Enzymatically enriching naringenin with hydroxylated and/or methoxylated phenolic compounds

Whole-cell bioconversion of naringenin to high added value hydroxylated compounds using Yarrowia lipolytica 2.2ab in surface and liquid cultures

The bioconversion process of bioactive naringenin by whole-cells of Yarrowia lipolytica 2.2ab for the production of increased value-added compounds is successfully achieved in surface and liquid cultures. This approach is an alternative to the commercial production of these bioactive compounds from vegetable sources, which are limited due to their low concentrations and the complexity of the purification processes. The experimentation rendered seven value-added compounds in both surface and liquid bioconversion cultures. Some of the compounds produced have not been previously reported as products from the bioconversion processes, such as the case of ampelopsin. Biosynthetic pathways were suggested for the naringenin bioconversion using whole-cells of Y. lipolytica 2.2ab. Finally, the extracts obtained from the naringenin bioconversion in liquid cultures showed higher percentage of inhibition of DPPH· and ABTS· radicals up to 32.88 and 2.08 times, respectively, compared to commercial naringenin.

Soil organic matter attenuates the efficacy of flavonoid-based plant-microbe communication

Plant-microbe interactions are mediated by signaling compounds that control vital plant functions, such as nodulation, defense, and allelopathy. While interruption of signaling is typically attributed to biological processes, potential abiotic controls remain less studied. Here, we show that higher organic carbon (OC) contents in soils repress flavonoid signals by up to 70%. Furthermore, the magnitude of repression is differentially dependent on the chemical structure of the signaling molecule, the availability of metal ions, and the source of the plant-derived OC. Up to 63% of the signaling repression occurs between dissolved OC and flavonoids rather than through flavonoid sorption to particulate OC. In plant experiments, OC interrupts the signaling between a legume and a nitrogen-fixing microbial symbiont, resulting in a 75% decrease in nodule formation. Our results suggest that soil OC decreases the lifetime of flavonoids underlying plant-microbe interactions.

Improved oxidation of naringenin to carthamidin and isocarthamidin by Rhodotorula marina

A novel single-step microbial transformation process for the efficient production of carthamidin and isocarthamidin from naringenin by yeast Rhodotorula marina in an aerated bioreactor was described. The biotransformation led to the total product concentration of 233 mg/l. The highest conversion efficiency observed for carthamidin was 0.31 mg/mg of naringenin and for isocarthamidin 0.47 mg/mg of naringenin.