The effect of Lantana camara on the liver of sheep

Sub-chronic toxicopathological study of lantadenes of Lantana camara weed in Guinea pigs

Background

In the field conditions, animals regularly consume small quantities of lantana leaves either while grazing or due to mixing with regular fodder.

The hypothesis of this study was that consumption of lantana toxins over a long period of time leads to progression of sub-clinical disease.

Toxicopathological effects of sub-chronic (90 days) administration of lantadenes of L. camara were investigated in guinea pigs. For this, a total of 40 animals were divided into 5 groups whereby groups I, II, III and IV were orally administered lantadenes, daily at the dose of 24, 18, 12, and 6 mg/kg bw, respectively while group V was control. The animals were evaluated by weekly body weight changes, haematology, serum liver and kidney markers, tissue oxidative markers and histopathology.

Results

The results of significant decrease in weekly body weights, haematology, liver and kidney marker enzymes (alanine aminotransaminase, aspartate aminotransaminase, acid phosphatase and creatinine), oxidation stress markers (lipid peroxidation, reduced glutathione, superoxide dismutase and catalase) in liver and kidneys, histopathology, and confirmation of fibrous collagenous tissue proliferation by Masson’s Trichome stain showed that lantadenes led to a dose-dependent toxicity in decreasing order with the highest dose (24 mg/kg bw) producing maximum lesions and the lowest dose (6 mg/kg bw) producing minimum alterations.

Conclusions

The study revealed that lantadenes which are considered to be classical hepatotoxicants in acute toxicity produced pronounced nephrotoxicity during sub-chronic exposure. Further studies are needed to quantify the levels of lantadenes in blood or serum of animals exposed to lantana in field conditions which would help to assess the extent of damage to the vital organs.

A review of the hepatotoxic plant Lantana camara

Lantana (Lantana camara Linn) is a noxious weed that grows in many tropical and subtropical parts of the world. Ingestion of lantana foliage by grazing animals causes cholestasis and hepatotoxicity. Both ruminants and nonruminant animals such as guinea pigs, rabbits, and female rats are susceptible to the hepatotoxic action of lantana toxins. The hepatotoxins are pentacyclic triterpenoids called lantadenes. Molecular structure of lantadenes has been determined. Green unripe fruits of the plant are toxic to humans. Lantana spp. exert allelopathic action on the neighboring vegetation. The allelochemicals have been identified as phenolics, with umbelliferone, methylcoumarin, and salicylic acid being the most phytotoxic. In addition to phenolics, a recent report indicates lantadene A and B as more potent allelochemicals. Management of lantana toxicosis in animals is achieved by drenching with activated charcoal and supportive therapy. Recent reports on the bilirubin clearance effect of Chinese herbal tea Yin Zhi Huang (decoction of the plant Yin Chin, Artemisia capillaries, and three other herbs) or its active ingredient 6,7-dimethylesculetin, in jaundice are very exciting and warrant investigations on its, possible, ameliorative effects in lantana intoxicated animals. Research is being conducted on new drug discovery based on natural products in different parts of the lantana plant.

A toxidez de diversas lantanas para bovinos e ovinos no Brasil

Neste estudo sobre a toxidez das lantanas para bovinos e ovinos, verificou-se situação semelhante à que ocorre na Austrália, que nem todas as espécies de Lantana e nem todos os taxa de Lantana camara que ocorrem no Brasil, são tóxicos. Verificou-se, que foram tóxicas as amostras de lantanas procedentes de Boa Vista (RO), Castanhal (PA), Cáceres (MT), Serra Talhada (PE), Cabo Frio e Quatis (RJ) e Canoinhas (SC). Outras amostras procedentes de Cruzeiro do Sul (Acre), Castanhal (PA), Chapada dos Guimarães e Lambari d´Oeste (MT), Jaguaribe (CE), Vitória da Conquista e Wanderley (BA), Vitória (ES), Vassouras, Parati e Itaguaí (RJ) não revelaram toxidez nas doses administradas (40 g/kg). A dose letal das amostras submetidas à experimentação no Brasil foi bastante constante (40 g/kg), com duas exceções: as folhas frescas da lantana procedente de Canoinha (SC) foram muito mais tóxicas (10 g/kg) e as folhas frescas e as dessecadas da lantana de Serra Talhada (PE) foram muito menos tóxicas, pois somente causaram intoxicação não-letal com a dose de 40g/kg/dia administradas durante 30 dias. Históricos sobre a observação de fotossensibilização em bovinos, ligados à ingestão de lantanas foram obtidos em Serra Talhada (PE), Cáceres (MT), Cabo Frio (RJ), Quatis (RJ) e Canoinhas (SC). Verificou-se que não é possível estabelecer uma correlação entre a cor das inflorescências das lantanas e sua toxidez, confirmando a constatação feita na Austrália, que o potencial de intoxicar não está necessariamente relacionada com a cor das flores.

Estudos complementares sobre a toxidez de Lantana camara (Verbenaceae) em bovinos

Descreve-se, no município de Quatis, RJ, a ocorrência de um surto de intoxicação por Lantana camara var. aculeata em bovinos, caracterizado por acentuada icterícia, lesões de fotossensibilização, constipação e edema subcutâneo dos membros. A reprodução experimental da doença, com êxito letal, através da administração de dose única de 40 g/kg de L. camara var. aculeata, confirmou a planta como causa do surto; doses únicas de 20 g/kg, 10 g/kg e 5 g/kg causaram respectivamente, grave intoxicação, leve intoxicação e ausência de sintomas. Experimentos com doses repetidas permitem concluir que essa planta apresenta efeito acumulativo, quando ingerida em doses diárias de 10 g/kg (1/4 da dose letal); a administração de quatro doses de 5 g/kg (1/8 da dose letal) ou de oito doses de 2,5 g/kg (1/16 da dose letal) reproduziram o quadro grave de intoxicação. Subdoses menores, de 1,25 g/kg (1/32 da dose letal), administradas durante 34 dias, não produziram quaisquer sinais clínicos. Os exames histológicos dos casos naturais e experimentais revelaram, além de bilestase, alterações regressivas nos hepatócitos e no epitélio dos túbulos renais.

A review of the noxious plant Lantana camara

Lantana camara is one of the ten most noxious weeds in the world. It is toxic to animals and exerts allelopathic action on neighbouring vegetation. The pathological and biochemical effects of the lantana plant in cattle, sheep and guinea pigs have been determined. The chemical nature of lantana toxin(s) and the precise mechanism by which lantana induces cholestasis have not yet been defined clearly. Lantana toxicity is manifested in three phases: the release and absorption of toxins in the gastrointestinal tract; the hepatic phase resulting in cholestasis, hyperbilirubinaemia, hyperphylloerythrinaemia, and finally the tissue phase wherein cell injury results from the accumulation of bilirubin and phylloerythrin. Thus, therapeutic measures should be aimed at arresting one or more of these phases. The different means for control of lantana viz. mechanical, cultural, chemical and biological are discussed with regards to their effectiveness. A number of potential uses of lantana plant have been suggested but none has been exploited on a large scale. Future research is required in order to identify the lantana toxin, antidotes against lantana poisoning, cell-bilirubin/phylloerythrin interactions, cheaper weedicides, allelochemics and finally to obtain more effective phytophagous insects for fighting the lantana menace.

Outbreaks of photosensitisation and deaths in cattle due to Myoporum aff. Insulare R. Br. toxicity

Outbreaks of photosensitisation and deaths in cattle on 5 farms in Victoria occurred following access to Myoporum affinity insulare. Signs were observed 2 to 6 days after access to myoporum trees or pruned branches and included depression, anorexia, photosensitisation, constipation, agalactia, jaundice, and mucosal petechiation. Serum gamma glutamyl transferase and aspartate amino transferase levels were elevated in all cases. Gross findings in fatally intoxicated cows consisted of widespread haemorrhages and pale yellow mottling of the liver. Distinctive histological lesions of periportal hepatic necrosis and bile duct proliferation were seen in all cases. An 8-month-old heifer given 30 g/kg fresh minced leaves by stomach tube died approximately 70 h after initial dosing. Post-mortem findings of widespread haemorrhage and hepatic periportal necrosis and bile duct proliferation were identical to those of field cases.

Biochemical changes in hepatic microsomes of guinea-pig under lantana toxicity

1. Lantana intoxication of guinea-pig caused a decrease in hepatic microsomal protein content, the phospholipid: protein ratio, and the cholesterol: protein ratio. 2. Activities of aniline hydroxylase, aminopyrine N-demethylase, NADH-cytochrome c reductase, NADH-ferricyanide reductase, UDP-glucuronosyl transferase, cytochrome P-450 and glucose 6-phosphatase were decreased. 3. Activities of Mg2+ -ATPase and Na+ -K+ -ATPase were increased. However, activities of 5-nucleotides and NADPH-cytochrome c reductase were unaffected. 4. The liver endoplasmic reticulum is an important target organelle during lantana poisoning of guinea-pigs.

Changes in blood constituents of guinea pigs in lantana toxicity

Lantana toxicity of guinea pigs elicited an increase in hematocrit, erythrocyte and leukocyte number, hemoglobin, urea-nitrogen and bilirubin contents in the blood of the affected animals. Most of the bilirubin was present in the conjugated form. Enzyme activities of glutamic oxaloacetic transaminase, acid phosphatase, lactate dehydrogenase, glutamate dehydrogenase, sorbitol dehydrogenase in the blood plasma of affect animals exhibited a marked increase. Acid phosphatase activity was inhibited by tartrate. Enzyme activity of alkaline phosphatase remained unchanged while that of glutamic pyruvic transaminase showed a marginal decrease.

A review of the toxicity of Lantana camara (Linn) in animals

Lantana poisoning has been taking a heavy toll of livestock year after year. All aspects of the problem are reviewed. Lantana poisoning in cattle, sheep, buffalo, and guinea pigs caused obstructive jaundice, photosensitization, and rise in serum glutamicoxaloaetic transaminase activity. The symptoms could be reproduced in sheep by administration of purified Lantadene A. Liver and kidneys are the most affected organs during lantana poisoning. Intoxication of guinea pigs with Lantana camara leads to marked alterations in major tissue constituents in liver an kidneys. Hepatic and renal xanthine oxidase activity is also elevated during lantana poisoning. No antidote is available against the toxic section of Lantana camara. Symptomatic treatments have been proposed with limited success. Knowledge of the biochemical mechanism of lantana intoxication at the cellular, subcellular, and molecular levels is essential in order to evolve a successful antidote and more rational therapy during lantana intoxication.

Fragility of erythrocytes in animals affected by lantana poisoning

Clinical observations on four male cow calves and three other lantana poisoned animals under field conditions have been made along with hematological studies, including observations on plasma bilirubin content and osmotic fragility of erythrocytes. Four healthy male cow calves served as control. Five clinically advanced cases succumbed within 1 to 10 days of observation. Hematocrit values in four of the seven affected animals were abnormally high. The total plasma bilirubin content in the fatal cases was of the order of 5 to 50 times the normal value while, in calves that recovered, it was not more than 3 times. The osmotic fragility of erythrocytes was measured by the rate of hemolysis in decreasing concentrations of saline. The erythrocytes of normal animals resisted hemolysis till the saline concentration was lowered to 0.60%, and it was complete at the low saline concentration of 0.30%. However, in lantana poisoned animals, hemolysis started even in 0.72% saline and was complete at a saline concentration of 0.44%. The hemolysis curves of animals that died were far removed from the normal, but those of the calves that recovered and the one that died but had the lowest bilirubin content closely approached the normal curve.

Lantadene A toxicity in sheep. A model for cholestasis

Liver injury occurred after sheep were injected intravenously with the triperpene acid lantadene A, the toxic principle of the tropical plant Lantana camara. A single dose of 1--3 mg/kg of the compound caused mild hepatocellular injury characterized by transient rises in serum enzymes, with or without hyperbilirubinaemia. Higher doses resulted in hepatic necrosis. When low doses of the triterpene were given repeatedly over several days a cholestatic syndrome developed which appeared identical with that caused by consumption of the plant. This is a disease model which may be of value in experimental studies of intrahepatic cholestasis. This study provides evidence that lantadene A is hepatotoxic and does not require metabolism in the alimentray tract for toxicity in sheep.

The oral toxicity for sheep of triterpene acids isolated from Lantana camara

Toxic Lantana camara taxa growing in Queensland all contain the triterpene acids lantadene A, reduced lantadene A and lantadene B. These when dosed as pure compounds orally to sheep were similarly toxic at 65 to 75, 42 to 80 and 200 to 300 mg/kg body weight respectively, causing jaundice, photosensitisation, kidney and liver lesions typical of natural and experimental lantana poisoning. Because of its comparative toxicity and abundance lantadene A is the most significant toxic principle in the plant. Reduced lantadene A because of its low concentration in the leaves (5% of lantadene A) and lantadene B because of its significantly lower toxicity are thus unlikely to be of much importance in the poisoning of ruminants following consumption of the plant. In addition, the structural features of both lantadene A and B molecules given to sheep by the oral route do not conform to the chemical structures previously reported to be required for liver damaging action of the verbenaceous triterpenes administered to rabbits by the intraperitoneal route.

The influence of hepatic microsomal amidopyrine demethylase activity on halothane hepatotoxicity in the horse

The hepatotoxic effect of oral halothane in the horse is increased by pretreatment with phenobarbitone or DDT but not by chlorpromazine. Phenobarbitone and DDT increase the activity of hepatic amidopyrine N-demethylase but chlorpromazine does not. Carbon disulphide protects the liver of the horse against halothane.

Toxicity of Jatropha cucurcas for goats

Eleven Nubian goats were fed with Jatropha curcas seeds at doses ranging from 0.25 g to 10g/kg/day. All dose levels were found to be toxic with fatal conswquences within 2 to 21 days. Liver biopsy samples taken 2 days after the start of feeding and subsequent biopsies showed congestion, varying degrees of fatty change, considerable reduction in glycogen content and necrosis of the hepatocytes. Lack of appetite, reduced water consumption, diarrhoea, dehydration, sunken eyes and a steadily deteriorating condition were important clinical signs of Jatropha intoxication goats. In all animals there was a decrease in the level of glucose and a marked rise in the concentration of arginase and glutamate oxaloacetate transminase (GOT) in the serum. Post-mortem examination revealed haemorrhage in the rumen, reticulum, kidney, spleen and heart, catarrhal or haemorrhagic abomasitis and enteritis, congestion and oedema of the lung and excessive fluid in serous cavities.

Location of liver injury and extent of bilirubinaemia in experimental liver lesions

Reports on experimental hepatotoxicities in domestic animals were reviewed in order to investigate the relationship between the location of liver lesions and hyperbilirubinaemia. A purely centrilobular lesion tends to produce little effect on bilirubin concentration in the circulation. A mild to moderate hyperbilirubinaemia is predictable if a centrilobular lesion is extensive enough to include cells of the outer zones, however, even an apparently mild periportal liver lesion, but one that affects the integrity of cell membranes, results in a marked rise in bilirubin concentration in the circulation.