Biomedical subjects

A Ros Barceló

Publications and source records attributed to A Ros Barceló.

At least 19 recordsLinked to original sources

PubMed2007

Structural motifs of syringyl peroxidases predate not only the gymnosperm-angiosperm divergence but also the radiation of tracheophytes.

* The most distinctive variation in the monomer composition of lignins in vascular land plants is that found between the two main groups of seed plants. Thus, while gymnosperm lignins are typically composed of guaiacyl (G) units, angiosperm lignins are largely composed of similar levels of G and syringyl (S) units. * However, and contrary to what might be expected, peroxidases isolated from basal (Cycadales and Ginkgoales) and differentially evolved (Coniferales and Gnetales) gymnosperms are also able to oxidize S moieties, and this ability is independent of the presence or absence of S-type units in their lignins. * The results obtained led us to look at the protein database to search for homologies between gymnosperm peroxidases and true eudicot S-peroxidases, such as the Zinnia elegans peroxidase. * The findings showed that certain structural motifs characteristic of eudicot S-peroxidases (certain amino acid sequences and beta-sheet secondary structures) predate the gymnosperm-angiosperm divergence and the radiation of tracheophytes, since they are found not only in peroxidases from basal gymnosperms, ferns and lycopods, but also in peroxidases from the moss Physcomitrella patens (Bryopsida) and the liverwort Marchantia polymorpha (Marchantiopsida), which, as typical of bryophytes, do not have xylem tissue nor lignins.

Amino Acid Motifs↗

PubMed2006

The apoplastic antioxidant system in Prunus: response to long-term plum pox virus infection.

This work describes, for the first time, the changes taking place in the antioxidative system of the leaf apoplast in response to plum pox virus (PPV) in different Prunus species showing different susceptibilities to PPV. The presence of p-hydroxymercuribenzoic acid (pHMB)-sensitive ascorbate peroxidase (APX) (class I APX) and pHMB-insensitive APX (class III APX), superoxide dismutase (SOD), peroxidase (POX), NADH-POX, and polyphenoloxidase (PPO) was described in the apoplast from both peach and apricot leaves. PPV infection produced different changes in the antioxidant system of the leaf apoplast from the Prunus species, depending on their susceptibility to the virus. In leaves of the very susceptible peach cultivar GF305, PPV brought about an increase in class I APX, POX, NADH-POX, and PPO activities. In the susceptible apricot cultivar Real Fino, PPV infection produced a decrease in apoplastic POX and SOD activities, whereas a strong increase in PPO was observed. However, in the resistant apricot cultivar Stark Early Orange, a rise in class I APX as well as a strong increase in POX and SOD activities was noticed in the apoplastic compartment. Long-term PPV infection produced an oxidative stress in the apoplastic space from apricot and peach plants, as observed by the increase in H2O2 contents in this compartment. However, this increase was much higher in the PPV-susceptible plants than in the resistant apricot cultivar. Only in the PPV-susceptible apricot and peach plants was the increase in apoplastic H2O2 levels accompanied by an increase in electrolyte leakage. No changes in the electrolyte leakage were observed in the PPV-inoculated resistant apricot leaves, although a 42% increase in the apoplastic H2O2 levels was produced. Two-dimensional electrophoresis analyses revealed that the majority of the polypeptides in the apoplastic fluid had isoelectric points in the range of pI 4-6. The identification of proteins using MALDI-TOF (matrix-assisted laser desorption/ionization-time of flight) and peptide mass fingerprinting analyses showed the induction of a thaumatin-like protein as well as the decrease of mandelonitrile lyase in peach apoplast due to PPV infection. However, most of the selected polypeptides showed no homology with known proteins. This fact emphasizes that, at least in Prunus, most of the functions of the apoplastic space remain unknown. It is concluded that long-term PPV infection produced an oxidative stress in the leaf apoplast, contributing to the deleterious effects produced by PPV infection in leaves of inoculated, susceptible Prunus plants.

Antioxidants↗

PubMed2006

Characterization of the last step of lignin biosynthesis in Zinnia elegans suspension cell cultures.

The last step of lignin biosynthesis in Zinnia elegans suspension cell cultures (SCCs) catalyzed by peroxidase (ZePrx) has been characterized. The k(3) values shown by ZePrx for the three monolignols revealed that sinapyl alcohol was the best substrate, and were proportional to their oxido/reduction potentials, signifying that these reactions are driven exclusively by redox thermodynamic forces. Feeding experiments demonstrate that cell wall lignification in SCCs is controlled by the rate of supply of H(2)O(2). The results also showed that sites for monolignol beta-O-4 cross-coupling in cell walls may be saturated, suggesting that the growth of the lineal lignin macromolecule is not infinite.

Asteraceae↗

PubMed2006

Two distinct cell sources of H2O2 in the lignifying Zinnia elegans cell culture system.

The use of transdifferentiating Zinnia elegans mesophyll cells has proved useful in investigations of the process of xylem differentiation from cambial derivatives. Cultured mesophyll cells can be induced by external stimuli to proceed through temporally controlled developmental programs which conclude in the formation of single-cell-derived dead vascular tracheids and parenchyma-like elements. However, there is a gap in our knowledge concerning the role played by reactive oxygen species (O(2) (-) and H(2)O(2)) in the development of these vascular elements. In this study, we show by the following four independent and highly selective methods that transdifferentiating Z. elegans mesophyll cells are capable of producing reactive oxygen species: the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay, which monitors O(2) (-) production, and the xylenol orange, 2,7-dichlorofluorescein diacetate, and CeCl(3) assays, which monitor H(2)O(2) production and localization. The joint use of these biochemical (XTT and xylenol orange) assays and cytochemical (2,7-dichlorofluorescein diacetate and CeCl(3)) probes revealed that transdifferentiating Z. elegans mesophyll cells do not show an oxidative burst but live in a strongly oxidative state during the entire culture period. In this state, H(2)O(2) is produced by both tracheary and parenchyma-like elements, the nonlignifying parenchyma-like cells acting quantitatively as the main source. The existence of these two sources of H(2)O(2) in this in vitro cell culture system may be especially relevant during the later stages of tracheary cell wall lignification, in which lignifying tracheary elements become hollow. In the case of differentiating tracheary elements, H(2)O(2) was located in the same place and at the same time as the onset of tracheary element lignification, i.e., at the primary cell wall during secondary thickening, supporting the view that the H(2)O(2) produced by this in vitro culture system is destined for use during lignin biosynthesis.

Asteraceae↗

PubMed2005

Cloning and molecular characterization of the basic peroxidase isoenzyme from Zinnia elegans, an enzyme involved in lignin biosynthesis.

The major basic peroxidase from Zinnia elegans (ZePrx) suspension cell cultures was purified and cloned, and its properties and organ expression were characterized. The ZePrx was composed of two isoforms with a M(r) (determined by matrix-assisted laser-desorption ionization time of flight) of 34,700 (ZePrx34.70) and a M(r) of 33,440 (ZePrx33.44). Both isoforms showed absorption maxima at 403 (Soret band), 500, and 640 nm, suggesting that both are high-spin ferric secretory class III peroxidases. M(r) differences between them were due to the glycan moieties, and were confirmed from the total similarity of the N-terminal sequences (LSTTFYDTT) and by the 99.9% similarity of the tryptic fragment fingerprints obtained by reverse-phase nano-liquid chromatography. Four full-length cDNAs coding for these peroxidases were cloned. They only differ in the 5'-untranslated region. These differences probably indicate different ways in mRNA transport, stability, and regulation. According to the k(cat) and apparent K(m)(RH) values shown by both peroxidases for the three monolignols, sinapyl alcohol was the best substrate, the endwise polymerization of sinapyl alcohol by both ZePrxs yielding highly polymerized lignins with polymerization degrees > or =87. Western blots using anti-ZePrx34.70 IgGs showed that ZePrx33.44 was expressed in tracheary elements, roots, and hypocotyls, while ZePrx34.70 was only expressed in roots and young hypocotyls. None of the ZePrx isoforms was significantly expressed in either leaves or cotyledons. A neighbor-joining tree constructed for the four full-length cDNAs suggests that the four putative paralogous genes encoding the four cDNAs result from duplication of a previously duplicated ancestral gene, as may be deduced from the conserved nature and conserved position of the introns.

Amino Acid Sequence↗

PubMed2005

Nitric oxide production by the differentiating xylem of Zinnia elegans.

Nitric oxide (NO) is currently regarded as a signal molecule involved in plant cell differentiation and programmed cell death. Here, we investigated NO production in the differentiating xylem of Zinnia elegans by confocal laser scanning microscopy to answer the question of whether NO is produced during xylem differentiation. Results showed that NO production was mainly located in both phloem and xylem regardless of the cell differentiation status. However, there was evidence for a spatial NO gradient inversely related to the degree of xylem differentiation and a protoplastic NO burst was associated with the single cell layer of pro-differentiating thin-walled xylem cells. Confirmation of these results was obtained using trans-differentiating Z. elegans mesophyll cells. In this system, the scavenging of NO by means of 2-phenyl-4,4,5,5-tetramethyl imidazoline-1-oxyl-3-oxide (PTIO) inhibits tracheary element differentiation but increases cell viability. These results suggest that plant cells, which are just predetermined to irreversibly trans-differentiate in xylem elements, show a burst in NO production, this burst being sustained as long as secondary cell wall synthesis and cell autolysis are in progress.

Apoptosis↗

PubMed2004

Xylem parenchyma cells deliver the H2O2 necessary for lignification in differentiating xylem vessels.

Lignification in Zinnia elegans L. stems is characterized by a burst in the production of H(2)O(2), the apparent fate of which is to be used by xylem peroxidases for the polymerization of p-hydroxycinnamyl alcohols into lignins. A search for the sites of H(2)O(2) production in the differentiating xylem of Z. elegans stems by the simultaneous use of optical (bright field, polarized light and epi-polarization) and electron-microscope tools revealed that H(2)O(2) is produced on the outer-face of the plasma membrane of both differentiating (living) thin-walled xylem cells and particular (non-lignifying) xylem parenchyma cells. From the production sites it diffuses to the differentiating (secondary cell wall-forming) and differentiated lignifying xylem vessels. H(2)O(2) diffusion occurs mainly through the continuous cell wall space. Both the experimental data and the theoretical calculations suggest that H(2)O(2 )diffusion from the sites of production might not limit the rate of xylem cell wall lignification. It can be concluded that H(2)O(2) is produced at the plasma membrane in differentiating (living) thin-walled xylem cells and xylem parenchyma cells associated to xylem vessels, and that it diffuses to adjacent secondary lignifying xylem vessels. The results strongly indicate that non-lignifying xylem parenchyma cells are the source of the H(2)O(2) necessary for the polymerization of cinnamyl alcohols in the secondary cell wall of lignifying xylem vessels.

Asteraceae↗

PubMed2004

Zinnia elegans uses the same peroxidase isoenzyme complement for cell wall lignification in both single-cell tracheary elements and xylem vessels.

The nature of the peroxidase isoenzyme complement responsible for cell wall lignification in both Zinnia elegans seedlings and Z. elegans tracheary single-cell cultures have been studied. Results showed that both hypocotyls and stems from lignifying Z. elegans seedlings express a cell wall-located basic peroxidase of pI approximately 10.2, which was purified to homogeneity. Molecular mass determination under non-denaturing conditions showed an M(r) of about 43 000, similar to that of other plant peroxidases. The purified Z. elegans peroxidase showed absorption maxima at 403 (Soret band), and at 496-501 and 632-635 (alpha and beta absorption bands), indicating that this enzyme is a high spin ferric haem protein, belonging to the plant peroxidase superfamily, the prosthetic group being ferric protoporphyrin IX. The N-terminal amino acid sequence of this Z. elegans basic peroxidase was KVAVSPLS (peptide motif in bold), which shows strong homologies with the N-amino acid terminus of other strongly basic plant peroxidases. Isoenzyme and western blot analyses showed that this peroxidase isoenzyme is also expressed in trans-differentiating Z. elegans tracheary single-cell cultures. The results also showed that Z. elegans tracheary single-cell cultures not only express the same peroxidase isoenzyme as the Z. elegans lignifying xylem, but that this peroxidase isoenzyme acts as a marker of tracheary element differentiation in Z. elegans mesophyll single-cell cultures. From these results, it may be concluded that Z. elegans uses a single programme, i.e. an identical peroxidase isoenzyme complement, for lignification of the xylem, regardless of the existence of different ontogenesis pathways from either mesophyll cells (in the case of tracheary elements) or cambial derivatives (in the case of xylem vessels).

Asteraceae↗

PubMed2003

Peroxidase from Catharanthus roseus (L.) G. Don and the biosynthesis of alpha-3',4'-anhydrovinblastine: a specific role for a multifunctional enzyme.

We have characterized a basic peroxidase with alpha-3',4'-anhydrovinblastine (AVLB) synthase activity, which was purified from Catharanthus roseus leaves. This enzyme was the single peroxidase isoenzyme detected in C. roseus leaves, and the single AVLB synthase activity detected in C. roseus extracts. It was observed that the monomeric substrates of AVLB, vindoline and catharanthine, are both suitable electron donors for the oxidizing intermediates of the basic peroxidase, compounds I and II. Results also showed that the reaction proceeds by a radical-propagated mechanism. Substrate specificity studies of the enzyme revealed that it was also able to oxidize several common peroxidase substrates, indicating a broad range of substrate specificity that is characteristic of class III plant peroxidases. Cytochemical studies showed that the enzyme is localized in C. roseus mesophyll vacuoles, in individual spots at the inner surface of the tonoplast. This particular location suggests a meaningful spatial organization that led to the proposal of a metabolic channeling model for the peroxidase-mediated synthesis of AVLB. The importance of this type of mechanism in the regulation of peroxidase isoenzyme functions in vivo is discussed. In view of the results obtained it is concluded that the basic peroxidase present in C. roseus leaves fulfills all the requirements to be considered as an AVLB synthase, and it is proposed that this specific function of this multifunctional enzyme is determined by metabolic channeling resulting from specific protein-protein interactions.

Catharanthus↗

PubMed2002

H(2)O(2) generation during the auto-oxidation of coniferyl alcohol drives the oxidase activity of a highly conserved class III peroxidase involved in lignin biosynthesis.

Characterization of lignified Zinnia elegans hypocotyls by both alkaline nitrobenzene oxidation and thioacidolysis reveals that coniferyl alcohol units are mainly found as part of 4-O-linked end groups and aryl-glycerol-beta-aryl ether (beta-O-4) structures. Z. elegans hypocotyls also contain a basic peroxidase (EC 1.11.1.7) capable of oxidizing coniferyl alcohol in the absence of H(2)O(2). Results showed that the oxidase activity of the Z. elegans basic peroxidase is stimulated by superoxide dismutase, and inhibited by catalase and anaerobic conditions. Results also showed that the oxidase activity of this peroxidase is due to an evolutionarily gained optimal adaptation of the enzyme to the microM H(2)O(2) concentrations generated during the auto-oxidation of coniferyl alcohol, the stoichiometry of the chemical reaction (mol coniferyl alcohol auto-oxidized/mol H(2)O(2) formed) being 0.496. These results therefore suggest that the H(2)O(2) generated during the auto-oxidation of coniferyl alcohol is the main factor that drives the unusual oxidase activity of this highly conserved lignin-synthesizing class III peroxidase.

Chromatography, High Pressure Liquid↗

PubMed2002

Comparative study of the products of the peroxidase-catalyzed and the polyphenoloxidase-catalyzed (+)-catechin oxidation. Their possible implications in strawberry (Fragaria x ananassa) browning reactions.

The peroxidase- and polyphenoloxidase-catalyzed oxidations of (+)-catechin yield several products showing different degrees of polymerization, which are apparently responsible for the pigment decay and the associated browning reaction that occurs in processed strawberry fruits and their derived foods. In this work, we have purified both peroxidase and polyphenoloxidase from Oso Grande cv. strawberry fruits, and comparatively analyzed the products of their enzyme-mediated (+)-catechin oxidation. The joint analysis by reversed-phase and size-exclusion HPLC of the (+)-catechin oxidation products obtained with both enzymes indicate that they were qualitatively the same: dehydrodicatechin B4, a (+)-catechin quinone methide, dehydrodicatechin A, a (+)-catechin trimer, and a (+)-catechin oligomer with polymerization degree equal to or greater than 5. The main quantitative differences between the oxidative reactions were the great amount of oligomer formed in the case of the polyphenoloxidase-mediated reaction and the low amount of (+)-catechin reacted in the case of the peroxidase-mediated reaction. One of the possible reasons for such low levels of (+)-catechin consumption in the case of the peroxidase-mediated reaction was the possible inhibition by products of the enzyme-catalyzed oxidation. In fact, the peroxidase-mediated (+)-catechin oxidation was differentially inhibited by dehydrodicatechin A, showing a competitive type inhibition and a k(I) of 6.4 microM. In light of these observations, these results suggest that brown polymer formation, estimated as oligomeric compounds resulting from (+)-catechin oxidation, in strawberries is mainly due to polyphenoloxidase, and although peroxidase also plays an important role, it is apparently auto-regulated by product (dehydrodicatechin A) inhibition.

Catechin↗

PubMed2002

O-4-Linked coniferyl and sinapyl aldehydes in lignifying cell walls are the main targets of the Wiesner (phloroglucinol-HCl) reaction.

The nature and specificity of the Wiesner test (phloroglucinol-HCl reagent) for the aromatic aldehyde fraction contained in lignins is studied. Phloroglucinol reacted in ethanol-hydrochloric acid with coniferyl aldehyde, sinapyl aldehyde, vanillin, and syringaldehyde to yield either pink pigments (in the case of hydroxycinnamyl aldehydes) or red-brown pigments (in the case of hydroxybenzaldehydes). However, coniferyl alcohol, sinapyl alcohol, and highly condensed dehydrogenation polymers derived from these cinnamyl alcohols and aldehydes did not react with phloroglucinol in ethanol-hydrochloric acid. The differences in the reactivity of phloroglucinol with hydroxycinnamyl aldehydes and their dehydrogenation polymers may be explained by the fact that, in the latter, the unsubstituted (alpha,beta-unsaturated) cinnamaldehyde functional group, which is responsible for the dye reaction, is lost due to lateral chain cross-linking reactions involving the beta carbon. Fourier transform infrared spectroscopy and thioacidolysis analyses of phloroglucinol-positive lignifying plant cell walls belonging to the plant species Zinnia elegans L., Capsicum annuumvar. annuum, Populus albaL., and Pinus halepensisL. demonstrated the presence of 4- O-linked hydroxycinnamyl aldehyde end groups and 4- O-linked 4-hydroxy-3-methoxy-benzaldehyde (vanillin) end groups in lignins. However, given the relatively low abundance of 4- O-linked vanillin in lignifying cell walls and the low extinction coefficient of its red-brown phloroglucinol adduct, it is unlikely that vanillin contributes to a great extent to the phloroglucinol-positive stain reaction. These results suggest that the phloroglucinol-HCl pink stain of lignifying xylem cell walls actually reveals the 4- O-linked hydroxycinnamyl aldehyde structures contained in lignins. Histochemical studies showed that these aldehyde structures are assembled, as in the case of coniferyl aldehyde, during the early stages of xylem cell wall lignification.

Arachidonic Acids↗

PubMed1999

H(2)O(2)-mediated pigment decay in strawberry as a model system for studying color alterations in processed plant foods.

Phenolic and pigment (anthocyanin) stability in processing-ripe strawberries in response to aging under mildly oxidizing conditions, provoked by exogenous application of H(2)O(2), has been studied to design a simplified model system to study color alterations (pigment decay) that occur in strawberry-derived foods during processing and storage. The results showed that phenolic metabolism in strawberry slices during aging under mildly oxidizing conditions may be either oxidative (independent of exogenous H(2)O(2)) or peroxidative (dependent on exogenous H(2)O(2)), and that feeding strawberry slices with H(2)O(2) stimulates the oxidative phenomena which take place in their absence, such as the processes of anthocyanin and catechin degradation. The results also showed that because both (+)-catechin and anthocyanin levels in strawberry slices fall as H(2)O(2) increases, both p-hydroxybenzoic acid and brown polymeric compounds are formed. Comparison of these results with controls in the absence of H(2)O(2) suggests that peroxidase may play an important role in catechin consumption and in anthocyanin degradation and brown polymer formation during the aging of strawberry slices under mildly oxidizing conditions.

Color↗

PubMed1998

Purification and characterization of alpha-3',4'-anhydrovinblastine synthase (peroxidase-like) from Catharanthus roseus (L.) G. Don.

An H2O2-dependent enzyme capable of coupling catharanthine and vindoline into alpha-3',4'-anhydrovinblastine (AVLB) was purified to apparent homogeneity from Catharanthus roseus leaves. The enzyme shows a specific AVLB synthase activity of 1.8 nkat/mg, and a molecular weight of 45.40 kDa (SDS-PAGE). In addition to AVLB synthase activity, the purified enzyme shows peroxidase activity, and the VIS spectrum of the protein presents maxima at 404, 501 and 633 nm, indicating that it is a high spin ferric heme protein, belonging to the plant peroxidase superfamily. Kinetic studies revealed that both catharanthine and vindoline were substrates of the enzyme, AVLB being the major coupling product.

Chromatography, Affinity↗

PubMed1997

Cytochemical localization of phenol-oxidizing enzymes in lignifying Coleus blumei stems.

The cytochemical localization of the phenol oxidases, laccase and peroxidase, has been studied in pro-lignifying and lignifying Coleus blumei stem sections using 4-methoxy-alpha-naphthol as substrate. The results illustrated that, for short incubation times, both pro-lignifying and lignifying Coleus sections showed H2O2-dependent phenol oxidase (peroxidase-like) activity in epidermal and vascular tissues, while no detectable H2O2-independent phenol oxidase (laccase-like) activity was found in Coleus tissues. For long incubation times, H2O2-independent phenol-oxidases can also be detected in these tissues, however, this is probably due to the partial capability of intercellular washing fluid Coleus peroxidase to oxidize 4-methoxy-alpha-naphthol in the absence of exogenously added H2O2. This illustrates not only the importance of the substrate used, but also the importance of the incubation time, in the cytochemical localization of phenol oxidizing enzymes.

Histocytochemistry↗

PubMed1997

Lignification in plant cell walls.

Cell wall lignification is a complex process occurring exclusively in higher plants; its main function is to strengthen the plant vascular body. This process involves the deposition of ill-defined phenolic polymers, the so-called lignins, on the extracellular polysaccharidic matrix. These polymers arise from the oxidative coupling of three cinnamyl alcohols in a nonrandom reaction, in which cell wall polysaccharides appear to influence the freedom of cinnamyl alcohol radicals, giving rise to a highly orchestrated process. This review is focused on the most recent advances in the chemical, biochemical, cytological, physiological, and evolutive aspects of cell wall lignification. As we shall see throughout this review, there are still some open questions to be answered which may serve as the basis of future endeavors.

Cell Wall↗

PubMed1995

Effect of fosetyl-A1 on peroxidase from grapevine (Vitis vinifera) cells.

Grapevine (Vitis vinifera cv. Monastrell) suspension cell cultures were treated with fosetyl-A1, a widely used systemic fungicide for grapevine diseases caused by oomycetes, and examined at the electron microscope level for peroxidase cytochemistry. The results showed that treatment with fosetyl-A1 provokes an activation of both vacuolar sap and tonoplast-located peroxidase, already described as due to the basic peroxidase isoenzyme, B5, which was previously characterized as a constitutive marker of disease resistance against Plasmopara viticola in axillary bud cultures of Vitis spp. This activation of peroxidase isoenzyme B5, as seen at the electron microscope level, was confirmed by cytophotometric methods, but is in contrast with the unchanged enzyme level determined by biochemical methods. These results suggest a metabolic activation of peroxidase isoenzyme B5 as a consequence of fosetyl-A1 treatment, probably due to an acidification of the vacuole. This response was accompanied by the appearance of myelin-like structures inside the cytoplasm and osmiophylic-bodies inside the mitochondria. However, the latter structural changes cannot easily be related to the above described specific peroxidase response.

Biotransformation↗

PubMed1994

Purification of a basic peroxidase isoenzyme from Capsicum fruits and the immunoinhibition of its capsaicin oxidation capacity by antibodies raised against horseradish peroxidase.

Pepper fruits contain a peroxidase isoenzyme of basic pI, the peroxidase isoenzyme B6, located in vacuoles and the principal component of peroxidase polymorphism in the whole fruit. This isoenzyme was purified by preparative isoelectric focusing in glycerol-stabilized 3.0-10.0 pH gradients and characterized for its ability to oxidize capsaicin (8-methyl-N-vanillyl-6-nonenamide). Spectrophotometric studies illustrated that the capsaicin oxidation by pepper peroxidase isoenzyme B6 was H2O2-dependent and was totally abolished by antibodies raised against horseradish peroxidase. From these studies, it can be concluded that capsaicin is oxidized by pepper peroxidase isoenzyme B6, thus confirming a role for this peroxidase isoenzyme in capsaicin turnover and degradation.

Animals↗