Chemical characterisation and toxicity assessment in vitro and in vivo of the hydroethanolic extract of Terminalia argentea Mart. leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Terminalia argentea Mart. (Combretaceae), known mainly as "capitão", is a native tree, not endemic, that occurs in the Amazon, Caatinga, Cerrado and Atlantic Forest in Brazil. Leaf infusion is popularly mentioned by riverine communities that inhabit the microregion of Northern Araguaia (Mato Grosso, Brazil) for the treatment of gastric ulcer, bronchitis and haemorrhage. Considering the wide medicinal use, lack of studies that evaluate the safety of use and the scarcity of phytochemical studies of T. argentea leaves, this work was carried out with the objective of evaluating the toxicity of the hydroethanolic extract of the leaves of T. argentea Mart. (HETa) in experimental models in vivo and in vitro, as well as to advance the phytochemical analysis of HETa. MATERIALS AND METHODS: HETa was prepared by macerating the leaf powder in hydroethanolic solution. Phytochemical characterisation was carried out by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and mass spectrometry through direct flow infusion coupled with electrospray ionization and ion-trap analyzer (DFI-ESI-IT-MS analyses) The contents of phenols, flavonoids and phytosterols were analysed by colorimetric methods. Cytotoxicity was assessed by the Alamar blue assay on Chinese hamster ovary epithelial cells (CHO-K1) and human gastric adenocarcinoma cells (AGS). In vitro genotoxicity of HETa (10, 30 or 100 µg/mL) was assessed by micronucleus (MN) and comet tests using CHO-K1 cells. The acute toxicity assessment was performed by oral administration of HETa in single dose Swiss mice (males and females) up to 2000 mg/kg and sub-chronic toxicity by daily oral administration of HETa (50, 200 and 800 mg/kg) in Wistar rats for 30 days. The parameters related to the clinical and toxicological observations were determined every 6 days and at the end of the treatment the blood was collected for biochemical and haematological analysis, and some organs were removed for macroscopic and histopathological analysis. RESULTS: Preliminary phytochemistry and TLC analysis of HETa revealed the presence of phenolic compounds (18.8%), flavonoids (10.8%), saponins, tannins and phytosterols (19%). The HPLC data revealed the presence of gallic acid, rutin, ellagic acid, catechin, quercetin and kaempferol. In the analysis by DFI-ESI-IT-MS, the presence of gallic acid, rutin, ellagic acid and quercetin was confirmed and identified caffeic acid, quinic acid, galloylmucic acid, quercetin xyloside, quercetin rhamnoside, quercetin glucoside, caffeoyl ellagic acid, quercetin galloyl xyloside, terminalin, quercetin galloyl glucose, corilagin, quercetin digalloyl xyloside, quercetin digalloyl glucoside, punicalin and punicalagin. HETa showed no cytotoxic effect on CHO-K1 and AGS cells. In the MN assay, HETa increased the number of MNs and nuclear buds (NBUDs) in binucleate cells at the three concentrations tested and the nucleoplasmic bridges (NPBs) number at 30 µg/mL. In the comet test, HETa (10 and 100 µg/mL) alone showed a genotoxic effect on CHO-K1 cells. In pre-treatment, HETa at all concentrations tested prevented DNA damage induced by H2O2. In co-treatment with H2O2, HETa showed genotoxic effects at the three concentrations, and post-treatment DNA damage in exposed CHO-K1 cells to H2O2 was repaired in 22.5% with 10 µg/mL HETa. In the acute toxicity test, the HETa did not cause death in the mice, being verified only by piloerection and reversible in 2 h in males and in 4 days in females. No macroscopic changes were observed in the analysed organs. In the sub-chronic toxicity test, the HETa did not cause death in the rats after 30 days and the few changes were: absolute (103/mm3) and relative (%) values of basophils increased by 477.8% and 423% (p < 0.001), respectively, with 50 mg/kg; reduction in feed intake (23.6%, p < 0.01) only on day 18; total cholesterol concentration (13.1%, p < 0.05) and relative heart weight (13.2% %, p < 0.05) at a dose of 800 mg/kg. These effects were not dose-dependent nor followed by clinical signs and symptoms of intoxication, nor of macroscopic and histopathological changes in the organs of animals treated with HETa. CONCLUSIONS: The results demonstrated that HETa had no cytotoxic in vitro effects for CHO-K1 and AGS cells. In in vitro genotoxicity assays, the HETa induced different responses, according to concentration and experimental condition. In the MN test the HETa presented genotoxic potential by increasing the number of MNs, NBUDs and NPBs. In the comet assay, HETa was genotoxic by itself and in the co-treatment protocol with H2O2. In pre-treatment or post-treatment protocols with H2O2, HETa presented an antigenotoxic effect by preventing or repairing, respectively, the genotoxicity induced by H2O2. In the in vivo models, HETa was shown to be relatively safe after acute administration in mice [no-observed-adverse effect level (NOAEL) of 2000 mg/kg] and sub-chronic in rats (NOAEL of 800 mg/kg), confirming the riverine information that it is non-toxic in the dosage used. Phytochemical analysis of HETa revealed the presence of phenolic compounds, flavonoids, saponins, tannins and phytosterols. Among the flavonoids and tannins, we highlight gallic acid, rutin, ellagic acid, quercetin, caffeic acid, quinic acid, corilagin, punicalin and punicalagin. Thus, it can be stated that HETa has a good safety margin for therapeutic use.

Evaluation of the safety, gastroprotective activity and mechanism of action of standardised leaves infusion extract of Copaifera malmei Harms.

ETHNOPHARMACOLOGICAL RELEVANCE: Copaifera malmei Harms (Fabaceae) is a plant that occurs in the central region of Brazil, where the plant's leaves infusion is popularly used to treat gastric ulcer and inflammatory diseases. This study was aimed to investigate the gastroprotective activity and mode of action of the plants' leaves infusion in order to establish the scientific basis for such usage, and to assess its potential as a source of an anti-ulcer agent. MATERIALS AND METHODS: Leaves infusion extract of the plant (SIECm) was prepared, freeze dried and lyophilised. Its qualitative and quantitative phytochemical constituents were investigated using TLC and HPLC techniques. The safety profile was evaluated on CHO-k1 epithelial cells viability using the Alamar blue assay, and by acute toxicity test in mice. The gastroprotection and anti-ulcer efficacy of the SIECm (25, 100 and 400mg/kg, p.o.) were tested using acute (acidified ethanol, piroxicam and water restrain stress), and chronic (acetic acid) experimental ulcer models. The plausible mode of action of the SIECm was assessed using gastric secretion, gastric barrier mucus, nitric oxide, and its antioxidant (myeloperoxidase and catalase) effects in mice and rats. The histopathological analyses of the ulcerated tissues as well as the extract's activity on Helicobacter pylori were also investigated. RESULTS: Phytochemical tests indicated the presence of mainly phytosterols, phenolics and flavonoids. The SIECm exhibited no cytotoxic effects on the CHO-k1 cells, and no oral acute toxicity in mice. It prevented against the acute induced ulcerations by enhancing gastroprotection through gastric mucus production, NO modulation, antioxidant, reduced gastric secretion and enhanced chronic ulcers healing process, as shown by reduction/prevention of epithelial and vascular damage, in addition to reduction in leucocyte infiltration. The SIECm however did not exhibit activity against H. pylori. CONCLUSION: The SIECm is safe, contain useful phytochemicals and exhibited significant gastroprotective/anti-ulcer effects. The results justify its folkloric usage, and provided scientific evidence of its potential as a source of new phytodrug to treat gastric ulcers.

Gastroprotective and ulcer-healing mechanisms of ellagic acid in experimental rats.

Ellagic acid (EA), a plant-derived polyphenol, exhibits antioxidant, anti-inflammatory, and gastroprotective effects. Its gastroprotective mechanisms have not been fully elucidated nor have its effects on chronic ulcer previously been described. Toward these ends, the antiulcer activities of EA were evaluated in acute (ethanol and indomethacin) and chronic (acetic acid) ulcer models in Wistar rats. In this study, oral administration of EA significantly prevented the gastric ulceration caused by ethanol, indomethacin, and acetic acid treatments. Its gastroprotective mechanism in ethanol-induced ulcer were partly due to intensification in the endogenous production of nitric oxide, an antioxidant effect by replenishing depletion of endogenous nonprotein sulfhydryls and attenuation of tumor necrosis factor-α increase, whereas in indomethacin ulcer, it is partly due to a reduction in the plasma level of leukotriene B(4). In acetic acid ulcer, promotion of ulcer-healing effects was partly due to attenuation of the elevated levels of the inflammatory cytokines TNF-α, interferon-γ, and interleukins-4 and -6. These findings suggest that ellagic acid exerts its antiulcer activity by strengthening the defensive factors and attenuating the offensive factors.