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Investigation of the biosynthetic origins of chromenes in Piper aduncum e Peperomia obtusifolia

Grant number: 11/16815-8
Support type:Scholarships in Brazil - Master
Effective date (Start): March 01, 2012
Effective date (End): July 31, 2013
Field of knowledge:Physical Sciences and Mathematics - Chemistry - Organic Chemistry
Principal Investigator:Maysa Furlan
Grantee:Amauri Alves de Souza Júnior
Home Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The chromenes represent an important class of compounds isolated from Piperaceae several species and show several biological activities, including antifungal, trypanocidal, antioxidant and anti-parasitic. These compounds have a high structural diversity and the biosynthetic origins for these compounds is different in Piper and Peperomia. The diversification of metabolic pathways is corroborated by the presence a group methyl as substituent on the aromatic ring. With this, the biogenesis suggested for chromene accumulated in Peperomia is based on the polyketide pathway, aldol condensation pathway, and as a precursor orsellinic acid, while the chromenes isolated from Piper species, are biosynthesized by shikimate pathway, providing chromene with pattern of substitution the aromatic ring characteristic of the pathway C6-C1. Studies conducted showed that both the chromenes isolated from Piper as a Peperomia, present prenylations the aromatic system. Currently, it is accepted that the isoprene units (IPP and DMAPP) are derived from the mevalonate pathway (compartmentalized in the cytosol) and pyruvate-triose (compartmentalized in plastids). The prenylation of p-hydroxybenzoic acid occurs by triose pyruvate pathway, while the subsequent prenylations occur by mevalonate pathway. The triose-pyruvate has apparently a diurnal circadian rhythm. The circadian rhythm of cyclase involved in a prenyl unit for formation of the group chromene is still unknown. In view of this, Piper aduncum and Peperomia obtusifolia were adopted as a model for determining the circadian rhythm of cyclase and production of chromene. In addition to the circadian studies, this project aims to carry out enzyme assays using the likely precursors (orsellinic acid and p-hydroxybenzoic acid), incorporation of labeled precursors with stable isotopes in enzyme extract, including the [1-13C]-D-glucose, malonyl-CoA and sodium acetate, analysis of enzymatic fractions by two-dimensional electrophoresis and mass spectrometry (in order to find differences in protein expression). The results of these experiments will help explain the difference in proteomic level and on different routes to the formation of chromene showing accumulation in species of Piper and Peperomia.