Seasonal effect of Brazilian propolis on seric biochemical variables

Original paper

SEASONAL EFFECT OF BRAZILIAN PROPOLIS ON SERIC BIOCHEMICAL VARIABLES

J. M. SFORCIN1, E. L. B. NOVELLI¹, S. R. C. FUNARI¹

1 Department of Microbiology and Immunology, Biosciences Institute, UNESP, 18618-000, Botucatu, SP, Brazil.

ABSTRACT: Propolis has been the subject of recent scientific investigation due to its biological properties, such as antibiotic, antiinflammatory, anesthetic, healing, immunomodulatory, antioxidant, and carcinostatic. The purpose of this study was to analyze the biochemical profile of propolis-treated rats to observe whether propolis might lead to side effects after administration. Evaluation of total protein, glucose, urea, creatinine, triglycerides, cholesterol, and HDL-cholesterol concentrations and determination of aminotransferases (AST and ALT) and lactic dehydrogenase (LDH) in propolis-treated rat serum were performed. The seasonal effect on propolis activity was also analyzed, considering the biochemical variables evaluated. The lack of clinically important changes in seric biochemical variables is probably because propolis showed no biological side effects under these conditions. A possible seasonal effect on the biochemical determinations was not observed.

KEYWORDS: Propolis; season; biochemistry; serum.

INTRODUCTION

Propolis has attracted public interest since it is a natural product with many biological properties. It has been used since ancient times in folk medicine in many parts of the world. The ancient Egyptians used it to embalm their dead; in the Balkan states, propolis is still one of the most frequently used medications today (8,17).

Ethanolic and aqueous propolis extracts have been shown to inhibit several oxidative reactions, with significant antioxidative properties (24). Ethanol-soluble derivative of propolis possesses photoactive compounds, as shown by photodynamic reactions (25). Strehl et al. (22) observed that propolis exerts some of its antiinflammatory and anti-infection properties through the inhibition of dihydrofolate reductase activity, which plays an important role in the intermediary metabolism, mainly in rapidly dividing cells, such as bacteria or uncontrolled growing tissues like tumors.

More than 180 propolis constituents have been identified by gas chromatography-mass spectrometry (GC-MS). These compounds can be grouped as follows: free aromatic acids; flavonoids; benzyl, methylbutenyl, phenylethyl, cinnamyl, and other esters of these acids; chalcones and dihydrochalcones; terpenoids and others as sugars, ketones, and alcohols (3,10,26). Although in small quantities, these compounds can have important positive and negative effects on the therapeutic properties.

Although few in number, some cases of propolis allergy and contact dermatitis have been reported (11), differently from the common allergy to honey, which contains allergens derived from flowers. Kaneeda and Nishina (13), after oral propolis administration to mice, observed no anatomical abnormality in these animals, suggesting the absence of side effects after propolis treatment.

In view of the lack of publications about the seasonal effects on propolis activity and possible side effects, the aim of this work was to analyze the biochemical profile of rats after propolis administration, by determining some seric biochemical variables. Considering its complex composition, we also tried to investigate the seasonal profile of Brazilian propolis activity.

MATERIALS AND METHODS

Propolis samples

Propolis was collected in the Beekeeping Section of the Botucatu School of Veterinary Medicine and Animal Husbandry, UNESP. Propolis samples were obtained from colonies of africanized honeybees (Apis mellifera, L.) and collected throughout a whole year using plastic nets. At the end of each month, nets were taken and frozen to promote propolis removal (23). Samples were pooled by season.

Hydroalcoholic solutions of propolis

Propolis obtained in each season was stirred and 30% ethanolic extracts of propolis (EEP) were prepared (30g of propolis to 100ml of 95^o ethyl alcohol). This was protected from bright light and moderately shaken at room temperature. After a week, the extracts were filtered and used to prepare 10% propolis hydroalcoholic solutions (20).

Animal groups and treatment

Forty-two male rats (Rattus norvegicus) weighing 200 g were divided into 6 groups (G1, G2, G3, G4, G5, G6) of 7 rats each.

G1, G2, G3, and G4 received 10% propolis hydroalcoholic solutions from spring, summer, autumn, and winter samples, respectively G5 received 10% hydroalcoholic solution (Labsynth) to observe a possible ethanol effect as propolis solvent. G6, control, received salt solution (0.9% NaCl). Animals received 0.4 ml by gavage twice a day for 3 days (12). Each rat received approximately 100mg of propolis per day.

Serum samples and biochemical determinations

After treatment, the animals were sacrificed by overetherization and decapitation, and blood samples were collected and centrifuged at 3,000 rpm for 15 minutes. Serum was used for total protein, glucose, urea, creatinine, triglycerides, cholesterol, and HDL-cholesterol concentrations and determinations of aminotransferases (AST and ALT) and lactic dehydrogenase (LDH).

Determinations were performed using an automated biochemical analyzer (Multianalyser Technicon RA-XT, Bayer do Brasil).

Statistical analysis

Analysis of Variance was used to examine the treatment effect, and comparison between the means was performed by Tukey test, with 0.05 was significant level (27).

RESULTS

Propolis administration to rats showed no alterations in the seric levels of total protein, glucose, urea, creatinine, triglycerides, cholesterol, HDL-cholesterol and LDH, AST, and ALT (Table 1).

Significantincreased seric AST activities were observed only in ratstreated with hydroalcoholic solution, when compared to the control groupand those treated with propolis (p<0.01).

Table 1 summarizes all biochemical determinations. In general, no alterations were seen in biochemical variables in serum of propolis-treated rats.

A possible seasonal effect on the biochemical determinations was not observed.

Table 1.
Seasonal effect on the biochemical profile of propolis-treated rats.

DISCUSSION

The large number of chemical components in propolis may justify its many biological activities. However, it is possible to hypothesize that its complex composition may lead to damage in the organism.

In thiswork, biochemical determinations in rats treated with propolis from eachseason were performed 72h after propolis administration, since alterationsin biochemical components may be seen hours or few days after treatment,before histopathological alterations may be observed.

Lauwerys et al. (15) reported the importance of choosing the biological components to be determined in dose-effect relation studies, mainly when the drug action mechanism, as in propolis, is not clear. Thus, alterations in these variables help in the understanding of biological effects related to treatment.

In a previous work, we showed that 24 h after propolis administration to rats, ALT and amylase had no alterations in specific activities. Since these enzymes are related to damage in the liver and pancreas, respectively, it might be hypothesized that propolis did not affect these tissues (20).

Frankiewicz and Scheller (7), after treating elderly patients with propolis capsules, observed normal concentrations of glucose, urea, cholesterol, and normal aminotransferase activities. Dobrowolski et al. (6) observed elevated activities of seric ALT and AST in arthritic rats, reversing this effect after propolis treatment.

In this assay, propolis administration to rats did not induce alterations in ALT and AST specific activities. These enzymes are widely distributed in tissues: AST is predominantly found in the heart, liver, skeletal muscle, kidney, and pancreas; ALT in the liver, kidney, and heart. Seric levels of these enzymes have been thought to be a tool to study both cell viability and changes in cell membrane permeability (16,19). AST activity was significantly higher in the hydroalcoholic solution-treated group, when compared to the propolis-treated groups and control group (p<0.01). However, this enzyme activity was normal in the propolis-treated animals, despite being in hydroalcoholic solution (Table 1).

Cohen et al. (5) first reported the contribution of serum LDH isoenzymes to the diagnosis of specific organ injury, mainly in cardiac damage. Experimental works of Steinebach and Wolterbeek (21) also demonstrated LDH importance as an index of cell viability. After treatment with propolis, LDH specific activities were normal.

Cohen et al. (5) first reported the contribution of serum LDH isoenzymes to the diagnosis of specific organ injury, mainly in cardiac damage. Experimental works of Steinebach and Wolterbeek (21) also demonstrated LDH importance as an index of cell viability. After treatment with propolis, LDH specific activities were normal.

Kedzia et al. (14) found serum glucose at physiological levels after administering propolis to rabbits. Our data also revealed normal seric glucose concentrations in propolis-treated groups.

With regard to lipid metabolism, serum concentrations of triglycerides, cholesterol, and HDL-cholesterol showed no alteration after propolis treatment. These data are in agreement with Kedzia et al. (14), who observed blood pressure reduction in rats after propolis ingestion, suggesting its beneficial role in preventing atherogenesis.

In this work, the evidence that propolis does not induce kidney damage came from urea and creatinine determinations. Urea concentration in blood is a consequence of its production rate during amino acid catabolism and its excretion by the kidney. Creatinine concentration in blood is a result of the balance between creatinine production by the muscle and excretion by the kidney. Nagyova et al. (18) reported that urea and creatinine determinations as a parameter of kidney damage.

As well as other determinations presented here, no alteration was seen in total protein seric concentration in propolis-treated groups. Giurgea et al. (9) suggested that this apitherapic diminishes amino acid concentrations in blood, inducing protein synthesis and showing anabolic effects.

In a joint project, the chemical composition of our propolis samples was analyzed. Seasonal differences were not significant and were predominantly quantitative (1,2,4). In relation to absence of seasonal effect, one could hypothesize that differences in propolis activities could be found in samples from different geographical regions, since local flora influences its chemical composition, and probably, its biological properties.

ACKNOWLEDGEMENTS

The authors wish to thank Dr. Paulo Roberto Curi for statistical analysis; Mr. Guerino Santo Bianchi Filho, Maria Conceição Tenore do Carmo, and Luiz Carlos Fioravante for technical assistance; Ms. Sônia Maria Faraldo for computer assistance; and Mrs. Célia Sforcin Guimarães for text editing.

Received June 4, 2001

Accepted August 8, 2001

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Publication Dates

• Publication in this collection
  16 Sept 2002
• Date of issue
  2002

History

• Received
  04 June 2001
• Accepted
  08 Aug 2001