Veratric acid

All air and moisture sensitive reactions were carried out using dry solvents and under a static atmosphere of nitrogen. All solvents and reagents were of commercial quality and were purchased from Sigma-Aldrich (St. Louis, MO, USA). p-Anisic acid (9), vanillic acid (10), veratric acid (11), 3,4,5-trimethoxybenzoic acid (13), p-anisaldehyde (2), vanillin (3), veratric aldehyde (4), piperonal (5), casein peptone, peptone from soybean, yeast extract, meat extract, malt extract, sucrose, maltose, glucose, Amberlite® XAD1180N (20–60 mesh) and Na₂SO₄ were purchased from Sigma-Aldrich.
Piperonylic acid (12) was obtained by oxidation of piperonal (5) using silver oxide as oxidant (Pearl 1950 (link)). p-Anisyl alcohol (14), vanillyl alcohol (15), veratryl alcohol (16) and piperonyl alcohol (17) were prepared by NaBH₄ reduction of the corresponding aldehydes. 3,4,5-Trimetoxybenzaldehyde (6) was obtained through MnO₂ oxidation of 3,4,5-trimethoxybenzyl alcohol (18), which in turn was obtained by LiAlH₄ reduction of 3,4,5-trimethoxybenzoic acid (13).

Syringaldazine (4-hydroxy-3,5-dimethoxybenzaldehyde azine), ferulic acid (4-hydroxy-3-methoxycinnamic acid), and veratric acid (3,4-dimethoxybenzoic acid) were supplied by Sigma-Aldrich (St. Louis, MO, USA), while l-asparagine was purchased from Merck (Darmstadt, Germany). All other products used were of reagent or analytical grade and purchased locally.

Free anisic acid (1a) and veratric acid (1b) were purchased from Sigma-Aldrich (Poznan, Poland). Phosphatidylcholines with O-methylated derivatives of phenolcarboxylic acids, 1,2-dianisoyl-sn-glycero-3-phosphocholine (3a), 1,2-diveratroyl-sn-glycero-3-phosphocholine (3b), 1-palmitoyl-2-anisoyl-sn-glycero-3-phosphocholine (5b), 1-anisoyl-2-palmitoyl-sn-glycero-3-phosphocholine (8a) and 1-veratroyl-2-palmitoyl-sn-glycero-3-phosphocholine (8b), were synthesized in the Department of Chemistry, Wroclaw University of Environmental and Life Sciences, according to the procedure described previously [23 (link)]. Stock solutions of all compounds were prepared in the mixture ethanol: DMSO (v/v, 1:1; both purchased from Sigma-Aldrich, Poznan, Poland) and were then diluted in cell culture media. Chemical structures of the studied compounds are presented in Figure 11.