3,4-Dihydroxystyrene

Hydroxycinnamic acid (HCA) decarboxylation by lactic acid bacteria (LAB) results in the production of 4-vinylplenols with great impact on the sensorial characteristics of foods. The determination of LAB decarboxylating capabilities is key for optimal strain selection for food production. The activity of LAB strains from the Ohio State University-Parker Endowed Chair (OSU-PECh) collection potentially capable of synthesizing phenolic acid decarboxylase was evaluated after incubation with HCAs for 36 h at 32 °C. A high-throughput method for monitoring HCAs decarboxylation was developed based on hypsochromic shifts at pH 1.0. Out of 22 strains evaluated, only Enterococcus mundtii, Lactobacillus plantarum and Pediococcus pentosaceus were capable of decarboxylating all p-coumaric, caffeic and ferulic acids. Other strains only decarboxylated p-coumaric and caffeic acid (6), only p-coumaric acid (2) or only caffeic acid (1), while 10 strains did not decarboxylate any HCA. p-Coumaric acid had the highest conversion efficiency, followed by caffeic acid and lastly ferulic acid. Results were confirmed by HPLC-DAD-ESI-MS analyses, showing the conversion of HCAs into their 4-vinylphenol derivatives. This work can help improve the sensory characteristics of HCA-rich foods where fermentation with LAB was used during processing.

4-Vinylcatechol (4VC) has been identified as an aroma compound in roasted foods, especially coffee. It is also a component in traditional herbal medicines. This compound may be subconsciously ingested through foods and herbs. Recent experimental evidence has shown that 4VC possesses an antioxidative action. However, the antioxidative action of 4VC at cellular levels is not well characterized. The effects of 4VC (0.1-100 µM) were examined on rat thymic lymphocytes without and with oxidative stress induced by 300 µM hydrogen peroxide (H2O2). Cell treatment with 100 µM 4VC alone for 4 h significantly increased the population of dead cells. Thus, 4VC at 100 µM or above elicits cytotoxicity. However, 4VC at sublethal concentrations (1-10 µM) significantly attenuated the H2O2-induced increase in cell lethality in a concentration-dependent manner. While application of 10 µM 4VC slowed the process of cell death induced by H2O2, 4VC did not antagonize the H2O2-induced reduction of cellular nonprotein thiols. Although 4VC at 10 µM did not affect intracellular Ca2+ and Zn2+ levels, the agent potentiated the H2O2-induced increases in these levels. These actions of 10 µM 4VC are adverse to the cells under the oxidative stress. However, 10 µM 4VC partly attenuated the cell death induced by 100 nM A23187, a calcium ionophore. There are conflicting actions of 4VC at 1-100 µM on the cells under oxidative stress although the agent is used for an antioxidant. Thus, caution is required when using 4VC as a therapeutic agent.

Coffee is a widely consumed beverage worldwide and has a high content of chlorogenic acids, polyphenols, methylxanthines, and volatile flavor compounds. Scientific evidence to support the beneficial health effects of coffee is limited, and validated urinary biomarkers of coffee intake are therefore needed. We observed 23 common putative biomarkers of coffee intake in three separate parallel intervention studies by ultra-high-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight-mass spectrometry (UHPLC-ESI-QTOF-MS) and multivariate analyses. Baseline samples from the NU-AGE study were used to confirm and validate 16 of these candidate biomarkers, including their robustness, time response, and dose response. These validated candidate biomarkers are N-methylpyridinium cation, 1-methyl-1H-pyrrole-2-carboxaldehyde, 1H-pyrrole-2-carboxaldehyde sulfate, 3-piperidinemethanol, furfurylidene-furfurylamine, 2-furoylglycine, N-substituted-5-(aminoethyl) furan-2-carbaldehyde derivative, 3',4'-dihydroxyacetophenone sulfate, caffeine, dihydroxystyrene glucuronide, ferulic acid sulfate, 4-ethylcatechol glucuronide, 3-feruloylquinic acid, 3,4-dihydroxystyrene sulfate, one unknown glucuronide, and one unknown sulfate. Combinations of candidate biomarkers gave a better prediction of coffee consumption than individual biomarkers. The robustness of the combined biomarkers requires additional validation in cohort studies covering other populations.