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PubMed2004

Vascular and anti-oxidant actions of flavonols and flavones.

1. Flavonols and flavones are plant-derived polyphenolic compounds that are commonly consumed in the diet. Epidemiological studies indicating that high dietary intake of flavonols reduces the risk of mortality due to coronary heart disease have provoked interest in the mechanism of this cardioprotective effect. 2. We have investigated the structure-activity relationships of a range of flavonols and flavones with regard to their vascular relaxant and anti-oxidant activity. In rat isolated thoracic aorta, the synthetic flavonol 3',4'-dihydroxyflavonol (DiOHF) was found to be a significantly more potent vasorelaxant than the naturally occurring compounds chrysin, apigenin, luteolin, quercetin and fisetin. Similarly, DiOHF was significantly more potent than those compounds in the inhibition of calcium-induced contraction of the rat aorta. 3. 3',4'-Dihydroxyflavonol was also found to significantly inhibit superoxide radical generation in a cell-free system in the presence of xanthine/xanthine oxidase or by rat isolated aorta in the presence of NADPH. In the presence of oxidant stress generated by pyrogallol or xanthine/xanthine oxidase, endothelium-dependent relaxation of rat aortic rings was impaired. 3',4'-Dihydroxyflavonol was able to significantly improve endothelium-dependent relaxation in the presence of those oxygen radical generators. 4. In addition, DiOHF was found to significantly improve dilatation in the rat hindquarters vasculature after exposure to ischaemia and reperfusion. 3',4'-Dihydroxyflavonol was found to be equally effective whether applied before ischaemia or during ischaemia just before reperfusion. 5. In conclusion, DiOHF is an effective vasodilator and anti-oxidant that is able to prevent vascular reperfusion injury. We suggest that DiOHF may be useful as an adjunct to thrombolytic therapy in the management of reperfusion injury.

Animals↗
PubMed1961

The formation of an isoprenaline-like substance from adrenaline.

Intravenous injections of adrenaline, but not those of noradrenaline, caused the appearance of a substance which resembled isoprenaline in R(F) value and pharmacological activity in blood withdrawn from the lower abdominal aortae of chloralosed cats rested after acute adrenalectomy and induction of lasting block in autonomic ganglia with hexamethonium. The formation of the isoprenaline-like compound was prevented by pretreatment with pyrogallol but not by pretreatment with reserpine, cocaine, phentolamine, dibenamine, harmaline, or iproniazid. The liver proved a main site of the origin of this isoprenaline-like substance.

Animals↗
PubMed1963

UPTAKE OF 5-HYDROXYTRYPTAMINE AND ADRENALINE IN THE LIVER.

A dose of 5-hydroxytryptamine caused a greater contraction of the cat nictitating membrane when injected into the jugular vein than when injected into the portal vein. The difference is attributed to uptake or destruction of 5-hydroxytryptamine by the liver. The effects of portal and jugular injections became equal after administration of the monoamine oxidase inhibitors iproniazid or harmaline. Isoniazid, which does not inhibit monoamine oxidase, did not have this effect. Similarly, the effect of a portal injection of adrenaline was less than the effect of an equal jugular injection of adrenaline. Iproniazid and harmaline increased the effect of a portal injection, but not to equal the effect of a jugular injection. Isoniazid had no effect. Pyrogallol did not alter the ratio between the effects of portal and jugular injections of adrenaline, but increased the responses to both.

Animals↗
PubMed1969

Steroid potentiation of responses to sympathomimetic amines in aortic strips.

1. Responses to catecholamines (adrenaline, noradrenaline, nordefrine) were enhanced by 17beta-oestradiol, progesterone and desoxycorticosterone in untreated and reserpine pretreated aortic strips. Responses to tyramine, believed mediated via endogenous catecholamines, were enhanced only in untreated strips.2. Responses to sympathomimetic amines lacking the catechol nucleus (phenylephrine, synephrine, methoxamine) were potentiated inconsistently by the steroids and reserpine pretreatment reduced markedly the frequency of potentiated responses.3. Known inhibitors of catechol-O-methyl transferase (tropolone, U-0521, pyrogallol) potentiated responses to catecholamines and abolished the enhancing effects of the steroids-when the steroids were given first, there was no further increase in response to catecholamines on adding inhibitors of catechol-O-methyl transferase.4. Experiments with the oil-immersion technique, to eliminate diffusion of drug from the tissue, indicated that 17beta-oestradiol, progesterone and desoxycorticosterone decreased the rate at which aortic strips inactivated adrenaline by O-methylation.5. It is concluded that 17beta-oestradiol, progesterone and desoxycorticosterone potentiate responses to catecholamines in aortic strips by inhibiting a major mechanism for their inactivation.

Animals↗
PubMed1991

Actions of dipyridamole on endogenous and exogenous noradrenaline in the dog mesenteric vein.

1. In the isolated mesenteric vein of the dog, dipyridamole inhibited both the excitatory junction potential (e.j.p.) and the slow depolarization evoked by perivascular nerve stimulation, to 60-70% of control, with no change in the postjunctional membrane potential. These inhibitory actions of dipyridamole were not modified by 8-phenyltheophylline or phentolamine, suggesting that the inhibition did not involve either the actions of endogenous adenosine or the prejunctional alpha-autoregulation mechanism. 2. Dipyridamole did not produce any detectable effects on either the facilitation process of the e.j.ps or the postjunctional membrane depolarization produced by exogenously applied noradrenaline (NA). 3. Dipyridamole reduced the outflow of both the NA and the 3,4-dihydroxyphenylglycol (DOPEG) evoked by perivascular nerve stimulation to below 10% of control, the effect being much greater than that of exogenously applied adenosine (to about 90% of the control). 4. Exogenously-added NA was degraded by incubation with a segment of the vein. Dipyridamole itself produced degradation of NA and accelerated the NA-induced degradation. By contrast, pyrogallol, but not pargyline or imipramine, prevented the NA-induced degradation. 5. It is suggested that dipyridamole degrades NA directly, and also indirectly through activation of catechol-O-methyl transferase, with no alteration of the activity of monoamine oxidase or of the uptake mechanisms of NA into nerve terminals.

Adenosine↗
PubMed1992

Nitric oxide and relaxation of pig lower urinary tract.

1. We studied the non-adrenergic, non-cholinergic (NANC) nerve-mediated relaxation induced by electrical stimulation in pig isolated lower urinary tract smooth muscle, and the possible involvement of the L-arginine (L-ARG)/nitric oxide (NO) pathway in this response. 2. Trigonal strips, precontracted by noradrenaline (NA), carbachol or endothelin-1 (ET-1), relaxed frequency-dependently in response to electrical stimulation. Maximum relaxation was obtained at 6-8 Hz, and amounted to 56 +/- 2%, 77 +/- 3% and 62 +/- 6% of the agonist-induced tension in preparations contracted by NA, carbachol, or ET-1, respectively. Exposure to NG-nitro-L-arginine (L-NOARG; 10(-7)-10(-5) M) concentration-dependently reduced the relaxant response in preparations contracted by NA. L-NOARG (10(-6) M) reduced the maximal response to 51 +/- 8% of control. L-NOARG (10(-5) M) abolished all relaxation, and unmasked a contractile component; D-NOARG had no effect. Also in trigonal preparations, where the tension had been raised by carbachol or ET-1, L-NOARG (10(-5) M) markedly reduced relaxations evoked by electrical stimulation. 3. In trigonal preparations contracted by NA, maximal relaxation was increased after pretreatment with L-ARG (10(-3) M), and the inhibitory effect of L-NOARG (10(-6) M) was prevented. Incubation of the trigonal strips with methylene blue had no effect on relaxations elicited at frequencies less than 6 Hz, but a small inhibition was observed at higher frequencies. 4. Administration of NO (present in acidified solution of NaNO2) induced concentration-dependent relaxations in trigonal preparations contracted by NA, carbachol, or ET-1.L-NOARG (10-5 M) and L-ARG (10-3M) had no effect on these relaxations. However, methylene blue (10-S M) significantly shifted the concentration-response curve for NO to the right. NANC-relaxation and NO-induced relaxation of trigonal preparations were both inhibited by oxyhaemoglobin (10-5 M) and pyrogallol (10-4 M).5. In urethral preparations precontracted by NA, electrical stimulation caused frequency-dependent relaxations. A maximum relaxation of 73 +/- 4% was obtained at 10 Hz. Also in the urethra, NANCrelaxation was blocked by L-NOARG (10-5 M), and a contractile response generally appeared.6. Detrusor strips treated with alpha-beta methylene ATP (10-i M) and atropine (10-6 M), and then contracted by ET-1, showed relaxations (19 +/- 3% of the induced tension) in response to electrical field stimulation (2-20 Hz) only when the tension was high. No response at all, or small contractions, were found in response to electrical stimulation in K+ (35 mM)-contracted detrusor strips. Detrusor preparations contracted by carbachol were concentration-dependently relaxed by exogenously administered NO, SIN-1 (NO-donor), and isoprenaline, whereas vasoactive intestinal polypeptide had minor effects. NO and SIN-1 induced maximal relaxations of 63 +/- 3% and 70 +/- 4%, respectively, of the tension induced by carbachol. Isoprenaline produced an almost complete relaxation (96 +/- 4%).7. The results suggest that NANC-nerve mediated relaxation, involving the L-ARG/NO pathway, can be demonstrated consistently in the pig trigonal and urethral, but not in detrusor smooth muscle. The importance of this pathway for lower urinary tract physiology and pathophysiology remains to be established.

Animals↗
PubMed1996

Effect of Cu2+ on relaxations to the nitrergic neurotransmitter, NO and S-nitrosothiols in the rat gastric fundus.

1. The effects of addition of Cu2+ and chelation of Cu2+ were studied on relaxations in response to S-nitrosothiols and on relaxations to non-adrenergic non-cholinergic (NANC) nerve stimulation, nitric oxide (NO) and glyceryl trinitrate (GTN) in the rat gastric fundus. 2. The S-nitrosothiols S-nitroso-L-cysteine (NOCys, 1-300 nM), S-nitrosoglutathione (GSNO, 0.01-3 microM) and S-nitroso-N-acetyl-D,L-penicillamine (SNAP, 0.01-3 microM) induced concentration-dependent relaxations of the rat gastric fundus muscle strip. The relaxant potencies of the S-nitrosothiols were NOCys > SNAP > GSNO. Relaxations to NOCys were transient and comparable to those to NANC nerve stimulation and NO whereas relaxations to GSNO and SNAP were sustained. The relaxations to NOCys, GSNO and SNAP were significantly and concentration-dependently enhanced by CuSO4 (3-30 microM). The order of relaxant potency in the presence of CuSO4 was reversed to GSNO approximately SNAP > NOCys. 3. In the presence but not in the absence of 0.1 microM GSNO, CuSO4 (1 microM) induced a rapid and transient relaxation which was inhibited by the superoxide radical generator, pyrogallol (30 microM). CuCl2 but not FeSO4 mimicked the effect of CuSO4. 4. Electrical stimulation (0.5-8 Hz) of the rat gastric fundus strips induced frequency-dependent relaxations which were previously shown to be nitrergic in nature and which were not affected by CuSO4 (3-30 microM). Relaxations to NO (3-100 nM) and GTN (0.01-1 microM) were not affected by 3 and 10 microM CuSO4 but were inhibited by 30 microM CuSO4. 5. The Cu2+ chelator, bathocuproine (3-30 microM) significantly and concentration-dependently inhibited the relaxations to NOCys (0.01-3 microM), GSNO (0.01-10 microM) and SNAP (0.01-3 microM). The inhibitory effect of 10 microM bathocuproine was reversed by 3 microM CuSO4. 6. Bathocuproine (3-30 microM) had no effect on the relaxations to NANC nerve stimulation (0.5-8 Hz) or on the concentration-response curve to NO (0.01-0.3 microM), whereas relaxations to GTN (0.01-1 microM) were significantly inhibited by 30 microM bathocuproine. 7. From these results we conclude that relaxations to S-nitrosothiols and to nitrergic stimulation of the rat gastric fundus are differentially affected by addition and chelation of Cu2+, suggesting that the nitrergic NANC neurotransmitter in the rat gastric fundus is not an S-nitrosothiol but is more likely to be free nitric oxide.

Adenosine Triphosphate↗
PubMed2006

Oxygen reduces accumulation of type IV collagen in endothelial cell subcellular matrix via oxidative stress.

Anchorage-dependent cells in culture attach initially to proteins adsorbed to the culture substrate from the medium, and produce and deposit a subcellular matrix during the course of the cultivation. The aim of this study was to determine whether the concentration of O(2) in the culture atmosphere affects the accumulation of type IV collagen and laminin under human endothelial-cell monolayers. Enzyme-linked immunoassays on decellularized polystyrene substrates showed less type IV collagen, but not less laminin, under cells incubated in the standard atmosphere (5% CO(2) in air, i.e., approximately 20% O(2)) compared to an atmosphere of 5% O(2) and 5% CO(2) in N(2). Type IV collagen accumulation was inhibited via oxidative stress, because the inhibitory effect of 20% O(2) was antagonized by antioxidant ascorbic acid, and mimicked by prooxidant pyrogallol and exogenous H(2)O(2). Measurements of endogenous H(2)O(2) accumulation demonstrated that endothelial cells partially adapt to the high O(2) concentration. These results may have implications in endothelium modeling in vitro and in engineering of endothelial cell sheets and endothelialized vascular grafts.

Analysis of Variance↗
PubMed1999

Purification and characterization of a hydroperoxidase from the cyanobacterium Synechocystis PCC 6803: identification of its gene by peptide mass mapping using matrix assisted laser desorption ionization time-of-flight mass spectrometry.

A cytosolic catalase-peroxidase from the cyanobacterium Synechocystis PCC 6803 was purified to homogeneity by a six-step purification procedure. It is a homodimeric enzyme with a subunit molecular mass of 85 kDa. The isoelectric point of the protein is at pH 5.5; Michaelis constant, turnover number, and catalytic efficiency of the catalase activity for H2O2 were measured to be 4.8 mM, 3450 s-1, and 7.2 x 10(5) M-1 s-1, respectively. Preparation and spectroscopy of the pyridine ferrohemochrome identified an iron protoporphyrin IX as the prosthetic group. The enzyme was shown to exhibit both catalase and peroxidase activities, both of which were inhibited by cyanide, leading to a high-spin to low-spin transition of the heme iron center as detected by a shift of the Soret peak from 405 to 421 nm. The catalase-specific inhibitor 3-amino-1,2,4-triazole proved ineffective. o-Dianisidine, pyrogallol and guaiacol functioned as a peroxidatic substrate, but no reaction was detected with NADH, NADPH, glutathione, and ascorbate. Peptide mass mapping using matrix assisted laser desorption ionization time-of-flight mass spectrometry showed the identity between the purified protein and a putative katG gene derived from the genome of Synechocystis PCC 6803. A comparison of amino acid sequences of the catalase-peroxidase from Synechocystis PCC 6803 and those from other bacteria showed a high homology around the assumed distal and proximal histidine residues, suggesting a highly conserved histidine as the fifth ligand of the heme iron.

Amino Acid Sequence↗
PubMed1998

A structural comparison of molybdenum cofactor-containing enzymes.

This work gives an overview of the recent achievements which have contributed to the understanding of the structure and function of molybdenum and tungsten enzymes. Known structures of molybdo-pterin cofactor-containing enzymes will be described briefly and the structural differences between representatives of the same and different families will be analyzed. This comparison will show that the molybdo-pterin cofactor-containing enzymes represent a very heterogeneous group with differences in overall enzyme structure, cofactor composition and stoichiometry, as well as differences in the immediate molybdenum environment. Two recently discovered molybdo-pterin cofactor-containing enzymes will be described with regard to molecular and EPR spectroscopic properties, pyrogallol-phloroglucinol transhydroxylase from Pelobacter acidigallici and acetylene hydratase from Pelobacter acetylenicus. On the basis of its amino acid sequence, transhydroxylase can be classified as a member of the dimethylsulfoxide reductase family, whereas classification of the tungsten/molybdenum-containing acetylene hydratase has to await the determination of its amino acid sequence.

Bacteria, Anaerobic↗
PubMed1992

Contact dermatitis in hairdressers: the Italian experience. Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali.

A multicenter study was performed in 9 Italian centers by members of the GIRDCA, to evaluate the frequency and source of contact sensitization in a group of 302 hairdressers with dermatitis. Occupational habits and use of preventive measures were specifically investigated both in these 302 hairdressers and in a further group of 240 hairdressers who answered a questionnaire. The results showed the presence of an occupationally relevant sensitization in 60.9% of the 302 hairdressers. This proportion included 52 hairdressers who had negative patch tests to the hairdressers' series but showed positive reactions to other allergens, such as nickel, rubber additives, preservatives and fragrances, which were judged relevant to their occupation. Among hair dyes, PPD caused 73 reactions (24.2%), PAP 32 reactions (10.6%), ONPPD 24 reactions (7.9%), and PTD 40 reactions (13.2%). A low incidence of sensitization was detected in our hairdressers to resorcinol and pyrogallol (1.3% for each substance). Among permanent wave allergens, positive reactions to GMTG were found in 11.3% of patients, while ATG gave a lower rate of positive reactions (5.0%). Allergic contact dermatitis due to APS was also relatively common (11.3%). 4 hairdressers in this study gave a positive reaction 30 min after a provocative test with latex gloves, patch testing to the rubber series being negative. Enquiry regarding preventive measures revealed that the majority of hairdressers use gloves when doing hair dyeing, but rarely use them for washing dyed hair or for doing permanent waving. The infrequent use of preventive measures by Italian hairdressers was confirmed by the results of the questionnaire, and possibly explains the high frequency of skin problems (12.5%) in the hairdressing population that was specifically interviewed.

Adolescent↗
PubMed1992

Contact dermatitis in hairdressers' clients.

The aim of our study was to report the frequency of sensitization to hairdressing allergens in a group of patients with contact dermatitis, in whom previous treatments with hair dyes or permanent wave solutions were suspected to be the cause. 49 of 261 hairdressers' clients (18.7%), who were patch tested with the hairdressers' screening series in the years 1985-1990, showed one (27) or more (22) positive reactions to hairdressing chemicals. This study confirms hair dyeing to be the procedure associated with the highest risk of sensitization among hairdressers' clients. Among hair dye allergens, PPD is the most frequent sensitizer (7.3%). A low rate of sensitization to the PPD derivatives PAP, ONPPD and PTD was detected in these clients, there being no differences in the frequency of sensitization to the 3 substances (4.2%, 4.6% and 4.6%, respectively). Only 0.4% of clients were positive to resorcinol, while pyrogallol showed a 2.3% rate of sensitization. Sensitization to GMTG was found in 3.3% of patients. ATG was an infrequent sensitizer (1.1%). Allergic contact dermatitis due to APS is quite rare (2.7%), in view of the widespread use of this compound. A positive open patch test in 1 hairdressers' client, who complained of generalized urticaria after hair bleaching, confirmed the diagnosis of immediate contact reaction due to APS. Sensitization to hairdressing allergens among consumers (18.7%) is possibly more frequent than sensitization to other cosmetic ingredients. We previously detected a 14.3% rate of sensitization to cosmetic ingredients in patients with suspected allergic contact dermatitis caused by cosmetics. On the other hand, reactions to cosmetic ingredients were also common in our patients. This may indicate that hairdressers' clients make greater use of cosmetics than average.

Adolescent↗
PubMed1993

Allergic reactions to a hairdressers' series: results from 9 European centres. The European Environmental and Contact Dermatitis Research Group (EECDRG).

To obtain data on the frequency of sensitization among European hairdressers, the patch test results from 9 centres were evaluated. 8 allergens recommended by the ICDRG and EECDRG in the hairdressing series and PPD from the standard series were used to patch test 809 hairdressers and 104 clients suspected of contact sensitization. Among hairdressers, the mean frequencies of sensitization ranked as follows: GMT 19%, PPD 15%, APS 8%, PTD 8%, ONPPD 4% and PADH 4%. In contrast to GMT in acid permanent waves, the frequency of sensitization to AMT in alkaline permanent waves was only 4%. Frequencies of sensitization to pyrogallol and resorcinol were 0.8% and 0.6%, respectively. The frequencies of sensitization showed marked regional variations, particularly that to GMT, which was highest in Germany (51%), followed by Spain (22%) and London (19%). Clients of hairdressers showed a similar rank order of sensitization frequency, with the exception of APS, which was completely negative in this (small) series.

Beauty Culture↗
PubMed2002

Blood copper concentrations and cuproenzyme activities in a colony of cats.

BACKGROUND: There is little published information on plasma copper and whole blood copper concentrations in cats, and except for extracellular superoxide dismutase (EC SOD), we are unaware of published values for cat cuproenzyme activities. OBJECTIVE: In this study we determined plasma and whole blood copper concentrations, plasma ceruloplasmin (CP), EC SOD and diamine oxidase (DAO) activities, and erythrocyte superoxide dismutase (RBC SOD) activity in a specific pathogen-free colony of cats. Results were evaluated for differences based on age and sex. METHODS: Blood was obtained from 20 adult cats (10 males, 10 females; >1 year of age) and 20 immature cats (10 males, 10 females; <1 year of age). Copper concentrations were determined using atomic absorption spectrophotometry. EC SOD and RBC SOD activities were determined using the pyrogallol oxidation method, and CP activity was determined by the oxidation of 0 dianisidine dihydrochloride. DAO activity was measured using a colorimetric assay. Differences among groups were analyzed using ANOVA. RESULTS: There were significant differences in mean plasma copper concentration, and CP and DAO activities (P=.001,.0001, and.02, respectively) among the 4 groups of cats. No age differences were identified. Male cats had significantly greater mean (+/- SEM) plasma copper (15.4 +/- 0.9 micromol/L versus 11.3 +/- 0.6 micromol/L; P =.001) concentrations, and CP (66.8 +/- 2.9 U/L versus 39.7 +/- 2.1 U/L; P=.0001) and DAO (6.68 +/- 0.16 U/L versus 6.15 +/- 0.1 U/L; P =.03) activities compared with female cats. Males had significantly greater whole blood copper concentrations (16.16 +/- 0.55 micromol/L versus 13.36 +/- 0.52 micromol/L; P =.002) than female cats. CONCLUSION: Differences exist between male and female cats with respect to blood copper concentrations, and CP and DAO activities.

Aging↗
PubMed1969

Modulation of noradrenaline incorporation by nerve activities in the rat submaxillary gland.

1. Rats were anaesthetized with chloralose and prepared for electrical stimulation of the cervical sympathetic trunk. The effect of such stimulation was studied on the incorporation of intravenously infused [(3)H]noradrenaline, [(3)H]adrenaline or [(3)H]dopamine by the submaxillary gland.2. A train of 200 stimuli every min for 30 min at 20/sec increased the total incorporation of [(3)H]noradrenaline by 92% over the unstimulated side of the gland, at 50/sec by about 200% and at 3.3/sec by about 30%. The incorporation of [(3)H]adrenaline and of [(3)H]dopamine was also increased by sympathetic stimulation.3. The increases in unaltered [(3)H]noradrenaline and its metabolites were proportional to the increase in total radioactivity.4. Mean venous outflow from the gland was decreased by 15-30% by the sympathetic stimulation.5. After elimination of extraneuronal binding of noradrenaline by ligation of the common excretory ducts, nerve stimulation still increased incorporation.6. Inhibition of normetanephrine production by pyrogallol did not antagonize the nerve impulse-mediated increase of [(3)H]noradrenaline incorporation. alpha-Methyltyrosine was also without effect.7. Desmethylimipramine and bretylium completely abolished the nerve impulse-mediated increase of [(3)H]noradrenaline incorporation in concentrations which did not affect the control uptake or abolish adrenergic transmission.8. Reserpine, guanethidine and phenoxybenzamine antagonized both the control and nerve impulse-mediated incorporations of [(3)H]noradrenaline.9. The results indicate that nerve impulses modulate the incorporation of transmitter amine at the neuronal membrane. Possible mechanisms for this modulation are discussed.

Animals↗
PubMed1977

Extradiol cleavage of 3-methylcatechol by catechol 1,2-dioxygenase from various microorganisms.

The isofunctional enzymes of catechol 1,2-dioxygenase from species of Acinetobacter, Pseudomonas, Nocardia, Alcaligenes, and Corynebacterium oxidize 3-methylcatechol according to both the intradiol and extradiol cleavage patterns. However, the enzyme preparations from Brevibacterium and Arthrobacter have only the intradiol cleavage activity. Comparison of substrate specificity among these isofunctional dioxygenases shows striking differences in the oxidation of 3-methylcatechol, 4-methylcatechol and pyrogallol.

Journal Article↗
PubMed1987

Transformations of chloroguaiacols, chloroveratroles, and chlorocatechols by stable consortia of anaerobic bacteria.

Metabolically stable consortia of anaerobic bacteria obtained by enrichment of sediment samples with 3,4,5-trimethoxybenzoate (TMBA), 3,4,5-trihydroxybenzoate (gallate [GA]), or 5-chlorovanillin (CV) were used to study the anaerobic transformation of a series of chloroveratroles, chloroguaiacols, and chlorocatechols used as cosubstrates. Experiments were carried out with growing cultures, and the following pathways were demonstrated for metabolism of the growth substrates: (i) TMBA produced GA, which was further degraded without the formation of aromatic intermediates; (ii) GA formed pyrogallol, which was stable to further transformation; and (iii) CV was degraded by a series of steps involving de-O-methylation, oxidation of the aldehyde group, and decarboxylation to 3-chlorocatechol before ring cleavage. Mono-de-O-methylation of the cosubstrates occurred rapidly in the order 4,5,6-trichloroguaiacol greater than 3,4,5-trichloroguaiacol approximately 3,4,5-trichloroveratrole approximately tetrachloroveratrole greater than tetrachloroguaiacol and was concomitant with degradation of the growth substrates. For the polymethoxy compounds--chloroveratroles, 1,2,3-trichloro-4,5,6-trimethoxybenzene, and 4,5,6-trichlorosyringol--de-O-methylation took place sequentially. The resulting chlorocatechols were stable to further transformation until the cultures had exhausted the growth substrates; selective dechlorination then occurred with the formation of 3,5-dichlorocatechol from 3,4,5-trichlorocatechol and of 3,4,6-trichlorocatechol from tetrachlorocatechol. 2,4,5-, 2,4,6-, and 3,4,5-trichoroanisole and 2,3,4,5-tetrachloroanisole were de-O-methylated, but the resulting chlorophenols were resistant to dechlorination. These results extend those of a previous study with spiked sediment samples and their endogenous microflora and illustrate some of the transformations of chloroguaiacols and chlorocatechols which may be expected to occur in anaerobic sediments.

Anisoles↗
PubMed1989

Metabolism of Ferulic Acid by Paecilomyces variotii and Pestalotia palmarum.

Ferulic acid metabolism was studied in cultures of two micromycetes producing different amounts of phenol oxidases. In cultures of the low phenol oxidase producer Paecilomyces variotii, ferulic acid was decarboxylated to 4-vinylguaiacol, which was converted to vanillin and then either oxidized to vanillic acid or reduced to vanillyl alcohol. Vanillic acid underwent simultaneously an oxidative decarboxylation to methoxyhydroquinone and a nonoxidative decarboxylation to guaiacol. Methoxyhydroquinone and guaiacol were demethylated to yield hydroxyquinol and catechol, respectively. Catechol was hydroxylated to pyrogallol. Degradation of ferulic acid by Paecilomyces variotii proceeded mainly via methoxyhydroquinone. The high phenol oxidase producer Pestalotia palmarum catabolized ferulic acid via 4-vinylguaiacol, vanillin, vanillyl alcohol, vanillic acid, and methoxyhydroquinone. However, the main reactions observed with this fungus involved polymerization reactions.

Journal Article↗