Propolis extracts are effective against Trypanosoma cruzi and have an impact on its interaction with host cells

Biosynthesis of Ag-Pt bimetallic nanoparticles using propolis extract: Antibacterial effects and catalytic activity on NaBH4 hydrolysis

The critical environmental issues of antibiotic resistance and renewable energies supply urge researching materials synthesis and catalyst activity on hydrogen production processes. Aiming to analyse the antibacterial effect of platinum-silver (Ag-Pt) nanoparticles (NPs) and the catalyst effect on NaBH₄ hydrolysis that can be used for hydrogen generation technology, in this work, Ag-Pt NPs were prepared using aqueous propolis extract. Various methods were used for the characterization (Uv-vis Spectroscopy, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and X-ray diffraction Spectroscopy (XRD)). The antimicrobial activity of Ag-Pt bimetallic nanoparticles was evaluated in vitro by the microdilution method against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Staphylococcus epidermidis, and Serratia marcescens. The results confirmed the antimicrobial activity of bimetallic NPs Ag-Pt concentrations of (25, 50, and 100 μg/ml). A concentration of 100 μg/ml showed low bacterial viability varying between 22.58% and 29.67% for the six tested bacteria. For the catalyst activity on NaBH₄ hydrolysis, the results showed high turnover factor (TOF) and low activation energy of 1208.57 h^-1 and 25.61 kJ/mol, respectively, with high hydrogen yield under low temperature. Synthesized Ag-Pt NPs can have great potential for biological and hydrogen storage applications.

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.

Effects of Propolis on Infectious Diseases of Medical Relevance

Infectious diseases are a significant problem affecting the public health and economic stability of societies all over the world. Treatment is available for most of these diseases; however, many pathogens have developed resistance to drugs, necessitating the development of new therapies with chemical agents, which can have serious side effects and high toxicity. In addition, the severity and aggressiveness of emerging and re-emerging diseases, such as pandemics caused by viral agents, have led to the priority of investigating new therapies to complement the treatment of different infectious diseases. Alternative and complementary medicine is widely used throughout the world due to its low cost and easy access and has been shown to provide a wide repertoire of options for the treatment of various conditions. In this work, we address the relevance of the effects of propolis on the causal pathogens of the main infectious diseases with medical relevance; the existing compiled information shows that propolis has effects on Gram-positive and Gram-negative bacteria, fungi, protozoan parasites and helminths, and viruses; however, challenges remain, such as the assessment of their effects in clinical studies for adequate and safe use.

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.

Antitrypanosomal, antileishmanial and cytotoxic activities of Brazilian red propolis and plant resin of Dalbergia ecastaphyllum (L) Taub

The treatment for leishmaniasis and Chagas disease can be hard and painful, such that many patients give up on the treatment. In order to find an alternative path for the treatment of these diseases, researchers are using natural products to fight these parasites. The aim of this study was to evaluate the antiprotozoan and cytotoxic activities of red propolis samples collected from different Brazilian states and seasons whilst searching for possible activity differences. We also compared the red propolis results with the ones obtained for the plant resin extract collected from Dalbergia ecastaphyllum trees. The hydroethanolic red propolis extracts from Pernambuco and Alagoas, and the D. ecastaphyllum resin were evaluated regarding their antileishmanial, antitrypanosomal and cytotoxic activity. All extracts showed antiprotozoan and cytotoxic activity. RP-PER showed to be more cytotoxic against protozoan parasites and fibroblast cells. All propolis extracts showed a higher cytotoxic activity when compared to resin extracts. The propolis sample collected in Pernambuco during the rainy season killed the parasites with lower concentrations than the sample collected in the dry season. The IC₅₀ observed against the parasites could be used without high fibroblast cell damage.

Propolis Diterpenes as a Remarkable Bio-Source for Drug Discovery Development: A Review

Propolis is one of the complex, but valuable, bio-sources for discovering therapeutic compounds. Diterpenes are organic compounds composed of four isoprene units and are known for their biological and pharmacological characteristics, such as antibacterial, anticancer, and anti-inflammatory activities. Recently, advancements have been made in the development of antibacterial and anticancer leads from propolis-isolated diterpenes, and scrutiny of these compounds is being pursued. Thus, this review covers the progress in this arena, with a focus on the chemistry and biological activities of propolis diterpenes. It is anticipated that important information, in a comprehensive and concise manner, will be delivered here for better understanding of natural product drug discovery research.

Antioxidative Effects of Tetramethylpyrazine on Acute Ethanol-Induced Lipid Peroxidation

Acute p.o. administration of 99.5% ethanol (0.1 ml) to fasted mice produced heart toxicity. Pretreatment with p.o. administration of tetramethylpyrazine (TMP) could prevent such toxicity effectively and dose-dependently. The maximal antioxidative effect against 99.5% ethanol-induced heart toxicity could be observed at 1 hour after TMP administration. In order to further investigate the heart protective mechanism of TMP, both lipid peroxidation level in vivo and superoxide scavenging activity were conducted. TMP exhibited a dose-dependently anti-lipid peroxidation effect in mice heart homogenate, and results indicated that 99.5% ethanol-induced intoxicated mice hearts have higher malonic dialdehyde (MDA) levels compared with those in TMP administrated mice hearts. These results suggest that the potentially heart protective mechanism of TMP could be contributed, at least in part, to its prominent anti-lipid peroxidation and anti-free radical formation effects, hence it could protect the heart from lipid peroxidation-induced heart toxicity.

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.

Effect of galangin supplementation on oxidative damage and inflammatory changes in fructose-fed rat liver

The study examined the effects of galangin (GA) on oxidative stress, inflammatory cytokine levels and nuclear factor-kappa B (NF-κB) activation in fructose-fed rat liver. Adult male albino Wistar rats were divided into 4 groups. Groups 1 and 4 received the control diet containing starch as the source of carbohydrate while groups 2 and 3 were fed a diet containing fructose. Groups 3 and 4 additionally received GA (100μg/kg, p.o) from the 15th day. At the end of 60 days, the levels of plasma glucose, insulin and triglycerides, insulin sensitivity indices and oxidative stress markers in the liver were determined. Cytokines of interest were assayed by ELISA and RT-PCR and NF-κB p65 nuclear translocation by Western blot and RT-PCR. Compared to control diet-fed animals, fructose-fed animals developed hyperglycemia, hyperinsulinemia, hypertriglyceridemia and insulin resistance (IR) (all p<0.01). GA prevented the rise in plasma glucose, insulin and triglycerides and improved insulin sensitivity. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels in plasma and the mRNA and protein levels of TNF-α and transforming growth factor-β1(TGF-β(1)) in liver were significantly higher in fructose-fed rats than control rats. However, treatment with GA downregulated the expression of these cytokines. Translocation of NF-κB into the nucleus was also increased in fructose diet-fed animals, which was prevented by GA. These results suggest that GA prevents oxidative damage and has a downregulatory effect on the inflammatory pathway in liver of fructose-fed rats.

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.

The potential use of propolis as a cariostatic agent and its actions on mutans group streptococci

Propolis is a resinous substance made by bees. It possesses many biological activities, and many studies have reported its potential application in the control of dental caries. However, variability in the chemical composition of propolis is a potential problem in its quality control, especially since propolis has already been incorporated into products for oral use. Therefore, a critical analysis of the available data on propolis is warranted. The present review discusses the in vitro and in vivo studies published in the period between 1978 and 2008 regarding the effects of propolis on Streptococcus mutans growth, bacterial adherence, glucosyltransferase activity, and caries indicators. Several investigations carried out with crude propolis extracts, isolated fractions, and purified compounds showed reductions in Streptococcus mutans counts and interference with their adhesion capacity and glucosyltransferase activity, which are considered major properties in the establishment of the cariogenic process. Data from in vivo studies have demonstrated reductions in Streptococcus mutans counts in saliva, the plaque index, and insoluble polysaccharide formation. These findings indicate that propolis and/or its compounds are promising cariostatic agents. However, the variation in the chemical composition of propolis due to its geographical distribution is a significant drawback to its routine clinical use. Thus, further studies are needed to establish the quality and safety control criteria for propolis in order for it to be used in accordance with its proposed activity.

Triclabendazole progress report, 2005–2009: an advancement of learning?

Triclabendazole (TCBZ) remains the drug of choice for treating infections of the liver fluke,Fasciola hepaticain livestock and has become the main drug used to treat human cases of the disease as well. Cases of resistance in livestock continue to be reported, suggesting that the problem is increasing. In order to address the problem, there is a need for better understanding of drug action. A ‘state-of-play’ review on different aspects of TCBZ activity was published by the present author in 2005. The main purpose of the current review is to assess what progress has been made in the past four years towards understanding the main aspects of drug activity, including drug pharmacokinetics and pharmacodynamics and an understanding of the mechanism(s) of resistance. Also, what advances have been made in identifying alternative compounds and using drug combinations to enhance TCBZ activity. Stemming from a number ofin vivostudies, it has become evident that fluke isolates of differing sensitivity to TCBZ differ in some of their biological parameters, and information on this interesting phenomenon will be presented. An update on the use of TCBZ for human fascioliasis is also given. The review will indicate what progress has been made, but will also highlight areas that remain inadequately understood and require greater research focus.

Inhibitory effect of Egyptian propolis on Fasciola gigantica eggs with reference to its effect on Clostridium oedematiens and correlation to chemical composition

The chemical composition of the propolis samples was investigated by GC/MS and HPLC. 91 compounds have been identified, 26 compounds are being new to propolis. Siwa oasis propolis was characterized by the presence of diprenyl-dihydrocoumaric acids (4.15%), coumarate esters (10.93%), benzofuran lignans (13.47%) and valeric acids derivatives (11.42%). Matrooh sample was characterized by the presence of new ferulate esters, hydroxy acetophenones and furanon derivatives, furofuran lignans and sterol from pregnane type. Dakahlia propolis was a typical poplar propolis. The present study proved evidence of inhibitory activity of propolis on the vitality and hatchability of immature F. gigantica eggs, where three different localities in Egypt were tested for this purpose. The Siwa propolis showed the highest inhibitory effect than the other sources. The complete failure of development and death of all immature eggs were recorded at concentration of 200 microg mL(-1) of Siwa, 400 microg mL(-1) of Matrooh and 800 microg mL(-1) of Dakahlia propolis. The exposed F. gigantica egg shell revealed the same features as the non exposed egg shell when scanning with the electron microscopy. The three propolis samples showed inhibition in the growth of associated bacterium Clostridium oedematiens (Clostridium novyi) type B to fascioliasis. The inhibition varied according to the propolis origin.

Reversal of acetaminophen induced subchronic hepatorenal injury by propolis extract in rats

The ethanolic extract of propolis (200mg/kg, p.o.) was evaluated against acetaminophen (APAP; 20mg/kg, p.o.) induced subchronic hepatorenal injury in rats. Administration of APAP significantly increased the release of serum transaminases, alkaline phosphatase, lactate dehydrogenase, γ-glutamyl transpeptidase, bilirubin and serum proteins, whereas concomitantly decreased hemoglobin, blood sugar and albumin. Hepatorenal reduced glutathione and activities of superoxide dismutase and catalase, hepatic CYPs i.e., aniline hydroxylase and amidopyrine-N-demethylase were significantly decreased after APAP intoxication. Lipid peroxidation showed significant elevation in both organs significantly after APAP assault. Total proteins, glycogen contents and the activities of certain metabolic enzymes i.e., adenosine triphosphatase, alkaline phosphatase and acid phosphatase were altered after APAP administration. Propolis extract exhibited curative effects by reversing APAP induced alterations in blood biochemical variables, CYP enzymes and markers of oxidative stress. Histopathological analysis of liver and kidney was consistent with the biochemical findings and led us to conclude the curative potential of propolis against APAP induced hepatorenal injury.

Effects of Brazilian propolis on Leishmania amazonensis

Leishmaniasis, an endemic parasitosis that leads to chronic cutaneous, mucocutaneous or visceral lesions, is part of those diseases, which still requires improved control tools. Propolis has shown activities against different bacteria, fungi, and parasites. In this study we investigated the effect of four ethanolic extracts of typified propolis collected in different Brazilian states, on Leishmania amazonensis performing assays with promastigote forms, extracellular amastigotes, and on infected peritoneal macrophages. Ethanolic extracts of all propolis samples (BRG, BRPG, BRP-1, and BRV) were capable to reduce parasite load as monitored by the percentage of infected macrophages and the number of intracellular parasites. BRV sample called red propolis, collected in the state of Alagoas, and containing high concentration of prenylated and benzophenones compounds, was the most active extract against L. amazonensis. The anti-Leishmania effect of BRV sample was increased in a concentration and time dependent manner. BRV treatment proved to be non-toxic to macrophage cultures. Since BRV extract at the concentration of 25 microg/ml reduced the parasite load of macrophages while presented no direct toxic to promastigotes and extracellular amastigotes, it was suggested that constituents of propolis intensify the mechanism of macrophage activation leading to killing of L. amazonensis. Our results demonstrate, for the first time, that ethanolic extracts of Brazilian propolis reduce L. amazonensis infection in macrophages, and encourage further studies of this natural compound in animal models of leishmaniasis.

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.

An in vitro effect of propolis on adult worms of Fasciola gigantica

The effect of Siwa propolis on adult flukes was evaluated using scanning electron microcopy. It gave an overview of the surface architecture of the tegument of Fasciola gigantica apical cone. The base of the spines appeared to be "flaking off" and showed severe blebbing after 24h incubation with 10 micro/ml propolis. This swelling became so sever and the spines were barely visible, on increasing the concentration to 20 micro/ml. Besides, there were many large blebs on the apical cone, a number of which appeared to have burst, causing lesions and the tegument was marked by a number of pits caused by the loss of spines. With the higher concentration of 30 micro/ml, erosion of the surface had occurred to such extent that no tegument remained, only a mass of fibrous structures. The tegumental changes occurred following incubation in propolis were compared with those observed with triclabendazole (TCBZ) "Fasinex" because of its high efficacy against both mature and immature flukes.

In VitroAmoebicidal Activity of Propolis onAcanthamoeba castellanii

PURPOSE

The aim of this study was to investigate the in vitro effects of an ethanolic extract of propolis on the growth and adherence of Acanthamoeba castellanii trophozoites and cysts.

METHODS

The effect of propolis with concentrations of 8.0, 6.0, 5.0, 4.0, 3.0, and 2.0 mg/mL on the proliferation of A. castellanii trophozoites, and with a concentration of 62.25, 31.25, 15.62, 7.81, 3.90, 1.95, and 0.97 mg/mL on the proliferation of A. castellanii cysts, at 1, 3, 6, 12, 24, 48, and 72 h were examined in vitro.

RESULTS

After 1-72 h, incubation in concentrations between 2.0 and 6.0 mg/mL, its effect was amoebistatic; at concentrations of 8.0 mg/mL and higher, its effect was amoebicidal. After 48 h or longer incubation times at 15.62 mg/mL and at higher concentrations, the propolis extract was cysticidal. At concentrations of 1.97 mg/mL or lower, there was no observable effect at any time point.

CONCLUSIONS

These findings indicate that ethanolic extract of propolis has amoebicidal, as well as cysticidal, properties for Acanthamoeba trophozoites and cysts. Propolis alone, or in combination with other amoebicidal agents, may be used in clinical practice after further investigations.

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.

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.

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.

In-vitro trypanocidal activity evaluation of crude extract and isolated compounds from Baccharis dracunculifolia D.C. (Asteraceae)

We have performed a trypanocidal bioactivity-guided study of Baccharis dracunculifolia (Asteraceae), the main botanical origin of Brazilian green propolis. The leaf rinse extract of B. dracunculifolia, at a concentration of 3.0 mg mL(-1), displayed 100% lysis of trypomastigote forms of the Y strain of Trypanosoma cruzi (2 x 10(6) parasites mL(-1)). The chromatographic fractionation of the leaf rinse, using several techniques, afforded the isolation of the compounds isosakuranetin (1), aromadendrin-4'-methylether (2), baccharis oxide (3), ferulic acid (4), dihydrocinnamic acid (5), 3-prenyl-4-(dihydrocinnamoyloxy)-cinnamic acid (6), and friedelanol (7). The chemical structures of all compounds were established by UV-vis, (1)H and (13)CNMR data analysis in comparison with the literature. Compounds 1 and 3 were the most active in the trypanocidal assay, showing IC50 values (inhibitory concentration required for 50% inhibition) of 247.6 and 249.8 microM, respectively. Compounds 2, 4, and 6 displayed moderate activity, whilst compounds 5 and 7 were inactive.

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.

Phytochemical compounds involved in the anti-inflammatory effect of propolis extract

Two ethanolic propolis extracts (EPE) with and without the caffeic acid phenethyl ester (CAPE), CAPE and galangin (major components of propolis) were investigated for anti-inflammatory activity in rats using carrageenin foot oedema, carrageenin pleurisy and adjuvant arthritis. In our experiments, EPE with CAPE and CAPE alone significantly inhibited carrageenin oedema, carrageenin pleurisy and adjuvant arthritis. In contrast EPE without CAPE and galangin did not exhibit anti-inflammatory effects in acute and chronic inflammation. These results suggest that the anti-inflammatory activity of propolis is due to CAPE.

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).

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.

In vitro antimicrobial activity of propolis dry extract

In this study the antibacterial and antifungal properties of propolis, a natural product of bees, have been investigated against different pathogens. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined according to NCCLS standards on 320 strains including Staphylococcus aureus, Group A beta-hemolytic streptococci, Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae, Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans. Time-kill curves were assessed for susceptible microorganisms, testing 0, 0.5, 1, 2, 4 x MIC for propolis, by counting viable bacteria after 0, 3, 6, 24 hours and viable yeasts after 0, 3, 6, 24 and 48 hours. Propolis showed good antimicrobial activity against most of the isolates, particularly S. pneumoniae, H. influenzae and M. catarrhalis, but not against Enterobacteriaceae. Time-kill curves demonstrated bacteriostatic rather than bactericidal activity of propolis, the latter being evident only at high concentrations.

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

Propolis, a bee product, can be regarded as one of the potential natural sources in folk medicine, displaying strong antimicrobial activity. Previous work showed that propolis extracts exhibited in vitro activity against Trypanosoma cruzi (Higashi and de Castro, 1994). Different formulations of propolis were administered to experimentally Trypanosoma cruzi-infected mice and the parasitemia kinetics and survival rate were monitored. The oral administration of ethanolic extracts up to 1.2 g propolis/kg per day or propolis offered ad libitum in the drinking water (up to 4 g/kg per day) or added to the food (up to 5 g/kg per day) did not interfere with both parameters. The differences between in vitro and in vivo trypanocidal activity of propolis and future perspectives are discussed.