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PubMedDate not supplied

[Lipoxygenase inhibitors induce rat hepatocyte apoptosis in primary culture].

Arachidonic acid metabolites have been shown to have a wide range of effects on cell proliferation and viability. In this study, the effects of lipoxygenase (LO) inhibitors nordihydroguaiaretic acid (NDGA) and caffeic acid (CA) on the viability of cultured rat hepatocytes (HC) were investigated. As a result, treatment with NDGA and CA for 4 h and 24 h decreased ALT release from HC and increased a number of apoptotic cells. Apoptosis inducing effects of general LO inhibitor NDGA were more pronounced, than those of 5-LO inhibitor CA. The results suggest that lipoxygenase pathway of arachidonic acid metabolism, in particular 5-LO, is essential regulator of hepatocyte survival and apoptosis.

Animals↗
PubMed2006

Baicalin attenuates oxygen-glucose deprivation-induced injury via inhibiting NMDA receptor-mediated 5-lipoxygenase activation in rat cortical neurons.

The flavonoid baicalin exerts neuroprotective effects but the mechanism is not fully clarified. On the other hand, 5-lipoxygenase (5-LOX) activation is involved in ischemic neuronal injury. In this study, we determined whether baicalin protects rat cortical neurons against oxygen-glucose deprivation (OGD)-induced ischemic-like injury, if so, whether this effect relates to 5-LOX activation. After the neurons were injured by 1.5-h OGD and 24-h recovery, their viability reduced and necrosis occurred; these injuries were attenuated by baicalin (1 and 5microM) as well as caffeic acid (a 5-LOX inhibitor, 5 and 25microM) and MK-801 (an NMDA receptor antagonist, 1-10microM). OGD-induced 5-LOX translocation to the nuclear envelope as detected by immunoblotting, immunocytochemistry and 5-LOX transfection; this translocation was inhibited by baicalin (5microM) and MK-801 (5microM) but not by caffeic acid (5microM). During 0.5- to 2-h recovery after 1.5-h OGD, the production of 5-LOX metabolites, cysteinyl leukotrienes, was increased; this increased production was inhibited by baicalin and MK-801, while both the increased and baseline production were inhibited by caffeic acid. In addition baicalin and MK-801, not caffeic acid, inhibited glutamate-induced elevation of intracellular calcium. These results indicate that baicalin attenuates ischemic-like injury in the neurons, and this effect partly relates to the inhibition of NMDA receptor-mediated 5-LOX activation.

Animals↗
PubMed2004

An amperometric biosensor for polyphenolic compounds in red wine.

In the present work, a biosensor was developed with Laccase Coriolus Versicolor as the biological reconnaissance element immobilized on derivatized polyethersulphone membranes and applied to a Pt-Ag, AgCl US electrode base. Its application to several polyphenols usually found in red wine (caffeic acid, gallic acid, catechin, rutin, trans-resveratrol, quercetin and malvidin) was tested. It was observed that an amperometric response was obtained for catechin at +100 mV (versus Ag, AgCl) and caffeic acid at -50 mV in acetate buffer solutions (pH 4.5) having 12% ethanol. At pH 3.5 and +100 mV the biosensor was sensitive to both substrates and their response was additive. A limit of detection of 1.0 x 10(-6) M, linearity ranging from 2.0 to 14.0 x 10(-6) M, high sensitivity (0.0566 mAM(-1)) and reproducibility (R.S.D. <10%) were achieved for equimolar mixed solutions of catechin and caffeic acid. Under the same experimental conditions the other polyphenols tested individually did not yield any biosensor response. The application of the biosensor to red wine samples required a previous solid phase extraction for polyphenols enrichment. In fact, attempts to apply the biosensor in red wine using the "standard addition" methodology showed that large interferences occurred, as was to be expected. Reduction currents of -0.33 +/- 0.03 nA were obtained when the biosensor was used with the wine extract at +100 mV. This current could be ascribed to catechin and caffeic acid, although some interference by other polyphenols at the matrix level seemed to persist. The present biosensor showed promising applications for the wine analysis in future.

Biosensing Techniques↗
PubMed2004

[Assessment of antioxidant activity of natural compound by water- and lipid-soluble antioxidant factor].

We evaluated the antioxidant activity of natural compounds in water-soluble and lipid-soluble phases and found that ferulic acid, quercetin and caffeic acid showed stronger activity in the water-soluble phase. Various fractions isolated from Bidens pilosa showed this activity mainly in the water-soluble phase. Antioxidant activity in the lipid-soluble phase of propolis depended on the lipophilic extraction.

Antioxidants↗
PubMed1990

Inhibitors of lipoxygenase increase the ovulation rate in the in-vitro perfused luteinizing hormone-stimulated rabbit ovary.

In order to determine whether leukotrienes, products of the lipoxygenase pathway, are involved in ovulation, pairs of rabbit ovaries were treated with the lipoxygenase inhibitors nordihydroguaiaretic acid (NDGA) and caffeic acid (CA) while being perfused in vitro. The control ovaries from each rabbit received luteinizing hormone (LH) (1.5-2.25 micrograms ml-1) while the contralateral ovaries were treated with LH + NDGA (100 microM) or LH + CA (100 microM). The numbers of ovulations from both the LH + NDGA- and LH + CA-treated ovaries were significantly higher (P less than 0.05) than from their respective LH-stimulated controls. Treatment with NDGA alone in the perfusate did not cause any ovulation, while CA alone caused one ovulation from one of six ovaries perfused. Ovarian tissue levels of prostaglandins after 7 h of perfusion with LH + NDGA or with LH alone showed that, in five of the six ovaries perfused in this group, the tissue levels of PGE2, 6-keto-PGF1 alpha and PGF2 alpha were higher in the presence of NDGA. The mean differences were significant (P less than 0.05) for prostacyclin but not significant (P greater than 0.05) for PGE2 and PGF2 alpha. Our interpretation of the findings is that, when used for blocking the lipoxygenase pathway, NDGA and CA increase the substrate availability for the cyclo-oxygenase pathway of arachidonic acid metabolism, resulting in a net increase in prostaglandins. The increased ovarian levels of prostaglandins, especially prostacyclin, may cause the observed increase in ovulation rate. Consequently, although the leukotrienes may be involved in the mechanism of ovulation in the rabbit, their effects appear to be less pronounced than those of prostaglandins.

Animals↗
PubMed2006

Phenolic acids in Fructus Xanthii and determination of contents of total phenolic acids in different species and populations of Xanthium in China.

OBJECTIVE: To study the chemical constituents of Fructus Xanthii and to determine the contents of total phenolic acids (TPA) in fruits of Xanthium from different populations for evaluating the quality of them. METHODS: Components in Fructus Xanthii were isolated and purified by various column chromatographies and the contents of TPA were determined by ultraviolet spectrophotometry with chlorogenic acid (CHA) as reference substance. RESULTS: Six caffeoylquinic acids along with caffeic acid and ferulic acid were isolated from Fructus Xanthii. The contents of TPA of the samples collected from 29 populations in China varied from 0.31% to 1.44%. Among the samples originated from two species and 1 variety of Xanthium, the contents of TPA in X. sibiricum var. subinerme samples with an average of 0.36% were relatively lower than those in other 2 species. While the content of TPA in Sample 3 collected from Shanghai was 1.44% and the highest among all the samples, and that in Sample 12 from Xinjian of Jiangxi Province was 0.38% and the lowest among the X. sibiricum samples. CONCLUSION: 5-O-caffeoylquinic acid, 1,4-di-O-caffeoylquinic acid and 4,5-di-O-caffeoylquinic acid were isolated from Xanthium plant for the first time. The difference of contents of TPA in samples from different species and different populations in China was relatively significant. Fructus Xanthii in Shanghai and Sanming of Fujian Province were considered high quality if contents of TPA were used as reference for quality evaluating.

Caffeic Acids↗
PubMed2005

Determination of active ingredients of Ilex Purpurea Hassk and its medicinal preparations by capillary electrophoresis with electrochemical detection.

A method based on capillary electrophoresis with electrochemical detection has been developed for the separation and determination of isovanillic acid, gentisic acid, kaempferol, quercetin, caffeic acid and protocatechuic acid in Ilex Purpurea Hassk and its medicinal preparations for the first time. The effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be separated in a 50 mmoll(-1) borate buffer (pH 9.0) within 21 min. A 300 microm diameter carbon disk electrode has a good response at +0.95 V (versus SCE) for all analytes. The response was linear over three orders of magnitude with detection limits (S/N=3) ranging from 3 x 10(-8) to 2 x 10(-7)gml(-1) for the analytes. The method has been successfully applied to the analysis of real sample, with satisfactory results.

Aquifoliaceae↗
PubMed2006

Effect of methyl jasmonate on secondary metabolites of sweet basil (Ocimum basilicum L.).

The effect of methyl jasmonate (MeJA) in terms of its induction of inherent bioactive chemicals in sweet basil (Ocimum basilicum L.) was evaluated after MeJA was sprayed on healthy basil plants. The total phenolic content of the sweet basil significantly increased after 0.1 and 0.5 mM MeJA treatments compared with the control not subjected to MeJA. Two phenolic compounds, rosmarinic acid (RA) and caffeic acid (CA), were identified as strong antioxidant constituents of the sweet basil. Their amounts also significantly increased after the MeJA treatment. In addition, eugenol and linalool increased 56 and 43%, respectively, by the 0.5 mM MeJA treatment. Due to the accumulation of RA, CA, and eugenol, which possess strong 2,2-diphenyl-1-picrylhydrazyl (DPPH*) free radical scavenging activities, the antioxidant activity of the sweet basil extract was 2.3-fold greater than that of the control after the 0.5 mM MeJA treatment. In the DPPH* assay, the EC50 values of RA, CA, and eugenol were determined as 23, 46, and 59 microM, respectively, which indicated they were 6-, 3-, and 2.4-fold more efficient than BHT (140 microM). Besides, an unidentified HPLC peak in the methanolic extract of the sweet basil was 4.3-fold higher than that of the control after the 0.5 mM MeJA treatment.

Acetates↗
PubMed2003

Anticancer activity of phenolic acids of natural or synthetic origin: a structure-activity study.

Several phenolic acids-caffeic and gallic acid derivatives-were synthesized and screened for their potential antiproliferative and cytotoxic properties, in different human cancer cell lines: mammary gland and cervix adenocarcinomas and lymphoblastic leukemia. The selected phenols were structurally related, which allowed us to gather important information regarding the structure-activity relationships underlying the biological activity of such compounds. This is proposed to be due to a balance between the antioxidant and pro-oxidant properties of this kind of agent. Distinct effects were found for different cell lines, which points to a significant specificity of action of the drugs tested. It was verified, for the types of cancer investigated, that the trihydroxylated derivatives yielded better results than the dihydroxylated ones. Tests in noncancerous cells, human lung fibroblasts, were also undertaken, in view of determining the toxic side effects of the compounds studied.

Adenocarcinoma↗
PubMed1989

Effects of lipoxygenase and glutathione pathway inhibitors on leukemic cell line growth.

We have examined the effects of various inhibitors of the lipoxygenase pathway of arachidonic acid metabolism on the growth of three well-characterized human leukemia cell lines, HL-60, K-562, and KG-1. An intact lipoxygenase pathway, and the synthesis of leukotriene C4 (LTC4), which requires reduced glutathione, is essential for in vitro growth of normal myeloid progenitors (CFU-GM). We tested the effects of nordihydroguiaretic acid (NDGA) and caffeic acid (CA), inhibitors of lipoxygenase; buthionine sulfoximine (BSO), which inhibits glutathione synthesis; and Acivicin, a glutamine antagonist, on these cell lines and compared the effects with those seen on CFU-GM. In semisolid culture, all three cell lines were inhibited by NDGA, CA, and BSO in a dose-dependent manner similar to that in CFU-GM but were relatively resistant to Acivicin. In liquid culture, all three cell lines exhibited relative resistance to inhibition by both BSO and Acivicin, with KG-1 also demonstrating relative resistance to inhibition by NDGA and CA. The inhibition of HL-60 by CA could be completely reversed by the addition of exogenous leukotriene D4. The dependence on the lipoxygenase pathway may be altered to varying degrees in different leukemic lines and may depend on culture conditions. Whether these changes may contribute to the pathogenesis of leukemia or merely represent secondary metabolic changes is yet to be determined.

Buthionine Sulfoximine↗
PubMed1988

Evidence that the establishment of pregnancy requires activation of lipoxygenase and phospholipase-A2.

The present work investigates the possibility that lipoxygenase products are involved in the biochemical mechanisms of blastocyst implantation by utilizing nordihydroguaiaretic acid (NDGA) and caffeic acid (CA), inhibitors of lipoxygenase enzymes, and quinacrine (QU), an inhibitor of phospholipase-A2. It has been shown previously that inhibition of cyclooxygenase results in blockade of implantation. The inhibitors were dissolved in a standard medium and 5 microliter of the solutions were micro-injected into the uterine horns of day-4 pregnant mice. The contralateral horns acted as controls and received only vehicle. A sham-operated group provided normal controls. In 14 NDGA-treated mice, the control horns contained 40 implantations while the treated horns contained only 6 small implantations and 8 resorbing sites. These control horns were comparable to the sham controls. In 14 CA-treated mice, treated horns contained 17 small implantations plus 4 resorptions, whereas the control horns contained 26 small implantations and 4 resorptions. Twelve QU-treated mice exhibited 7 small implantations and 4 resorptions in the treated horns, plus 24 small sites and no resorptions in the control horns. Fourteen sham-operated mice had 95 implantation sites and no resorptions in their 28 horns. The results provide evidence for the involvement of the lipoxygenase enzymes and phospholipase-A2 in the initial implantation process and in the subsequent development of early pregnancy.

Animals↗
PubMed2000

Modifications in lignin and accumulation of phenolic glucosides in poplar xylem upon down-regulation of caffeoyl-coenzyme A O-methyltransferase, an enzyme involved in lignin biosynthesis.

Caffeoyl-coenzyme A O-methyltransferase (CCoAOMT) methylates, in vitro, caffeoyl-CoA and 5-hydroxyferuloyl-CoA, two possible precursors in monolignol biosynthesis in vivo. To clarify the in vivo role of CCoAOMT in lignin biosynthesis, transgenic poplars with 10% residual CCoAOMT protein levels in the stem xylem were generated. Upon analysis of the xylem, the affected transgenic lines had a 12% reduced Klason lignin content, an 11% increased syringyl/guaiacyl ratio in the noncondensed lignin fraction, and an increase in lignin-attached p-hydroxybenzoate but otherwise a lignin composition similar to that of wild type. Stem xylem of the CCoAOMT-down-regulated lines had a pink-red coloration, which coincided with an enhanced fluorescence of mature vessel cell walls. The reduced production of CCoAOMT caused an accumulation of O(3)-beta-d-glucopyranosyl-caffeic acid, O(4)-beta-d-glucopyranosyl-vanillic acid, and O(4)-beta-d-glucopyranosyl-sinapic acid (GSA), as authenticated by (1)H NMR. Feeding experiments showed that O(3)-beta-d-glucopyranosyl-caffeic acid and GSA are storage or detoxification products of caffeic and sinapic acid, respectively. The observation that down-regulation of CCoAOMT decreases lignin amount whereas GSA accumulates to 10% of soluble phenolics indicates that endogenously produced sinapic acid is not a major precursor in syringyl lignin biosynthesis. Our in vivo results support the recently obtained in vitro enzymatic data that suggest that the route from caffeic acid to sinapic acid is not used for lignin biosynthesis.

Acyl Coenzyme A↗
PubMed2005

Screening of raw coffee for thiol binding site precursors using "in bean" model roasting experiments.

The purpose of the following study was to investigate the influence of coffee roasting on the thiol-binding activity of coffee beverages, and to investigate the potential of various green bean compounds as precursors of thiol-binding sites by using promising "in bean" model roast experiments. Headspace gas chromatographic analysis on coffee brews incubated in the presence of the roasty-sulfury smelling 2-furfurylthiol for 20 min at 30 degrees C in septum-closed vessels revealed that the amounts of "free" thiol decreased drastically with increasing the roasting degree of the beans used for preparation of the brews. A half-maximal binding capacity (BC(50)) of 183 mg of 2-furfurylthiol per liter of standard coffee beverage was determined for a roasted coffee (CTN value of 67), thus demonstrating that enormous amounts of the odor-active thiol are "bound" by the coffee. Furthermore, biomimetic "in bean" precursor experiments have been performed in order to elucidate the precursor for the thiol-binding sites in the raw coffee bean. These experiments opened the possibility of studying coffee model reactions under quasi-natural roasting conditions and undoubtedly identified chlorogenic acids as well as thermal degradation products caffeic acid and quinic acid as important precursors for low-molecular-weight thiol-binding sites. In particular, when roasted in the presence of transition metal ions, chlorogenic acids and even more caffeic acid showed thiol-binding activity which was comparable to the activity measured for the authentic coffee brew.

Binding Sites↗
PubMed2005

Polypodium leucotomos extract: antioxidant activity and disposition.

The extract of the fern Polypodium leucotomos (PL, Fernblock) is an oral photoprotectant with strong antioxidative properties. Recent studies to determine its chemical composition have shown 4-hydroxycinnamic acid (p-coumaric), 3 methoxy-4-hydroxycinnamic acid (ferulic), 3,4-dihydroxycinnamic acid (caffeic), 3-methoxy-4-hydroxybenzoic acid (vanillic) and 3-caffeoilquinic acid (chlorogenic) to be among its major phenolic components. No conclusive data are available, however, on the H2O2-scavenging capacity of these compounds, or on their absorption and metabolism following their oral intake. In the present work, their antioxidative capacity was assessed by the luminol/H2O2 assay, their absorption studied using Caco-2 cells to resemble the intestinal barrier, and their metabolism investigated using cultured primary rat hepatocytes. The antioxidant capacity of PL components increased in a concentration-dependent manner, with ferulic and caffeic acids the most powerful antioxidants. The apparent permeability results correspond to a human post-oral administration absorption of 70-100% for all tested substances. Coumaric, ferulic and vanillic acids were metabolized by CYP450-dependent mono-oxygenases and partially conjugated to glucuronic acid and sulfate. These phenolic compounds may contribute to the health benefits afforded by this oral photoprotectant.

Animals↗
PubMed1992

Identification of effective component from a traditional herbal medicine and the inhibitory effects on experimental glomerular lesion in mice.

Effective constituents for renal disease were partially purified from a herbal prescription. The efficacy on renal diseases was examined using an experimental model system of glomerular lesion in mice induced by Agkistrodon acutus venom (Ac1-P). The extract of boiling water of the herbal prescription (P-3) was first fractionated by ether into an acidic fraction and a mixture of basic and neutral fractions. The acidic fraction was proved to be more effective and then further examined by thin layer chromatography and spectrophotometry. One of the main components was confirmed to be caffeic acid which had inhibitory effect on renal failure in mice by Ac1-P. This effect was considered to be caused by caffeic acid inhibiting the proteolytic enzyme activity of Ac1-P. Caffeic acid should thus have prophylactic or inhibitory effect on glomerular disease in which proteolytic enzymes may have pathogenic roles.

Animals↗
PubMed2004

Antioxidant activity of olive phenols: mechanistic investigation and characterization of oxidation products by mass spectrometry.

In this work, the antioxidant activity of olive phenols is first characterized by their stoichiometries n(tot)(number of radicals trapped per antioxidant molecule) and their rate constants for the first H-atom abstraction k(1) by the stable radical DPPH. It appears that oleuropein, hydroxytyrosol and caffeic acid have the largest k(1) values, whereas dihydrocaffeic acid, an intestinal metabolite of caffeic acid, is the best antioxidant in terms of n(tot). For phenols with a catechol moiety n(tot) is higher than two, implying an antioxidant effect of their primarily formed oxidation products. A HPLC-MS analysis of the main products formed in the AAPH-induced oxidation of olive phenols reveals the presence of dimers and trimers. With hydroxytyrosol and dihydrocaffeic acid, oligomerization can take place with the addition of water molecules.The antioxidant activity of olive phenols is then evaluated by their ability to inhibit the AAPH-induced peroxidation of linoleic acid in SDS micelles. It is shown that olive phenols and quercetin act as retardants rather than chain breakers like alpha-tocopherol. From a detailed mechanistic investigation, it appears that the inhibition of lipid peroxidation by olive phenols can be satisfactorily interpreted by assuming that they essentially reduce the AAPH-derived initiating radicals. Overall, olive phenols prove to be efficient scavengers of hydrophilic peroxyl radicals with a long lasting antioxidant effect owing to the residual activity of some of their oxidation products.

Antioxidants↗
PubMed2001

Antimutagenicity of deacylated anthocyanins in purple-fleshed sweetpotato.

The antimutagenicity of the 3-sophoroside-5-glucoside of cyanidin and 3-sophoroside-5-glucoside of peonidin, the anthocyanin derivatives deacylated from the 3-(6,6'-caffeylferulylsophoroside)-5-glucoside of cyanidin (YGM-3) and 3-(6,6'-caffeylferulylsophoroside)-5-glucoside of peonidin (YGM-6) which had been purified from the sweetpotato with purple-colored flesh, was investigated by using Salmonella typhimurium TA 98. A comparison of the antimutagenicity between YGM-3 and YGM-6 and the deacylated derivatives showed that the activity of cyanidin was stronger than that of peonidin. Deacylation of the peonidin-type pigment markedly decreased this antimutagenicity. Caffeic acid showed the strongest antimutagenicity of the constituent organic acids of the anthocyanin pigments, caffeic acid, ferulic acid, and p-hydroxybenzoic acid. These results suggest that the cathecol structure plays an important role in the strong antimutagenicity of anthocyanin pigments.

Acetylation↗
PubMedDate not supplied

Egyptian propolis: 3. Antioxidant, antimicrobial activities and chemical composition of propolis from reclaimed lands.

The free radical scavenging effect of two propolis samples collected from reclaimed land, Egypt as well as of vitamin C and caffeic acid in 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical system was determined. The antimicrobial (Staphylococcus aureus; Escherichia coli and Candida albicans) activity was also investigated. The results of the free radical scavenging effect of El-Saff and Ismailia propolis showed a concentration-dependent activity. The antioxidant activity was varied according to the examined material. It was obvious that caffeic acid and vitamin C showed the highest activity if compared with the propolis samples. El- Saff propolis had a higher antioxidant activity than Ismailia propolis, it showed a higher antibacterial activity against Staphylococcus aureus and a higher anti-fungal activity against Candida albicans. While the Ismailia propolis had a higher antibacterial activity against Escherichia coli, than El-Saff propolis. The chemical composition of propolis samples was investigated by GC/MS, where 75 compounds were identified, 22 being new for propolis. The Ismailia propolis was characterized by the presence of a highly significant amount of aromatic acid esters (47.3%) and triterpenoids (17.3%), while El-Saff propolis contained 3% and 1.9% respectively. The new esters belonged to 4-methoxyhydrocinnamic acid, hydroferulic acid and ferulic acid. El-Saff propolis had a very high significant amount (27%) of 2,6-bis-(pentanyloxy)-4-pentanylphenethanol, which is also a new compound for propolis.

Anti-Bacterial Agents↗