Effect of different formulations of propolis on mice infected with Trypanosoma cruzi

Propolis Has an Anticancer Effect on Early Stage Colorectal Cancer by Affecting Epithelial Differentiation and Gut Immunity in the Tumor Microenvironment

Colorectal cancer (CRC) is one of the most common cancers and is the second leading cause of cancer-related death in the world. Due to the westernization of diets, young patients with CRC are often diagnosed at advanced stages with an associated poor prognosis. Improved lifestyle choices are one way to minimize CRC risk. Among diet choices is the inclusion of bee propolis, long recognized as a health supplement with anticancer activities. Understanding the effect of propolis on the gut environment is worth exploring, and especially its associated intratumoral immune changes and its anticancer effect on the occurrence and development of CRC. In this study, early stage CRC was induced with 1,2-dimethylhydrazine (DMH) and dextran sulfate sodium (DSS) for one month in an animal model, without and with propolis administration. The phenotypes of early stage CRC were evaluated by X-ray microcomputed tomography and histologic examination. The gut immunity of the tumor microenvironment was assessed by immunohistochemical staining for tumor-infiltrating lymphocytes (TILs) and further comparative quantification. We found that the characteristics of the CRC mice, including the body weight, tumor loading, and tumor dimensions, were significantly changed due to propolis administration. With further propolis administration, the CRC tissues of DMH/DSS-treated mice showed decreased cytokeratin 20 levels, a marker for intestinal epithelium differentiation. Additionally, the signal intensity and density of CD3+ and CD4+ TILs were significantly increased and fewer forkhead box protein P3 (FOXP3) lymphocytes were observed in the lamina propria. In conclusion, we found that propolis, a natural supplement, potentially prevented CRC progression by increasing CD3+ and CD4+ TILs and reducing FOXP3 lymphocytes in the tumor microenvironment of early stage CRC. Our study could suggest a promising role for propolis in complementary medicine as a food supplement to decrease or prevent CRC progression.

Antiparasitic Properties of Propolis Extracts and Their Compounds

Propolis is a bee product that has been used in medicine since ancient times. Although its anti-inflammatory, antioxidant, antimicrobial, antitumor, and immunomodulatory activities have been investigated, its anti-parasitic properties remain poorly explored, especially regarding helminths. This review surveys the results obtained with propolis around the world against human parasites. Regarding protozoa, studies carried out with the protozoa Trypanosoma spp. and Leishmania spp. have demonstrated promising results in vitro and in vivo. However, there are fewer studies for Plasmodium spp., the etiological agent of malaria and less so for helminths, particularly for Fasciola spp. and Schistosoma spp. Despite the favorable in vitro results with propolis, helminth assays need to be further investigated. However, propolis has shown itself to be an excellent natural product for parasitology, thus opening new paths and approaches in its activity against protozoa and helminths.

The Strong Anti-Kinetoplastid Properties of Bee Propolis: Composition and Identification of the Active Agents and Their Biochemical Targets

The kinetoplastids are protozoa characterized by the presence of a distinctive organelle, called the kinetoplast, which contains a large amount of DNA (kinetoplast DNA (kDNA)) inside their single mitochondrion. Kinetoplastids of medical and veterinary importance include Trypanosoma spp. (the causative agents of human and animal African Trypanosomiasis and of Chagas disease) and Leishmania spp. (the causative agents of the various forms of leishmaniasis). These neglected diseases affect millions of people across the globe, but drug treatment is hampered by the challenges of toxicity and drug resistance, among others. Propolis (a natural product made by bees) and compounds isolated from it are now being investigated as novel treatments of kinetoplastid infections. The anti-kinetoplastid efficacy of propolis is probably a consequence of its reported activity against kinetoplastid parasites of bees. This article presents a review of the reported anti-kinetoplastid potential of propolis, highlighting its anti-kinetoplastid activity in vitro and in vivo regardless of geographical origin. The mode of action of propolis depends on the organism it is acting on and includes growth inhibition, immunomodulation, macrophage activation, perturbation of the cell membrane architecture, phospholipid disturbances, and mitochondrial targets. This gives ample scope for further investigations toward the rational development of sustainable anti-kinetoplastid drugs.

Wound healing: time to look for intelligent, 'natural' immunological approaches?

There is now good evidence that cytokines and growth factors are key factors in tissue repair and often exert anti-infective activities. However, engineering such factors for global use, even in the most remote places, is not realistic. Instead, we propose to examine how such factors work and to evaluate the reparative tools generously provided by 'nature.' We used two approaches to address these objectives. The first approach was to reappraise the internal capacity of the factors contributing the most to healing in the body, i.e., blood platelets. The second was to revisit natural agents such as whey proteins, (honey) bee venom and propolis. The platelet approach elucidates the inflammation spectrum from physiology to pathology, whereas milk and honey derivatives accelerate diabetic wound healing. Thus, this review aims at offering a fresh view of how wound healing can be addressed by natural means.

Antioxidant, antimicrobial, antiparasitic, and cytotoxic properties of various Brazilian propolis extracts

Propolis is known for its biological properties and its preparations have been continuously investigated in an attempt to solve the problem of their standardization, an issue that limits the use of propolis in food and pharmaceutical industries. The aim of this study was to evaluate in vitro antioxidant, antimicrobial, antiparasitic, and cytotoxic effects of extracts of red, green, and brown propolis from different regions of Brazil, obtained by ethanolic and supercritical extraction methods. We found that propolis extracts obtained by both these methods showed concentration-dependent antioxidant activity. The extracts obtained by ethanolic extraction showed higher antioxidant activity than that shown by the extracts obtained by supercritical extraction. Ethanolic extracts of red propolis exhibited up to 98% of the maximum antioxidant activity at the highest extract concentration. Red propolis extracts obtained by ethanolic and supercritical methods showed the highest levels of antimicrobial activity against several bacteria. Most extracts demonstrated antimicrobial activity against Staphylococcus aureus. None of the extracts analyzed showed activity against Escherichia coli or Candida albicans. An inhibitory effect of all tested ethanolic extracts on the growth of Trypanosoma cruzi Y strain epimastigotes was observed in the first 24 h. However, after 96 h, a persistent inhibitory effect was detected only for red propolis samples. Only ethanolic extracts of red propolis samples R01Et.B2 and R02Et.B2 showed a cytotoxic effect against all four cancer cell lines tested (HL-60, HCT-116, OVCAR-8, and SF-295), indicating that red propolis extracts have great cytotoxic potential. The biological effects of ethanolic extracts of red propolis revealed in the present study suggest that red propolis can be a potential alternative therapeutic treatment against Chagas disease and some types of cancer, although high activity of red propolis in vitro needs to be confirmed by future in vivo investigations.

The immunomodulatory and anticancer properties of propolis

Propolis, a waxy substance produced by the honeybee, has been adopted as a form of folk medicine since ancient times. It has a wide spectrum of alleged applications including potential anti-infection and anticancer effects. Many of the therapeutic effects can be attributed to its immunomodulatory functions. The composition of propolis can vary according to the geographic locations from where the bees obtained the ingredients. Two main immunopotent chemicals have been identified as caffeic acid phenethyl ester (CAPE) and artepillin C. Propolis, CAPE, and artepillin C have been shown to exert summative immunosuppressive function on T lymphocyte subsets but paradoxically activate macrophage function. On the other hand, they also have potential antitumor properties by different postulated mechanisms such as suppressing cancer cells proliferation via its anti-inflammatory effects; decreasing the cancer stem cell populations; blocking specific oncogene signaling pathways; exerting antiangiogenic effects; and modulating the tumor microenvironment. The good bioavailability by the oral route and good historical safety profile makes propolis an ideal adjuvant agent for future immunomodulatory or anticancer regimens. However, standardized quality controls and good design clinical trials are essential before either propolis or its active ingredients can be adopted routinely in our future therapeutic armamentarium.

[Propolis: origin, composition and properties]

La propolis est une substance résineuse récoltée par les abeilles (Apis mellifera) dont la composition biochimique dépend de l’origine botanique. Cette revue dresse une liste non exhaustive des différentes propolis étudiées sur les différents continents avec leurs principaux composés. Les divers effets biologiques et/ou thérapeutiques attribués à la propolis et/ou à ses principaux constituants sont passés en revue. Enfin, bien que prometteur, un travail pour établir des critères de qualité reste indispensable.

Susceptibility of Trypanosoma evansi to propolis extract in vitro and in experimentally infected rats

Current therapy of Trypanosoma evansi infections is not effective for the vast majority of animals with relapsing parasitemia and clinical signs. Recently, attention is being focused on the antiparasitic activity of propolis. This study evaluated the susceptibility of T. evansi to propolis extract in vitro and in vivo. A dose-dependent trypanocidal activity of propolis extract was observed in vitro. All trypomastigotes were killed 1 h after incubation with 10 μg mL(-1) of the extract. In vivo, the concentrations of 100, 200, 300 and 400 mg kg(-1) administered orally for 10 consecutive days showed no curative effect, and the rats died from the disease. However, rats treated with the two highest concentrations of propolis extract showed higher longevity than the other groups. Based on these data, we concluded that T. evansi is susceptible to propolis in vitro. Despite the lack of curative efficacy observed in vivo at the concentrations tested, the propolis extract can prolong life in rats infected with the protozoan.

Experimental chemotherapy for Chagas disease: 15 years of research contributions from in vivo and in vitro studies

Chagas disease, which is caused by the intracellular parasite Trypanosoma cruzi, is a neglected illness with 12-14 million reported cases in endemic geographic regions of Latin America. While the disease still represents an important public health problem in these affected areas, the available therapy, which was introduced more than four decades ago, is far from ideal due to its substantial toxicity, its limited effects on different parasite stocks, and its poor activity during the chronic phase of the disease. For the past 15 years, our group, in collaboration with research groups focused on medicinal chemistry, has been working on experimental chemotherapies for Chagas disease, investigating the biological activity, toxicity, selectivity and cellular targets of different classes of compounds on T. cruzi. In this report, we present an overview of these in vitro and in vivo studies, focusing on the most promising classes of compounds with the aim of contributing to the current knowledge of the treatment of Chagas disease and aiding in the development of a new arsenal of candidates with anti-T. cruzi efficacy.

IMUNOMODULAÇÃO PELA PRÓPOLIS

RESUMO A própolis, uma substância resinosa produzida pelas abelhas melíferas a partir de exsudatos coletados em diferentes partes das plantas, tem sido utilizada há séculos na medicina popular devido as suas propriedades terapêuticas. Esta substância apresenta atividade antiinflamatória, antitumoral, antioxidante e imunomoduladora, embora muitos dos seus mecanismos de ação sejam desconhecidos. A imunomodulação pela própolis pode estar associada tanto com a estimulação quanto com a supressão de determinados eventos da resposta imune. Os efeitos antagônicos e muitas vezes não complementares sobre o sistema imunológico podem ser decorrentes da grande variabilidade química existente entre diferentes amostras de própolis, bem como das diferentes metodologias adotadas nos estudos científicos, resultando em variada ação farmacológica. Este artigo teve como objetivo revisar e discutir alguns aspectos relacionados à ação da própolis sobre o sistema imunológico.

The effect of propolis in experimental Acanthamoeba keratitis

PURPOSE

To examine the effect of propolis in a rat model of Acanthamoeba keratitis and to determine its in vitro cytotoxicity in cultured corneal epithelial cells.

METHODS

Eighteen Wistar albino rats were used. Cultured corneal epithelial cells obtained from two healthy rats for in vitro cytotoxicity of propolis. Corneal stromal inoculation was performed in 16 rats with amoebic culture containing 1 x 10(6) amoeba/mL. Rats with Acanthamoeba keratitis 5 days later after the inoculation were divided randomly into four groups, and eight eyes of each group were treated with study drugs. The propolis, chlorhexidine (CHX), propolis plus CHX and control eyes were treated with topical propolis, 0.002% CHX, propolis plus 0.002% CHX and lubricant eye drops, respectively. The study drugs were instilled every one hour for 10 days. All eyes were examined and keratitis graded by slit-lamp biomicroscopy on days 2, 5 and 10 during the administration of the study drugs. After the completion of keratitis grading, all the 16 rats were humanely killed and their corneas were excised and used for Acanthamoeba culture to evaluate presence of Acanthamoeba growth after treatment 14 days later.

RESULTS

Concentrations of propolis higher than 7.81 mg/mL cause damage to corneal epithelial cells in the experiment of in vitro cytotoxicity of propolis on corneal epithelial cells. The keratitis grade on day 2 in the CHX eyes was significantly lower than that in the control eyes (P < 0.05). The keratitis grades on days 5 and 10 in the propolis, CHX and propolis plus CHX eyes were significantly lower compared with those on days 5 and 10 in the control eyes (P < 0.05). In the propolis eyes, the keratitis grade on day 5 was significantly lower than that on day 2 (P < 0.05), and it was significantly lower on day 10 compared with that on day 5 (P < 0.05). In the CHX and propolis plus CHX eyes, the keratitis grade on day 10 was significantly lower compared with that on days 2 and 5 (P < 0.05). In the control eyes, there was no significant difference in the keratitis grades on days 2, 5 and 10 (P > 0.05). The culture positivity at Acanthamoeba growth after treatment experiment in the propolis, CHX and propolis plus CHX eyes was significantly lower than that in the control eyes (P < 0.05).

CONCLUSIONS

We suggest that propolis had amoebicidal properties in this rat model of Acanthamoeba keratitis. Further investigations to evaluate the antimicrobial activity of the individual fractions of the resin could yield more information about its mechanism of action in treating this disease.

Propolis and the immune system: a review

Propolis has been used empirically for centuries and it was always mentioned as an immunomodulatory agent. In recent years, in vitro and in vivo assays provided new information concerning its mechanisms of action, thus a review dealing with propolis and the immune system became imperative. This review compiles data from our laboratory as well as from other researchers, focusing on its chemical composition and botanical sources, the seasonal effect on its composition and biological properties, its immunomodulatory and antitumor properties, considering its effects on antibody production and on different cells of the immune system, involving the innate and adaptive immune response. In vitro and in vivo assays demonstrated the modulatory action of propolis on murine peritoneal macrophages, increasing their microbicidal activity. Its stimulant action on the lytic activity of natural killer cells against tumor cells, and on antibody production was demonstrated. Propolis inhibitory effects on lymphoproliferation may be associated to its anti-inflammatory property. In immunological assays, the best results were observed when propolis was administered over a short-term to animals. Propolis antitumor property and its anticarcinogenic and antimutagenic potential are discussed. Since humans have used propolis for different purposes and propolis-containing products have been marketed, the knowledge of its properties with scientific basis is not only of academic interest but also of those who use propolis as well. This review opens a new perspective on the investigation of propolis biological properties, mainly with respect to the immune system.

Activity of Brazilian and Bulgarian propolis against different species of Leishmania

Extracts of propolis samples collected in Brazil and Bulgaria were assayed against four Leishmania species--Leishmania amazonensis, L. braziliensis, L. chagasi from the New World, and L. major from the Old World--associated to different clinical forms of leishmaniasis. The composition of the extracts has been previously characterized by high temperature high resolution gas chromatography coupled to mass spectrometry. Considering the chemical differences among the extracts and the behavior of the parasites, it was observed significant differences in the leishmanicidal activities with IC50/1 day values in the range of 2.8 to 229.3 microg/ml . An overall analysis showed that for all the species evaluated, Bulgarian extracts were more active than the ethanol Brazilian extract. As the assayed propolis extracts have their chemical composition determined it merits further investigation the effect of individual components or their combinations on each Leishmania species.

Immunomodulation produced by a green propolis extract on humoral and cellular responses of mice immunized with SuHV-1

Despite recent technological advances in vaccine production, most the vaccines depend on the association with adjuvant substances. This work evaluated the adjuvant capacity of an ethanol extract of green propolis associated to inactivated Suid herpesvirus type 1 (SuHV-1) vaccine preparations. Mice inoculated with SuHV-1 vaccine plus aluminum hydroxide and 5mg/dose of propolis extract presented higher levels of antibodies when compared to animals that received the same vaccine without propolis. The use of SuHV-1 vaccine with propolis extract alone did not induce significant levels of antibodies, however it was able to increase the cellular immune response, evidenced by the increase in the expression of mRNA to IFN-gamma. Besides, propolis increased the percentage of protected animals against challenge with a lethal dose of SuHV-1. The effect of green propolis extract on the humoral and cellular immune responses may be exploited for the development of effective vaccines.

The effect of Bulgarian propolis against Trypanosoma cruzi and during its interaction with host cells

Propolis has shown activity against pathogenic microorganisms that cause diseases in humans and animals. The ethanol (Et-Blg) and acetone (Ket-Blg) extracts from a Bulgarian propolis, with known chemical compositions, presented similar activity against tissue culture-derived amastigotes. The treatment of Trypanosoma cruzi-infected skeletal muscle cells with Et-Blg led to a decrease of infection and of the intracellular proliferation of amastigotes, while damage to the host cell was observed only at concentration 12.5 times higher than those affecting the parasite. Ultrastructural analysis of the effect of both extracts in epimastigotes revealed that the main targets were the mitochondrion and reservosomes. Et-Blg also affected the mitochondrion-kinetoplast complex in trypomastigotes, offering a potential target for chemotherapeutic agents.

A propolis extract and the labeling of blood constituents with technetium-99m

Since ancient times propolis has been employed for many human purposes because to their favourable properties. Blood constituents labeled with technetium-99m (99mTc) have been used in nuclear medicine procedures. Some authors have reported that synthetic or natural drugs can interfere with the labeling of blood constituents with 99mTc. The aim of this work was to evaluate the action of a propolis extract on the labeling of blood elements with 99mTc. Samples of whole blood of male Wistar rats were incubated in sequence with an aqueous propolis extract at different concentrations, stannous chloride and 99mTc, as sodium pertechnetate. Blood samples were centrifuged to separate plasma and blood cells, soluble and insoluble fractions of plasma and blood cells were also separated after precipitation in trichloroacetic acid solution and centrifugation. The radioactivity was counted and the percentage of incorporated radioactivity (%ATI) for each fraction was calculated. The data obtained showed that the aqueous propolis extract used decreased significantly the %ATI in plasma proteins at higher concentration studied. Results suggest that at high concentration the constituents of this extract could alter the labeling of plasma proteins competing with same binding sites of the 99mTc on the plasma proteins or acting as antioxidant compounds.

In vitro effects of propolis on Giardia duodenalis trophozoites

In order to improve the current chemotherapy of Giardia infection, potential antigiardial agents have been screened, including natural products. Propolis, a resinous hive product collected by bees, has attracted attention as a useful and popular substance with several therapeutic activities. The present study was carried out aiming to evaluate the in vitro effects of an ethanolic extract of propolis on the growth and adherence of Giardia duodenalis trophozoites. Propolis inhibited the growth of trophozoites and the level of inhibition varied according to the extract concentration and incubation times. The highest reduction of parasite growth was observed in cultures exposed to 125, 250 and 500 microg/ml of propolis, in all incubation periods (24, 48, 72 and 96 h). Growth reduction by 50% was observed in 125 microg/ml propolis-treated cultures, while the concentrations of 250 and 500 microg/ml were able to inhibit growth by more than 60%. Propolis also inhibited parasite adherence and all assayed propolis concentrations promoted the detachment of trophozoites. Light microscope observations revealed changes of the pear-shaped aspect of the cell and reduction of flagellar beating frequency in the great part of the trophozoites. Our results hold the perspective for the utilization of propolis as an antigiardial agent.

Treatment of Trypanosoma cruzi-infected mice with propolis promotes changes in the immune response

Ethanol extract of Bulgarian propolis (Et-Blg) was administered by oral route in doses ranging from 25 to 100mg/kg body weight in experimental Trypanosoma cruzi-infected Swiss mice. Treatment with 50mg Et-Blg/kg body weight/day led to a decrease in parasitemia and showed no hepatic or renal toxic effect. Treatment with Et-Blg led to a decrease in the spleen mass and modulated the initial inflammatory reaction as demonstrated by analysis of the leukocyte profile in peripheral blood, quantification of T cells subsets, and phenotypic markers in the spleen. Preferential expansion of CD8(+) and partial inhibition in the increase of CD4(+)CD69(+) and CD8(+)CD69(+) in CD4(+)CD44(+) and CD8(+)CD44(+) and in the decrease of CD8(+)CD62L in Trypanosoma cruzi-infected mice were also observed. Taken together, our data indicate that treatment of Trypanosoma cruzi-infected mice with Et-Blg interferes with the basic properties of immune cells.

Chemical compositions and antimicrobial activities of four different Anatolian propolis samples

Propolis means a gum that is gathered by bees from various plants. It is known for its biological properties, having antibacterial, antifungal and healing properties. The aims of this study were to evaluate the antimicrobial activity of four different Anatolian propolis samples on different groups of microorganisms including some oral pathogens and comparison between their chemical compositions. Ethanol extracts of propolis (EEP) were prepared from four different Anatolian propolis samples and examined whether EEP inhibit the growth of the test microorganisms or not. For the antimicrobial activity assays, minimum inhibitory concentrations (MIC) were determined by using macrodilution method. The MIC values of the most effective propolis (TB) were 2 microg/ml for Streptococcus sobrinus and Enterococcus faecalis, 4 microg/ml for Micrococcus luteus, Candida albicans and C. krusei, 8 microg/ml for Streptococcus mutans, Staphylococcus aureus, Staphylococcus epidermidis and Enterobacter aerogenes, 16 microg/ml for Escherichia coli and C. tropicalis and 32 microg/ml for Salmonella typhimurium and Pseudomonas aeruginosa. The chemical compositions of EEP's were determined by high-temperature high-resolution gas chromatography coupled to mass spectrometry. The main compounds of four Anatolian propolis samples were flavonoids such as pinocembrin, pinostropin, isalpinin, pinobanksin, quercetin, naringenin, galangine and chrysin. Although propolis samples were collected from different regions of Anatolia all showed significant antimicrobial activity against the Gram positive bacteria and yeasts. Propolis can prevent dental caries since it demonstrated significant antimicrobial activity against the microorganisms such as Streptococcus mutans, Streptococcus sobrinus and C. albicans, which involves in oral diseases.

PRÓPOLIS: UMA REVISÃO DOS RECENTES ESTUDOS DE SUAS PROPRIEDADES FARMACOLÓGICAS

RESUMO Própolis de Apis mellifera L. (Hymenoptera, Apidae) é um produto da colméia, elaborado a partir de exsudatos de resinas que as abelhas recolhem de determinadas plantas. A composição química da própolis é complexa e relacionada à diversidade vegetal encontrada em torno da colméia. Embora a própolis seja utilizada em medicina popular por milhares de anos, a falta de padrões que avaliem de maneira precisa suas atividades farmacológicas, dificulta a estandardização de produtos comerciais que garanta sua eficácia e segurança terapêutica para humanos e outros animais. Nesta revisão estão sumarizados alguns desenvolvimentos recentes da pesquisa farmacológica da própolis, enfocando-se as atividades antiinflamatórias, antimicrobianas, antineoplásica e antioxidante.

Antitrypanosomal activity of Brazilian propolis from Apis mellifera

Extracts from different samples of Brazilian propolis were obtained by Soxhlet extraction or maceration at room temperature using ethanol, water, and accombination of both solvents. Analysis of their composition using HPLC revealed that no major differences were seen when a propolis sample was subject to different extraction methods. The activity of the 15 extracts was assayed against bloodstream trypomastigotes of Trypanosoma cruzi, the etiologic agent of Chagas' disease. Multivariate analysis was applied to evaluate the efficiency of the different extracts and the trypanocidal activity. The extracts could be divided into two groups. In the first, in which, extracts were obtained by reflux in Soxhlet using 100% ethanol, there was a lower content of bioactive compounds and consequently lower trypanocidal activity. Extract 136-Et100 stands out in this group, since it had the highest levels of bioactive compounds together with highest activity against the parasite when compared with all other extracts. The second group comprises extracts with intermediate levels of bioactive compounds and higher activity against T. cruzi.

Chemical composition and microbicidal activity of extracts from Brazilian and Bulgarian propolis

AIMS

The chemical composition of ethanol extracts from a Brazilian (Et-Bra) and a Bulgarian (Et-Blg) propolis, and their activity against the protozoan Trypanosoma cruzi, several fungi and bacteria species were determined.

METHODS AND RESULTS

The chemical composition was determined by high temperature high resolution gas chromatography coupled to mass spectrometry. Microbiological activity was assayed in vitro against T. cruzi, Candida albicans, Sporothrix schenckii, Paracoccidioides brasiliensis, Neisseria meningitidis, Streptococcus pneumoniae and Staphylococcus aureus.

CONCLUSIONS

Et-Bra and Et-Blg, although with totally distinct compositions, were active against T. cruzi and the three species of fungi. Et-Blg was more effective than Et-Bra against bacteria, particularly N. meningitidis and Strep. pneumoniae.

SIGNIFICANCE AND IMPACT OF THE STUDY

Although with different classes of components, both propolis extracts showed microbicidal activity. For the bactericidal activity it was possible to establish a positive correlation with the high content of flavonoids of the Bulgarian extract.

Mechanisms involved in the relaxant action of the ethanolic extract of propolis in the guinea-pig trachea in-vitro

This study examines the mechanisms by which the standardised ethanolic extract of propolis induces relaxation of the guinea-pig trachea in-vitro. In guinea-pig trachea with or without epithelium and contracted by histamine, the propolis extract caused reproducible and graded relaxation, with a mean EC50 value of 3.8 or 10.5 microg mL(-1) and Emax of 100%, respectively. The propolis extract-induced relaxation was markedly reduced (26+/-9 and 96+/-3%) when guinea-pig tracheas were exposed to Krebs solution containing elevated K+ in the medium (40 or 80 mM). Pre-incubation of guinea-pig tracheas with tetraethylamonium (100 mM) or with 4-aminopyridine (10mM) reduced the propolis extract-induced relaxation by 31+/-10% and 28+/-2%. Likewise, apamin (0.1 microM), charybdotoxin (0.1 microM) or iberiotoxin (0.1 microM) caused marked inhibition of propolis extract-mediated relaxation in guinea-pig trachea (percentage of inhibition: 65+/-3%, 60+/-5% and 65+/-9%, respectively). Also, glibenclamide (1 microM) inhibited the relaxant response caused by the propolis extract by 57+/-4%. Omega-conotoxin GIVA (0.1 microM) or capsaicin (1 microM) produced small but significant inhibition (30+/-5% or 47+/-7%, respectively) of the propolis extract-induced relaxation. The vasoactive intestinal peptide (VIP) antagonist D-p-Cl-Phe6,Leu17[VIP] porcine (0.1 microM) inhibited relaxation by 55+/-5%, while propranolol (1 microM) induced a parallel rightward displacement (about 20 fold) of the propolis extract concentration-response curve. Finally, the propolis extract-induced relaxation was inhibited by the nitric oxide synthase inhibitor L-N(G)-nitroarginine (L-NOArg, 100 microM) (48+/-6%), and by the soluble guanylatecyclase inhibitormethylene blue (10 microM) (37+/-6%), whilethe moreselectivesoluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolol[4,3-alquinoxalin-1-one (ODQ, 1 microM) produced only a parallel (about 3 fold) rightward displacement of the propolis extract concentration-response curve. Collectively, these results support the notion that the propolis extract-mediated relaxation in the guinea-pig trachea involves the release of nitric oxide, probably from sensory neurons, besides the activation of soluble guanylate cyclase and activation of Ca2+- and ATP-sensitive K+ channels. Furthermore, the stimulation of beta2-adrenergic and VIP receptors also seems to account for its relaxant action.

A critical review on Chagas disease chemotherapy

In this "Critical Review" we made a historical introduction of drugs assayed against Chagas disease beginning in 1912 with the works of Mayer and Rocha Lima up to the experimental use of nitrofurazone. In the beginning of the 70s, nifurtimox and benznidazole were introduced for clinical treatment, but results showed a great variability and there is still a controversy about their use for chronic cases. After the introduction of these nitroheterocycles only a few compounds were assayed in chagasic patients. The great advances in vector control in the South Cone countries, and the demonstration of parasite in chronic patients indicated the urgency to discuss the etiologic treatment during this phase, reinforcing the need to find drugs with more efficacy and less toxicity. We also review potential targets in the parasite and present a survey about new classes of synthetic and natural compounds studied after 1992/1993, with which we intend to give to the reader a general view about experimental studies in the area of the chemotherapy of Chagas disease, complementing the previous papers of Brener (1979) and De Castro (1993).

Recent progress in pharmacological research of propolis

Propolis is a resinous hive product collected by honeybees from various plant sources. It is a popular folk medicine possessing a broad spectrum of biological activities. It has also been used as a health drink in various Asian, European and American countries. Several groups of researchers have focused their attention on the biological activity of propolis and its active principles. Many scientific articles are published every year in different international journals related to the pharmacological properties of propolis. This review article compiles recent findings (since 1995) on the pharmacological properties of propolis focusing on its antihepatotoxic, antitumour, antioxidative, antimicrobial and antiinflammatory properties. The possible mechanism of action of propolis as well as the active compounds are discussed.

Phenolic compounds from Brazilian propolis with pharmacological activities

Four compounds were isolated from Brazilian propolis. They are identified as: (1) 3-prenyl-4-hydroxycinnamic acid (PHCA), (2) 2,2-dimethyl-6-carboxyethenyl-2H-1-benzopyrane (DCBEN), (3) 3,5-diprenyl-4-hydroxycinnamic acid (DHCA), and (4) 2,2-dimethyl-6-carboxyethenyl-8-prenyl-2H-1-benzopyran (DPB). The structures of the compounds were determined by MS and NMR techniques. All compounds were assayed against Trypanosoma cruzi and the bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus faecalis. Compounds (1) to (4) were active against T. cruzi. Except (1), all compounds presented activity against the bacteria tested. When compounds (1)-(3) were tested in the guinea pig isolated trachea, all induced a relaxant effect similar to propolis extract.

Seasonal effect on Brazilian propolis antibacterial activity

The behavior of microorganisms towards the antibiotic action of propolis has been widely investigated. Since reports dealing with seasonal effect on propolis activity are not available, this assay was carried out aiming to observe the in vitro antimicrobial activity of propolis, collected during the four seasons, on bacterial strains isolated from human infections. Dilution of ethanolic extract of propolis (EEP) in agar was the method performed, with serial concentrations ranging from 0.4 to 14.0% (% v/v). The behavior of some bacteria was analysed according to the incubation period in medium plus propolis, and the survival curve was plotted. It was verified that the growth of Gram-positive bacteria is inhibited by low propolis concentrations (0.4%) whereas Gram-negative bacteria were less susceptible to this substance, the minimal inhibitory concentration ranging from 4.5 to 8.0%. There was no significant difference with regards to the seasonal effect on the survival curve of Staphylococcus aureus and Escherichia coli; after incubation with propolis, there was an efficient antimicrobial action, mainly towards Gram-positive bacteria.

Anti-hyperalgesic effect of an ethanolic extract of propolis in mice and rats

Propolis, or bee glue, which contains a complex mixture of secondary metabolites, has long been used in many countries for the management of several diseases. The purpose of this study was to evaluate, by means of several pharmacological models, the anti-hyperalgesic effect of propolis collected in the south of Brazil. The abdominal constrictions induced in mice by intraperitoneal injection of acetic acid (0.6%), kaolin (50 mg kg-1) or zymosan (40 mg kg-1) were inhibited to different extents by an extract of propolis (1-60 mg kg-1) administered intraperitoneally 30 min earlier; mean ID50 (concentrations resulting in 50% inhibition) values were 2.7, 10.8 and 10.7 mg kg-1, respectively, and maximum inhibition was 58 +/- 5, 57 +/- 10 and 51 +/- 5%, respectively. Given orally (25-200 mg kg-1, 1h previously) propolis also inhibited the abdominal constrictions induced by acetic acid (maximum inhibition 43 +/- 5%). When injected intraperitoneally (3-60 mg kg-1, 30 min previously), propolis attenuated both the neurogenic (first phase) and inflammatory (second phase) pain responses and paw oedema caused by intraplantar injection of formalin (2.5%); maximum inhibition was 32 +/- 5, 43 +/- 6 and 19 +/- 2%, respectively. Oral administration of propolis (25-200 mg kg-1, 1 h previously) inhibited both phases and reduced the oedema formation associated with the second phase of the formalin test (maximum inhibition 22 +/- 5, 33 +/- 6 and 26 +/- 3%) and extract of propolis (3-30 mg kg-1 i.p. or 25-100 mg kg-1 p.o., respectively 30 min and 1 h previously) significantly inhibited capsaicin-induced pain with maximum inhibition of 39 +/- 8 and 41 +/- 8%, respectively. When assessed in the Randall-Sellito test of pain, the extract of propolis (3-30 mg kg-1, i.p., 30 min previously) significantly reversed the hyperalgesia induced by intraplantar injection of bradykinin (3 nmol per paw) in rats (P < 0.01). In contrast with morphine the extract of propolis (< or = 100 mg kg-1, 30 min previously) was ineffective when assessed in the tail-flick and hot-plate thermal assays. Naloxone (5 mg kg-1 i.p.) reversed (P < 0.01) the effect of morphine (5 mg kg-1 s.c.) by 70 and 94% respectively in the first and second phases of the formalin test, but did not interfere with the analgesic effect of propolis (10 mg kg-1 i.p., 30 min previously). These results show that ethanolic extract of propolis, given systemically, has significant anti-hyperalgesic action when assessed in chemical, but not thermal, models of nociception in mice and rats. Its analgesic action seems to be unrelated to release or activation of the opioid system.

Review of the biological properties and toxicity of bee propolis (propolis)

Propolis is a multifunctional material used by bees in the construction and maintenance of their hives. Use of propolis by humans has a long history, predated only by the discovery of honey. Use of products containing propolis have resulted in extensive dermal contact and it is now increasingly being used a dietary supplement. Unlike many 'natural' remedies, there is a substantive database on the biological activity and toxicity of propolis indicating it may have many antibiotic, antifungal, antiviral and antitumour properties, among other attributes. Although reports of allergic reactions are not uncommon, propolis is relatively non-toxic, with a no-effect level (NOEL) in a 90-mouse study of 1400 mg/kg body weight/day.