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Enhanced cytotoxicity in a Z-photoisomer of a benzopyran derivative of propolis.

(Z)-2,2-Dimethyl-8-(3-methyl-2-butenyl)-benzopyran-6-propenoic acid (1) was isolated from Brazilian propolis, together with the known benzopyran derivative, (E)-2, 2-dimethyl-8-(3-methyl-2-butenyl)-benzopyran-6-propenoic acid (2). The structure was determined by spectroscopic analyses, which included 1D and 2D (1)H and (13)C NMR experiments, as well as MS, IR, and UV spectroscopy. Compound 2 rapidly changed to 1 under UV irradiation conditions (365 nm), and the reverse reaction was also observed. The ratio of 1 to 2 reached 2.3 when the reaction began from either 1 or 2, indicating a photostationary state. Compound 1 displayed an approximate 7-fold stronger cytotoxicity against human lung carcinoma cells (HLC-2) compared with 2.

Antineoplastic Agents, Phytogenic↗

Apoptosis and suppression of tumor growth by artepillin C extracted from Brazilian propolis.

Artepillin C was extracted from Brazilian propolis. Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) has a molecular weight of 300.40 and possesses antibacterial activity. When artepillin C was applied to human and murine malignant tumor cells in vitro and in vivo, artepillin C exhibited a cytotoxic effect and the growth of tumor cells was clearly inhibited. The artepillin C was found to cause significant damage to solid tumor and leukemic cells by the MTT assay, DNA synthesis assay, and morphological observation in vitro. When xenografts of human tumor cells were transplanted into nude mice, the cytotoxic effects of artepillin C were most noticeable in carcinoma and malignant melanoma. Apoptosis, abortive mitosis, and massive necrosis combined were identified by histological observation after intratumor injection of 500 microg of artepillin C three times a week. In addition to suppression of tumor growth, there was an increase in the ratio of CD4/CD8 T cells, and in the total number of helper T cells. These findings indicate that artepillin C activates the immune system, and possesses direct antitumor activity.

Animals↗

Free radical scavenging by ethanol extract of propolis.

The free radical scavenging ability of an ethanolic extract of propolis (EEP) was demonstrated by electron spin resonance spectroscopy, when 2,2-diphenyl-1-picrylhydrazyl (DPPH) was treated with increasing concentrations of EEP. It was shown that the DPPH signal intensity was inversely related to the EEP concentration and to the reaction time. It is assumed that the ability of components in EEP to donate a hydrogen atom is responsible for the lowering of the DPPH-EEP signal, and reflect the anti-oxidative nature of EEP.

Antioxidants↗

Antitumor and anticytopenic effects of aqueous extracts of propolis in combination with chemotherapeutic agents.

Using an ICR mouse model bearing a syngeneic Ehrlich ascitis carcinoma, the present study was undertaken to examine the effects of crude, water-soluble propolis (CWSP) on tumor progression, chemotherapeutic efficacy, and hematopoiesis in the peripheral blood. It was demonstrated that CWSP, administered subcutaneously, resulted in marked regression of tumor growth in mice, at the early phase after tumor inoculation (CWSP, p < 0.05 vs. saline control). Molecular analysis indicated that the CWSP is composed of 8.4% protein, 4.2% quercetin plus a variety of saccharides with a molecular weight of 29 kDa. Orally administered CWSP did not produce any regression for the observation period (oral CWSP, p > 0.05 vs. saline control). Peritoneal injection of CWSP into neonatal mice resulted in an increased lymphocyte/polymorphonuclear leukocyte ratio activity, indicating the potential activation of lymphoid cell lineages. These observations suggest that subcutaneously injected CWSP could regulate the development of tumors by possibly stimulating multicellular immunity. In addition, oral administration of CWSP concurrently with 5-fluorouracil (5-FU) or mitomycin C (MMC), significantly increased tumor regression as compared with the respective chemotherapy alone, illustrating the adjuvant effect of orally administered CWSP for tumor regression when combined with chemotherapeutic agents. To examine further the potential usefulness of CWSP for chemotherapeutic regimens, which induce profound multilineage hematopoietic suppression, mice that received CWSP orally in addition to a 5-FU or MMC were followed for absolute numbers of platelets and white and red blood cells. The oral administration of CWSP significantly ameliorated the cytopenia induced by 5-FU, resulting in recovery of white as well as red blood cell counts (5-FU plus CWSP, p < 0.05 vs. 5-FU alone or water control; white blood cells on day 15, red blood cells on day 25), but no marked effects on platelet counts was observed (5-FU plus CWSP, p > 0.05 vs. 5-FU alone or water control). On the other hand, CWSP significantly reduced all three MMC-induced cytopenias, especially at the later stage of the chemotherapeutic course (after day 30), suggesting repetitive requirements of oral administration of CWSP. In summary, subcutaneous administration of an aqueous CWSP resulted in marked regression of transplanted tumors. Orally administered CWSP combined with chemotherapeutic agents significantly increased tumor regression and ameliorated the cytopenia induced by the chemotherapeutic agents alone. These results suggest the benefits of potential clinical trials using CWSP combined with chemotherapeutic agents in order to maximize enhanced immunity while potentially minimizing postchemotherapeutic deteriorated reactions.

Administration, Cutaneous↗

Cytoprotection by propolis ethanol extract of acute absolute ethanol-induced gastric mucosal lesions.

Acute p.o. administration of absolute ethanol (1.0 ml/kg) to fasted rats produced extensive necrosis of gastric mucosa. Pretreatment with p.o. administration of propolis ethanol extract (PEE) could effectively and dose-dependently prevent such necrosis. This protective effect is called "cytoprotection. "The maximal cytoprotective effect against absolute ethanol (AE)-induced gastric mucosal lesion was observed 1 hour after PEE administration. A gross examination of the gastric mucosa showed a marked improvement in groups receiving PEE. In order to further investigate the gastric protective mechanism of PEE, lipid peroxidation (LPO) levels in vivo and in vitro were estimated. PEE exhibited dose-dependent superoxide scavenging activity and antioxidant effects on AE-induced LPO in rat gastric mucosal homogenates. It was concluded that the gastric protective mechanism of PEE was due, at least in part, to its ability to inhibit LPO, and hence indirectly protect the gastric mucosa from oxidative stress.

Administration, Oral↗

Protective effect of propolis ethanol extract on ethanol-induced renal toxicity: an in-vivo study.

Acute p.o. administration of absolute ethanol (10 ml/kg) to fasted mice would produce extensive renal failure. Pretreatment with p.o. administration of propolis ethanol extract (PEE) could prevent such renal failure effectively and dose dependently. This renal protective effect of PEE may be contributed, at least in part, to its antioxidative activity. The maximal antioxidative effect against absolute ethanol (AE)-induced renal failure could be observed 1 hour after PEE administration. In order to further investigate the renal protective mechanism of PEE, lipid peroxidation and superoxide scavenging activity were conducted in vivo. PEE exhibited dose-dependent antioxidative effects on lipid peroxidation in mice renal homogenate. Results indicated that mice with acute renal failure have higher malonic dialdehyde (MDA) levels compared with those in PEE administered mice. It was concluded that the renal protective mechanism of PEE could be contributed, at least in part, to its prominent superoxide scavenging effect; hence, it could protect, indirectly, the kidney from superoxide-induced renal damages.

Acute Kidney Injury↗

Antibacterial properties of propolis (bee glue).

Propolis (bee glue) was found to have antibacterial activity against a range of commonly encountered cocci and Gram-positive rods, including the human tubercle bacillus, but only limited activity against Gram-negative bacilli. These findings confirm previous reports of antimicrobial properties of this material, possibly attributable to its high flavonoid content.

Anti-Bacterial Agents↗

Brazilian natural dietary components (annatto, propolis and mushrooms) protecting against mutation and cancer.

Considering the high number of new cancer cases in Brazil (approximately 470000 cases in 2005) and the remarkable differences in the incidence of this disease around the world, the development of chemopreventive strategies using foods widely consumed would have a huge impact, both medically and economically. This review summarizes some of our studies conducted to verify the anti-mutagenic and anti-carcinogenic potential of some Brazilian natural dietary constituents (annatto, mushrooms, and propolis). Overall data have shown a clear role for these compounds in preventing mutation and specific preneoplastic lesions. Taken together, these agents indicate a favorable side-effect profile and may prove to be a promising alternative for cancer prevention strategies, although more investigation is needed to fully explore this issue.

Agaricales↗

Influence of propolis water solution on heart mitochondrial function.

The effect of propolis water solution (PWS) on the respiration of rat heart mitochondria with NAD-linked (pyruvate + malate), FAD-linked (succinate) substrates and fatty acids (palmitoyl-L-carnitine) was investigated in this study. PWS at the lowest concentration of 4 microg mL(-1) of phenolic compounds (PC) had no effect on mitochondrial respiration with all investigated substrates. PWS at concentrations of 63 and 125 microg mL(-1) of PC caused a significant decrease of basal (24 and 54%) and maximal (58 and 70%) respiration rates with succinate as substrate. At these PWS concentrations the oxidation of pyruvate + malate and palmitoyl-L-carnitine was diminished to a lower degree: the basal respiration rate decreased by 13-18% and the maximal respiration rate by 15-28%. Succinate oxidation was affected, probably because of the inhibition of succinate dehydrogenase by the 1,2-benzenedicarboxylic acid esters found in PWS. The PWS-caused decrease in the mitochondrial respiration rate with pyruvate + malate and fatty acids could be due to diminished activities of respiratory chain complexes and/or ADP/ATP translocator.

Animals↗

Four di-O-caffeoyl quinic acid derivatives from propolis. Potent hepatoprotective activity in experimental liver injury models.

The water extract of propolis (PWE) showed a strong hepatoprotective activity against CCl4-toxicity in rats and D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced liver injury in mice. The PWE also showed a significant hepatoprotective activity against CCl4-induced liver cell injury in cultured rat hepatocytes. The in vitro hepatoprotective activity guided fractionation and chemical analysis led to the isolation of four dicaffeoyl quinic acid derivatives from the PWE. The structure of these isolates was determined to be methyl 3,4-di-O-caffeoyl quinate (1), 3,4-di-O-caffeoyl quinic acid (2), methyl 4,5-di-O-caffeoyl quinate (3), and 3,5-di-O-caffeoyl quinic acid (4) by spectroscopic methods. These compounds were more potent hepatoprotective agents than glycyrrhizin at a concentration of 10 micrograms/ml and 1 was the most potent among the four compounds in the cultured hepatocytes. Quinic acid (5) alone did not show hepatoprotective effects in cultured rat hepatocytes against CCl4-toxicity. On the other hand, chlorogenic acid (6) or caffeic acid alone was found to be less potent than the dicaffeoyl quinic acid derivatives.

Animals↗

Potent antihepatotoxic activity of dicaffeoyl quinic acids from propolis.

Hepatoprotective activity guided chemical analyses led to the isolation of two dicaffeoyl quinic acid derivatives, methyl 3,4-di-O-caffeoyl quinate (1) and 3,4-di-O-caffeoyl quinic acid (2) from water extract of propolis, and their structures were determined by the use of 2D NMR. These compounds were stronger antihepatotoxic agents than glycyrrhizin.

Alanine Transaminase↗

Effects of propolis on hypoxanthine-xanthine oxidase-induced toxicity in cultivated human cells and on neutrophil elastase activity.

The inhibition of the proliferation rate of the immortalized human cell line ECV 304 after oxidant damage by oxygen radicals generated in a hypoxanthin-xanthine oxidase system and the protection provided by various propolis extracts was determined. Best inhibition was demonstrated by 60-80% ethanolic extracts (IC50 of approximately 2 microg dry weight/ml) and by the ethyl acetate extract (IC50 of 6.9 microg dry weight/ml). The beneficial effect of polar extracts was quite weak. Human neutrophil elastase activity was inhibited distinctively by ethanolic (60 to 96%) and ethyl acetate extracts (IC50 of approximately 2 microg dry weight/ml). Both activities seem to be responsible for the anti-inflammatory effect of the extract.

Cells, Cultured↗

Synergistic antitumor effect of polyphenolic components of water soluble derivative of propolis against Ehrlich ascites tumour.

Effect of two preparation (Croatian and Brazilian) of water-soluble derivative of propolis (WSDP), caffeic acid, quercetin, chrysin, naringenin (components present in WSDP) on the development of Ehrlich ascites tumour (EAT) was evaluated. Test components (50 mg/kg) were given perorally or intraperitoneally 2 h prior the intraperitonel injection of EAT (2 x 10(6)) cells. It was observed that all test compounds effectively inhibited tumour growth and the proliferation of EAT. The volume of ascitic fluid induced by EAT cells and total number of cells present in the peritoneal cavity was markedly reduced in EAT-bearing mice treated with test components. In treated mice the number of polymorphonuclear (PMN) cells in the peritoneal cavity was increased while the number of macrophages was decreased. The macrophage spreading activity revealed that WSDP and all test compounds affected the functional state of macrophages increasing their tumorcidal activity; the effect of WSDP was most pronounced indicating synergistic effect of components present in WSDP. Antitumor activity of WSDP may be the result of different specific mechanism(s) of flavonoids present as compared to individual flavonoid given alone. It is likely that the part of antitumor efficacy of test components against EAT cells was the results of increased activity of macrophages.

Administration, Oral↗

Cyclodextrin-enclosed substances of Brazilian propolis.

By using beta-cyclodextrin-inclusion as a unique technique, an efficient separation of pharmacologically active phenolic compounds from Brazilian propolis was achieved to provide one new compound, 3-(3-hydroxy-3-methyl-butyl)-5-prenyl-4-hydroxycinnamic acid, together with two common cinnamic acid derivatives, artepillin C and capillartemisin A, and two known flavanols, aromadendrin and 3,5,7-trihydroxy-4'-methoxyflavanol.

Cyclodextrins↗

A new prenylated flavonoid from propolis collected in Okinawa, Japan.

The new prenylflavonoid, isonymphaeol-B (1), together with three known compounds, nymphaeol-A (2), nymphaeol-B (3), and nymphaeol-C (4), were isolated from propolis collected in Okinawa, the southern-most prefecture of Japan. The structure of each compound was determined by spectral methods, including mass spectrometry and 2D NMR. Each compound had 1,1-diphenyl-2-picryl-hydrazyl radical-scavenging activity.

Biphenyl Compounds↗

The ability of ethanolic extract of propolis (EEP) to protect mice against gamma irradiation.

Ethanolic extract of propolis (EEP) was tested as a protective agent against gamma irradiation in mice. The mice were exposed to 6 Gy gamma irradiation from a 60Co source, and were treated intraperitoneally with EEP, administered before and after their irradiation. While the non-treated mice expired within 12 weeks, the mice that received a series of EEP treatments survived the irradiation, and their leucocyte count as well as their spleens' plaque-forming activity returned to normal. It is suggested that an antioxidant and a free radical scavenger in the EEP are responsible for the radiation protective effect of the extract of this natural product.

Animals↗