Om P. Sharma

Microbial degradation of tannins – A current perspective

Tannins are water-soluble polyphenolic compounds having wide prevalence in plants. Hydrolysable and condensed tannins are the two major classes of tannins. These compounds have a range of effects on various organisms – from toxic effects on animals to growth inhibition of microorganisms. Some microbes are, however, resistant to tannins, and have developed various mechanisms and pathways for tannin degradation in their natural milieu. The microbial degradation of condensed tannins is, however, less than hydrolysable tannins in both aerobic and anaerobic environments. A number of microbes have also been isolated from the gastrointestinal tract of animals, which have the ability to break tannin-protein complexes and degrade tannins, especially hydrolysable tannins. Tannase, a key enzyme in the degradation of hydrolysable tannins, is present in a diverse group of microorganisms, including rumen bacteria. This enzyme is being increasingly used in a number of processes. Presently, there is a need for increased understanding of the biodegradation of condensed tannins, particularly in ruminants.

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.

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 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.

Chemical composition and antibacterial activity of essential oils of Lantana camara, Ageratum houstonianum and Eupatorium adenophorum.

Essential oils have applications in folk medicine, food preservation, and as feed additives. The essential oils of Lantana camara Linn. (Verbenaceae), Ageratum houstonianum Mill. (Asteraceae) and Eupatorium adenophorum Spreng. (Asteraceae) were analyzed by Gas chromatography-mass spectrometry (GCMS). In L. camara oil, of the total identified (83.91%) volatile constituents, five constituents [3,7,11-trimethyl-1,6,10-dodecatriene (28.86%), β-caryophyllene (12.28%), zingiberene (7.63%), γ-curcumene (7.50%) and α-humulene (3.99%)] represented the major ones. In A. houstonianum oil, among the total identified volatile constituents (94.51%), three [precocene-II (52.64%), precocene-I (22.45%) and β-caryophyllene (9.66%)] represented the major ones. In E. adenophorum oil, of the total identified volatile constituents (84.95%), six [1-napthalenol (17.50%), α-bisabolol (9.53%), bornyl acetate (8.98%), β-bisabolene (6.16%), germacrene-D (5.74%) and α- phellandrene (3.85%)] represented the major ones. The antibacterial activity expressed as Minimum Bactericidal Concentration (MBC) (μg/mL) was determined by the broth dilution method. The essential oil of E. adenophorum had antibacterial activity against Arthrobacter protophormiae, Escherichia coli, Micrococcus luteus, Rhodococcus rhodochrous, and Staphylococcus aureus with MBC values of 200, 100, 100, 12.5, and 200, respectively. The essential oil of A. houstonianum showed antibacterial activity against M. luteus and R. rhodochrous with MBC of 100 and 12.5, but not against A. protophormiae, E. coli, and S. aureus. The essential oil of L. camara showed antibacterial activity against A. protophormiae, M. luteus, R. rhodochrous and S. aureus with MBC of 50, 25, 12.5, and 200, respectively, but not against E. coli. MBC was lowest for R. rhodochrous for all the three essential oils.

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.

Potential antitumor agents from Lantana camara : Structures of flavonoid -, and phenylpropanoid glycosides

Abstract Besides the known glycosides, verbascoside and a flavone glycoside, a novel flanonol glycoside named camaraside and a new phenylpropanoid glycoside, lantanaside have been isolated from the leaves of Lantana camara and defined as 3,5-dihydroxy-4′,6-dimethoxyflavonol-7-O-glucopyranoside and 3,4-dihydroxy-,β-phenylethyl-O-α-L-rhamnopyranosyl (1→3)-4-O- cis- caffeoyl- β -D-glucopyranoside respectively by spectroscopic methods and chemical transformations.

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.

Levels of lantadenes, bioactive pentacyclic triterpenoids, in young and mature leaves of Lantana camara var. aculeata.

Levels of the lantadene pentacyclic triterpenes were quantified in young and mature leaf samples of Lantana camara var. aculeata, by HPLC. The amount of different lantadenes (mg/100 g dry wt.) in young and mature leaf samples, respectively, was: lantadene A, 491.5 +/- 6.3, 805.9 +/- 52.8; lantadene B, 347.0 +/- 3.0, 522.3 +/- 37.1; lantadene C, 191.3 +/- 10.3, 424.8 +/- 39.1; lantadene D, 49.7 +/- 5.3, 177.4 +/- 19.0; reduced lantadene A, 19.1 +/- 2.3, 28.7 +/- 4.5; reduced lantadene B, 13.0 +/- 1.3, 18.6 +/- 1.2; and 22 beta-hydroxyoleanonic acid, 82.5 +/- 11.4, 167.7 +/- 30.1.