Evaluation of the acute toxicity of ellagic acid and gallic acid incorporated in Poloxamer407® gel, in Zophobas morio larvae

Gallic acid (GA) has antioxidant, anti-inflammatory and antimicrobial properties, while ellagic acid (EA) demonstrates anticancer, antiviral and photoprotective activity. In this study, the combination of these substances incorporated into a poloxamer gel was tested to verify the individual effect of the substances, in addition to taking advantage of a probable complementary effect, aiming to provide additional therapeutic benefits. As a result of the incorporation, formulations containing GA, EA and GA + EA were obtained, which were evaluated for the effects of the Freeze-thaw cycle on pH, which revealed a significant decrease (p < 0.05) in most samples, including the vehicle (without drug) and the gel containing both drugs. No sample showed variation outside the normal pH range for the skin, with values ranging from 4.8 to 6.0. Regarding conductivity, the GA, EA and GA + EA formulations showed a reduction (p < 0.05) after the freeze-thaw cycle. The drug content in the formulations ranged from 95.86% to 101.35% initially to 91.30% to 101.51% after the freeze-thaw cycle. Regarding the drug release, the results revealed the following cumulative percentages: GA-3% - 92.58% after 1.5 h; AE-3% - 51.60% after 6 h; GA + EA (1.5% = 1.5%) - 99.91% after 2 h; GA + EA- (1.5% = 1.5%) released 57.06%, after 6 h. Regarding toxicity, it was observed that the group treated with GA showed a lower survival rate of the larvae (40%) at the dose 3000 mg/Kg in the formulation. Following the same trend, in the acute lethal concentration (ALC50) test performed using Zophobas morio larvae, an ALC50 of 2191.51 mg/Kg was observed for GA at 48 h. Melanin analysis showed a decrease in concentrations of 30 mg/Kg in the GA group, 3 mg/Kg of EA and 3, 300, 3000 mg/Kg of GA + EA, of the pure drugs. In the groups with the drugs incorporated into the gel, there was a significant decrease (P < 0.05) in melanin in the vehicle (gel), at concentrations of 300 and 3000 mg/Kg of GA and EA. On the other hand, in the combination of GA + EA, a reduction was observed at concentrations of 3 and 30 mg/Kg when compared to the control group. Thus, the gel showed good quality as a pharmaceutical formulation for topical use and low toxicity, making it promising for use in skin therapies.

Identification of Ellagic Acid from Plant Rhodiola rosea L. as an Anti-Ebola Virus Entry Inhibitor

The recent 2014-2016 West African Ebola virus epidemic underscores the need for the development of novel anti-Ebola therapeutics, due to the high mortality rates of Ebola virus infections and the lack of FDA-approved vaccine or therapy that is available for the prevention and treatment. Traditional Chinese medicines (TCMs) represent a huge reservoir of bioactive chemicals and many TCMs have been shown to have antiviral activities. 373 extracts from 128 TCMs were evaluated using a high throughput assay to screen for inhibitors of Ebola virus cell entry. Extract of Rhodiola rosea displayed specific and potent inhibition against cell entry of both Ebola virus and Marburg virus. In addition, twenty commercial compounds that were isolated from Rhodiola rosea were evaluated using the pseudotyped Ebola virus entry assay, and it was found that ellagic acid and gallic acid, which are two structurally related compounds, are the most effective ones. The activity of the extract and the two pure compounds were validated using infectious Ebola virus. The time-of-addition experiments suggest that, mechanistically, the Rhodiola rosea extract and the effective compounds act at an early step in the infection cycle following initial cell attachment, but prior to viral/cell membrane fusion. Our findings provide evidence that Rhodiola rosea has potent anti-filovirus properties that may be developed as a novel anti-Ebola treatment.

Genotoxicity of polar and apolar extracts obtained from Qualea multiflora and Qualea grandiflora

ETHNOPHARMACOLOGICAL RELEVANCE

The species Qualea grandiflora and Qualea multiflora, which belong to the Vochysiaceae family, are common in the Brazilian savannah (Cerrado biome), and the local inhabitants use these species to treat external ulcers and gastric diseases and as an anti-inflammatory agent. Studies have demonstrated that these plants contain compounds that exhibit pharmacological activities; however, the risks associated with their consumption are not known.

MATERIAL AND METHODS

In the present study, the mutagenicity of polar and apolar extracts from Qualea grandiflora and Qualea multiflora were assessed by employing the Ames assay with and without metabolic activation. Additionally, phytochemical analyses (HPLC-ESI-IT-MS, HPLC-UV-PDA and GC-IT-MS) were performed to identify the chemical constituents present in these species, including the evaluation of physico-chemical properties, such as polarity or apolarity of the organic compounds, which are related to each fraction obtained. These studies provide important information regarding the biochemical behaviour of these compounds.

RESULTS

All extracts exhibited mutagenicity, inducing frameshift mutations and base substitutions in DNA. Phytochemical analysis identified terpenes, ellagic acid derivatives and phytosteroids.

CONCLUSIONS

The mutagenicity observed might be due to the presence of pentacyclic triterpenes and polyphenols, which are able to generate reactive oxygen species (ROS) and result in the potential to cause DNA damage. The genetic risk identified in this present work shows that special attention should be considered for the use of compounds obtained from these plant species in medicinal treatments. Further studies must be conducted to identify safe therapeutic doses.

Response of digestive gland cells of freshwater mussel Unio tumidus to phenolic compound exposure in vivo

The exposure of freshwater mussels Unio tumidus to phenolic compounds (tannic, ellagic and gallic acid) in vivo caused changes in proteins and DNA function of digestive gland cells. The mussels were exposed to various concentrations of tested polyphenols (60, 200 and 500 microM) for 24 and 48 h and their antioxidant and pro-oxidant effects were determined. The number of SH-groups was quantified spectrophotometrically using Ellman's reagent. Oxidative modification of proteins increased in the digestive gland cells in a dose- and time-dependent manner. The level of nuclear DNA damage was investigated using the comet assay. The results revealed that polyphenolic acids induce single and double-strand breaks in DNA. The highest changes were observed for tannic and gallic acids and the smallest ones for ellagic acid. 1h of DNA repair process was also studied using the same method. The data obtained in this experiment demonstrate that the most effective DNA repair occurs in the cells exposed to phenolic compounds for 24h. A longer incubation (up to 48 h) does not decrease the capacity of the repair mechanism. The antioxidant activity of the tested phenols was analyzed spectrofluorimetrically using a fluorescence probe DCFH-DA (dichlorofluorescein-diacetate). The experimental data showed that the tested acids can act as antioxidants when used at higher doses (200 and 500 microM) against the reactive oxygen species present in the digestive gland cells. The most effective was ellagic acid, also applied at the smallest dose of 60 microM, in comparison with tannic and gallic acids. In conclusion, our results demonstrate that chosen water-soluble polyphenols, which are located in various plant tissues and are also found in the aquatic environment, can influence organisms living in the water. They can be exposed to these chemicals that cause morphological alterations and changes in certain physiological processes in their organs (i.e. digestive gland cells of bivalve molluscs).

Antioxidative and oxidative changes in the digestive gland cells of freshwater mussels Unio tumidus caused by selected phenolic compounds in the presence of H2O2 or Cu2+ ions

Research on biomarkers as early bioindicators of perturbation in populations and individuals has received increasing interest during recent decades. These ecotoxicity studies allow us to measure the impact of environmental stressors and to monitor and evaluate the degradation or restoration of systems. In the present study we used bivalve molluscs (mussels), which are sensitive biomarkers of aquatic ecosystem pollution, to assess the effects of three polyphenols: tannic acid, ellagic acid and gallic acid. These compounds were used in the 1-60 microM concentration range, alone and in the presence of H(2)O(2) (40 and 100 microM) or Cu(2+) ions (50 microM). The fluorescence probe dichlorofluorescein-diacetate (DCFH-DA) was used to measure reactive oxygen species (ROS). The oxidation of DCFH-DA to the fluorescent DCF (dichlorofluorescein) by the phenolic compounds was investigated spectrofluorimetrically. The results showed that the polyphenols tested can act as antioxidants against the ROS present in the digestive gland cells, but their activity is decreased after incubation with hydrogen peroxide or copper ions. SH-groups were determined spectrophotometrically using Ellman's reagent. The results showed that oxidative modification of proteins increased in a concentration-dependent manner in cells incubated with polyphenols (above 15 microM) alone. Incubation of the cells with phenolic acids and H(2)O(2) or Cu(2+) ions revealed that the phenolic acids had prooxidant properties in all concentrations used except for 1 microM tannic and ellagic acid and 40 microM H(2)O(2). DNA fragmentation was estimated by a fluorescence method using Hoechst 33258/propidium iodine binding. The data showed that the phenolic acids alone and in the presence of hydrogen peroxide or copper ions can induce apoptosis and necrosis. The methods used and results obtained indicate that the polyphenols selected can act not only as antioxidants but also as prooxidants in digestive gland cells of Unio tumidus.

Oxidatively modified proteins and DNA in digestive gland cells of the fresh-water mussel Unio tumidus in the presence of tannic acid and its derivatives

The oxidative effect of tannic acid and its two derivatives (ellagic and gallic acid), naturally occurring plant polyphenols, has been studied on digestive gland cells of the fresh-water mussel Unio tumidus. A spectrophotometric method was used to determine the protein thiol groups after incubation of the cells with the polyphenols at concentrations of 1, 15 and 60 microM. The results showed that the oxidative modification of proteins increased in a concentration-dependent manner but no changes were observed at the concentration of 1 microM. The comet assay (single-cell gel electrophoresis assay) with the formamido-pyrimidine glycosylase (FPG) protein was used to assess oxidative DNA base damage. The cells were treated with polyphenols at the concentrations of 30 and 60 microM and post-incubated with FPG. FPG strongly enhanced DNA damage induced by the polyphenols, indicating that N-7 guanine oxidation is responsible for the observed effect. Using the comet assay in combination with proteinase K we were able to demonstrate the presence of DNA-protein cross-links as the probable cause of the decrease in DNA migration. After treatment of the cells with tannic acid and its metabolites at concentrations of 120, 180 and 240 microM, they were post-incubated with proteinase K. After this treatment an increased DNA migration was observed, indicating the presence of DNA-protein cross-links. We have also used a fluorescence method with Hoechst 33258/propidium iodide DNA-binding dyes to study the extent of DNA fragmentation after exposure of the cells to polyphenols at concentrations of 1, 5 and 60 microM. The results demonstrate that the polyphenols can induce apoptosis and necrosis at higher concentrations (5 and 60 microM). All experimental data suggest that tannic, ellagic and gallic acids at concentrations above 1 microM are able to interact with proteins and DNA, which leads to their degradation or changes in their function.

Effects of tannins on Chinese hamster cell line B14

Tannins, naturally occurring plant phenols, have been recognized as antioxidants, but toxic effects have also been observed. In the current investigation, the interaction of this type of compounds with Chinese hamster cells (cell line B14) has been examined. This study reports on the results of experiments in which B14 cells were exposed to tannins: tannic, ellagic and gallic acids in the concentration range 15-240 microM. The cytotoxic and genotoxic effects of these compounds were studied. The colorimetric MTT assay to assess cytotoxicity and the Comet assay for detection of DNA damage were used. In this paper, we also demonstrated the influence of tannins on the fluidity of the plasma membrane. This experiment was carried out by a spectrofluorometric method using two fluorescent probes: 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 12-(9-anthroyloxy)stearic acid (12-AS). The tannins increased the fluidity in the internal region of the lipid bilayer, but no changes at the surface of the plasma membrane were observed. The results of the MTT assay showed that tannins could decrease the viability of cells and that their cytotoxicity was highest at the concentration of 60 microM. The degree of toxicity of these compounds was not correlated with the concentration used. The data obtained from the Comet assay showed that the tannins could also contribute to formation of DNA single-strand breaks.

Effects of DX-9065a, an inhibitor of factor Xa, on ellagic acid-induced plantar skin thrombosis assessed in tetrodotoxin- and N(omega)-nitro-L-arginine-treated rats

Effects of DX-9065a ((+)-2S-2-[4-[[(3S)-1-acetimidoyl-3-pyrrolidinyl]oxy]phenyl]-3-[7-amidino-2-naphthyl]propanoic acid hydrochloride pentahydrate), a dibasic propanoic acid and an inhibitor of factor Xa, were compared with those of argatroban, a low molecular weight thrombin inhibitor, on the ellagic acid-induced plantar skin thrombosis in the rats treated with tetrodotoxin and N(omega)-nitro-L-arginine. Plantar skin blood flow was measured with laser Doppler flow meters, and skin temperature of the hindlimb was monitored simultaneously. In order to induce thrombus in plantar skin vasculature, ellagic acid (300 microg, i.a.) was injected into a branch of femoral artery. The formation of thrombus in femoral and plantar vessels was assessed by light microscopy. Ellagic acid decreased plantar skin blood flow and skin temperature. Intravenous injections of DX-9065a (3 mg/kg) and argatroban (1-3 mg/kg) significantly inhibited the ellagic acid-induced disturbance of plantar skin blood flow and lowering skin temperature without affecting bleeding time. The oral administration of DX-9065a (30-100 mg/kg) significantly prevented the decrease in skin temperature induced by ellagic acid, but it partially inhibited the disturbance of plantar skin blood flow. DX-9065a and argatroban also prolonged prothrombin time in a dose-dependent manner. These results suggest that DX-9065a effectively prevented thrombosis produced by ellagic acid in the skin circulation without a risk of bleeding.

Inhibition of cellular transformation by berry extracts

Recent studies have examined and demonstrated the potential cancer chemopreventive activity of freeze-dried berries including strawberries and black raspberries. Although ellagic acid, an abundant component in these berries, has been shown to inhibit carcinogenesis both in vivo and in vitro, several studies have reported that other compounds in the berries may also contribute to the observed inhibitory effect. In the present study, freeze-dried strawberries (Fragara ananassa, FA) or black raspberries (Rubus ursinus, RU) were extracted, partitioned and chromatographed into several fractions (FA-F001, FA-F003, FA-F004, FA-F005, FA-DM, FA-ME from strawberries and RU-F001, RU-F003, RU-F004, RU-F005, RU-DM, RU-ME from black raspberries). These extracts, along with ellagic acid, were analyzed for anti-transformation activity in the Syrian hamster embryo (SHE) cell transformation model. None of the extracts nor ellagic acid by themselves produced an increase in morphological transformation. For assessment of chemopreventive activity, SHE cells were treated with each agent and benzo[a]pyrene (B[a]P) for 7 days. Ellagic acid, FA-ME and RU-ME fractions produced a dose-dependent decrease in transformation compared with B[a]P treatment only, while other fractions failed to induce a significant decrease. Ellagic acid, FA-ME and RU-ME were further examined using a 24 h co-treatment with B[a]P or a 6 day treatment following 24 h with B[a]P. Ellagic acid showed inhibitory ability in both protocols. FA-ME and RU-ME significantly reduced B[a]P-induced transformation only when co-treated with B[a]P for 24 h. These results suggest that a methanol extract from strawberries and black raspberries may display chemopreventive activity. The possible mechanism by which these methanol fractions (FA-ME, RU-ME) inhibited cell transformation appear to involve interference of uptake, activation, detoxification of B[a]P and/or intervention of DNA binding and DNA repair.

Effect of aspirin-dipyridamole and heparin and their combination on venous thrombosis in hypercoagulable or thrombotic animals

Epsilon-amino-caproic acid (EACA) induces a clinically-useful anti-haemorrhagic, mildly thrombotic state while ellagic acid (EA) induces a severe hypercoagulable one. Reversal of these states may on occasion be necessary. The effectiveness of the antiplatelet drugs, aspirin and dipyridamole (ASA/D), in reducing thrombus weight was studied in normocoagulable animals and animals made hypercoagulable with EACA (333mg/kg) or EA (1.2mg/kg). Heparin (114iu/kg) was tested in the EACA group, both alone and in combination with ASA/D. Thrombogenicity was measured by weight formed on intravenous platinum wire in one hour. In normocoagulable animals, ASA/D reduced thrombus by 32%. Ellagic acid trebled mean thrombus weight and ASA/D reduced this by 49%, but did not restore normality. EACA increased mean thrombosis by one sixth. Treatment with heparin reduced this by 48% to a level well below that of untreated animals. Addition of a single dose of aspirin/dipyridamole to the heparin regime, reduced thrombosis by a further 31%, reaching to 21% of control thrombus. The results were statistically significant. Kaolin-activated blood clotting time was shortened by EA, but EACA had little effect on it, while ASA/D slightly and heparin markedly lengthened it.

Preventive effect of argatroban on ellagic acid-induced cerebral thromboembolism in rats

The preventive effect of argatroban, a synthetic thrombin inhibitor, on cerebral infarction was evaluated with ellagic acid (EA)-induced cerebral thromboembolism in rats. Platelet-rich thrombi containing fibrin and EA crystal were formed in the microarteries in the affected hemisphere by the injection of EA suspension into the cerebral arteries. The mortality in saline control was over 80% 6 h after the EA injection. Argatroban decreased the mortality to 0% at a dose of 3 mg/kg/h, and significantly reduced the ischemic area in the affected cerebral hemisphere. Heparin also decreased the mortality to 30% at a dose of 600 U/kg/h, but marked bleeding was observed at the incised wound. These findings suggest that argatroban is a more effective and safer anticoagulant than heparin for the prevention of ischemic damage on cerebral thrombosis.

The thrombopenic effect of ellagic acid in the rat. Another model of platelet stimulation "in vivo"

In the rat, intravenous injection of large doses (30 mg/Kg) of ellagic acid (EA) induced a decrease in the plasma level of fibrinogen and in the blood platelet content and an increase of the activated partial thromboplastin time. The long-lasting thrombocytopenia was inhibited by heparin (4 mg/Kg), defibrase (20 U/Kg), clocoumarol (4 mg/Kg) and CCI 17810 (120 mg/Kg). It was not inhibited by aspirin (90 mg/Kg), indomethacin (8 mg/Kg), ketoprofen (4-10 mg/Kg), epsilon-aminocaproic acid (150 mg/Kg), methysergide (4 mg/Kg), chlorpromazine (10 mg/Kg) and promethazine (4 mg/Kg). On the contrary, the small doses of indomethacin (4 mg/Kg) and of ketoprofen (0.5-2 mg/Kg) increased the thrombopenic effect of EA. EA induced the accumulation of Cr51-labelled platelets into the lungs and the liver, accompanied by a 64% fall in Cr51 blood radioactivity. The platelet stimulating effect of EA would depend on an intravascular coagulation which occurs in the whole cardiovascular system. It is suggested that the pro-aggregating derivatives of arachidonic acid had a minor role in this stimulation. The intravascular coagulation induced by EA was accompanied by a swelling of the lymph nodes and of the spleen. In immune platelet depleted rats, EA induced only the swelling of lymph nodes.

Ellagic acid toxicity and interaction with benzo[a]pyrene and benzo[a]pyrene 7,8-dihydrodiol in human bronchial epithelial cells

Ellagic acid, a plant phenol present in various foods consumed by humans, has been reported to have both anti-mutagenic and anti-carcinogenic potential. To evaluate the potential anti-carcinogenic property of ellagic acid, we tested its effects on the toxicity of benzo[a]pyrene and benzo[a]pyrene, 7,8-dihydrodiol and binding of benzo[a]pyrene to DNA in cultured human bronchial epithelial cells. The toxicity of ellagic acid itself for human bronchial epithelial cells was also determined. Using a colony-forming efficiency assay, it was found that a nontoxic concentration of ellagic acid (5 micrograms/ml) enhanced the toxicity of benzo[a]pyrene 7,8-dihydrodiol in human bronchial epithelial cells. In contrast, ellagic acid at concentrations of 1.5 and 3.0 micrograms/ml inhibited binding of benzo[a]pyrene metabolites to DNA in these cells. An explanation for the potentiating effect of ellagic acid on the toxicity of benzo[a]pyrene, 7,8-dihydrodiol will require further investigation into the possible mechanisms of interaction between these two compounds.