Tolerance to the nephrotoxic component of Narthecium ossifragum in sheep: the effects of repeated oral doses of plant extracts

Photosensitisation of livestock grazing Narthecium ossifragum: Current knowledge and future directions

Photosensitisation diseases can cause production and animal welfare losses world-wide. In North-West Europe a photosensitisation disease complex known as 'plochteach', 'yellowses', 'saut' and 'alveld' occurs in lambs on extensive pastures containing bog asphodel (Narthecium ossifragum). Affected lambs develop lesions on the ears, face and sometimes the back, with erythema, oedema, ulceration and necrosis that can be followed by secondary infection and death. Adult sheep appear unaffected, the incidence in lambs varies from year to year and there are variations in susceptibility between- and within-breeds. The definitive cause remains uncertain although ingestion of N. ossifragum, which contains hepatotoxic saponins, has been implicated in the aetiology. However, problems replicating the disease complex by feeding N. ossifragum in a controlled environment have led to alternative hypotheses, including possible intake of toxins from fungal spores and cyanobacteria. Further research is required to assess the putative role of N. ossifragum, the scale of economic and animal welfare losses associated with the disease, how best to identify affected animals before external clinical signs appear and the treatment and management of clinical cases. Given the challenges involved in isolating the causative agent(s) of plochteach, an animal breeding route may be effective if heritability of resistance/susceptibility can be demonstrated.

Toxicological evaluations of methanolic extract of Moringa oleifera leaves in liver and kidney of male Wistar rats

BACKGROUND

This study was conducted to investigate toxicological effects associated with prolonged consumption of Moringa oleifera leaves as a beverage.

METHODS

Thirty rats were used in this study. They were grouped into five groups of six rats. Rats in group I received 2 mL/kg body weight (b.w.) of corn oil (vehicle). Animals in groups II, III, IV and V received 50, 100, 200 and 400 mg/kg b.w. of methanolic extract of M. oleifera (MEMO) for 8 weeks. Serum collected was analyzed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein, albumin, globulin, blood urea nitrogen (BUN) and creatinine.

RESULTS

There was a significant (p<0.05) increase in serum total protein and globulin in a dose-dependent manner. Rats that received MEMO at 200 and 400 mg/kg b.w. showed a significant (p<0.05) increase in serum ALT, AST, BUN and creatinine which pointed to hepatic and kidney damage. All experimental animals that received MEMO had a significant (p<0.05) increase in body weight in a dose-dependent manner.

CONCLUSIONS

This study therefore confirms for the first time that chronic administration of M. oleifera leaves might predispose to hepatic and kidney damage.

Toxicological Evaluation of Pooled Selected Fractions of Mimosa invisa and Protective Effect of Herbal Decoction

The study was undertaken to evaluate the toxicity produced by the pooled selected fractions of Mimosa invisa in rabbits. An attempt was made to protect the animal from the toxicity using a decoction containing Hygrophila auriculata, Tribulus terrestris and Boerhaavia diffusa. Eighteen adult rabbits were divided into three groups of six animals each. Group I served as control. Group II received pooled fraction of M. invisa at 0.4 g/kg orally. Group III was administered with pooled fraction along with the decoction containing H. auriculata, T. terrestris and B. diffusa equivalent to 5 g/kg. The experiment was conducted for 20 days. Group II showed significant increase in biochemical parameters like alanine transaminase, aspartate transaminase, gamma glutamyl tranferase, creatine kinase, alkaline phosphatase, creatinine and urea, suggesting liver and kidney toxicity. Histopathological examination of the liver and kidney supported these findings. Heart also showed mild histopathological changes. Administration of decoction reversed the biochemical and histopathological changes, indicating the protective effect of decoction.

Accumulation of sapogenin conjugates and histological changes in the liver and kidneys of lambs suffering from alveld, a hepatogenous photosensitization disease of sheep grazing Narthecium ossifragum

Sixteen lambs exhibiting hepatogenous photosensitization (alveld) after grazing pasture containing Narthecium ossifragum and seven nonphotosensitized lambs grazing the same pastures were studied. All the alveld-affected lambs revealed liver damage dominated by single cell necrosis, portal fibroplasia and bile duct proliferation. Crystalloid clefts were demonstrated in the bile ducts of two and in the hepatocytes and Kupffer cells of nine photosensitized lambs. Plasma bilirubin concentration was severely increased in ten of the cases of alveld whereas the activity of aspartate aminotransferase was moderately to severely increased in seven cases. The activity of glutamate dehydrogenase was moderately elevated in one of the photosensitized lambs. The main histopathological findings in the kidneys from the alveld-affected lambs were dilated tubules, often with eosinophilic material in the tubular lumina. Regenerative changes were seen in a large proportion of the renal sections. Elevated plasma concentrations of urea and creatinine, and the renal histopathological changes, suggested that the photosensitized lambs had been through a phase of renal injury. Analysis of the free and conjugated sapogenin content in liver tissue and bile was performed by gas chromatography-mass spectrometry. There were significantly higher concentrations of conjugated episapogenins in both the liver and bile in the alveld-affected lambs than in the nonphotosensitized lambs.

Ruminal metabolism in sheep of saponins from Yucca schidigera

Fifty-five mg per kg live weight of crystallized Yucca schidigera saponins, corresponding to 26 mg/kg live weight of sapogenins, was given daily intraruminally to two lambs for 11 consecutive days. Neither of the lambs showed any sign of toxicity throughout the experimental period. One lamb was killed 5 h after the last dose and GC-MS analysis of the free and conjugated sapogenin content samples of liver, and of the contents of the rumen, omasum, abomasum, duodenum, jejunum, ileum, colon and rectum, of faecal samples collected before dosing started, and of parts of the administered Yucca saponin were performed. The Yucca material contained mainly sarsasapogenin and smilagenin saponins. Ingested saponins were quickly hydrolysed in the rumen to free sapogenins and, in part, epimerized at C-3 to afford episapogenins. The absorption of free sapogenins appeared to occur in the jejunum. The metabolism of Yucca saponins was identical to that of Narthecium ossifragum saponins, and it is suggested that Yucca saponins could replace N. ossifragum saponins for toxicity studies on the latter plant.