Post-initiation effects of a super critical extract of propolis in a rat two-stage carcinogenesis model in female F344 rats

Ethanol-Extracted Brazilian Propolis Exerts Protective Effects on Tumorigenesis in Wistar Hannover Rats

The present study was conducted over a course of 104 weeks to estimate the carcinogenicity of ethanol-extracted Brazilian green propolis (EEP). Groups of 50 male and 50 female Wistar Hannover rats, 6-week-old at commencement were exposed to EEP at doses of 0, 0.5 or 2.5% in the diet. Survival rates of 0.5% and 2.5% EEP-treated male and female rats, respectively, were significantly higher than those of respective control groups. Overall histopathological evaluation of neoplasms in rat tissues after 2 years showed no significant increase of tumors or preneoplastic lesions in any organ of animals administered EEP. Significantly lower incidences of pituitary tumors in 0.5% EEP male and 2.5% EEP female groups, malignant lymphoma/leukemia in both 2.5% EEP-treated males and females and total thyroid tumors in 0.5% EEP male group were found. Administration of EEP caused significant decreases of lymphoid hyperplasia of the thymus and lymph nodes in 2.5% EEP-treated rats, tubular cell hyperplasia of kidneys in all EEP groups, and cortical hyperplasia of adrenals in EEP-treated females. In the blood, significant reduction of neutrophils in all EEP-treated males and band neutrophils in 2.5% EEP-treated females was found indicating lower levels of inflammation. Total cholesterol and triglicerides levels were significantly lower in the blood of 2.5% EEP-treated female rats. In conclusion, under the conditions of the 2-year feeding experiment, EEP was not carcinogenic, did not induce significant histopathological changes in any organ, and further exerted anti-inflammatory and antitumorigenic effects resulting in increase of survival of Wistar Hannover rats.

Chemical Composition and Biological Activity of Extracts Obtained by Supercritical Extraction and Ethanolic Extraction of Brown, Green and Red Propolis Derived from Different Geographic Regions in Brazil

The variations in the chemical composition, and consequently, on the biological activity of the propolis, are associated with its type and geographic origin. Considering this fact, this study evaluated propolis extracts obtained by supercritical extraction (SCO2) and ethanolic extraction (EtOH), in eight samples of different types of propolis (red, green and brown), collected from different regions in Brazil. The content of phenolic compounds, flavonoids, in vitro antioxidant activity (DPPH and ABTS), Artepillin C, p-coumaric acid and antimicrobial activity against two bacteria were determined for all extracts. For the EtOH extracts, the anti-proliferative activity regarding the cell lines of B16F10, were also evaluated. Amongst the samples evaluated, the red propolis from the Brazilian Northeast (states of Sergipe and Alagoas) showed the higher biological potential, as well as the larger content of antioxidant compounds. The best results were shown for the extracts obtained through the conventional extraction method (EtOH). However, the highest concentrations of Artepillin C and p-coumaric acid were identified in the extracts from SCO2, indicating a higher selectivity for the extraction of these compounds. It was verified that the composition and biological activity of the Brazilian propolis vary significantly, depending on the type of sample and geographical area of collection.

Mitigating effect of Indian propolis against mitomycin C induced bone marrow toxicity

A major drawback with cancer chemotherapy is its severe toxic effects on non-target tissues. Assessment of natural products for their protective effect against anticancer drugs-induced toxicity is gaining importance in cancer biology. The present study was aimed at assessing the protective effect of hydroethanolic extract of Indian propolis (HEIP) against mitomycin C (MMC)-induced genotoxicity and cytotoxicity. Swiss albino mice were injected with various doses of HEIP (100, 200, 300, 400, 600 and 800 mg/kg b. wt., i.p) 1 h prior to MMC (8 mg/kg, i.p.) injection. The geno- and cyto-toxicities were evaluated in mice by performing bone marrow micronucleus and TUNEL assays. In vitro antioxidant and lipid peroxidation inhibitory assays were carried out to understand the mechanism of the protective effects. The significant increase in the frequency of micronculeated cells (12.51 ± 0.48), apoptotic cells (23.43 ± 1.86) and reduction in P/N ratio (0.69 ± 0.04) compared with control indicated the potential geno- and cytotoxic effects of MMC in bone marrow. Pretreatment with HEIP resulted in the significant recovery of the toxic effects induced by MMC. HEIP at 400 mg/kg b. wt. was found to be the optimum dose imparting the maximum protective effects. The in vitro antioxidant and lipid peroxidation inhibitory assays suggest that the extract possesses substantial free radical scavenging activities. In conclusion, HEIP possesses substantial geno- and cyto-protective properties against MMC, which could be mediated through efficient free radical scavenging and inhibitory effect on lipid peroxidation.

Propolis in dentistry and oral cancer management

Propolis, known as bee glue, is a wax-cum-resin substance, which is created out of a mix of buds from some trees with the substance secreted from the bee's glands. Its diverse chemical content is responsible for many valuable properties. Multiple applications of propolis have been studied and described in detail for centuries. However, currently available information on propolis is scarce. A literature search in the PubMed database was performed for English language articles, using the search terms propolis, oral health, dentistry, and oral cancer; no restrictions were used for publication dates. The aim of the article was to review propolis and its applications in dentistry including oral cancer.

Chemical composition of muscle after pollen application in nutrition of broiler chickens

Principle purpose of this study was to monitor the chemical composition of breast and thigh muscular part of chickens of hybrid combination Ross 308 and to verify the differences due to use of pollen extract in feed mixture at a dose of 400 and 800 mg.kg-1 during the feeding of 42 days. We did not find significant differences (P≥0.05) in followed chemical compounds of thigh muscle with the skin and subcutaneous fat between the groups with and without application of pollen extract: in contents of water (68.49-70.12 g.100g-1), protein (18.82-18.98 g.100g-1), fat (9.96-11.53 g.100g-1) and in energy value (692.20-752.36 kJ.100g-1). Significant differences (P≤0.05) were found only in protein content of breast muscle between the control group (23.96 g.100g-1) and experimental group I (23.28 g.100g-1). Values of water content (73.97-74.32 g.100g-1), fat content (1.07-1.40 g.100g-1) and energy (441.65-446.64 kJ.100g-1) in breast muscle between the evaluated groups were balanced (P≥0.05). The results show that pollen extract at the concentration used in feed mixture did not effect basic chemical composition of the most valuable parts of the chicken Ross 308 carcass and we can apply it in their nutrition. Application at a dose of 800 mg.kg-1 seems to be more positive.

J, Kačániová M, Čuboň J, Mellen M, Mihok M, Eliman IOE. Sensory evaluation of meat chickens Ross 308 after application of propolis in their nutrition

The objective of the experiment was to verify the effect of propolis extract in Ross 308 broiler on the sensory quality of breast and thigh muscle modified by baking at temperature 200 ºC for 60 minutes and finish baking for a period of 10-15 minutes. In the experiment were used 180 chickens divided into 2 groups (control and experimental group) with 90 chickens (45 ♂ and 45 ♀). Fattening lasted 40 days. The chickens were fed  ad libitum with the same starter feed mixtures to 21 days and from 22 days of age through 40 days of age with the grower feed mixtures in the both followed groups. Feed mixtures were made without antibiotics and coccidiostatics. The feed mixtures used in experimental group were enriched with the feed extract of propolis in a dose of 0.2 g.kg-1. After heat treatment of breast and thigh muscle 60 pieces chickens (30 pieces ♀, ♂ 30 pieces) of each group samples were sensory analyzed (smell, taste, juiciness, softness). Statistically significant differences were found by sex (P≤0.05 to 0.001) in aroma and taste of cocks in the thigh muscle (+0.290 points, +0.300 points) and hens (P≤0.01) in flavor (+0.250 points) and softness (+0.372 points) in breast muscle. Sensory assessment of the individual characters of either gender had significant differences (P≤0.05 to 0.001) in favor of the experimental group achieved only in the evaluation of the smell in the breast (+0.207 points) as well as thigh muscle (+0.207 points). In the final evaluation the most valuable parts of Ross 308 chickens carcass were found a positive effect of propolis extract on their sensory properties, but significant differences (P≤0.01) were observed only in chickens in the breast muscle (+0.917 points) compared with control group. The results have confirmed that propolis extract in a dose of 0.2 g.kg-1 feed mixture can be applied in the diet of chickens, as it positively affects the sensory quality of Ross 308 chickens meat, which is one of the most important parts of chicken meat for use in human food chain.

Absence of chemopreventive influence of propolis on the rat liver altered foci development

Propolis (bee glue) is a complex mixture of natural substances that exhibits a broad spectrum of biological activities. As the possibility exists that it may exert a chemopreventive role against cancer development, the present study aimed to evaluate the chemopreventive influence of a Brazilian aqueous propolis extract (APE) in a rat two-stage (initiation-promotion) medium-term bioassay for chemical liver carcinogenesis. Male Wistar rats were sequentially initiated with diethylnitrosamine (DEN, 200mg/kgb.w.) and, 2 weeks later, exposed to a diet containing hexachlorobenzene (HCB, 100ppm) and to APE 0.1% through drinking water for 6 weeks. Appropriate control groups were also established. The animals were sacrificed at the weeks 8th and 30th when liver samples were processed to evaluate the development of altered hepatocyte foci (AHF) identified under hematoxylin and eosin (H&E) staining and by the immunohistochemical expression of the enzyme glutathione S-transferase placental form (GST-P). The results indicate that APE 0.1% did not protect against the development of any of the differentially identified putative preneoplastic foci in DEN-initiated animals, exposed or not to the promoting agent HCB. Also, APE 0.1% by itself did not significantly induce any AHF, what is in line with its already known absence of genotoxic potential. Our results indicate that an aqueous extract of Brazilian propolis did not exert chemoprevention on the hepatocarcinogenesis process chemically induced in the rat.

The contribution of plukenetione A to the anti-tumoral activity of Cuban propolis

Increasing efforts are directed toward finding applications for natural products and their derivatives in the treatment of human diseases. Among such products, propolis, a resinous substance produced by honey bees from various plant sources, has been found to be a promising source of potential therapeutics. In the present work, we aimed at studying the perspective of Cuban propolis as a source of possible anti-cancer agents. We found an anti-metastatic effect in mice and considerable cytotoxicity without cross-resistance in both wild-type and chemoresistant human tumor cell lines. Plukenetione A--identified for the first time in Cuban propolis--induced G0/G1 arrest and DNA fragmentation in colon carcinoma cells. Furthermore, the activities of both topoisomerase I and DNA polymerase were inhibited, while the expression of topoisomerase II-beta, EGF receptor, and multidrug resistance-related protein genes was found repressed. We assume that plukenetione A contributes to the anti-tumoral effect of Cuban propolis mainly by targeting topoisomerase I as well as DNA polymerase.

Antitumor effect of stilbenoids from Vateria indica against allografted sarcoma S-180 in animal model

Dipterocarpaceous plants contain various resveratrol oligomers that exhibit a variety of biological activities, such as antibacterial and antitumor effects. Previously, we found that vaticanol C, a resveratrol tetramer, exhibits strong cytotoxicity against various tumor cell lines. In the present study, we examined the antitumor activity of the ethanol extract from the stem bark of Vateria indica, which has been traditionally used for health and healing diseases as Ayurveda in India. High-performance liquid chromatography analysis showed that the extract contains bergenin, hopeaphenol, vaticanol B, vaticanol C, and epsilon-viniferin. The in vitro assay displayed the extract's anti-cancer activity against mouse sarcoma 180 cells (IC50=29.5 microM). In the animal study, the tumor growth of sarcoma S-180 cells subcutaneously allografted in DDY mice was significantly retarded by oral administration of the extract (30 or 100 mg/kg body weight: P < 0.001). The extract did not show significant toxicity to mice even at a dosage of 1000 mg/kg body weight by daily oral administration for 28 days. These results demonstrated that the ethanol extract containing various stilbenoids from the stem bark of V. indica has the potent antitumor activity.

Effect of a propolis extract and caffeic acid phenethyl ester on formation of aberrant crypt foci and tumors in the rat colon

We have studied the effect of propolis and its main active ingredient caffeic acid phenetyl ester (CAPE) on formation of aberrant crypt foci (ACF) and tumors in the rat colon in vivo. CAPE (50 mg/kg i.p.) reduced the formation of ACF and tumor induced by azoxymethane, while propolis ethanolic extract was without effect. These results suggest a potential anti-carcinogenesis of CAPE but not propolis.

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.

Modifying effects of propolis on MeIQx promotion of rat hepatocarcinogenesis and in a female rat two-stage carcinogenesis model after multiple carcinogen initiation

The modifying effects of the dietary administration of water- and ethanol-extracted propolis produced in Brazil (WB and EB, respectively) on 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) promotion of rat hepatocarcinogenesis were investigated in a medium-term liver bioassay system with use of male Fischer 344 rats. The number and area of glutathione S-transferase placental form (GST-P)-positive foci in rats given 0.5% WB were significantly increased compared with the group given MeIQx alone. Furthermore, the numbers of GST-P-positive foci were higher in rats given 0.1% WB or EB than in those given the basal diet alone. The modifying effects of propolis on other organs were also examined in female Fischer 344 rats given multiple carcinogens for initiation. Rats received water- and ethanol-extracted propolis produced in Brazil and Uruguay (WB, EB, WU, and EU, respectively) in the diet after exposure to three different carcinogens. The incidence of total mammary tumors was significantly lower in rats given EU than in the control group. These results indicate that a water extract of propolis exerts a cocarcinogenic effect on MeIQx hepatocarcinogenesis while promoting the effect at low dose in a two-stage hepatocarcinogenesis model. Moreover, they suggest that ethanol-extracted propolis may be an inhibitor of mammary gland carcinogenesis.