Accessing p-Hydroxycinnamic Acids: Chemical Synthesis, Biomass Recovery, or Engineered Microbial Production?

p-Hydroxycinnamic acids (i. e., p-coumaric, ferulic, sinapic, and caffeic acids) are phenolic compounds involved in the biosynthesis pathway of lignin. These naturally occurring molecules not only exhibit numerous attractive properties, such as antioxidant, anti-UV, and anticancer activities, but they also have been used as building blocks for the synthesis of tailored monomers and functional additives for the food/feed, cosmetic, and plastics sectors. Despite their numerous high value-added applications, the sourcing of p-hydroxycinnamic acids is not ensured at the industrial scale except for ferulic acid, and their production cost remains too high for commodity applications. These compounds can be either chemically synthesized or extracted from lignocellulosic biomass, and recently their production through bioconversion emerged. Herein the different strategies described in the literature to produce these valuable molecules are discussed.

Bioaccessibility of polyphenols associated with dietary fiber and in vitro kinetics release of polyphenols in Mexican 'Ataulfo' mango (Mangifera indica L.) by-products.

The biological properties of polyphenol (PP) depend on its bioaccessibility and bioavailability. Therefore, part of PP released from the food matrix in the gastrointestinal tract through enzymatic hydrolysis is at least partially absorbed. The aim of this study is to determine the bioaccessibility of PP associated with dietary fiber (DF) and the kinetics release of PP in mango (Mangifera indica L.) 'Ataulfo' by-products by an in vitro model. Soluble and insoluble DF values were 7.99 and 18.56% in the mango paste and 6.98 and 22.78% in the mango peel, respectively. PP associated with soluble and insoluble DF was 6.0 and 3.73 g GAE per 100 g in the paste and 4.72 and 4.50 g GAE per 100 g in the peel. The bioaccessibility of PP was 38.67% in the pulp paste and 40.53% in the peel. A kinetics study shows a release rate of 2.66 and 3.27 g PP min(-1) in the paste and peel, respectively. The antioxidant capacity of the paste increased as digestion reached a value of 2.87 mmol TE min(-1) at 180 min. The antioxidant capacity of the peel had its maximum (28.94 mmol TE min(-1)) between 90 and 120 min of digestion; it started with a value of 2.58 mmol TE min(-1), and thereafter increased to 4.20 mmol TE min(-1) at 180 min. The major PPs released during the digestion of paste were gallic and hydroxybenzoic acids, while in the peel, they were hydroxycinnamic and vanillic acids. It was concluded that these phenolic compounds are readily available for absorption in the small intestine and exert different potential health benefits.

Phenolic-enriched fractions from brewers' spent grain possess cellular antioxidant and immunomodulatory effects in cell culture model systems.

BACKGROUND: Large quantities of brewers' spent grain (BSG), a co-product of the brewing industry, are produced annually. BSG contains hydroxycinnamic acids, and phenolic-rich extracts from BSG have previously demonstrated the ability to protect against oxidant-induced DNA damage. The present study investigated the anti-inflammatory potential of eight phenolic extracts from BSG: four pale (P1-P4) and four black (B1-B4) extracts. RESULTS: BSG extracts were more cytotoxic in Jurkat T than U937 cells, with lower IC50 values in Jurkat T cells, measured using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Pale BSG extracts P2 and P3 showed the greatest anti-inflammatory potential, significantly (P < 0.05) reducing interleukin-2 (IL-2), interleukin-4 (IL-4, P2 only), interleukin-10 (IL-10) and interferon-γ (IFN-γ) production. In addition, extracts P1-P3 and B2-B4 showed significant (P < 0.05) antioxidant effects, determined by the cellular antioxidant activity assays superoxide dismutase, catalase and glutathione content (GSH). CONCLUSION: Phenolic extracts from BSG, particularly the pale BSG extracts, have the ability to reduce a stimulated cytokine production and may also protect against cellular oxidative stress. Results of the present study highlight the potential of BSG phenolic extracts to act as functional food ingredients, providing an alternative use and improving the value of this brewing industry co-product.