R.K. Dawra

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.

Effect of tannin-rich leaves of oak (Quercus incana) on various microbial enzyme activities of the bovine rumen

1. The objective of the present experiment was to study the effects of oak (Quercus incana) leaves rich in tannins on various enzyme activities of the bovine rumen. 2. The procedure employed was incubation of tannin-rich, very-low-tannin or virtually tannin-free leaves in nylon-gauze bags in the rumen, and determination of enzyme activities in microbes tightly bound to the solid matrix and in microbes loosely plus tightly attached to the solid matrix. 3. The activities of urease (EC 3.5.1.5), carboxymethylcellulose, glutamate dehydrogenase (EC 1.4.1.2) and alanine aminotransferase (glutamic-pyruvic transaminase) (EC 2.6.1.2) were significantly lower in the tannin-rich group, whereas the activities of glutamate ammonia ligase (glutamine synthetase) (EC 6.3.1.2; both gamma-glutamyltransferase (EC 2.3.2.2) and the forward reaction) were higher in the tannin-rich group. These changes were more marked in micro-organisms tightly bound to the solid matrix than in the more complex microbial compartment. 4. The protein, DNA and RNA contents, and protein: RNA ratio, were significantly lower in the tannin-rich group, whereas no difference was observed for protein: DNA between the groups. 5. Effects of tannin-containing extracts of oak leaves on various rumen enzymes in vitro showed a trend similar to that observed in nylon-gauze bags, suggesting that the changes observed in various compartments were due to the tannins of oak leaves.

Protein-binding capacity of microquantities of tannins

The physiological effect of tannins is studied in terms of their protein-binding or precipitation capacity. A number of assays based on binding of hemoglobin or bovine serum albumin (BSA) and subsequent determination of unbound protein in supernatant or tannin in a protein-tannin complex are available but with various limitations. These methods are unable to estimate protein-binding capacity, if the quantity of tannin available is low. In the method reported here, tannins or other phenolics were applied on chromatography paper and reacted with BSA and unbound BSA was washed off. The protein in the tannin-protein complex was measured spectrophotometrically after staining with Ponceau S. It required microquantities of sample. Using this method the protein-binding capacity of total leaf extract and hydrolyzable and condensed tannins of Quercus incana, Q. semecarpofolia, and Q. dilatata was determined. The protein binding capacities of ellagic acid and quercetin (microgram BSA/mg) were 297.3 and 78.0, respectively.

Protein precipitation assay for quantitation of tannins: Determination of protein in tannin-protein complex

A protein precipitation method for the determination of tannins has been developed. The protein in the tannin-protein complexes was measured using the ninhydrin assay of amino acids released by alkaline hydrolysis of the complex. Standard protein and the complex were hydrolyzed with 13.5 N NaOH at 120 degrees C for 20 min and the amino acids released were measured with ninhydrin. Tannins did not interfere in the determination of protein by ninhydrin assay. The bovine serum albumin (BSA) precipitated (y; mg) increased linearly with increase in tannic acid (x) from 0.2 to 0.9 mg (y = 2.598x - 0.258). The protein precipitation capacities (mg BSA precipitated/g dry wt) measured by the method for young and mature leaves of oaks were Quercus incana (young, 42.21; mature, 79.51), Q. ilex (young, 1.86; mature, 1.86), and Q. semecarpifolia (young, 733.54; mature, 304.32). The method can provide valuable information on the mechanisms of protein-tannin interactions and nutritional and physiological significances of tannins.

A review of the toxicosis and biological properties of the genus Eupatorium

Eupatorium genus grows wild in many parts of the world. A number of species of Eupatorium are toxic to grazing animals. Milk sickness in humans is caused by ingestion of milk of the animals reared on the pastures infested with Eupatorium rugosum (white snakeroot). While some information is available on the toxins in various species of Eupatorium, ambiguities still persist in extrapolation of the data to field incidence of toxicosis. Eupatorium genus has been used for its medicinal properties for many decades. A number of bioactive natural products have been reported in the extracts of Eupatorium spp. and the genus is a promising bioresource for preparation of drugs and value-added products.

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.

Isolation and partial purification of lantana (Lantana camara L.) toxins

A partially purified toxin fraction and lantadene A were obtained from Lantana camara L. leaves by batch extraction, column chromatography and fractional crystallization. Toxicity was tested in guinea pigs. The total number of chemical entities in the partially purified toxin preparation was 7, the 2 major ones being lantadene A and lantadene B. Lantadene A was nontoxic in itself. Likewise, another fraction containing lantadene A, lantadene B and 3 more components with higher polarity was found to be nontoxic. The toxic component(s) are different from lantadene A/B but appear to resemble them very closely.

Hepatotoxicity of Eupatorium adenophorum to rats.

Freeze dried Eupatorium adenophorum leaf powder mixed in rat feed at a level of 25% elicited hepatotoxicity. The affected animals were jaundiced and had marked increase in plasma bilirubin levels and activities of alkaline phosphatase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase. The liver of intoxicated animals had focal areas of necrosis and bile duct proliferation. Elevation in plasma bilirubin concomitant with alterations in enzyme profile and histopathological lesions are consistent with liver injury and cholestasis. This is the first report of the toxicity of E. adenophorum to rats.

A triterpenoid acid, lantadene D from Lantana camara var. Aculeata

Abstract A novel triterpenoid, lantadene D, has been isolated from the leaves of the hepatotoxic plant Lantana camara var. aculeata . Its structure has been established as 22-β-isobutyroyloxy-3-oxoolean-12-en-28-oic acid.

Thin-layer chromatographic separations of lantadenes, the pentacyclic triterpenoids from lantana (Lantana camara) plant

Abstract Seven solvent systems of varying suitability are reported for the thin-layer chromatographic separation of lantadenes isolated from the heptatotoxic plant Lantana camara var. aculeata . Hexane-methanol-ethyl acetate (85:10:5) was found to be the most suitable for the separation of lantadene A, B, C, D, reduced lantadene A and reduced lantadene B. Lantadenes could be detected on thin layers of silica gel G using Liebermann-Burchard reagent, vanillin-sulphuric acid and primulin sprays.