Germination,duplication cycle and septum formation are altered by caffeine,caffeic acid and cinnamic acid in <Emphasis Type="Italic">Aspergillus nidulans</Emphasis>

Phytogenous Phenolic and benzene compounds have been described as being responsible for many biological activities including antifungal effects. The effect of caffeine and cinnamic and caffeic acids on a model fungus, Aspergillus nidulans, was investigated at its initial stage of germination. Conidia did not germinate in the presence of cinnamic acid (1 mM). Caffeine and caffeic acid exerted a negative effect on germination, on the nuclear duplication cycle and on first septum formation. The effects of caffeine were dose-dependent; effects of caffeic acid (1 mM) were more intense than those of caffeine (10 mM).     

Excess boron reduces polyphenol oxidase activities in embryo and endosperm of maize seed during germination

The effects of increasing concentrations of boron (0, 0.1, 1, 10 and 20 mM) as boric acid on the rate of germination and polyphenol oxidase activities in embryo and endosperm tissues of maize seeds (Zea mays L. cv. Arifiye) were studied. The germination percentage of maize seeds was not affected by boron concentrations up to 10 mM, and decreased by 20 mM. Distilled water and lower boron concentrations (0.1 and 1 mM) increased polyphenol oxidase activities at the beginning of germination up to 12 h whereas its excess levels (10 and 20 mM) decreased polyphenol oxidase activities in embryos and endosperm during germination. Polyphenol oxidase activities with o-diphenolic substrates (caffeic acid, catechol and dopa) were found to be higher than with a monophenolic substrat (tyrosine) in both embryos and endosperms. Further, caffeic acid oxidizing polyphenol oxidase was found to show more activity in embryos of the seeds germinating in distilled water when compared to other substrates.     

Caffeic acid decreases salinity-induced root nodule superoxide radical accumulation and limits salinity-induced biomass reduction in soybean

Caffeic acid (3,4-dihydroxycinnamic acid; CA) is a cinnamic acid occurring naturally in a variety of plant species. In this study, the effects of caffeic acid (100 μM caffeic acid) on soybean root nodule superoxide content, cell viability and superoxide dismutase (SOD; EC 1.15.1.1) activity were evaluated in the presence and absence of salinity stress (imposed by application of 70 mM NaCl), along with the effects of CA on growth of soybean in the presence or absence of salinity. Treatment with CA caused a decrease in superoxide content, enhanced cell viability and SOD activity, with changes in SOD activity accounted for by increased activity of two manganese SOD isoforms and one copper/zinc SOD isoform. Furthermore, CA improved soybean growth under salinity but reduced soybean biomass in the absence of salinity. We suggest that CA improves soybean salinity stress tolerance, possibly via signals that regulate accumulation of reactive oxygen species (ROS) during salinity stress.     

Caffeine modulates phosphorylation of insulin receptor substrate-1 and impairs insulin signal transduction in rat skeletal muscle

Caffeine decreases insulin sensitivity and insulin-stimulated glucose transport in skeletal muscle; however, the precise mechanism responsible for this deleterious effect is not understood fully. We investigated the effects of incubation with caffeine on insulin signaling in rat epitrochlearis muscle. Caffeine (≥1 mM, ≥15 min) suppressed insulin-stimulated insulin receptor substrate (IRS)-1 Tyr(612) phosphorylation in a dose- and time-dependent manner. These responses were associated with inhibition of the insulin-stimulated phosphorylation of phosphatidylinositol 3-kinase (PI3K) Tyr(458), Akt Ser(473), and glycogen synthase kinase-3β Ser(9) and with inhibition of insulin-stimulated 3-O-methyl-d-glucose (3MG) transport but not with inhibition of the phosphorylation of insulin receptor-β Tyr(1158/62/63). Furthermore, caffeine enhanced phosphorylation of IRS-1 Ser(307) and an IRS-1 Ser(307) kinase, inhibitor-κB kinase (IKK)-α/β Ser(176/180). Blockade of IKK/IRS-1 Ser(307) by caffeic acid ameliorated the caffeine-induced downregulation of IRS-1 Tyr(612) phosphorylation and 3MG transport. Caffeine also increased the phosphorylation of IRS-1 Ser(789) and an IRS-1 Ser(789) kinase, 5'-AMP-activated protein kinase (AMPK). However, inhibition of IRS-1 Ser(789) and AMPK phosphorylation by dantrolene did not rescue the caffeine-induced downregulation of IRS-1 Tyr(612) phosphorylation or 3MG transport. In addition, caffeine suppressed the phosphorylation of insulin-stimulated IRS-1 Ser(636/639) and upstream kinases, including the mammalian target of rapamycin and p70S6 kinase. Intravenous injection of caffeine at a physiological dose (5 mg/kg) in rats inhibited the phosphorylation of insulin-stimulated IRS-1 Tyr(612) and Akt Ser(473) in epitrochlearis muscle. Our results indicate that caffeine inhibits insulin signaling partly through the IKK/IRS-1 Ser(307) pathway, via a Ca(2+)- and AMPK-independent mechanism in skeletal muscle.     

Caffeine treatment inhibits drug-induced calcium release from sarcoplasmic reticulum and caffeine contracture but not tetanus in frog skeletal muscle

Effects of pretreatment with caffeine on Ca2+ release induced by caffeine, thymol, quercetin, or p-chloromercuriphenylsulfonic acid (pCMPS) from the heavy fraction of sarcoplasmic reticulum (SR) were studied and compared with those effects on caffeine contracture and tetanus tension in single fibers of frog skeletal muscle. Caffeine (1-5 mM) did induce transient Ca2+ release from SR vesicles, but subsequent further addition of caffeine (10 mM, final concentration) induced little Ca2+ release. Ca2+ release induced by thymol, quercetin, or pCMPS was also inhibited by pretreatment with caffeine. In single muscle fibers, pretreatment with caffeine (1-5 mM) partially reduced the contracture induced by 10 mM caffeine. However, tetanus tension was almost maximally induced by electrical stimulus in caffeine-treated fibers. These results indicate that SR, which becomes less sensitive to caffeine, thymol, quercetin, or pCMPS by pretreatment with caffeine, can still respond to a physiological signal transmitted from transverse tubules.     

The kinetics and mechanisms of reactions of iron(III) with caffeic acid, chlorogenic acid, sinapic acid, ferulic acid and naringin

The kinetics and mechanisms of the reactions of iron(III) with the hydroxy cinnamic acid based ligands caffeic, chlorogenic, sinapic and ferulic acids and the flavonoid naringin have been investigated in aqueous solution. The mechanisms for caffeic and chlorogenic acid are generally consistent with the formation of a 1:1 complex that subsequently decays through an electron transfer reaction. On reaction with iron(III), ferulic and sinapic acids undergo an electron transfer without the prior formation of any complex. There was no evidence of electron transfer occurring in the complex formed when iron(III) is reacted with naringin. Rate constants for k1 (formation) and k(-1) (dissociation) have been evaluated for the complex formation reactions of [Fe(H2O)6(OH)]2+ with caffeic acid, chlorogenic acid and naringin. Analysis of the kinetic data yielded stability constants, equilibrium constants for protonation of the iron(III) chlorogenic acid complex initially formed, together with the rate constants for complex decomposition through intramolecular electron transfers and in the case of caffeic acid and chlorogenic acid, rate constants for the iron(III) assisted decomposition of the initial complex formed. Some of the suggested mechanisms and calculated rate constants are validated by calculations carried out using global analysis of time dependent spectra.     

N-Caffeoyl serotonin as selective COX-2 inhibitor

The inhibitory effects of the synthetic serotonin analogues (1-8) on COX (1 and 2) were evaluated. Two serotonin derivatives (4 and 8) showed inhibitory effect of COX (1 and 2). Especially, 4 exhibited excellent inhibitions on COX-2 with extremely high potency (IC(50)=42.5 μM). The inhibitory activities of cinnamic acid derivatives and serotonin were evaluated to clarify whether inhibitory activities of compound 4 and 8 are due to cinnamic acid moiety or serotonin moiety. Caffeic acid and N-caffeoyl serotonin (4) exhibited selective inhibition of COX-2 compared to aspirin. Comparison caffeic acid with 4 suggested that the linkage of caffeic acid and serotonin enhance COX-2 inhibition. Comparison of structures of caffeic acid and sinapic acid implied that catechol moiety of cinnamic acid derivatives is a major contributing factor for selective inhibition of COX-2. The selective COX-2 inhibitory activity of compound 4 is significant and could be employed as drugs against inflammatory and allergy.     

Developmental and cytogenetic effects of caffeine on mouse blastocysts, alone or in combination with benzo(a)pyrene

Mouse blastocysts were treated with caffeine and/or benzo(a)pyrene (BP), and the effects on development and on induction of sister chromatid exchanges (SCEs) were examined. Caffeine interfered with blastocyst development in a dose-related manner. At 4 mM, the highest concentration tested, caffeine interfered with development of blastocysts to all four endpoints: hatching, trophoblast outgrowth, inner cell mass (ICM) growth, and two-layer (primary endoderm and ectoderm) differentiation of ICMs. At 2 mM, caffeine reduced the incidence of both ICM growth and differentiation but did not affect hatching or formation of trophoblast outgrowths. At 1 mM, caffeine interfered only with ICM differentiation. Cell proliferation was least sensitive to caffeine and was reduced at concentrations of greater than or equal to 2 mM. Induction of SCEs was most sensitive to caffeine exposure; an increase in SCE frequency was observed at 0.1 and 0.5 mM. When caffeine was added to cultures with BP (1 microM, a concentration that was not embryotoxic and did not induce SCEs), both embryotoxic effects and SCE frequency were increased. The enhancing effect on SCE induction was particularly marked; as little as 0.1 mM caffeine was sufficient to cause doubling of induced SCE frequencies when added to cultures with BP.     

Enhanced Lignin Monomer Production Caused by Cinnamic Acid and Its Hydroxylated Derivatives Inhibits Soybean Root Growth

Cinnamic acid and its hydroxylated derivatives (p-coumaric, caffeic, ferulic and sinapic acids) are known allelochemicals that affect the seed germination and root growth of many plant species. Recent studies have indicated that the reduction of root growth by these allelochemicals is associated with premature cell wall lignification. We hypothesized that an influx of these compounds into the phenylpropanoid pathway increases the lignin monomer content and reduces the root growth. To confirm this hypothesis, we evaluated the effects of cinnamic, p-coumaric, caffeic, ferulic and sinapic acids on soybean root growth, lignin and the composition of p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) monomers. To this end, three-day-old seedlings were cultivated in nutrient solution with or without allelochemical (or selective enzymatic inhibitors of the phenylpropanoid pathway) in a growth chamber for 24 h. In general, the results showed that 1) cinnamic, p-coumaric, caffeic and ferulic acids reduced root growth and increased lignin content; 2) cinnamic and p-coumaric acids increased p-hydroxyphenyl (H) monomer content, whereas p-coumaric, caffeic and ferulic acids increased guaiacyl (G) content, and sinapic acid increased sinapyl (S) content; 3) when applied in conjunction with piperonylic acid (PIP, an inhibitor of the cinnamate 4-hydroxylase, C4H), cinnamic acid reduced H, G and S contents; and 4) when applied in conjunction with 3,4-(methylenedioxy)cinnamic acid (MDCA, an inhibitor of the 4-coumarate:CoA ligase, 4CL), p-coumaric acid reduced H, G and S contents, whereas caffeic, ferulic and sinapic acids reduced G and S contents. These results confirm our hypothesis that exogenously applied allelochemicals are channeled into the phenylpropanoid pathway causing excessive production of lignin and its main monomers. By consequence, an enhanced stiffening of the cell wall restricts soybean root growth.     

A series of cinnamic acid derivatives and their inhibitory activity on intestinal α-glucosidase

Inhibition of α-glucosidase and α-amylase delays the digestion of starch and disaccharides to absorbable monosaccharides, resulting in a reduction of postprandial hyperglycemia. Finding effective mammalian α-glucosidase inhibitors from natural sources can be beneficial in the prevention and treatment of diabetes mellitus. We investigated the inhibitory activity of cinnamic acid derivatives against rat intestinal α-glucosidase and porcine pancreatic α-amylase in vitro. Among 11 cinnamic acid derivatives, caffeic acid, ferulic acid, and isoferulic acid were the most potent inhibitors against intestinal maltase with IC₅₀ values of 0.74?±?0.01, 0.79?±?0.04, and 0.76?±?0.03?mM, respectively, whereas ferulic acid (IC₅₀?=?0.45?±?0.01?mM) and isoferulic acid (IC₅₀?=?0.45?±?0.01?mM) were effective intestinal sucrase inhibitors. However, all cinnamic acid derivatives were found to be inactive in pancreatic α-amylase inhibition. Kinetic analysis revealed that intestinal maltase was inhibited by caffeic acid, ferulic acid, and isoferulic acid in a mixed-inhibition manner. In addition, ferulic acid and isoferulic acid inhibited intestinal sucrase in a mixed type manner, whereas caffeic acid was a non-competitive inhibitor. The combination of isoferulic acid and acarbose showed an additive inhibition on intestinal sucrase. This study could provide a new insight into naturally occurring intestinal α-glucosidase inhibitors that could be useful for treatment of diabetes and its complications.     

茄子根系分泌物中香草醛和肉桂酸对黄萎菌的化感效应

采用室内培养和生物测定的试验方法,研究了不同浓度的香草醛和肉桂酸对黄萎菌（Verticillium dahliae）及茄子种子萌发、幼苗生长的化感效应.结果表明,香草醛和肉桂酸对茄子黄萎菌的化感效应存在差异,表现为所有浓度的肉桂酸都抑制了黄萎菌孢子萌发,当浓度为0.5mmol/L时抑制作用最大;香草醛在浓度为0.1mmol/L时抑制孢子萌发,其余浓度则表现出促进作用.对香草醛和肉桂酸的生物测定结果显示,当浓度为0.1mmol/L时,肉桂酸促进茄子种子萌发和幼苗生长,其余浓度则表现为抑制作用,并且随着浓度的加大抑制作用增强;香草醛在各浓度水平下都促进了茄子种子萌发和幼苗生长,当浓度为0.5mmol/L时促进作用最大.     

Excitation-contraction coupling in cardiac Purkinje fibers. Effects of caffeine on the intracellular [Ca2+] transient, membrane currents, and contraction

The effects of caffeine on tension, membrane potential, membrane currents, and intracellular [Ca2+], measured as the light emitted by the Ca2+-activated photoprotein aequorin, were studied in canine cardiac Purkinje fibers. An initial, transient, positive inotropic effect of caffeine was accompanied by a transient increase in the second component of the aequorin signal (L2) but not the first (L1). In the steady state, 4 or 10 mM caffeine always decreased twitch tension and greatly reduced both L1 and L2. At a concentration of 2 mM, caffeine usually reduced but occasionally increased the steady state twitch tension. However, 2 mM caffeine always reduced both L1 and L2. Caffeine eliminated the diastolic oscillations of intracellular [Ca2+] induced by high extracellular [Ca2+]. In voltage-clamp experiments, 10 mM caffeine reduced the transient outward current and the peak tension elicited by step depolarization from a holding potential of -45 mV. In the presence of 20 mM Cs+, 10 mM caffeine reduced slow inward current. However, the time course of this reduction was far slower than that in tension and light observed in separate experiments. The simplest explanation of the results is that caffeine inhibits the sequestration of Ca2+ by the sarcoplasmic reticulum. The results also suggest that in Purkinje fibers caffeine increases the sensitivity of the myofilaments to Ca2+.     

Caffeine sensitization of Chinese hamster ovary cells to heat killing

The effects of the methylxanthine, caffeine, on heat sensitization was investigated using Chinese hamster ovary (CHO) cells. Caffeine sensitized CHO cells to heat killing by reducing both the shoulder and the slope of the 44 degrees C survival curve. Heating was performed in suspension by addition of cells to preheated spinner flasks containing caffeine. Changes in intracellular free calcium levels, [Ca2+]i, were measured at 37 degrees C using the luminescent probe aequorin. Caffeine (1-5 mM) induced a transient increase in [Ca2+]i at 37 degrees C. The transient increase in [Ca2+]i was reduced 15-fold when 5 mM caffeine was added to aequorin-loaded cells suspended in Ca(2+)-free Hanks' balanced salt solution. However, 5 mM caffeine sensitized the cells to the same extent when they were suspended in either Ca(2+)-containing or Ca(2+)-free Hanks' balanced salt solution. The mechanism of heat sensitization by caffeine is still unknown.     

Caffeine effects on buccal muscles of Aplysia

1. Caffeine (35-70 mM) elicited contractions of Aplysia buccal muscle El. In a Ca2+-free medium, in which ACh-elicited contractions rapidly fail, caffeine elicited contractions of approximately the same size as in normal medium. 2. 5-HT (10(-8) M and 10(-7) M) did not enhance caffeine-elicited contractions. 3. Lower concentrations (1-10 mM) of caffeine inhibited ACh-elicited contractions. Caffeine (7 mM) reduced the contraction by 80%. 4. Caffeine (7 mM) reduced ACh-elicited depolarization by 60%. 5. Caffeine (7 mM) increased 45Ca2+ influx into Aplysia buccal muscle I5. The stimulation of influx of 45Ca2+ by 10(-3) M ACh was non-additive with the stimulation caused by caffeine, and 7 mM caffeine reduced the influx caused by 10(-3) M ACh.     

Lipase catalyzed reaction of L-ascorbic acid with cinnamic acid esters and substituted cinnamic acids

To perform the lipase-catalyzed synthesis of L-ascorbic acid derivatives from plant-based compounds such as cinnamic and ferulic acid under mild reaction conditions, the activities of immobilized Candida ntarctica lipase with different cinnamic acid esters and substituted cinnamic acids were compared. As a result, immobilized C. ntarctica lipase was found to prefer vinyl cinnamic acid to other esters such as allyl-, ethyl-, and isobutyl cinnamic acids as well as substituted cinnamic acids such as p-coumaric acid, caffeic acid, ferulic acid, and sinapic acid. Based on these results, large-scale synthesis of 6-O-cinnamyl-L-ascorbic acid ester was performed using immobilized C. ntarctica lipase in dry organic solvent, resulting in 68% yield (493 mg) as confirmed by ¹³C-NMR.     

Rat atrial muscle responses with caffeine: dose-response, force frequency, and postrest contractions.

Caffeine has been reported to have a positive and (or) a negative inotropic effect on cardiac muscle. In this study, the force-frequency and postrest characteristics of rat atrium were studied in the presence of caffeine (1.0-10 mM) to see if the interval between beats affected the response of cardiac muscle to caffeine. When stimulation frequency was 0.5 or 2.0 Hz, there was a positive followed by a negative inotropic response with 1, 5, or 10 mM caffeine. Incomplete relaxation occurred under these circumstances, giving rise to contracture. At low frequency of stimulation (0.1 Hz) caffeine had only a negative inotropic effect, and this effect was greater with 1 mM caffeine than with 5 mM caffeine. In the absence of caffeine, when stimulation at 0.5 or 3 Hz was interrupted, a pause of 2-20 s resulted in potentiation. When caffeine was present (2.0 mM), postrest potentiation was severely attenuated, but the steady-state contraction amplitude within the range 0.5-3.0 Hz was not different. These results are consistent with the hypothesis that caffeine induces a leak of Ca2+ from the sarcoplasmic reticulum, and this Ca2+ is extruded from the cell, possibly by Na+/Ca2+ exchange. Sarcoplasmic reticular uptake of Ca2+ and the translocation to release sites appear not to be affected by caffeine within 1-5 mM concentrations.     

Co-production of caffeic acid and p-hydroxybenzoic acid from p-coumaric acid by Streptomyces caeruleus MTCC 6638

In a culture medium of Streptomyces caeruleus MTCC 6638 grown with p-coumaric acid (5 mM) as the sole source of carbon, co-production of caffeic acid and p-hydroxybenzoic acid was observed. Both caffeic acid and p-hydroxybenzoic acid are important phenolic compounds with pharmaceutical importance. These biotransformed products were identified by high-performance liquid chromatography and electrospray ionization mass spectrometry. Obtained data suggest that p-coumaric acid was possibly utilized by two different routes, resulting in the formation of a hydroxycinnamate and a hydroxybenzoate compound. However, higher concentration of p-coumaric acid (10 mM) favoured caffeic acid formation. Addition of 5 mM p-coumaric acid into S. caeruleus cultures pre-grown on minimal medium with 1.0 g/l glucose resulted in the production of 65 mg/l caffeic acid. Furthermore, S. caeruleus cells were able to produce the maximum amount of caffeic acid when pre-grown on nutrient broth for 16 h. Under this condition, the addition of 5 mM p-coumaric acid was sufficient for the S. caeruleus culture to produce 150 mg/l caffeic acid, with a molar yield of 16.6% after 96 h of incubation.     

New insight into abnormal prion protein using monoclonal antibodies

Loblolly pine (Pinus taeda L.) cell suspension cultures secrete monolignols when placed in 8% sucrose/20 mM KI solution, and these were used to identify phenylpropanoid pathway flux-modulating steps. When cells were provided with increasing amounts of either phenylalanine (Phe) or cinnamic acid, cellular concentrations of immediate downstream products (cinnamic and p-coumaric acids, respectively) increased, whereas caffeic and ferulic acid pool sizes were essentially unaffected. Increasing Phe concentrations resulted in increased amounts of p-coumaryl alcohol relative to coniferyl alcohol. However, exogenously supplied cinnamic, p-coumaric, caffeic, and ferulic acids resulted only in increases in their intercellular concentrations, but not that of downstream cinnamyl aldehydes and monolignols. Supplying p-coumaryl and coniferyl aldehydes up to 40, 000-320,000-fold above the detection limits resulted in rapid, quantitative conversion into the monolignols. Only at nonphysiological concentrations was transient accumulation of intracellular aldehydes observed. These results indicate that cinnamic and p-coumaric acid hydroxylations assume important regulatory positions in phenylpropanoid metabolism, whereas cinnamyl aldehyde reduction does not serve as a control point.     

Chenoalbicin, a novel cinnamic acid amide alkaloid from Chenopodium album

The roots of Chenopodium album were infused in MeOH, and the extract was partitioned between AcOEt and H2O. AcOEt-Soluble material was subjected to different silica-gel column chromatographies and then purified by reverse-phase HPLC to afford a new cinnamic acid amide alkaloid as a racemic mixture. The new compound, named chenoalbicin (1), was characterized by extensive spectroscopic investigation, especially 1D and 2D NMR spectroscopy. Its effects on the germination and growth of Lactuca sativa L. has been studied. The results are reported as percentage differences of germination, root elongation, and shoot elongation from the control at concentrations ranging from 10(-4) to 10(-7) M.     

Evidence that a Ca2+ sparks/STOCs coupling mechanism is responsible for the inhibitory effect of caffeine on electro-mechanical coupling in guinea pig ureteric smooth muscle

Recent studies have highlighted the role of the sarcoplasmic reticulum (SR) in controlling excitability, Ca2+ signalling and contractility in smooth muscle. Caffeine, an agonist of ryanodine receptors (RyRs) on the SR has been previously shown to effect Ca2+ signalling but its effects on excitability and contractility are not so clear. We have studied the effects of low concentration of caffeine (1 mM) on Ca2+ signalling, action potential and contractility of guinea pig ureteric smooth muscle. Caffeine produced reversible inhibition of the action potentials, Ca2+ transients and phasic contractions evoked by electrical stimulation. It had no effect on the inward Ca2+ current or Ca2+ transient but increased the amplitude and the frequency of spontaneous transient outward currents (STOCs) in voltage clamped ureteric myocytes, suggesting Ca2+-activated K+ channels (BK) are affected by it. In isolated cells and cells in situ caffeine produced an increase in the frequency and the amplitude of Ca2+ sparks as well the number of spark discharging sites per cell. Inhibition of Ca2+ sparks by ryanodine (50 microM) or SR Ca2+-ATPase (SERCA) cyclopiazonic acid (CPA, 20 microM) or BKCa channels by iberiotoxin (200 nM) or TEA (1 mM), fully reversed the inhibitory effect of caffeine on Ca2+ transients and force evoked by electrical field stimulation (EFS). These data suggest that the inhibitory effect of caffeine on the action potential, Ca2+ transients and force in ureteric smooth muscle is caused by activation of Ca2+ sparks/STOCs coupling mechanism.