Corilagin prevents SARS-CoV-2 infection by targeting RBD-ACE2 binding.

BACKGROUND: The outbreak of coronavirus (SARS-CoV-2) disease caused more than 100,000,000 people get infected and over 2,200,000 people being killed worldwide. However, the current developed vaccines or drugs may be not effective in preventing the pandemic of COVID-19 due to the mutations of coronavirus and the severe side effects of the newly developed vaccines. Chinese herbal medicines and their active components play important antiviral activities. Corilagin exhibited antiviral effect on human immunodeficiency virus (HIV), hepatitis C virus (HCV) and Epstein-Barr virus (EBV). However, whether it blocks the interaction between SARS-CoV-2 RBD and hACE2 has not been elucidated. PURPOSE: To characterize an active compound, corilagin derived from Phyllanthus urinaria as potential SARS-CoV-2 entry inhibitors for its possible preventive application in daily anti-virus hygienic products. METHODS: Computational docking coupled with bio-layer interferometry, BLI were adopted to screen more than 1800 natural compounds for the identification of SARS-CoV-2 spike-RBD inhibitors. Corilagin was confirmed to have a strong binding affinity with SARS-CoV-2-RBD or human ACE2 (hACE2) protein by the BLI, ELISA and immunocytochemistry (ICC) assay. Furthermore, the inhibitory effect of viral infection of corilagin was assessed by in vitro pseudovirus system. Finally, the toxicity of corilagin was examined by using MTT assay and maximal tolerated dose (MTD) studies in C57BL/6 mice. RESULTS: Corilagin preferentially binds to a pocket that contains residues Cys 336 to Phe 374 of spike-RBD with a relatively low binding energy of -9.4 kcal/mol. BLI assay further confirmed that corilagin exhibits a relatively strong binding affinity to SARS-CoV-2-RBD and hACE2 protein. In addition, corilagin dose-dependently blocks SARS-CoV-2-RBD binding and abolishes the infectious property of RBD-pseudotyped lentivirus in hACE2 overexpressing HEK293 cells, which mimicked the entry of SARS-CoV-2 virus in human host cells. Finally, in vivo studies revealed that up to 300 mg/kg/day of corilagin was safe in C57BL/6 mice. Our findings suggest that corilagin could be a safe and potential antiviral agent against the COVID-19 acting through the blockade of the fusion of SARS-CoV-2 spike-RBD to hACE2 receptors. CONCLUSION: Corilagin could be considered as a safe and environmental friendly anti-SARS-CoV-2 agent for its potential preventive application in daily anti-virus hygienic products.

Dual hypopigmentary effects of punicalagin via the ERK and Akt pathways.

Punicalagin is a phenolic compound with antioxidant properties. However, the effects of punicalagin on melanin synthesis have been poorly evaluated. Therefore, we investigated the effects of punicalagin on melanogenesis in Mel-Ab cells. Punicalagin significantly inhibited melanin synthesis in a dose-dependent manner. In accordance with the melanin content, punicalagin also dose-dependently decreased tyrosinase activity. Punicalagin did not directly inhibit tyrosinase in a cell-free system but did downregulate the expression of microphthalmia-associated transcription factor (MITF) and tyrosinase. Therefore, we examined the effects of punicalagin on melanogenesis-related signaling pathways. Punicalagin induced extracellular signal-regulated kinase (ERK) and Akt phosphorylation but had no effect on ß-catenin level. We measured melanin content and MITF expression in the presence of the ERK pathway inhibitor PD98059 and/or the Akt pathway inhibitor LY294002. Cotreatment with PD98059 and LY294002 almost completely restored punicalagin-induced hypopigmentation. These data indicate that punicalagin inhibits melanin synthesis through ERK and Akt phosphorylation, with subsequent downregulation of MITF and tyrosinase.

A nematicidal tannin from Punica granatum L. rind and its physiological effect on pine wood nematode (Bursaphelenchus xylophilus).

The ethanol extract of Punica granatum L. rind was tested to show significant nematicidal activity against pine wood nematode. Three nematicidal compounds were obtained from the ethanol extract by bioassay-guided fractionation and identified as punicalagin 1, punicalin 2, and corilagin 3 by mass and nuclear magnetic resonance spectral data analysis. Punicalagin 1 was most active against PWN among the purified compounds with the LC50 value of 307.08µM in 72h. According to the enzyme assays in vitro, punicalagin 1 could inhibit the activity of acetylcholinesterase, amylase and cellulase from PWN with IC50 value of 0.60mM, 0.96mM and 1.24mM, respectively. The morphological structures of PWNs treated by punicalagin 1 were greatly changed. These physiological effects of punicalagin 1 on PWN may helpful to elucidate its nematicidal mechanism.

Flavonoids, gallotannins and ellagitannins in Syzygium guineense and the traditional use among Malian healers.

ETHNOPHARMACOLOGICAL RELEVANCE: Syzygium guineense has been traditionally used in Mali in West Africa for the treatment of different diseases such as stomach problems, wounds, inflammations and various female disorders. AIMS OF THE STUDY: (1) To perform an ethnopharmacological survey on the traditional use of S. guineense among Malian healers. (2) To isolate and identify chemical constituents from S. guineense leaves and to study their radical scavenging and enzyme inhibitory effects. MATERIALS AND METHODS: In four different districts in Mali, 44 healers were interviewed about their medicinal use of S. guineense. A methanol extract of the leaves of this tree was prepared and further fractionated using different chromatographic methods. Isolated compounds were identified by 1D and 2D NMR spectroscopy. Extracts and isolated compounds were investigated as DPPH radical scavengers and as inhibitors of xanthine oxidase and 15-lipoxygenase, and the methanol extract was tested for toxicity towards Artemia salina nauplii. RESULTS: Major uses by Malian healers were against dermatosis, pain, malaria/fever and for wound healing. There was little consensus about the use in the different districts. Leaves were most commonly used. From the methanol leaf extract, the flavonoids gallocatechin (1), myricetin (2), myricetin-3-O-glucoside (3), myricetin-3-O-rhamnoside (4), myricetin-3-O-glucuronide (5) and myricetin-3-O-ß-D-(6″-galloyl)galactoside (6), the gallotannins 1,2,3,6-tetra-O-galloyl-ß-D-glucose (7) and 1,2,3,4,6-penta-O-galloyl-ß-D-glucose (8), and the ellagitannins casuarictin (9) and casuarinin (10) were isolated. These ten polyphenols are all new for the species. The crude methanol extract was active as a radical scavenger and as an inhibitor of xanthine oxidase and 15-lipoxygenase. Among the isolated compounds, pentagalloylglucose was the best enzyme inhibitor (IC50 25±4µM for 15-lipoxygenase, 8±1µM for xanthine oxidase), while casuarictin (IC50 3.9±0.1µM), casuarinin (IC50 4.5±0.3µM) and pentagalloylglucose (IC50 5±1µM) showed the highest radical scavenging activity. The methanol extract was non-toxic to Artemia salina nauplii. CONCLUSION: S. guineense leaves are commonly used among Malian healers, however the traditional practice varies a lot between different regions. The leaves of S. guineense are rich in polyphenols; several are galloylated, either as galloylated flavonoids, gallotannins or ellagitannins. The high content of biologically active polyphenols might be important for medicinal effects of this plant and might give a rationale for the widespread usage of S. guineense in Mali.

Systemic Delivery of Nanoparticles Loaded with Pentagalloyl Glucose Protects Elastic Lamina and Prevents Abdominal Aortic Aneurysm in Rats.

Degeneration of elastin plays a vital role in the pathology and progression of abdominal aortic aneurysm (AAA). Our previous study showed that pentagalloyl glucose (PGG), a core derivative of tannic acid, hinders the development of AAAs in a clinically relevant animal model when applied locally. In this study, we tested whether targeted nanoparticles (NPs) can deliver PGG to the site of an aneurysm and prevent aneurysmal growth by protecting elastin. PGG-loaded albumin NPs with a surface-conjugated elastin-specific antibody were prepared. Aneurysms were induced by calcium chloride-mediated injury to the abdominal aorta in rats. NPs were injected into the tail vein after 10 days of CaCl2 injury. Rats were euthanized after 38 days. PGG delivery led to reduction in macrophage recruitment, matrix metalloproteinase (MMP) activity, elastin degradation, calcification, and development of aortic aneurysm. Such NP delivery offers the potential for the development of effective and safe therapies for AAA.

Effect of hydrolysable tannins on intestinal morphology, proliferation and apoptosis in entire male pigs.

This study aimed to evaluate the effect of hydrolysable tannin supplementation on morphology, cell proliferation and apoptosis in the intestine and liver of fattening boars. A total of 24 boars (Landrace × Large white) were assigned to four treatment groups: Control (fed commercial feed mixture) and three experimental groups fed the same diet supplemented with 1%, 2% and 3% of hydrolysable tannin-rich extract. Animals were housed individually with ad libitum access to feed and then slaughtered at 193 d of age and 122 ± 10 kg body weight. Diets supplemented with hydrolysable tannin affected the morphometric traits of the duodenum mucosa as reflected in increased villus height, villus perimeter and mucosal thickness. No effect was observed on other parts of the small intestine. In the large intestine, tannin supplementation reduced mitosis (in the caecum and descending colon) and apoptosis (in the caecum, ascending and descending colon). No detrimental effect of tannin supplementation on liver tissue was observed. The present findings suggest that supplementing boars with hydrolysable tannins at concentrations tested in this experiment has no unfavourable effects on intestinal morphology. On the contrary, it may alter cell debris production in the large intestine and thus reduce intestinal skatole production.

Ellagitannins in Cancer Chemoprevention and Therapy.

It is universally accepted that diets rich in fruit and vegetables lead to reduction in the risk of common forms of cancer and are useful in cancer prevention. Indeed edible vegetables and fruits contain a wide variety of phytochemicals with proven antioxidant, anti-carcinogenic, and chemopreventive activity; moreover, some of these phytochemicals also display direct antiproliferative activity towards tumor cells, with the additional advantage of high tolerability and low toxicity. The most important dietary phytochemicals are isothiocyanates, ellagitannins (ET), polyphenols, indoles, flavonoids, retinoids, tocopherols. Among this very wide panel of compounds, ET represent an important class of phytochemicals which are being increasingly investigated for their chemopreventive and anticancer activities. This article reviews the chemistry, the dietary sources, the pharmacokinetics, the evidence on chemopreventive efficacy and the anticancer activity of ET with regard to the most sensitive tumors, as well as the mechanisms underlying their clinically-valuable properties.

Metabolic fate of ellagitannins: implications for health, and research perspectives for innovative functional foods.

Consumption of dietary ellagitannins (ETs) has been associated with different health benefits. Nonetheless, ETs are not bioavailable as such and are metabolized in vivo. They are partially converted into ellagic acid (EA) in the upper gastrointestinal (GI) tract, but this first metabolite is also poorly bioavailable. In the lower GI tract, EA and residual ETs are metabolized by gut microbiota to produce urolithins, which, together with their conjugate relatives, persist at relatively high concentrations in plasma and urine for days after ingestion of dietary ETs. Thus, ETs and EA may exert local health benefits on the GI tract but systemic health benefits are more likely to result from urolithins. Cellular models suggest that, at physiological concentration, urolithins are active against chronic degenerative diseases. Health benefits have been proven in animal models and during clinical studies. Even so, the crucial involvement of gut microbiota in ET bioconversion induces important variability of physiological response among humans, giving rise to the concept of high and low urolithin producers. This variability among consumers in obtaining potential health benefits from dietary ETs raises new challenges for the functional food industry. Different research perspectives are discussed to tackle this significant issue for nutritionists, food technologists, and consumers.

Evaluation of an antiparasitic compound extracted from Galla chinensis against fish parasite Ichthyophthirius multifiliis.

Ichthyophthirius multifiliis (Ich) is an important ectoparasitic ciliate that parasitizes gills and skin of freshwater fish resulting in massive mortality of fish. Currently there is no chemotherapeutant available to treat Ich effectively and economically. There is an urgent need to discover effective and safe parasiticides to control ichthyophthiriasis. In this study, anti-Ich efficacy of pentagalloylglucose, a compound extracted from the plant Galla chinensis was evaluated and the toxicity of the compound on channel catfish was determined. Pentagalloylglucose can kill all theronts at concentrations of 2.5-20 mg/L during 5.6-233.9 min and terminate reproduction of tomonts at 40 mg/L. Pentagalloylglucose significantly reduced infective ability of theronts at 1, 2 and 5 mg/L. The survival of naive channel catfish was 70% when treated with 10 mg/L and 100% when treated with 20 mg/L of pentagalloylglucose. For Ich infected catfish, the survival was 53.3% when treated with 10 mg/L and 93.3% when treated with 20 mg/L of pentagalloylglucose. Pentagalloylglucose at 20 mg/L was effective for treating Ich infected catfish or preventing naive catfish from Ich infestation. Median lethal concentration of the compound to catfish was 151.3 mg/L, which was 5 times the median effective concentration (30.5 mg/L) for killing tomonts. The compound killed Ich by destroying the plasma membrane of the parasite. The result demonstrated pentagalloylglucose as a safe, effective potential parasiticide against I. multifiliis.

Geraniin down regulates gamma radiation-induced apoptosis by suppressing DNA damage.

Gamma ray irradiation triggers DNA damage and apoptosis of proliferating stem cells and peripheral immune cells, resulting in the destruction of intestinal crypts and lymphoid system. Geraniin is a natural compound extracts from an aquatic plant Nymphaea tetragona and possesses good antioxidant property. In this study, we demonstrate that geraniin rescues radiosensitive splenocytes and jejunal crypt cells from radiation-induced DNA damage and apoptosis. Isolated splenocytes from C57BL/6 mice treated with geraniin were protected against radiation injury of 2 Gy irradiation through the enhancement of the proliferation and attenuation of DNA damage. Also, geraniin inhibited apoptosis in radiosensitive splenocytes by reducing the expression level and immunoreactivity of proapoptotic p53 and Bax and increasing those of anti-apoptotic Bcl-2. In mice exposed to radiation, geraniin treatment protected splenocytes and intestinal crypt cells from radiation-induced cell death. Our results suggest that geraniin presents radioprotective effects by regulating DNA damage on splenocytes, exerting immunostimulatory capacities and inhibiting apoptosis of radiosensitive immune cells and jejunal crypt cells. Therefore, geraniin can be a radioprotective agent against γ-irradiation exposure.

Degradation of tannic acid by cold-adapted Klebsiella sp NACASA1 and phytotoxicity assessment of tannic acid and its degradation products.

BACKGROUND, AIM, AND SCOPE: The focus of the present study is to know the potential of bacterial isolate for tannic acid degradation at low temperature. Also, we tried to evaluate the suitability of phytotoxicity testing protocol for the determination of tannic acid toxicity. METHODS: Screening for tannic acid degrading bacterial strains was carried out by using microbial isolation techniques. The 16S rDNA amplicon of the isolate was used to identify the isolate. The effect of different concentrations of tannic acid and its degradation products on germination of Vigna unguiculata was evaluated. The study was carried out to determine total sugar and starch content of the used seeds and even to check the presence of α-amylase activity during seed germination. RESULTS: The isolated bacterium was identified as Klebsiella sp NACASA1 and it showed degradation of tannic acid in 40 (±0.85***) h at 15°C and pH 7.0. A gradual decrease in root/shoot length was observed with increasing concentration of tannic acid. There was 95.11 (±0.24**)% inhibition in α-amylase activity at 20,000 ppm tannic acid, as compared to control. No such effects were observed on germination, root-shoot length, and α-amylase activity with tannic acid degradation products. CONCLUSIONS: The results obtained confirmed that tannic acid may act as a toxic agent in plant cells. The simple biodegradation process presented in this study was found to be effective in reducing toxicity of tannic acid. Also, it reveals the potential of soil bacterium to degrade tannic acid at low temperature.

Oenothera paradoxa defatted seeds extract and its bioactive component penta-O-galloyl-ß-D-glucose decreased production of reactive oxygen species and inhibited release of leukotriene B4, interleukin-8, elastase, and myeloperoxidase in human neutrophils.

In this study, we analyzed ex vivo the effect of an aqueous extract of Oenothera paradoxa defatted seeds on the formation of neutrophil-derived oxidants. For defining active compounds, we also tested lypophilic extract constituents such as gallic acid, (+)-catechin, ellagic acid, and penta-O-galloyl-ß-D-glucose and a hydrophilic fraction containing polymeric procyanidins. The anti-inflammatory potential of the extract and compounds was tested by determining the release from activated neutrophils of elastase, myeloperoxidase, interleukin-8 (IL-8), and leukotriene B4 (LTB4), which are considered relevant for the pathogenesis of cardiovascular diseases. The extract of O. paradoxa defatted seeds displays potent antioxidant effects against both 4ß-phorbol-12ß-myristate-α13-acetate- and formyl-met-leu-phenylalanine-induced reactive oxygen species production in neutrophils with IC50 values around 0.2 µg/mL. All types of polyphenolics present in the extract contributed to the extract antioxidant activity. According to their IC50 values, penta-O-galloyl-ß-D-glucose was the more potent constituent of the extract. In cell-free assays, we demonstrated that this effect is partially due to the scavenging of O2- and H2O2 oxygen species. The extract and especially penta-O-galloyl-ß-D-glucose significantly inhibit elastase, myeloperoxidase IL-8, and LTB4 release with an IC50 for penta-O-galloyl-ß-D-glucose of 17±1, 15±1, 6.5±2.5, and around 20 µM, respectively. The inhibition of penta-O-galloyl-ß-D-glucose on reactive oxygen species and especially on O2- production, myeloperoxidase, and chemoattractant release may reduce the interaction of polymorphonuclear leukocyte with the vascular endothelium and by that potentially diminish the risk of progression of atherosclerosis development.

1,2,3,4,6-penta-O-galloyl-beta-D-glucose attenuates renal cell migration, hyaluronan expression, and crystal adhesion.

Calcium oxalate monohydrate (COM) crystals bind avidly to the surface of proliferating and migrating renal endothelial cells, and oxalate-induced peroxidative injury can promote crystal attachment to renal epithelial cells. 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG), isolated from a traditional herbal remedy, inhibits vascular endothelial growth factor (VEGF) stimulated proliferation and migration of human umbilical vein endothelial cells (HUVECs) and has antioxidant activity. This study was performed to determine if PGG altered calcium oxalate monohydrate (COM) crystal adhesion to cells, perhaps via a change in cell surface properties. PGG significantly decreased COM crystal adhesion to cultured MDCK I cells at a low concentration (<10 microM) which was not cytotoxic. PGG exerted anti-adhesion effects whether cells or crystals were pre-coated. PGG also inhibited cell migration after scrape-wounding, decreased subsequent adhesion of crystals to proliferating and migrating cells, and decreased expression of the crystal binding molecule hyaluronan. These findings suggest that PGG represents a potential urolithiasis prevention compound. Anti-crystal adhesion effects appear multifaceted involving crystal coating by PGG, as well as decreased cell migration and the associated surface expression of hyaluronan. The latter represents a novel mechanism of nephrolithiasis prevention.

[Effects of tannins in animal nutrition]. / Zur Wirkung von Gerbstoffen in der Tierernährung.

Tannins are watersoluble plant polyphenols that precipitate proteins. According to their chemical structure they can be divided into condensed tannins and hydrolysable tannins. Altogether, tannins are reported to have various physiological effects like anti-irritant, antisecretolytic, antiphlogistic, antimicrobial and antiparasitic effects. Phytotherapeutically tannin-containing plants are used to treat nonspecific diarrhoea, inflammations of mouth and throat and slightly injured skins. Studies with ruminants have also demonstrated that the denaturing properties of tannins can possibly be used to improve protein supply to the small intestine. Besides anthelmintic effects of condensed tannins have been observed in sheep and goats. On the other hand high tannin concentrations resulted in reduced animal performances and health disorders as well in ruminants as in monogastriers. Further scientific research is therefore needed to clarify whether tannins can be effectivly used in livestock feeding, for example in prophylaxis of diarrhoea or parasitic control.

Induction of neutral endopeptidase activity in PC-3 cells by an aqueous extract of Epilobium angustifolium L. and oenothein B.

An aqueous extract of Epilobium angustifolium and its main compound oenothein B (OeB), a dimeric macrocyclic ellagitannin, are specifically able to induce the neutral endopeptidase (NEP) in prostate cancer cells. The angiotensin-converting enzyme (ACE) is not influenced. Additionally, a weak but statistically significant inhibition of cell proliferation is observed. Simultaneous treatment of the cells with arabinosylcytosine and the extract as well as the OeB, leads to an additional enhancement of NEP activity. Taking into account the role of this peptidase in prostate cancer progression, our results might offer a pharmacological explanation for the use of Epilobium in folk medicine.

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.

Toxic effect of tannic and related compounds on human plasma proteins.

OBJECTIVE: To investigate the toxicity of tannic acid related compounds such as gallic acid and polyphenol on the activity of plasma proteins in vitro. Their electrophoretic results show extremely important information, albumin and globulin levels are remarkably changed and characterized by disorder in their fractions avere which occurred frequently. METHODS: All plasma proteins samples of sets A, B and C were treated in sequences with known different concentrations of gallic acid, gallotannin and polypholes, which were separated chromatographically from phenolic extract of fruit peel of punicaceae. These were then treated, A, B and C were subjected to electrophoresis techniques, for identification and quantitation. RESULTS: The electrophoretic patterns of treated plasma proteins samples, sets A, B and C are arised with remarkable changes in their fraction levels, compared to normal. The results in were also characterized by disorders in their electrophoretic pattern. In this way 5 fractions of treated plasma proteins could be distinguished after sustaining which are ablumin and alpha1, alpha2 and beta and gamma globulins. CONCLUSION: The biological activity of tannic acid related compounds on plasma proteins in vitro, is important in determining their toxicity, and this toxicity may be depend upon their metabolic processes in the liver. In addition, the electrophoretic techniques used for separation and identification of plasma protein is extremely important for future work in the area.

Isolation, identification, and characterization of compounds from acer rubrum capable of oxidizing equine erythrocytes.

OBJECTIVE: To identify compounds in Acer rubrum that cause hemolysis or oxidation of equine erythrocytes and determine whether these toxins are found in other Acer spp. SAMPLE POPULATION: Equine erythrocytes. PROCEDURE: Washed erythrocytes were incubated with extracts and fractions of Acer spp that were separated by thin layer chromatography. Methemoglobin and hemolysis were measured spectrophotometrically. Compounds within Acer spp fractions associated with cell oxidation or hemolysis were identified by gas chromatography-mass spectrometry. RESULTS: Erythrocytes incubated separately with either A. rubrum, A. saccharum, or A. saccharinum extracts had increased methemoglobin formation, compared with extract-free control samples. Two Acer spp fractions had toxic effects on erythrocytes in vitro. A major component of the Acer fraction that caused a significant amount of methemoglobin formation was identified as gallic acid. An amount of gallic acid equivalent to that found in A. rubrum extract significantly increased methemoglobin, compared with extract-free control erythrocytes, but caused less methemoglobin formation than A. rubrum extracts did. A potential co-oxidant, 2,3-dihydro-3,5-dihydroxy-6-methoxy-4H-pyran-4-one, was found in the A. rubrum extract and may have been responsible for increasing methemoglobin formation. A second A. rubrum fraction caused methemoglobin formation and significant hemolysis. A. saccharum and A. saccharinum extracts caused hemolysis but less than the A. rubrum extracts did. CONCLUSION AND CLINICAL RELEVANCE: Oxidants in A. rubrum are also found in A. saccharum and A. saccharinum, and the ingestion of A. saccharum and A. saccharinum poses a potential threat to horses.

Palatability of bird repellents to Rattus norvegicus.

The palatability to captive, mostly laboratory-bred, Norway rats (Rattus norvegicus) of cereal-based baits containing 0.02 g kg-1 brodifacoum, with and without bird-repellent additives, was compared in a no-choice experimental design. Methyl anthranilate (25 g kg-1), dimethyl anthranilate (25 g kg-1) and cinnamamide (2.5 g kg-1) reduced bait consumption by the rats, but all except one rat ate enough bait to receive a lethal dose. Cinnamamide (1 g kg-1), ortho-aminoacetophenone (0.1 g kg-1) and tannic acid (20 g kg-1) did not reduce bait consumption and all rats died after eating baits. The concentration of cinnamamide palatable to rats has only a low and short-lived repellency to birds, so it does not warrant further investigation. However, ortho-aminoacetophenone and tannic acid should now be field-tested for palatability to all three rat species in New Zealand and for repellency to native New Zealand birds.

Mutagenicity and antimutagenicity studies of tannic acid and its related compounds.

Tannic acid and its hydrolysed products such as ellagic acid, gallic acid and propyl gallate were tested for mutagenicities using Ames Salmonella tester strains TA98 and TA100. Also, the antimutagenic activities of these compounds against a number of direct mutagens including 2-nitrofluorene (2-NF), 4,4'-dinitro-2-biphenylamine, 1-nitropyrene, 1,3-dinitropyrene, 2-nitro-p-phenylenediamine, 3-nitro-o-phenylenediamine, 4-nitro-o-phenylenediamine were tested. None of these tannic acid compounds was mutagenic. They also failed to show antimutagenic activity towards the tested direct mutagens. However, tannic acid at non-growth inhibitory concentrations reduced the revertant numbers of TA98 in the presence of S9 mix when benzidine, 3,3'-4,4'-tetraminobiphenyl, 4-aminobiphenyl, and N,N-N', N'-tetramethylbenzidine were used as the mutagens. These results suggest that tannic acid, but not its hydrolytic products, affects the metabolic activation of these mutagens.