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PubMed1975

[Isolation and characterization of main albumin fractions of seeds from sunflower (Helianthus annuus L.) and rape (Brassica napus L.)].

The main fractions of the albumins from sunflower and rapeseeds (isolated by means of precipitation with ammonium sulphate or tannin + caffeine and subsequent gel chromatography) are low-molecular, very basic proteins. Their molecular weights range from 10 000 to 16 000, and their isoelectric points (determined by isoelectric focusing and free electrophoresis) are situated at pH greater than 10.0. From the circular dichroism in the wavelength range from 200 to 240 nm it is deduced that the main fraction of the rape albumin is a well-structured protein with 40-46% alpha-helix in aqueous and salt-containing solutions. Denaturation by heating is achieved only at temperatures about 100 degrees C and pH values greater than 9. 20% alpha-helix are left after the action of 8 M urea. This conformational stability is explained by the presence of disulphide linkages in the molecule.

Albumins↗
PubMed1995

The projection structure of microsomal glutathione transferase.

Through the use of electron crystallography, it has been possible to obtain high resolution structural information regarding a mammalian protein that spans the lipid bilayer. Two-dimensional crystals of the detoxification enzyme microsomal glutathione transferase were induced by slow detergent removal from a mixture containing low amounts of phospholipid. Images of specimens stabilized in tannin were collected using electron cryomicroscopy. The projection structure at 4 A shows tightly packed trimers of the protein. Each of them contains an inner core of six parallel alpha-helices delineating a central low density region. The helical bundle is partly surrounded by elongated domains.

Animals↗
PubMed2006

Influence of salivary organic substances on the discoloration of esthetic dental materials-a review.

The objective of this article was to review the articles on the interaction of salivary organic substances with resin-based dental materials and on the interaction of these organic substances with exogenous chemical agents, which results in discoloration. Original scientific articles or reviews on the saliva, acquired pellicle, and the interaction with pellicle and chemical agents related to dental resin-based materials were reviewed. Salivary esterases can increase or decrease the internal and external discoloration. The formation of acquired pellicle on the surface of a material varies by the properties of material, and the pellicle interacts with denaturation agents, such as tannin and chlorhexidine, to form stains and also adsorbs staining substances. Therefore, for the quality and longevity of restorations, protocols for the evaluation of the influence of organic substances on the extrinsic staining of restorative materials should be included in the evaluation of aesthetic restorative materials.

Dental Materials↗
PubMed1991

Stimulation of human peripheral blood polymorphonuclear cell iodination by lignin-related substances.

Lignin is a heterogenous natural product composed of phenylpropane units and is usually associated with hemicellulose in its native state. Until now little attention has been paid to the potential therapeutic utility of lignified products. Natural lignified products are demonstrated in the present study to stimulate iodination significantly (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN). This stimulation was significantly inhibited in the presence of myeloperoxidase inhibitors. These materials were almost completely deprived of their stimulation capacity by treatment with NaCIO2, but this capacity was not affected by severe treatment with H2SO4 or trifluoroacetic acid. Similar stimulating activity by chemically defined tannin-related polyphenolic compounds was observed. Degradation products or component units of lignin, and natural antitumor polysaccharides and their chemically modified derivatives (introduced with negatively or positively charged groups) and polysialoglycoproteins had little or no activity. The results indicate the importance of a polymerized phenolic structure for the stimulation of PMN iodination. Possible physiological relevance of the stimulation of iodination by lignified substances is discussed.

Antineoplastic Agents↗
PubMedDate not supplied

Mass spectrometry in grape and wine chemistry. Part I: polyphenols.

Mass spectrometry, had and still has, a very important role for research and quality control in the viticulture and enology field, and its analytical power is relevant for structural studies on aroma and polyphenolic compounds. Polyphenols are responsible for the taste and color of wine, and confer astringency and structure to the beverage. The knowledge of the anthocyanic structure is very important to predict the aging attitude of wine, and to attempt to resolve problems about color stability. Moreover, polyphenols are the main compounds related to the benefits of wine consumption in the diet, because of their properties in the treatment of circulatory disorders such as capillary fragility, peripheral chronic venous insufficiency, and microangiopathy of the retina. Liquid Chromatography-Mass Spectrometry (LC-MS) techniques are nowadays the best analytical approach to study polyphenols in grape extracts and wine, and are the most effective tool in the study of the structure of anthocyanins. The MS/MS approach is a very powerful tool that permits anthocyanin aglycone and sugar moiety characterization. LC-MS allows the characterization of complex structures of grape polyphenols, such as procyanidins, proanthocyanidins, prodelphinidins, and tannins, and provides experimental evidence for structures that were previously only hypothesized. The matrix-assisted-laser-desorption-ionization-time-of-flight (MALDI-TOF) technique is suitable to determine the presence of molecules of higher molecular weight with high accuracy, and it has been applied with success to study procyanidin oligomers up to heptamers in the reflectron mode, and up to nonamers in the linear mode. The levels of resveratrol in wine, an important polyphenol well-known for its beneficial effects, have been determined by SPME and LC-MS, and the former approach led to the best results in terms of sensitivity.

Agriculture↗
PubMed2007

New developments in natural products-based anti-AIDS research.

This review discusses anti-HIV natural products from several compound classes, including terpenoids, coumarins, alkaloids, polyphenols, tannins, and flavonoids. Natural products can provide novel anti-AIDS chemotherapeutic leads that are structurally unique or have new mechanisms of action. The drug discovery and development process proceeds from bioactivity-directed isolation and identification of a promising lead natural product, followed by rational design-based structural modification and structure-activity relationship analyses to optimize the lead compound as a drug candidate. This process is notably exemplified by the discovery of the modified betulinic acid derivative, DSB [PA-457], which is currently in Phase II clinical trial and is the first-in-class HIV maturation inhibitor (MI).

Acquired Immunodeficiency Syndrome↗
PubMed2005

Influence of food acidulants on bioaccessibility of zinc and iron from selected food grains.

Four common acidulants in Indian dietary, i. e., citric acid, tamarind (Tamarindus indica), amchur (Mangifera indica), and kokum (Garcinia indica) were examined for a possible influence on the bioaccessibility of zinc from selected food grains. Among the four acidulants examined, amchur and citric acid generally enhanced the bioaccessibility of zinc and iron from all the food grains studied. The increase in zinc bioaccessibility produced by citric acid was around 40% in rice and chickpea, while amchur produced around 60% increase from decorticated green gram. This positive influence of acidulants on zinc bioaccessibility from food grains was seen both in the raw and cooked form. Tamarind and kokum, the other two acidulants tested, generally did not have a favourable influence on zinc and iron bioaccessibility. This lack of positive influence of these two acidulants on mineral availability could be attributable to the presence of significant amounts of tannin in them. Citric acid and amchur also generally enhanced the bioaccessibility of iron from these food grains.

Biological Availability↗
PubMedDate not supplied

Qualitative analysis and HPLC isolation and identification of procyanidins from Vicia faba.

The soluble proanthocyanidins of the coloured seed coats of Vicia faba L. were isolated and separated by solvent partition. The chemical characteristics of the proanthocyanidins were elucidated by total oxidation and partial degradation in the presence of phloroglucinol followed by HPLC analysis. The native extract of proanthocyanidins contained (+)-gallocatechin, (-)-epigallocatechin, (+)-catechin and (-)-epicatechin units. Oligomeric procyanidins were purified by chromatography on Sephadex LH-20 and the accessible compounds were isolated by RP-HPLC using a Licrospher Li 100 Column. The structures of the purified oligomeric procyanidins were elucidated using a procedure involving TLC, UV spectroscopy, ESI-MS and HPLC analysis of the products from the phloroglucinol reaction. The major condensed tannins of Vicia faba comprise six compounds identified as two A-type procyanidin dimers, the procyanidin dimers B1, B2 and B3, and a procyanidin trimer.

Biflavonoids↗
PubMed2006

Bioactivity of extracts and isolated compounds from Vitex polygama (Verbenaceae) and Siphoneugena densiflora (Myrtaceae) against Spodoptera frugiperda (Lepidoptera: Noctuidae).

The effects of crude extracts, fractions and isolated compounds from Vitex polygama Cham. and Siphoneugena densiflora Berg were evaluated on the development of Spodoptera frugiperda JE Smith, a destructive insect pest of corn and several other crops. The extracts and fractions were incorporated into an artificial diet at 1 mg g(-1) and offered to the insect during its larval stage. Length and viability of larval and pupal stages as well as pupal weight were assessed. Isolated compounds were tested through superficial contamination of the diet at 0.1 mg g(-1). Weight and viability of ten-day-old larvae were determined. Methanolic and hydroalcoholic S. densiflora extracts caused 100% larval mortality, while leaf and fruit hydroalcoholic extracts from V. polygama were the most active. Among the isolated compounds, flavonoids presented the best insecticidal results, and tannins the best larval growth inhibition.

Animals↗
PubMed2002

The kinetics of reversal of pre-sickled erythrocytes by the aqueous extract of Cajanus cajan seeds.

The aqueous methanol extract (3:1, v/v) of the seeds of Cajanus cajan was investigated for antisickling properties. The extract possessed significant antisickling activity and was found to be concentration-dependent. The kinetics of reversal of presickled erythrocyte (HbSS) cells using the extract at 0.5 mg/mL, 1.0 mg/mL, 1.5 mg/mL, 2.0 mg/mL and 2.5 mg/mL showed first-order kinetics with rate constants of 5.833 x 10(-3) min(-1), 6.143 x 10(-3) min(-1), 5.957 x 10(-3) min(-1) 6.00 x 10(-3) min(-1) and 6.046 x 10(-3) min(-1), respectively, and with an average half-life 115.6 min. Phytochemical screening of the extract revealed the presence of free amino acids, phenolic compounds, tannins, globulins and saponins. These results show that the extract has potential use in the management of painful episodes experienced by sickle cell patients.

Adolescent↗
PubMed2002

Inhibitory effect against polymerase and ribonuclease activities of HIV-reverse transcriptase of the aqueous leaf extract of Terminalia triflora.

Dichloromethane, methanol and aqueous extracts from the leaves of Terminalia triflora were investigated for their inhibitory effect on polymerase and ribonuclease activities of HIV reverse transcriptase.The most potent activity was found in the aqueous extract, which inhibited both polymerase and ribonuclease activities of the enzyme with an IC50 of 1.6 micro g/mL and 1.8 micro g/mL respectively. The antiinfective activity of the extract was demonstrated in HLT4LacZ-IIIB cell culture with an IC50 of 1.0 micro g/mL. The extract was submitted to a purification process by extractive and chromatographic methods. The activity remained in the hydrophillic fraction. Tannins present in this active purified fraction, as determined by TLC and HPLC methods, could account for the anti HIV-RT activity found in the aqueous extract.

Anti-HIV Agents↗
PubMed2003

Endothelium-dependent contraction of rat thoracic aorta induced by gallic acid.

The vascular effect of a component of hydrolysable tannins, gallic acid, was examined in isolated rat thoracic aorta. Gallic acid exerted a contractile effect on the phenylephrine- or prostaglandin F(2/alpha)-precontracted endothelium-intact arteries. In endothelium-denuded arteries, the contractile response to-gallic acid was absent. Pretreatment with N(G)-nitro-L-arginine methyl ester (30 microM) abolished the gallic acid-induced contraction. Pretreatment with indomethacin (10 microM) or BQ610 (100 nM) had no observed effect. Pretreatment with gallic acid (1-10 microM) significantly attenuated the relaxation induced by acetylcholine, and that with 10 microM gallic acid also reduced the potency of sodium nitroprusside in the relaxation, without a reduction in efficacy, in endothelium-denuded arteries. These findings indicate that gallic acid induced endothelium-dependent contraction and strongly inhibited the endothelium-dependent relaxation rather than the endothelium-independent relaxation, probably through inhibition of endothelial nitric oxide (NO) production. Since NO plays an important role in vasodilative regulation and inflammatory disorders, these findings may also indicate that gallic acid interferes with the inflammatory responses.

Acetylcholine↗
PubMed2003

Anti-sickling potential of a Nigerian herbal formula (ajawaron HF) and the major plant component (Cissus populnea L. CPK).

The anti-sickling activities of the extracts of the roots of a plant Cissus populnea L. (CPK) (a major constituent of a herbal formula Ajawaron HF used in the management of sickle cell disease in south-west Nigeria) has been examined. Phytochemical examination of the extract showed the presence of anthraquinone derivatives, steroidal glycosides and cardiac glycosides. Alkaloids and tannins were completely absent in the CPK extracts. Evaluation of the anti-sickling activity involved the use of both positive (p-hydroxybenzoic acid, 5 microg/mL) and negative control (normal saline) for each set of experiments aimed at the inhibition of sodium metabisulphite-induced sickling of the HbSS red blood cells obtained from confirmed non-crisis state sickle-cell patients. The chloroform and water partitioned fractions of the cold methanol extracts of CPK exhibited a 62.2% and 52.9% inhibition of sickling, respectively, at 180 min. The herbal formula (HF) aqueous extract showed the highest anti-sickling activity on a weight by weight basis of all the extracts and fractions tested, giving a 71.4% inhibition of sickling at the end of 180 min incubation when compared with the normal saline control. The maximum percentage inhibition of sickling exhibited by the p-hydroxybenzoic acid control was 46.0% at 90 min incubation.

Anemia, Sickle Cell↗
PubMed2004

The antidiarrhoeal activity of Alchornea cordifolia leaf extract.

Diarrhoea is a public health problem in developing countries. It is therefore important and useful to identify plants with antidiarrhoeal activity. Alchornea cordifolia is quoted by many traditional healers as a plant with this activity. The antidiarrhoeal activity of its leaf extract was investigated against castor oil induced diarrhoea in mice, using morphine as the standard reference drug. A significant (p < 0.01) dose related (100 mg/kg, 200 mg/kg, 400 mg/kg, 800 mg/kg) antidiarrhoeal activity of A. cordifolia leaf ethanol extract was observed with 800 mg/kg extract being the most effective. It delayed mouse intestinal transit accelerated by castor oil, inhibited the production of diarrhoeal faeces and modified the fluid and electrolyte transport across the colonic mucosa when administered intraluminally. Phytochemical screening revealed the presence of tannins and flavonoids which may account for the increased colonic water and electrolyte reabsorption, a mechanism suggested for the antidiarrhoeal activity of A. cordifolia.

Animals↗
PubMed2005

Evaluation of some medicinal plant extracts for antidiarrhoeal activity.

The antidiarrhoeal effect of seven plant extracts namely: the aerial parts of Euphorbia paralias L. (EP), Bidens bipinnata L. (BB), Cynachum acutum L. (CyAc), Diplotaxis acris (Forssk.) Boiss (DA), Convolvulus fatmensis (CF) and Schouwia thebaica Webb (ST) and the leaves of Plantago major L. (PM), was evaluated on castor oil-induced diarrhoea, gastrointestinal movement in rats (charcoal meal) and on the motility of duodenum isolated from freshly slaughtered rabbits. A significant antidiarrhoeal effect of the tested plant extracts against castor oil-induced diarrhoea in rats was achieved by 200 and 400 mg/kg. The tested plant extracts decreased the gastrointestinal movement as indicated by the significantly (p<0.05 to 0.001) decreased distance travelled by the charcoal meal. The large dose of the tested plant extracts was slightly more effective than the small one. The antidiarrhoeal effect was confirmed by the reported dose dependent inhibition of the motility of duodenum isolated from freshly slaughtered rabbits. The EP and PM methanol extract produced a transient stimulation followed by inhibition in doses of less than 0.05 and 1.6 mg/kg, respectively. Higher concentrations caused rapid muscle relaxation. Tannins, flavonoids, unsaturated sterols/triterpenes, carbohydrates, lactones and proteins/amino acids were reported as major active constituents of the tested plants.

Administration, Oral↗
PubMed2006

Antispasmodic effect of Acorus calamus Linn. is mediated through calcium channel blockade.

Acorus calamus Linn. (Araceae) is a native of Central Asia and Eastern Europe and has widespread use in the traditional system of medicine for gastrointestinal disorders such as colic pain and diarrhoea. This study was aimed at providing a possible pharmacological basis to the use of this plant as an antispasmodic and antidiarrhoeal. In the isolated rabbit jejunum preparation the crude extract (Ac.Cr), which tested positive for the presence of alkaloid, saponins and tannins, caused inhibition of spontaneous and high K(+) (80 mm)-induced contractions, with respective EC(50) values of 0.42 +/- 0.06 and 0.13 +/- 0.04 mg/mL (mean +/- SEM; n = 6-8), thus showing spasmolytic activity, mediated possibly through calcium channel blockade (CCB). The CCB activity was confirmed when pre-treatment of the tissue with Ac.Cr (0.3-1.0 mg/mL) caused a rightward shift in the Ca(++) dose-response curves similar to that caused by verapamil, a standard calcium channel blocker. Activity-directed fractionation revealed that the CCB activity was concentrated in the n-hexane fraction while the ethylacetate fraction was less potent. These results suggest that the spasmolytic effect of the plant extract is mediated through the presence of CCB-like constituent(s) which is concentrated in the n-hexane fraction and this study provides a strong mechanistic base for its traditional use in gastrointestinal disorders such as colic pain and diarrhoea.

Acorus↗
PubMed2007

Screening of some medicinal plants from cameroon for beta-lactamase inhibitory activity.

In efforts to find new bioactive beta-lactamase inhibitors, this study investigated 16 Cameroonian plants belonging to 10 families which were evaluated for anti-beta-lactamase activity. The investigation showed that extracts 2, 6, 3 and 5 of the 16 plants investigated presented interesting in vitro beta-lactamase inhibition (over 90%), respectively, of the beta-lactamases TEM-1, OXA-10, IMP-1 and P99. These extracts were from Mammea africana (all beta-lactamases), Garcinia lucida, G. kola (OXA-10, IMP-1 and P99), Bridelia micrantha (OXA-10, P99), Ochna afzelii (OXA-10, P99), Prunus africana (IMP-1) and Adenia lobata (TEM-1). After elimination of tannins (according to the European Pharmacopoeia) the extracts from B. micrantha, G. lucida and M. africana were tested further for their anti-beta-lactamase activity. The extracts from B. micrantha and G. lucida exhibited potent inhibitory activity, respectively, of beta-lactamase OXA-10 (IC(50) = 0.02 mg/mL) and P99 (IC(50) = 0.01 mg/mL). The anti-beta-lactamase activity of M. africana extract was weak. The isolation and the structural elucidation of the active constituents of G. lucida and B. micrantha will provide useful leads in the development of beta-lactamase inhibitors.

Anti-Bacterial Agents↗
PubMed2001

Antidiarrhoeal activity of the aqueous extract of Terminalia avicennoides roots.

The antidiarrhoeal effects of the aqueous root extract of Terminalia avicennoides were evaluated in rodents. Studies were carried out on the isolated rabbit jejunum, gastrointestinal motility in vivo and on castor oil-induced diarrhoea in mice. The results revealed that the extract exhibited a concentration-dependent inhibition of the spontaneous pendular movement of the isolated rabbit jejunum and attenuated acetylcholine induced contractions. The extract (100, 200 and 400 mg/kg) also caused a dose-dependent decrease of gastrointestinal transit and markedly protected mice against castor oil-induced diarrhoea. The intraperitoneal LD(50) of the extract was found to be 871.4-917.4 mg/kg in mice (95% confidence). A preliminary phytochemical screening of the aqueous extract of T. avicennoides roots revealed the presence of tannins, saponins and flavonoids. The results obtained showed that the water extract of T. avicennoides roots may contain some biologically active principles that may be active against diarrhoea and this may be the basis for its use traditionally for gastrointestinal disorders.

Animals↗