Para coumaric acid

Shimadzu UV-1800 (Kyoto, Japon) spectrophotometer was used for absorption measurements. Hellma GmbH & Co. KG (Müllheim, Germany) quartz cuvettes with 1 cm optical thickness were used for the UV-Vis measurements.
All reagents were of analytical reagent grade unless otherwise stated. Quercetin (QR), gallic acid (GA), ferulic acid (FA), caffeic acid (CFA), catechin (CAT), epicatechin, trolox (TR), para-coumaric acid (p-CUM), L-ascorbic acid (AA), L-cysteine (CYS), morin (MR), rutin (RT), hydrogen peroxide (30% by mass), and N,N-Dimethyl-p-phenylenediamine (DMPD) were purchased from Sigma-Aldrich Chemie GmbH (Steinheim, Germany), and all other reagents from Merck KGaA (Darmstadt, Germany) and Sigma-Aldrich Chemie GmbH. Commercial orange juice and green tea samples were obtained from local markets.

Solvents for extraction and reagents for colorimetric tests of analytical grade were procured from Himedia Laboratories (Mumbai, India). For UPLC profiling, HPLC grade phenolic acid standards (gallic acid, chlorogenic acid, caffeic acid, vanillic acid, syringic acid, para-coumaric acid, ferulic acid, sinapic acid, salicylic acid, ellagic acid and trans-cinnamic acid) were purchased from Sigma-Aldrich (St. Louis, MO, USA), protocatechuic acid was procured from HWI Analytik GmbH (Ruelzheim, Germany). Solvents for UPLC separation (HPLC and LC–MS grade) were obtained from Merck Specialties (Mumbai, India).

The ABTS reagent was provided by Alfa Aesar, the Folin–Ciocalteu reagent was purchased from Merck (Darmstadt, Germany), and (+)-catechin 98%, quercetin, caffeic acid, syringic acid, ferulic acid, gallic acid (98%), protocatechuic acid, gentisic acid, parahydroxybenzoic acid, salicylic acid (99.9%), para-coumaric acid, trans-5-O-caffeoylquinic) acid, epicatechin, vanillic acid, cis-resveratrol, ferulic acid methyl ester and DPPH were obtained from Sigma- Aldrich (Darmstadt, Germany, Tokyo, Japan, Shanghai, China). methyl 4-hydroxy-3-methoxycinnamate (99%) and sinapic acid (98%) were purchased from Alfa Aesar (Kandel, Germany). Procyanidin B1, procyanidin B2, polydatin, hyperoside, carotenoid standards, β-carotene, lycopene, β-cryptoxanthin, lutein, and zeaxanthin were purchased from Extrasynthese (Genay, France). Trans-resveratrol was purchased from TCI Europe (Zwijndrecht, Belgium). The acetonitrile and the formic acid were purchased from Merck. quercetin (>95%) was obtained from Sigma-Aldrich (Bangalore, India). All spectrophotometric measurements were performed on the Analytik Jena Specord 200 Plus (Jena, Germany) spectrophotometer.

The Sorbus aucuparia L. berries were harvested from plantations from the Republic of Moldova. The ABTS reagent was provided by Alfa Aesar, the Folin–Ciocalteu reagent, formic acid, and acetronitrile were purchased from Merck (Darmstadt, Germany). (+)-catechin 98%, morin hydrate, ellagic acid (≥95%), benzoic acid, quercetin, caffeic acid, (+)-rutin trihydrate, syringic acid, ferulic acid, gallic acid (98%), protocatechuic acid, gentisic acid, parahydroxybenzoic acid, para-coumaric acid, quercetin (>95%), 3,5-dinitrobenzoic acid (99%), and cetyltrimethylammonium bromide were obtained from Sigma (Germany, Japan, China, India). D(-)-quinic acid (98%), sinapic acid (98%), and methyl 4-hydroxy-3-methoxycinnamate (99%) were purchased from Alfa Aesar (Kandel, Germany). Procyanidin B1, procyanidin B2, polydatin, hyperoside, carotenoid standards, β-carotene, lycopene, lutein, zeaxanthin, and β-cryptoxanthin were purchased from Extrasynthese (Genay, France). Trans-resveratrol was purchased from TCI Europe (Zwijndrecht, Belgium). All spectrophotometric measurements were performed on the Specord 200 Plus (Jena, Germany) spectrophotometer.

500 ml Erlenmeyer flasks containing 50 ml of 1/2YTSS medium and 1 mM para-coumaric acid (Sigma-Aldrich) were inoculated with 0.5 ml of an overnight culture and incubated at 130 rpm at 30°C for three days. Then, cultures were extracted once with an equal volume of ethyl acetate, dried in vacuo, resuspended in methanol and analyzed by HPLC. HPLC analysis was performed on a Beckman Coulter System Gold HPLC equipped with a diode array detector using an analytical Phenomenex C18 column (5 μm, 4.6 mm x 100 mm). Flow rate was 0.7 ml/min with a gradient of 10% acetonitrile in water to 100% acetonitrile over 25 min. Roseobacticides were identified according to their characteristic absorbance peak at 430 nm (Seyedsayamdost et al., 2011 (link)).

Analytical standards of levoglucosan (99%), acetosyringone (97%), acetovanillone (≥98%), para-coumaric acid (≥98%), ethylvanillin (99%), ferulic acid (99%), syringaldehyde (98%), and syringic acid (>95%), as well as L-ascorbic acid (SigmaUltra) were purchased from Sigma-Aldrich. An analytical standard of ¹³C₆ levoglucosan (98%) was obtained from Cambridge Isotope Laboratories. An analytical standard of vanillin (99%) was obtained from Acros Organics, and an analytical standard of vanillic acid (98%) was obtained from Alfa Aesar. An analytical standard of ammonium acetate (≥99%) and ultrapure acetonitrile (ACN, LC/MS grade) were obtained from VWR Chemicals. Sodium hydroxide (pellets, ≥99%), hydrochloric acid (HCl, suprapure, 30%), and water (LC-MS grade) were purchased from Merck KGaA. Ammonium hydroxide solution (NH₃, analytical grade, 25%) was obtained from Honeywell Fluka. Ultrapure methanol (MeOH, LC/MS grade) was obtained Carl Roth while ultrapure dichloromethane (DCM, LC-MS grade, ≥99.8%) was purchased from Fisher Scientific. Ultrapure water with 18.2 MΩ resistance was produced using a Milli-Q water system from Merck Millipore (Darmstadt, Germany). Solid-phase extraction columns (Oasis HLB, 6 mL tubes, 200 mg packing material and Oasis HLB, 1 mL tubes, 30 mg packing material) were purchased from Waters.