Showing papers in "Basic life sciences in 1992"

Plant polyphenols : synthesis, properties, significance

Abstract: Introduction: Reflections on the Chemistry and Affinities of the Major Commercial Tannins in the Context of their Industrial Use D.G. Roux. Biogenesis and Synthesis: Enzymes in the Biosynthesis of Hydrolyzable Tannins G.G. Gross. Biosynthesis of Flavenoids G. Hrazdina. Chemical Properties: Gallic Acid at its Metabolites E. Haslam. Chinquapinic Acid M. Adamczeski, et al. Biological Significance: Plant Phenolics as Expressions of Biological Diversity O.R. Gottlieb. Pharmacologically Active Tannins Isolated from Medicinal Plants T. Okuda, et al. Commercial Significance: Flavor, Color, and Stability in Fruit Products A.G.H. Lea. Tannins and the Qualities of Wines V.L. Singleton. Conclusions: Concluding Remarks P.E. Laks, R.W. Hemmingway. 54 additional articles. Index.

Antinutritional effects of condensed and hydrolyzable tannins.

Abstract: Despite major structural differences, hydrolyzable and condensed tannins often produce similar antinutritional effects. The most common effects are diminished weight gains and lowered efficiency of nutrient utilization. The major biochemical basis for these effects appears not to be inhibition of dietary protein digestion but rather a systemic inhibition of the metabolism of digested and absorbed nutrients, particularly protein. In the case of condensed tannins, this inhibition is probably not due to polymeric tannin molecules, which are not absorbed from the digestive tract, but to associated lower MW poly phenols, which are readily absorbed.

Pharmacologically active tannins isolated from medicinal plants.

Abstract: Starting with the isolation of a crystalline tannin (geraniin) of mild property from a popular herb medicine (Geranii herba), various polyphe-nolic compounds including those belonging to new classes of tannins (oligomeric hydrolyzable tannins, complex tannins, and other metabolites and condensates) have been isolated from various medicinal plants. Noticeable biological and pharmacological activities (inhibition of carcinogenesis, host-mediated antitumor activity, antiviral activity, and inhibition of active oxygen, such as inhibition of lipid peroxidation and lipoxygenase, xanthine oxidase, and monoamine oxidase) have been found for several of these polyphenolic compounds.

Condensed Tannins in Some Forage Legumes: Their Role in the Prevention of Ruminant Pasture Bloat

Abstract: for the past 20 years, the focus in our laboratory has been on finding the causes of ruminant pasture bloat and eventually breeding a bloatsafe alfalfa (Medicago saliva L.); i.e., with bloat potential reduced to the economic threshold. In the mid-seventies, the mechanisms of bloat were explored and found to be more physical than chemical. Characteristic of all bloating legumes after ingestion was a very rapid initial rate of ingestion by rumen microbes. Through the study of bloating and non-bloating legumes, factors were elucidated in the plant that would slow this process. One of these factors was the presence of condensed tannins in the herbage. Some of the non-bloating legumes contained these secondary metabolites, but no condensed tannins were found in any of the bloating legumes. Therefore, species containing an appreciable amount of condensed tannins in their leaves and stems are considered to be non-bloating. Conventional breeding methods have not been successful in producing an alfalfa with condensed tannins in its herbage. New approaches using tissue culture techniques are being attempted, but genetic engineering has the greatest potential for success.

Antitumor-Promoting Activities of Tannic Acid, Ellagic Acid, and Several Gallic Acid Derivatives in Mouse Skin

Abstract: Naturally occurring plant phenols with antimutagenic and anticarcinogenic activities were tested for their abilities to inhibit the biochemical and biological effects of the potent tumor promoter 12- O-tetradecanoylphorbol-13-acetate (TPA) in mouse epidermis in vivo. When applied topically to mouse skin, tannic acid (TA), ellagic acid, and several gallic acid derivatives all inhibit TPA-induced ornithine decarboxylase activity, hydroperoxide production, and DNA synthesis, three biochemical markers of skin tumor promotion. Moreover, in the two-step initiation-promotion protocol, the same phenolic compounds also inhibit the incidence and yield of skin tumors promoted by TPA. TA is the most effective of these treatments. Since they are already known to inhibit tumor initiation, the plant phenols protecting against skin tumor promotion by TPA may be universal inhibitors of multistage carcinogenesis. TA and other polyphenols, therefore, might be valuable in cancer therapy and/or prevention.

Widespread tannin intake via stimulants and masticatories, especially guarana, kola nut, betel vine, and accessories.

Abstract: Tannins are increasingly recognized as dietary carcinogens and as anti-nutrients interfering with the system’s full use of protein. Nevertheless, certain tannin-rich beverages, masticatories, and folk remedies, long utilized in African, Asiatic, Pacific, and Latin American countries, are now appearing in North American sundry shops and grocery stores. These include guarane (Paullinia cupana HBK.) from Brazil, kola nut (Colanitida Schott &, Endl. and C. acuminata Schott &, Endl.) from West Africa, and betel nut (Areca catechu L.) from Malaya. The betel nut, or arecanut, has long been associated with oral and esophageal cancer because of its tannin content and the tannin contributed by the highly astringent cutch from Acacia catechu L. and Uncaria gambir Roxb. and the aromatic, astringent ‘pan’ (leaves of Piper betle L.) chewed with it. In addition to the constant recreational/social ingestion of these plant materials, they are much consumed as aphrodisiacs and medications. Guarane and kola nut enjoy great popularity in their native lands because they are also rich in caffeine, which serves as a stimulant. Research and popular education on the deleterious effects of excessive tannin intake could do much to reduce the heavy burden of early mortality and health care, especially in developing countries.

Polyphenols from Bulgarian Medicinal Plants with Anti-Infectious Activity

Abstract: Three Bulgarian medicinal plants—Geranium macrorrhizum L. and G. sanguineum L. (Geraniaceae), and Epilobium hirsutum L. (Onagraceae) were analyzed phytochemically. Different polyphenols like flavonoids and tannins have been found to be principal constituents of the plants. A series of water or alcohol extracts was obtained, and their antiinfectious activity was tested. A significant inhibitory effect of wateralcohol extract and of four fractions from the polyphenolic mixture of E. hirsutum on the reproduction of influenza viruses in vitro, in ovo, and in vivo was established. Four extracts from G. macrorrhizum and three extracts from G. sanguineum were studied for in vitro inhibition of the growth of some Gram-negative bacteria (Klebsiella pneumoniae, Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa), Gram-positive bacterium (Staphylococcus aureus), and fungus (Candida albicans). Some geranium extracts caused a strong increase of the survival rate in an infection with K. pneumoniae in mice. Augmentation of the nonspecific host resistance in relation to the influence of the extracts on the classical complement activation pathway was also studied.

Plant polyphenolic complex inhibits the reproduction of influenza and herpes simplex viruses.

Abstract: A polyphenolic complex (PC), isolated from the Bulgarian medicinal plant Germanium sanguineum L., inhibited the reproduction of influenza virus types A and B in vitro and in ovo. It protected white mice in an experimental lethal influenza infection. When influenza viruses were treated with a high dose (1 mg/mL), their hemagglutination, neuraminidase and infections activities were reduced completely. It was assumed that the PC-specific inhibitory effect on influenza virus reproduction in tissue cultures (50 micrograms/mL) was mediated by partial inactivation of viral glycoproteins which prevented the initial stages of reproduction. The PC also affected the intracellular stages of viral replication. The effect was dependent on the mode of application, the viral strain, and the biological test system. The PC also inhibited the reproduction of herpes simplex virus in vitro. Infectious titers were reduced and newly synthesized virion with damaged protein envelopes were observed by electron microscopy.

The use of Tannin from Chestnut (Castanea Vesca)

Abstract: After mimosa and quebracho extracts, chestnut extract is the third most important vegetable tannin used for leather production. It is produced only in Europe on the northern side of the Mediterranean sea. The extract is prepared by hot water extraction of the bark and timber, followed by spray-drying of the solution. Analysis shows that there are insignificant variations in extract quality between batches, so the extract can be used with modern automated leather production systems. The extract contains approximately 75 percent active tanning substances. The primary component is castalagin, along with smaller amounts of vescalagin, castalin, and vescalin. A castalagin-based pharmaceutical product is currently in use for prevention and treatment of diarrhea in pigs and cattle that is caused by changes in diet. The beneficial effect is due to prevention of water losses through mucous membranes. The castalagin may also form chelates with iron, which influences the reabsorption of the metal in the animal digestive tract.

Prosopis cineraria leaf tannins: their inhibitory effect upon ruminal cellulase and the recovery of inhibition by polyethylene glycol-4000.

Abstract: The condensed tannins from the Prosopis cineraria leaves were purified and fractionated in two groups (K av 0.018 and 0.74) on a column of Sephadex LH-20 (2.5 × 27 cm) using 70 percent aqueous acetone as the eluent. The K av for catechin was 0.946. Upon acid hydrolysis, both the condensed tannin fractions yielded three pigments including cyanidin-chloride, which was separated by column chromatography using polyvinylpyrrolidone absorbent and was identified by paper chromatography (Rf Forestal 0.476) and absorption maxima (λmax 535 nm) in 1 percent HC1 in methanol. The condensed tannin fraction Kav 0.74 at 0.01 percent and 0.02 percent in incubations with butanol-acetone powder of rumen liquor, inhibited cellulase activity by 65.9 ± 2.1 and 78.99 ± 4.5 percent, respectively. Inclusion of 0.5 percent of polyethylene glycol -4000 in the incubation mixture, reduced the inhibition to 41 and 46 percent, respectively.

Study on the composition and structure of commercial chestnut tanning agent.

Abstract: Current research has focused on the composition of commercially used chestnut tannin extracts so as to provide a quantitative basis for studies of reactions, structure-property relationships, and applications of chestnut tannin extract. Two chestnut tannins, vescalagin and castalagin, have been isolated using chromatography on Sephadex LH-20 and cellulose. The structures of these compounds have been established by means of nuclear magnetic resonance and fast atom bombardment mass spectroscopy. Some other components have been found and analyzed by chromatography and spectroscopy, but their structures have not as yet been completely defined. These structural features, together with quantitative results for each component, provide a better understanding of the mode of action of complex commercial chestnut tannin extracts.

Plants of the Olympic Coastal Forests: ancient knowledge of materials and medicines and future heritage.

Abstract: The indigenous people of the west coast of Washington State’s Olympic Peninsula have used a wide variety of forest plants for centuries to make materials and medicines. The late David Forlines shared at least eight generations of the knowledge of uses of these plants for materials and medicines with us in hopes that this information might be used ‘to help science catch up with the old people.’ Dyes, paints, and adhesives were some of the materials made. The medicines were often administered as teas, but in some cases, fresh plant material was required. Some parallels were found to European and Chinese uses of similar species. Plants from the family Rosaceae had the greatest number of medicinal uses, but several other plant families known to contain polyphenols were also encountered. The role of polyphenols in the use of these plants is difficult to estimate because in many cases the plants have not been studied chemically. A preliminary screening indicated that many of the plants were rich in procyanidins and associated compounds.

Cotton condensed tannin: a potent modulator of alveolar macrophage host-defense function.

Abstract: Alveolar macrophages are the resident airway cells primarily responsible for the protection of the lungs against inhaled toxins and other biologically active material. A number of functional capabilities constitute their host-defense function. They can phagocytize and inactivate foreign material by production of reactive oxygen intermediates or the action of hydrolytic enzymes. In the absence of phagocytosis, macrophages can secrete reactive oxygen intermediates or enzymes that inactivate extracellular biolgically active material. They also can secrete metabolites of arachidonic acid and other cytokines that contribute to the inflammatory response of the lungs. Macrophages also secrete a variety of peptide and lipid chemotactic factors that lead to the recruitment of other inflammatory cells into the airways. The condensed tannins, which constitute a significant percentage of the water soluble compounds present in respirable cotton mill dust, dramatically alter the host-defense function of alveolar macrophages in vitro. Tannin inhibits both phagocytosis and production of reactive oxidants in a dose-dependent manner with EC50’s of 16 μg/mL and 3 μg/mL, respectively. This inhibition dramatically decreases the ability of resident alveolar macrophages to clear and detoxify potentially harmful inhaled particles. However, at similar concentrations, tannin stimulates the dose-dependent secretion (EC50 = 15 μg/mL) of a low molecular weight lipid neutrophil chemotactic factor that could result in an inflammatory reaction with the recruitment of neutrophils into the lungs.At slightly higher concentrations, tannin promotes the dose-dependent release of arachidonic acid from the macrophage membranes (EC50 = 65 μg/mL), which could also contribute to the local inflammatory reaction. Finally, tannin also causes secretion of the cytokine, interleukin-1, from the monocyte precursors of macrophages with an EC50 of 32 μg/mL. Interleukin-1 has been implicated as one of the causative agents in the development of fever.