated Apitherapy. Among the several bee products, propolis has been highlighted due to its several therapeutic and biological properties, mentioned in several scientific works, all over the world. 

Propolis is a balm-resinous substance that possesses several consistence and coloration, varying from brown to dark green. Bees collect it from several parts of the plants as sprouts, floral buttons and resinous exudates, being transported inside of the beehive and modified by the bees through its own enzymes. This substance is used by the bees in the entrance of the beehives in order to close openings, to avoid the penetration of cold wind and, mainly to prevent from natural enemies (fungus and bacteriae), besides being used to embalm small dead animals, killed by the bees, which could not be removed, thus avoiding their rotting. Propolis is also used as a construction material inside the beehive, welding honeycombs, frames and polishing the interior of the alveoli for the queen to do the posture. 

In countries of temperate climate from Europe and North America, the vegetables producing propolis are very few. The poplar, Populus L., of the family of Salicaceae is the main source. This vegetal species still can be found in Asia and North Africa. However, it is not regular in the tropics. There are several species in Brazil, from which we can extract this resin. However, few species were identified up to now, but roast-fish, aroeira, rosemary and eucalyptus are some examples of vegetables that produce propolis. 

This fact also has been contributing for our researches with propolis in Brazil. 

“ Chemical composition of propolis in natura "

The chemical composition of the propolis depends on the botanical ecology of each area and can still suffer influence of the genetic variety of the queens. In general, it is composed of 50% of resin and balm, 30% of wax, 10% of essential and aromatic oils, 5% of pollen and 5% of several other substances. Until the moment, more than 200 chemical compositions have been already identified in the propolis and among them: flavonoids, aromatic acids, terpenoids, aldehydes, alcohols, aliphatic acids and esters, amino acids, steroids, sugars, etc. 

There were found different types of propolis in Brazil, in studies recently carried out at our laboratory. To the whole, there were collected 500 samples of different areas of Brazil, approximately (Northeast, Southeast, Center West and South). These ones have been classified in twelve different groups, through its organoleptic characteristics, determined by morphologic observation. These characteristics are: coloration of the extracts and physical-chemical analysis through “high efficiency in reverse phase thin layer chromatography”  (absorbance in UV – visible range) etc.

However, some samples were not included in such classification, due to the fact that they have a physical chemical pattern that appears less frequently.

" Biological and/or Pharmacological Activities "

Some studies have been made, among the groups selected according to the methods described above, for the determination of the physiologic activity, such as anti-microbial, anti-inflammatory, antioxidant, antiviral and anticancer. 

The therapeutic properties of propolis have been motivating isolation researches, identification of chemical compounds, and the possible relationship of these with its biological activity. The presence of several phenolic compounds explains, partly, the great variety of the biological and therapeutic properties told in the literature, mainly in the last 3 decades. In the figures 1 and 2, some biological and therapeutic properties described in the literature can be seen.

Antibiotic: The antibiotic activity, in vitro, of the propolis was verified from several lineages Gram positive bacteriae (Bacillus brevis, B.polymyxa, B.pumilus, B. sphaericus, B. subtilis, Cellulomonas fimi, Nocardia globerula, Leuconostoc mesenteroides, Leuconostoc mesenteroides, Staphylococcus aureus and Streptococcus faecalis) and Gram negatives (Aerobacter aerogenes, Alcaligenes sp., Bordetella bronchiseptica, Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa and Serratia marcescens). Researches accomplished at our laboratory have been proving a high antibiotic strength, against certain bacteriae, like Staphylococcus aureus and Sptreptococcus mutans. Some of those propolis samples presented high concentrations of the flavonoids galangine and pinocembrine, which are considered to be antimicrobial agents. 

Anti-inflammatory Activity: Another biological activity attributed to the propolis is related to its anti-inflammatory action. Several mechanisms are related to the inflammatory processes, resulting in problems as arthritis reumathoid and artrosis or even the formation of edemas and pain sensation. There are reports in the literature, of the usage with success, of ethanolic extracts of propolis in laboratorial tests, in vitro and alive in. In several models in vitro, propolis presented an inhibition of the plaquetary aggregation and of the eicosanoid synthesis, suggesting that it possesses a powerful anti-inflammatory activity. In experiments using guinea pigs was verified that the propolis extracts presented a result comparable to the pattern commonly gotten, when using a drug like Diclofenac (Khayyal et al., 1993). Another work using ethanolic extract of propolis was accomplished at our laboratory, where there were evaluated different concentrations of alcohol for the preparation of the extracts and its relationship with inhibition of an enzyme called hialuronidase, that is responsible for a lot of the inflammatory processes, presently known.   Propolis, in those tests was observed to inhibite, in a considerable way, the activity of this enzyme. The ideal concentration of ethanol, for the preparation of the extract that presented the largest inhibition was 80%. 

Antioxidant activity: The oxidation of a certain material (as a piece of iron, fatty, or even human tissue) is related, mainly, to its degradation and/or deterioration. In the human body the oxidation is linked to the ageing process, mutation of the genetic material and of the degradation of the alive tissue. The responsible compositions for that malicious action are known as free radicals. In the nature, several substances fight those existing radicals, as the Vitamin C and the Vitamin E among others. Recently, propolis has been studied as an alternative to combat that oxidation. Its chemical composition, formed essentially by phenolic compounds suggests us to believe that it is a product with great antioxidant strength, once those compositions are known as such. In laboratory, some studies showed that one of the compositions present in propolis, known as CAPE, acts as an excellent antioxidant, thus inhibiting the formation of free radicals (Jaiswal et al., 1997). In our laboratory, studies were also carried out about the antioxidant activity of propolis: the results were very satisfactory because propolis inhibited the oxidation of a reaction mixture formed by b-carotene and linoleic acid, in almost 95%.  

Anti-fungal: Some authors demonstrated that among other activities, propolis has antimicotic action due to cynamic acid and a flavonoid named crisina. There are reports in the literature that a 50% propolis ointment cured with no return, 97 of 110 patients with Kerion on the scalp. In addition, other authors verified that the ethanolic extract of propolis has demonstrated an inhibitory activity on 17 dermatofite stumps, and also showed that propolis formulation with propylene glycol was same or superior to the one of the antifungae medications against the mushrooms M. kennels, T. rubrum, T. mentagrophytes and Scopulariopsis. Ghaly et. al. (1998) verified recently that the ethanolic extract of propolis at 3 and 4 grams per liter, reduced the germination percentage and the production of aflatoxin from mushroom Aspergillus flavus. 

Anesthetic: There are in the literature several reports on the anesthetic effect of propolis. Ghisalberti (1979) reports that propolis extract was capable to produce a total anesthetic effect in corneas of rabbits. The ethanolic extract of propolis (40g in 100 ml of ethanol 70%), was reported to be 3-5 times stronger than the cocaine used as an anesthetic, which was introduced in dental practice, in the old Soviet Union, in 1953. 

Antiprotozoa: The antiprotozoa activity of the propolis was confirmed in inflammations provoked by Trichomomas vaginalis (Scheller et.al., 1977). Later on, the effect of the propolis extract was verified on the growth, in vitro, of the protozoan Giardia lamblia, which presented an inhibitory effect of 98% (Towers et. al., 1990). Considering the perspectives of the propolis and its anti-protozoan activity, there is a lot to study and to know about the Brazilian propolis. 

Antiviral: The researches have been showing a positive effect of the propolis on the virulence and the duplication of some virus lineages, such as: herpes, adeno virus, corona virus, and rota virus. Besides, the effect in vitro of the propolis was already investigated on several viruses as herpes simplex types 1 and 2, mutant resistant to aciclovir, adenovirus type 2, virus of the vesicular estomatite and poliovirus type 2. 

Anticancer: There are in the literature some works telling on anticancer activity of propolis extracts. Compounds derived of cynamic acid and other, known as terpenoids showed good citotoxic activity. Our studies have been demonstrating that certain propolis groups (among the 12 classified until the moment) obstructed the growth of cancerous cells in laboratory experiments. In this study, these 12 types of propolis were placed in contact with different cancerous cells, of the intestine, kidney, sucks, nose and pharynx. After two weeks, enough time so that the cells reproduced and grew, ten samples had presented, in different degrees, not just inhibition of the growth, but partial destruction of the cells. The method of calculation of inhibition of tumors used in the study had, as comparison base, the results obtained by the drug Etoposide, the most powerful existing to combat the cancer. That method was developed by the National Institute of Cancer of the USA. When compared with the drug test, Etoposide, a pattern of different performance can be observed, suggesting, in that way, the existence of new citotoxic principles in the composition of the studied propolis. 

" The future "

Propolis has been used since the ancient times, but just in the last decades the researches have become more intensive, mainly with the coming of the natural and alternative medicines. As it can be noticed, the propolis is a substance with countless applications in the field of the functional victuals, cosmetics, veterinary, and, also of the medicine. One of the great problems found in the propolis is its variation in consequence of the vegetable diversity and, in smaller scale, the seasonal and environmental variations. In this way, studies of identification of vegetable origin and identification of biologically active compounds, as the ones now developed in our projects, will certainly help to define in the future, the type of appropriate propolis to each medicinal use. 

PICTURE 1:

Biological properties of propolis already described in the literature.

PICTURE 2:

Therapeutic properties of the propolis already described in the literature.

Source : Published on "Revista OESP – Alimentação" n° 27 de novembro/dezembro de 1.999.