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At least 1,423 records · Page 79Linked to original sources
PubMed2003

[Studies of poly(vinyl alcohol)/hydroxylapatite hydrogels compounds for cartilage implantation].

The structures and properties of polyvinyl alcohol (PVA)/hydroxylapatite(HA) composites were investigated. The components and processing conditions were studied for preparation of optimum compound hydrogels with good lubricating feature and high bioactivity. The properties, such as stretch strength, compress strength, friction, compress stress relaxation of various compound hydrogels were compared. The micro-morphology of PVA hydrogels and PVA/HA hydrogels were investigated by use of SEM. It was found that the addition of HA could improve the lubricating feature and mechanical strength of hydrogels, and its compress stress relaxation properties were closer to those of natural cartilages.

Biocompatible Materials↗
PubMed2000

Inhibition of endothelial cell activation by nitric oxide donors.

Because nitric oxide (NO) inhibits the expression of endothelial leukocyte adhesion molecules, NO-generating compounds have major therapeutic potential for use outside their classical indications. We report on the in vitro potential antiatherogenicity of two novel cysteine-containing NO donors, SP/W 3672, a fast spontaneous NO releaser, and its prodrug SP/W 5186, which liberates NO after bioactivation. The ability of these two compounds to inhibit monocyte adhesion and surface expression of endothelial adhesion molecules was evaluated and compared with that of other NO donors. SP/W 5186 and SP/W 3672 inhibited the adhesion of U937 monocytes to cultured human endothelial cells more potently than S-nitrosoglutathione (GSNO) or spermine NONOate, whereas nitroglycerin and isosorbide dinitrate were ineffective at comparable concentrations. A similar rank order of potency was found for the inhibition of expression of the adhesion molecules vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and E-selectin as well as for major histocompatibility complex class II antigen expression. Estimated IC(50) values for vascular cell adhesion molecule-1 were >400 microM for SP/W 4744 (control for SP/W 3672 lacking the cysteine moiety), 200 microM for GSNO and spermine NONOate, 80 microM for SP/W 3672, and 50 microM for SP/W 5186. Moreover, SP/W 5186 inhibited VCAM-1 mRNA levels more potently than GSNO. This effect was likely to be transcriptional because mRNA degradation was not affected. In conclusion, SP/W 3672 and SP/W 5186 are novel potent inhibitors of endothelial activation, and this effect appears to relate to their ability to liberate NO for prolonged periods of time, either spontaneously or after conversion to active hydrolytic products.

Cell Adhesion↗
PubMed1997

A selective inhibitor of arachidonate 5-lipoxygenase scavenging peroxide activator.

A novel compound termed YT-18 (2,3-dihydro-2,4,6,7-tetramethyl-2-[(4-phenyl-1-piperazinyl) methyl]-5-benzofuranamine) selectively inhibited 5-lipoxygenases of porcine leukocytes (IC50 value, 7.5 microM), human leukocytes (1.5 microM), and rat basophilic leukemia cells (14 microM), which are responsible for bioactive leukotriene synthesis. In contrast, the compound up to 1 mM had almost no effect on 12-lipoxygenases of leukocytes and platelets, 15-lipoxygenase, and cyclooxygenases-1 and -2. YT-18 also inhibited the leukotriene synthesis in intact rat basophilic leukemia cells. In the 5-lipoxygenase reaction, YT-18 caused a lag phase, thereby delaying the start of the reaction. The lag was abolished by the addition of 13-hydroperoxy-linoleic acid in a dose-dependent manner, and most (but not all) of the reduced 5-lipoxygenase activity was recovered.

Animals↗
PubMed2001

Analysis of the EPHX1 113 polymorphism and GSTM1 homozygous null polymorphism and oral clefting associated with maternal smoking.

Maternal cigarette smoking during the first trimester of pregnancy is associated with an increased risk of having a child with an oral cleft. Compounds present in cigarette smoke undergo bioactivation and/or detoxication. Phase I of this process results in the formation of reactive epoxides, which can form DNA adducts initiating and promoting mutagenesis, carcinogenesis, or teratogenesis. Microsomal epoxide hydrolase (mEH; gene symbol EPHX1) catalyzes hydrolysis of epoxides. Phase II involves attachment of a moiety (e.g., glutathione) to the compound mediated by a variety of enzymes, including glutathione S-transferase, generally resulting in a decreased reactivity. Recent studies suggest an association between the EPHX1 codon 113 polymorphism or homozygous null GSTM1 allele and the risk of carcinogenesis, emphysema, phenytoin-associated oral clefting, and the risk of spontaneous abortion. This study explores the association between EPHX1 codon 113 and homozygous null GSTM1 genotypes and oral clefting among infants whose mothers smoked during pregnancy. Case infants were diagnosed with isolated cleft lip with or without cleft palate (CL/P). EPHX1 codon 113 allelotyping was performed on 195 samples (85 cases, 110 controls) by PCR/RFLP analysis. 130 samples (79 cases, 51 controls) were tested for the GSTM1 homozygous null genotype using PCR. Using the odds ratio as a measure of association, we did not observe elevated risks of CL/P associated with either allelic comparison. This suggests that when mothers smoke periconceptionally, their infants having these alleles at either (or both) loci were not at substantially increased risk for CL/P compared to infants with the wild-type alleles.

Alleles↗
PubMed2005

Molecular mechanisms of toxicity of important food-borne phytotoxins.

At present, there is an increasing interest for plant ingredients and their use in drugs, for teas, or in food supplements. The present review describes the nature and mechanism of action of the phytochemicals presently receiving increased attention in the field of food toxicology. This relates to compounds including aristolochic acids, pyrrolizidine alkaloids, beta-carotene, coumarin, the alkenylbenzenes safrole, methyleugenol and estragole, ephedrine alkaloids and synephrine, kavalactones, anisatin, St. John's wort ingredients, cyanogenic glycosides, solanine and chaconine, thujone, and glycyrrhizinic acid. It can be concluded that several of these phytotoxins cause concern, because of their bioactivation to reactive alkylating intermediates that are able to react with cellular macromolecules causing cellular toxicity, and, upon their reaction with DNA, genotoxicity resulting in tumors. Another group of the phytotoxins presented is active without the requirement for bioactivation and, in most cases, these compounds appear to act as neurotoxins interacting with one of the neurotransmitter systems. Altogether, the examples presented illustrate that natural does not equal safe and that in modern society adverse health effects, upon either acute or chronic exposure to phytochemicals, can occur as a result of use of plant- or herb-based foods, teas, or other extracts.

Alkaloids↗
PubMed2005

Periplocoside E, an effective compound from Periploca sepium Bge, inhibited T cell activation in vitro and in vivo.

Periploca sepium Bge, a traditional Chinese herb medicine, is used for treating rheumatoid arthritis in China. Followed the bioactivity-guided isolation, the most potent immunosuppressive compound, periplocoside E (PSE), a pregnane glycoside, had been identified from P. sepium Bge. We investigated the immunosuppressive effects of PSE in vitro and in vivo. The results showed that PSE in a dose-dependent manner significantly inhibited the proliferation of splenocytes induced by concanavalin A and mixed lymphocyte culture reaction at no cytotoxic concentrations (<5 microM). Administration of PSE suppressed a delayed-type hypersensitivity reaction, and ovalbumin (OVA) induced antigen-specific immune responses in mice. In vivo treatment with PSE dose dependently suppressed OVA-induced proliferation and cytokine [interleukin (IL)-2 and interferon (IFN)-gamma] production from splenocytes in vitro. Purified T cells from OVA-immunized mice with PSE treatment showed its low ability for activation by OVA plus normal antigen presenting cell stimulation again in vitro. Further studies showed PSE dose dependently inhibited anti-CD3-induced primary T cell proliferation, activation for IL-2Ralpha (CD25) expression, and cytokine (IFN-gamma and IL-2) production also at the transcriptional level. PSE was highly specific and significantly inhibited the activation of extracellular signal-regulated kinase and Jun N-terminal kinase, whereas activation of p38 was not affected in T cells stimulated with anti-CD3. These results demonstrated that PSE is an immunosuppressive compound in P. sepium Bge, which directly inhibits T cell activation in vitro and in vivo. This study provided evidence to understand the therapeutic effects of P. sepium Bge and indicated that this herb is appropriate for treatment of T cell-mediated disorders, such as autoimmune diseases.

Animals↗
PubMed2004

Antioxidant phenolic compounds from rhizomes of Polygonum paleaceum.

Polygonum paleaceum Wall. ex Hook. f. is a small herb in Polygonaceae family. In southwest of China, the rhizomes of this plant were used as folk drug for the treatment of chronic gastritis, duodenal ulcers, dysentery, wound, pain, hemorrhage and irregular menstruation. The crude aqueous acetone extract exhibited high antioxidant activity (SC(50) = 16.72 micro/ml) in 1,1-diphenyl-2-picryldydrazyl (DPPH) radical-scavenging assay. With bioactivity-guided fractionations, 14 antioxidant phenolic compounds 1-14 were obtained from the air-dried rhizomes of this plant. Of them, compound 1, a new phenol named paleaceolactoside, was determined to be 3,5-dihydroxyl hexanoic acid 1,5-lactone 3-(6'-o-galloyl)-o-beta-D-glucopyranoside by detailed spectroscopic analysis. The radical-scavenging activity of all the isolated compounds was also described.

Antioxidants↗
PubMed2003

Opioid receptor ligands derived from food proteins.

During the last two decades a variety of food protein fragments has been demonstrated to elicit biological effects in various in vitro or in vivo test systems. A considerable part of these bioactive peptides are opioid receptor ligands, which may be regarded as exogenous supplements to the endogenous opioidergic systems of the human organism. Most of these food-derived opioid receptor ligands are fragments of the milk proteins alpha-, beta- or kappa-casein, alpha-lactalbumin, beta-lactoglobulin or lactotransferrin; however, also wheat gluten, rice albumin, bovine serum albumin or hemoglobin, i.e. possible constituents of meat, and even a protein from spinach could be demonstrated to contain fragments behaving like opioid receptor ligands. Practically all of these compounds display opioid agonist activity; only very few of them behave like opioid antagonists. Bioactive food protein derivatives have been termed " food hormones", which implies that these compounds display their bioactivities when released from food constituents, i.e. from their precursor molecules due to the action of gastrointestinal enzymes. The critical point in case of food protein-derived opioid receptor ligands is that only a minority of their bioactive effects demonstrated as yet has been observed upon oral or intragastric administration of these peptides or their precursor proteins and that most of these studies have been performed in animals. Thus, in terms of "evidence-based dietary supplementation" more studies are needed to prove effects of food protein-derived opioid receptor ligands or their precursors after oral administration in humans and, moreover, to prove a benefit for the consumer's organism.

Animals↗
PubMedDate not supplied

Synthesis of N-(4'-pyridoxyl)sphingosine and its uptake and metabolism by isolated cells.

N-(4'-pyridoxyl)sphingosine was synthesized and characterized as a stable compound for specialized delivery of a bioactive lipid. It was found to be facilely taken up by hepatocytes although by a mechanism more typical for lipids than the one used by natural vitamin B6. Some of the N-(4'-pyridoxyl)sphingosine was metabolically acted upon inside the cell to release pyridoxal 5'-phosphate and sphingosine, but formation of pyridoxal 5'-phosphate from the synthetic compound was poor compared with natural vitamin forms of B6, which may partly be due to entrapment within cell membranes and to constraints at the level of cytosolic pyridoxal kinase which is responsible for phosphorylation of the vitamin. Unlike the parent long-chain base, the B6 conjugate was not particularly cytotoxic. Furthermore, the compound was neither an activator nor inhibitor of the respiratory burst of human neutrophils. These findings identify N-(4'-pyridoxyl)sphingosine as an interesting tool for studies of the cellular transport, metabolism, and functions of both vitamin B6 and sphingosine.

Animals↗
PubMedDate not supplied

[biological activity of phosphorus analogs of amino acids].

Data available in literature on biological activity of the phosphorus analogues of amino acids are summarized. The most typical kinds of bioactivity of aminophosphonic, aminophosphinic and aminophosphonous acids are characterized. These compounds, both natural and synthetic, are shown to possess a wide spectrum of bioactivity and may be estimated as potential bioregulators.

Amino Acids↗
PubMedDate not supplied

Glutathione-dependent toxicity.

1. Recent studies show that glutathione conjugate formation is an important bioactivation mechanism for several groups of compounds with implications for organ-selective toxicity and carcinogenicity. 2. Vicinal dihaloalkanes, such as 1,2-dihaloethanes, yield S-(2-haloalkyl)glutathione conjugates that give rise to highly electrophilic episulphonium ions, which are involved in the cytotoxicity and mutagenicity of 1,2-dihaloethanes. 3. Nephrotoxic haloalkenes are metabolized to S-(haloalkenyl)- or S-(haloalkyl)-glutathione conjugates which, after metabolism to the corresponding cysteine conjugates, are bioactivated by renal cysteine conjugate beta-lyase to yield cytotoxic or mutagenic metabolites. 4. Finally, hepatic glutathione conjugate formation with hydroquinones and aminophenols yields conjugates that are directed to gamma-glutamyltransferase-rich tissues, such as the kidney, where they undergo alkylation or redox cycling reactions, or both, that cause organ-selective damage.

Aminophenols↗
PubMed2003

QSAR and QSPR study of derivatives 4-arylaminocoumarin.

Coumarin and its derivatives are reactive compounds, suitable for many syntheses. They are used as anticoagulants, antibacterial, animistic compounds. The interest in coumarins has increased because it was found that they reduce the HIV virus activity. The synthesis of 4-arylaminocoumarin derivatives from 4-hydroxycoumarin, has been carried out, and their antimycotic effects were tested. In the QSAR (quantitative structure-activity relationship) QSPR (quantitative structure-property-activity relationship) study we have used physicochemical properties and topological indices (Balaban index J(G), Wiener index W(G), information-theoretical index I(G), and valence connectivity index (G), to predict bioactivity of the newly synthesized coumarin compounds. By using methods of molecular modelling, the relationships between structure, properties and activity of coumarin compounds have been investigated. The best QSPR models were obtained using valence connectivity index or combination indices. According Rekker's method the best correlation of calculated values log P, has been obtained with the model based on the inhibition zone (I) 4-arylaminocoumarin derivatives expressed in mm. The results obtained in this study enable further synthesis of new coumarin derivatives and predict their biological activity and properties.

Journal Article↗
PubMed2000

Vibrational spectroscopic characterization of new calcium phosphate bioactive coatings.

In this work calcium phosphate (CaP) compounds with different PO(3-)(4)/HPO(2-)(4) R molar ratios in the 0.65-149 range were synthesized. In fact, all these CaPs contain different amounts of HPO(2-)(4) and PO(3-)(4) ions as well as the amorphous precursors (tricalcium phosphate and octacalcium phosphate) of hydroxyapatite deposition, which was shown by in vitro and in vivo measurements. Spectroscopical IR and Raman results showed the presence of bands whose intensity ratio can be related to the molar ratio R; in particular, the Raman I(962)/I(987) and the IR I(1035)/I(1125) intensity ratios were characterized as markers of the molar ratio. For these CaP compounds a nucleation model, which was based on the ability of HPO(2-)(4) ions to form strong H bonds with PO(3-)(4) ions, was proposed.

Calcium Phosphates↗
PubMed1993

Effects of nitric oxide-containing compounds on increases in cytosolic ionized Ca2+ and on aggregation of human platelets.

The present study was undertaken to determine the modulatory effects of nitric oxide (NO)-releasing compounds on increases in cytosolic ionized calcium ([Ca2+]i) and on aggregation of gel-filtered human platelets induced via diverse agonists. We used various sydnonimines and organic nitrates as donors of NO. Gel-filtered and fura-2-loaded platelets were stimulated with ADP (4-8 microM), collagen (2-10 micrograms/ml) or thrombin (0.02-0.05 IU/ml), respectively. Half-maximal inhibiting effects of sydnonimines on agonist-evoked increases in [Ca2+]i were observed between 30 and 1000 nM, while half-maximal inhibiting effects of the compounds on aggregation were between 3 and 500 nM. The compound C 87-3754, which is the bioactive metabolite of pirsidomine, was a much stronger inhibitor of increases in [Ca2+]i than of platelet aggregation. This was due to an enhanced NO release from this compound exposed to ultraviolet light during Ca2+ measurement. The organic nitrates isosorbide 5-mono-nitrate and nicorandil inhibited both aggregation and increase of cytosolic ionized calcium in stimulated platelets at half-maximal concentrations of approximately 200 microM. The present results suggest that some of the effects of NO on platelets are independent of cytosolic ionized calcium. The results also suggest that some of the inhibitory effects of NO-releasing compounds correspond rather to the presence of the A forms (NO-containing intermediates) than to the presence of free NO.

Calcium↗
PubMed1998

Development of bioactive functions in Hydrangeae Dulcis Folium. VII. Immunomodulatory activities of thunberginol A and related compounds on lymphocyte proliferation.

Immunomodulatory activities of constituents isolated from Hydrangeae Dulcis Folium and their related compounds on lymphocyte proliferation were investigated using splenocytes and lymph node cells. Thunberginol A (TA) significantly suppressed B lymphocyte proliferation stimulated by lipopolysaccharide (LPS) at 10(-5) M. However TA at a lower concentration (10(-6) M) and the other compounds, except hydrangenol and 3'-hydroxyhydrangeaic acid, tended to potentiate B lymphocytes proliferation (10(-5) M). On the other hand, thunberginol A significantly suppressed T lymphocyte proliferation stimulated by concanavalin A (Con A), but did not suppress phytohemagglutinin (PHA). Hydrocortisone and cyclosporin A strongly suppressed T lymphocyte proliferation induced by both Con A and PHA. These results suggest that thunberginol A acts on both B and T lymphocytes and may have a suppressive mechanism different from the known immunosuppressants. The cytotoxicity of TA for splenocytes seemed weaker than known immunosuppressants resulting from viability tests using MTT assay and the measurement of lactate dehydrogenase (LDH) released in the medium. Moreover, TA suppressed antigen-specific T lymphocyte proliferation in mice lymph node cells immunized with keyhole limpet hemocyanin (KLH). Thus, these findings show that TA has a suppressive effect on lymphocyte activation, and this inhibitory effect of TA seems to contribute to its suppressive effect on type IV allergies.

Animals↗
PubMed2001

Bioactivity of 25-hydroxy-, 26-hydroxy, 25,26-dihydroxy- and 25,26-epoxybrassinolide.

The bioactivity of 25-hydroxybrassinolide, (25S)- and (25R)-26-hydroxybrassinolide, (25S)- and (25R)-25,26-dihydroxybrassinolide, and of (25R)-25,26-epoxybrassinolide was tested in the rice leaf lamina inclination assay. The 25- and (25S)-26-hydroxy derivatives are known metabolites of the naturally-occurring phytohormone brassinolide, whereas the other compounds are novel, but closely related, congeners. When tested alone, all showed either no activity or only weak activity at relatively high doses. When coapplied with indole-3-acetic acid (IAA), an auxin that synergizes the effects of brassinosteroids, enhanced bioactivity was observed for each compound. However, even when applied together with IAA, none of the compounds proved more bioactive than brassinolide with or without IAA. We conclude from these results that enzymatic hydroxylation of endogenous brassinolide at C-25 and/or C-26 does not enhance brassinosteroid activity, and so does not comprise an activation pathway in brassinolide biosynthesis. Instead, these hydroxylations result in modest to appreciable metabolic deactivation.

Brassinosteroids↗
PubMed1999

Lyso-PAF analogues and lysophosphatidylcholines from the marine sponge Spirastrella abata as inhibitors of cholesterol biosynthesis.

A series of phospholipids, including previously undescribed compounds 4-7, were isolated by a bioactivity-guided fractionation from the marine sponge Spirastrella abata as inhibitors of cholesterol biosynthesis in human liver cells. These compounds were identified as lyso-PAF analogues (1-5) and lysophosphatidylcholines (6, 7) based on NMR and MS analyses. Compounds 1-7 specifically blocked the conversion of lanosterol into cholesterol in the Chang liver cell.

Animals↗