Chemometric analysis of Amaranthus retroflexus in relation to livestock toxicity in southern Australia.

Amaranthus retroflexus L., an introduced invasive weed in southern Australia, has been associated with acute renal failure and/or mortality in a number of livestock species. While its leaves, flowers and stems are generally reported to contain high levels of nitrogen, few studies have fully characterised the chemical composition of A. retroflexus foliage with respect to mammalian toxicity. We performed extensive metabolic profiling of stems, leaves, roots and inflorescence tissues of A. retroflexus collected from three spatially and/or temporally distinct toxicity outbreaks, and report on the 1) composition of primary and secondary metabolites in methanolic extracts of A. retroflexus tissues using HPLC and HPLC-MS QToF and 2) chemometric analysis of A. retroflexus extracts in relation to the associated toxin(s). All tissues of A. retroflexus possessed an abundance of N-containing metabolites, particularly quaternary ammonium compounds which were identified as betaines, two of which (valine betaine and isoleucine betaine) are rarely encountered in plants. Cytotoxicity to murine fibroblasts was highest in extracts of leaf tissue and was associated with a single, a small modified peptide with high similarity to N-acetyl-L-α-aspartyl-L-alanyl-L-α-aspartyl-L-α-glutamyl-O-(carboxymethyl)-L-tyrosyl-L-leucinamide, a synthetic phosphotyrosyl mimic involved in cell signaling processes. One possible mode of action leading to acute renal failure in grazing livestock by a modified peptide such as this is proposed.

Toxicity of Natural Deep Eutectic Solvent Betaine:Glycerol in Rats.

Natural deep eutectic solvents (NaDES) are new natural solvents in green chemistry that in some cases have been shown to allow better extraction of plant bioactive molecules compared to conventional solvents and higher phenolic compound absorption in rodents. However, there is a serious lack of information regarding their in vivo safety. The purpose of this study was to verify the safety of a NaDES (betaine:glycerol (1:2 mole ratio) of water) extract from green coffee beans, rich in polyphenols. Twelve 6-week-old male Wistar rats were randomized into two groups of 6 animals each and twice daily gavaged for 14 days either with 3 mL of water or 3 mL of phenolic NaDES extract. Oral administration of phenolic NaDES extract induced mortality in two rats. In addition, it induced excessive water consumption, reduced dietary intake and weight loss, hepatomegaly, and plasma oxidative stress associated with high blood lipid levels. In conclusion, this work demonstrated the toxicity of oral administration of the selected NaDES under a short-term condition. This occurs despite the fact that this NaDES extract contains polyphenols, whose beneficial effects have been shown. Therefore, complementary work is needed to find the best dose and formulation of NaDES that are safe for the environment and animals and ultimately for humans.

Betaine attenuates Alzheimer-like pathological changes and memory deficits induced by homocysteine.

Hyperhomocysteinemia (Hhcy) may induce memory deficits with ß-amyloid (Aß) accumulation and tau hyperphosphorylation. Simultaneous supplement of folate and vitamin B12 partially restored the plasma homocysteine level and attenuated tau hyperphosphorylation, Aß accumulation and memory impairments induced by Hhcy. However, folate and vitamin B12 treatment have no effects on Hhcy which has the methylenetetrahydrofolate reductase genotype mutation. In this study, we investigated the effects of simultaneous supplement of betaine on Alzheimer-like pathological changes and memory deficits in hyperhomocysteinemic rats after a 2-week induction by vena caudalis injection of homocysteine (Hcy). We found that supplementation of betaine could ameliorate the Hcy-induced memory deficits, enhance long-term potentiation (LTP) and increase dendritic branches numbers and the density of the dendritic spines, with up-regulation of NR1, NR2A, synaptotagmin, synaptophysin, and phosphorylated synapsin I protein levels. Supplementation of betaine also attenuated the Hcy-induced tau hyperphosphorylation at multiple AD-related sites through activation protein phosphatase-2A (PP2A) with decreased inhibitory demethylated PP2A(C) at Leu309 and phosphorylated PP2A(C) at Tyr307. In addition, supplementation of betaine also decreased Aß production with decreased presenilin-1 protein levels. Our data suggest that betaine could be a promising candidate for arresting Hcy-induced AD-like pathological changes and memory deficits.

Betaine in sub-acute and sub-chronic rat studies.

To evaluate the sub-acute and sub-chronic effect of large doses of betaine, this trimethyl glycine compound was fed to rats. Initial studies at BIBRA in the UK evaluated intakes of 0, 1, 2, and 5% betaine added to a maintenance chow designed for use in toxicology studies. Male and female Sprague-Dawley rats were followed for up to 90 days. No toxicity occurred, but at higher betaine intakes several serum chemistries were altered slightly, the MCV, MCH, and MCHC of red cells were reduced, and hepatocytes developed fatty droplets in direct proportion to betaine intake. Females were more affected than males. In a second study to assess reversibility in females, betaine effects were induced for 28 days, followed by a 28 day betaine-free period. All perturbations, except the reduced MCV and MCH, were reversed. As a follow up to BIBRA investigations, both 28 and 90 day feeding trials were conducted at Brandeis University using a rat chow with higher levels of energy, protein, and fat, with betaine added at 0, 0.5, 0.75, 1.0 and 5.0% of the diet. A similar broad range of clinical chemistries and physiological parameters were monitored, and hepatic lipid droplets were investigated in more detail. Liver lipid was actually reduced by betaine, and no significant adverse effects of clinical importance resulted from any dose. However, the MCV was again reduced at 5% betaine in the 28 day study. By 90 days all parameters were normal and comparable to controls. Based on these collective data, it was concluded that even at these high doses, betaine is nontoxic. Differences observed between the BIBRA and Brandeis studies were attributed to differences in the dietary formulations. Significant betainexdietxgrowth interactions were thought to reflect primary disparities in protein and energy concentrations, more than the addition of betaine per se.