Identification of phenolic compounds in isolated vacuoles of the medicinal plant Catharanthus roseus and their interaction with vacuolar class III peroxidase: an H2O2 affair?

• Type: Article in International Scientific Journal
• Date: 2011

Authors

Federico Ferreres (Author) Other; Raquel Figueiredo (Author) Other; Sara Bettencourt (Author) Other; Inês Carqueijeiro (Author) Other; Juliana Oliveira (Author) Other; Angel Gil-Izquierdo (Author) Other; David M. Pereira (Author) FFUP; Patrícia Valentão (Author) FFUP; Paula B. Andrade (Author) FFUP; Patrícia Duarte (Author) Other; Alfonso Ros Barcelo (Author) Other; Mariana Sottomayor (Author) Other

Journal

Title: Journal of Experimental Botany

Pages: 1-14

ISSN: 0022-0957

Publisher: Oxford University Press

Indexing

ISI Web of Knowledge - 130 Citations

Scopus - 148 Citations

Pubmed / Medline

Scientific classification

FOS: Medical and Health sciences > Other medical sciences

CORDIS: Health sciences > Pharmacological sciences > Pharmacognosy

Other information

Authenticus ID: P-002-RRR

Resumo (PT): Class III peroxidases (Prxs) are plant enzymes capable of using H2O2 to oxidize a range of plant secondary metabolites, notably phenolic compounds. These enzymes are localized in the cell wall or in the vacuole, which is a target for secondary metabolite accumulation, but very little is known about the function of vacuolar Prxs. Here, the physiological role of the main leaf vacuolar Prx of the medicinal plant Catharanthus roseus, CrPrx1, was further investigated namely by studying its capacity to oxidize co-localized phenolic substrates at the expense of H2O2. LCPAD- MS analysis of the phenols from isolated leaf vacuoles detected the presence of three caffeoylquinic acids and four flavonoids in this organelle. These phenols or similar compounds were shown to be good CrPrx1 substrates, and the CrPrx1-mediated oxidation of 5-O-caffeoylquinic acid was shown to form a co-operative regenerating cycle with ascorbic acid. Interestingly, more than 90% of total leaf Prx activity was localized in the vacuoles, associated to discrete spots of the tonoplast. Prx activity inside the vacuoles was estimated to be 1809 nkat ml21, which, together with the determined concentrations for the putative vacuolar phenolic substrates, indicate a very high H2O2 scavenging capacity, up to 9 mM s21. Accordingly, high light conditions, known to increase H2O2 production, induced both phenols and Prx levels. Therefore, it is proposed that the vacuolar couple Prx/secondary metabolites represent an important sink/buffer of H2O2 in green plant cells. <br> <br> Key words: H2O2, H2O2 scavenging and homeostasis, vacuolar class III peroxidases, vacuolar phenolic compounds, vacuolar secondary metabolites, vacuoles. <br> <a target="_blank" href=" http://jxb.oxfordjournals.org/content/early/2011/02/28/jxb.erq458.abstract"> Texto integral </a> <br> <br>

Abstract (EN): Class III peroxidases (Prxs) are plant enzymes capable of using H2O2 to oxidize a range of plant secondary metabolites, notably phenolic compounds. These enzymes are localized in the cell wall or in the vacuole, which is a target for secondary metabolite accumulation, but very little is known about the function of vacuolar Prxs. Here, the physiological role of the main leaf vacuolar Prx of the medicinal plant Catharanthus roseus, CrPrx1, was further investigated namely by studying its capacity to oxidize co-localized phenolic substrates at the expense of H2O2. LCPAD- MS analysis of the phenols from isolated leaf vacuoles detected the presence of three caffeoylquinic acids and four flavonoids in this organelle. These phenols or similar compounds were shown to be good CrPrx1 substrates, and the CrPrx1-mediated oxidation of 5-O-caffeoylquinic acid was shown to form a co-operative regenerating cycle with ascorbic acid. Interestingly, more than 90% of total leaf Prx activity was localized in the vacuoles, associated to discrete spots of the tonoplast. Prx activity inside the vacuoles was estimated to be 1809 nkat ml21, which, together with the determined concentrations for the putative vacuolar phenolic substrates, indicate a very high H2O2 scavenging capacity, up to 9 mM s21. Accordingly, high light conditions, known to increase H2O2 production, induced both phenols and Prx levels. Therefore, it is proposed that the vacuolar couple Prx/secondary metabolites represent an important sink/buffer of H2O2 in green plant cells. <br> <br> Key words: H2O2, H2O2 scavenging and homeostasis, vacuolar class III peroxidases, vacuolar phenolic compounds, vacuolar secondary metabolites, vacuoles. <br> <a target="_blank" href="http://jxb.oxfordjournals.org/content/early/2011/02/28/jxb.erq458.abstract "> Full text</a> <br> <br>

Language: English

Type (Professor's evaluation): Scientific