Tlc al foils

¹H and ¹³C NMR spectra were recorded on a Bruker AVANCE 500 spectrometer (500 MHz for ¹H, 125 MHz for ¹³C). Chemical shift values are given in δ (ppm) relative to the residual solvent signals for δ_H 7.26 ppm and δ_C 77.16 ppm (CDCl₃), and for δ_H 2.04 ppm and δ_C 20.00 ppm (CD₃COOD). Melting points were measured on a Boetius apparatus and are uncorrected. High-resolution mass spectra (HRMS) were recorded on a 6550 iFunnel Q-TOF LC/MS (Agilent Technologies) micro mass spectrometer by electrospray ionization (ESI). The elemental analyses were performed on a Eurovector EA3000 CHNS-O analyzer. Follow-up of the reactions and evaluation of the purity of the compounds were performed by thin layer chromatography (TLC) on Silica gel (60 Å medium pore diameter) on TLC Al foils with a fluorescent indicator 254 nm (Sigma-Aldrich). Chemicals were purchased from Sigma-Aldrich or Acros Organics and used as received. Solvents were dried and freshly distilled according to the common practice.

Dried lipid samples were resuspended in MeOH:CHCl₃ (1:1, vol/vol) and spotted onto 10 × 20 cm silica gel on TLC Al foils (Sigma-Aldrich). TLC was developed with a CHCl₃:MeOH:H₂O (130:50:8 vol/vol/vol) mobile phase (10 min at room temperature [RT]), and plates were stained with either MnCl₂/sulphuric acid or ninhydrin or bromocresol green. MnCl₂/sulphuric acid, a universal staining (43 ), was prepared with 0.8 g of MnCl₂ tetrahydrate dissolved in 240 mL of 50% (vol/vol) MeOH supplemented with 9 mL of concentrated sulphuric acid. To detect primary amines (pink color), ninhydrin 0.4% (wt/vol) (Sigma-Aldrich) was used. To reveal carboxylate-containing compounds (blue color) with a pK_a below 5.0 (44 ), bromocresol green (0.04 g) (Sigma-Aldrich) dissolved in absolute ethanol and NaOH 0.1 M was used. In the case of MnCl₂/sulphuric acid and ninhydrin stains, plates were heated at 100 °C until coloration developed, while direct ultraviolet (UV) (254 or 315 nm) visualization was performed with bromocresol green. Quantification of LX (Erg-Asp), PE, or PG spots was performed using the ImageJ software. Lipid spots signals (number of pixels, N) were normalized to that of PE (N_LX/N_PE). In the absence of LX (Erg-Asp), PG becomes visible at the same position; the PG/PE signal thus represents the background signal in the absence of LX.