Dopamine-derived pigments in nature: identification of decarboxybetalains in Amaranthaceae species.

A unique family of decarboxylated betalains derived from dopamine has recently been discovered. Due to the lack of chemical standards, the existence and distribution of decarboxylated betalains in nature remain unknown. Traditional betalains contain L-dihydroxyphenylalanine as the starting point of the biosynthetic pathway and betalamic acid as a structural and functional unit, while the recently discovered betalains rely on dopamine. Here, 30 dopamine-derived betalains were biotechnologically produced, purified, and characterized, creating an unprecedented library to explore their properties and presence in nature. The maximum absorbance wavelengths for the pigments ranged between 461 and 485 nm. HPLC analysis showed retention times between 0.6 and 2.2 min higher than traditional betalains due to their higher hydrophobicity. The presence of decarboxybetalains in nature was screened using HPLC-ESI-Q-TOF mass spectrometry in various species of the Amaranthaceae family: beetroot (Beta vulgaris subsp. vulgaris), Swiss chard (B. vulgaris var. cicla), celosia (Celosia argentea var. plumosa), and quinoa (Chenopodium quinoa). The latter species had the highest content of decarboxybetalains (28 compounds in its POEQ-143 variety). Twenty-nine pigments were found distributed among the different analyzed plant sources. The abundance of decarboxybetalains demonstrated in this work highlights these pigments as an important family of phytochemicals in the order Caryophyllales.

Flavonoids' Effects on Caenorhabditis elegans' Longevity, Fat Accumulation, Stress Resistance and Gene Modulation Involve mTOR, SKN-1 and DAF-16.

Flavonoids are potential nutraceutical compounds present in diary food. They are considered health-promoting compounds and promising drugs for different diseases, such as neurological and inflammatory diseases, diabetes and cancer. Therefore, toxicological and mechanistic studies should be done to assert the biological effects and identify the molecular targets of these compounds. In this work we describe the effects of six structurally-related flavonoids-baicalein, chrysin, scutellarein, 6-hydroxyflavone, 6,7-dihydroxyflavone and 7,8-dihydroxyflavone-on Caenorhabditis elegans' lifespan and stress resistance. The results showed that chrysin, 6-hydroxyflavone and baicalein prolonged C. elegans' lifespan by up to 8.5%, 11.8% and 18.6%, respectively. The lifespan extensions caused by these flavonoids are dependent on different signaling pathways. The results suggested that chrysin's effects are dependent on the insulin signaling pathway via DAF-16/FOXO. Baicalein and 6-hydroxyflavone's effects are dependent on the SKN-1/Nfr2 pathway. In addition, microarray analysis showed that baicalein downregulates important age-related genes, such as mTOR and PARP.

First description of betalains biosynthesis in an aquatic organism: characterization of 4,5-DOPA-extradiol-dioxygenase activity in the cyanobacteria Anabaena cylindrica.

The biosynthesis of betalamic acid, the structural unit of pigments betalains, is performed by enzymes with 4,5-DOPA-extradiol-dioxygenase activity. These enzymes were believed to be limited to plants of the order Caryophyllales and to some fungi. However, the discovery of Gluconacetobacter diazotrophicus as the first betalain-forming bacterium opened a new field in the search for novel biological systems able to produce betalains. This paper describes molecular and functional characterization of a novel dioxygenase enzyme from the aquatic cyanobacterium Anabaena cylindrica. The enzyme was found to be a homodimer of a polypeptide of 17.8 kDa that, opposite to previous related enzymes, showed a strong inhibition by excess of the precursor L-DOPA. However, its heterologous expression has allowed detecting the formation of the main compounds in the biosynthetic pathway of betalains. In addition, phylogenetic analysis has shown that this enzyme is not close related to enzymes from plants, fungi or proteobacteria such as G. diazotrophicus. The presence of enzymes that produce these health-promoting compounds is more diverse than expected. The discovery of this novel dioxygenase in the phylum cyanobacteria expands the presence of betalamic acid-forming enzymes in organisms of different nature with no apparent relationship among them.

Scaled-up biotechnological production of individual betalains in a microbial system.

The recent interest in plant pigment betalains as bioactive compounds and chemopreventive agents has led to the search for a reliable and scalable process to obtain them. The cloning of the novel and efficient enzyme 4,5-DOPA-extradiol dioxygenase from Gluconacetobacter diazotrophicus in an expression vector, and the subsequent heterologous expression in Escherichia coli cultures has led to the start-up of a biotechnological production system of individual pigments. The aim of this study was to search for the optimal conditions for the production of betalamic acid in microbial factories and the scaled-up obtention of the derived pigments. Four different betaxanthins and two betacyanins were obtained after the addition of non-transformable amines and amino acids and their condensation with the betalamic acid produced by the dioxygenase. The scaled-up obtention and purification of betalains improved the yields of the previous methodologies reaching quantities by up to 150 mg of pure compounds.