## 2 Materials and Methods
### Purification and Spectroscopic Characterization of the Prodrugs  
The reaction products were separated via glass column chromatography. The column was prepared with silica gel using a mixture of ethyl acetate/hexane/acetic acid/MeCN (50:25:8:17 (\(v/v/v\))) as the elution solvent. The fractions containing the product of interest were combined, the solvent was evaporated using a rotary evaporator, and the residue was analyzed via NMR (400 MHz Varian spectrometer; Varian, Palo Alto, CA, USA).  
For chromatographic purification of the glyceric prodrug, a preliminary extraction step was necessary to eliminate the excess unreacted glycerol. The whole initial sample was washed 3 times with 10 mL of toluene to remove the excess unreacted glycerol and extract the ester into the organic solvent. The solvent was removed with a rotary evaporator, and the purification of the glyceric ester was reached via glass column chromatography (product yields: **3**, 75%; **4**, 50%; and **6**, 63%). The physical state of the monoesters was oily, while the diester of erythritol was solid. NMR showed the following \({}^{1}\)H- and \({}^{13}\)C-NMR spectra (acquired with 400 MHz Varian Gemini spectrometer; Varian, Palo Alto, CA, USA); all the spectra are provided as Supplementary Materials. NMR spectra were recorded for DMSO-d6 solutions at room temperature. Chemical shifts are given in parts per million from Me4 Si as internal standard. Coupling constants (J) are reported in hertz (Hz). Patterns are indicated as follows: s: singlet d: doublet; dd: double doublet; t: triplet; q: quadruplet; m: multiplet:  
_IBU-erythritol ester (**3a/3b**; (2S,3R)-2,3,4-trihydroxybutyl (R)-2-(4-isobutylphenyl)propanoate and (2R,3S)-2,3,4-trihydroxybutyl (R)-2-(4-isobutylphenyl)propanoate_): \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta\) 7.18 (dd, \(J\) = 8.1, 1.9 Hz, 2 H); 7.08 (dd, \(J\) = 8.2, 2.0 Hz, 2 H); 4.23 (dd, \(J\) = 11.3, 2.9 Hz); 4.09 (dd, \(J\) = 11.3, 2.8 Hz); 3.99 (dd, \(J\) = 11.3, 7.2 Hz); 3.87 (dd, \(J\) = 11.3, 7.0 Hz); 3.71 (q, \(J\) = 7.5 Hz, 1 H); 3.51 (m, 2 H); 3.33 (m, 2 H); 2.39 (d, \(J\) = 7.1 Hz, 2 H); 1.81 (m, 1 H); 1.36 (dd, \(J\) = 7.1, 1.9 Hz, 3 H); 0.83 (d, \(J\) = 6.6 Hz, 6 H). \({}^{13}\)C NMR (101 MHz, DMSO-\(d_{6}\)) \(\delta\) 174.53; 140.13; 138.41; 129.45 (2 C); 127.57 (2 C); 72.75; 69.83; 67.03; 63.42; 44.71; 44.66; 30.03; 22.64 (2 C); 19.20.  
_1.3-diacylated IBU-erythritol ester (**4**; three possible configurations: (2R,3S)-2,3-dihydroxybutane-1,4-diyl (2R,2\({}^{\prime}\)R)-bis(2-(4-isobutylphenyl)propanoate), (2R,3S)-2,3-dihydroxybutane-1,4-diyl (2S,2\({}^{\prime}\)S)-bis(2-(4-isobutylphenyl)propanoate), and (2R,3S)-2,3-dihydroxy-4-(((R)-2-(4-isobutylphenyl)propanoate); \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta\) 7.16 (dd, \(J\) = 8.0, 2.0 4 H); 7.06 (dd, \(J\) = 8.1, 2.1 Hz, 4 H); 4.18 (dd, \(J\) = 11.2, 1.2 Hz, 1 H); 4.05 (dd, \(J\) = 11.3, 2.7 Hz, 1 H); 3.97 (m, 1 H); 3.86 (m, 1 H); 3.70 (m, 2 H); 3.51 (m, 1 H); 2.37 (d, \(J\) = 7.2 Hz, 5 H); 1.76 (m, 2 H); 1.34 (m, 6 H); 0.82 (d, \(J\) = 6.7 Hz, 12 H). \({}^{13}\)C NMR (101 MHz, DMSO-\(d_{6}\)) \(\delta\) 174.47; 140.14; 138.37; 129.46; 127.57; 69.66; 66.61; 66.49; 53,75; 44.66; 30.03; 22.62; 19.15.  
_IBU-glycerol ester (**6a/6b**; (S)-2,3-dihydroxypropyl (S)-2,(4-isobutylphenyl)propanoate_ and (\(R\))-2,3-dihydroxypropyl (S)-2-(4-isobutylphenyl)propanoate): \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta\) 7.17 (dd, \(J\) = 8.0, 1.8 Hz, 2 H); 7.08 (dd, \(J\) = 8.1, 1.9 Hz, 2 H); 4.04 (dd, \(J\) = 11.1, 4.5 Hz); 3.94 (m, 1 H); 3.84 (dd, \(J\) = 11.1, 6.2 Hz); 3.72 (q, \(J\) = 7.2 Hz, 1 H); 3.56 (m, 1 H); 3.25 (m, 2 H); 2.39 (d, \(J\) = 7.2 Hz, 2 H); 1.78 (hept, \(J\) = 6.8 Hz, 1 H); 1.35 (d, \(J\) = 7.2 Hz, 3 H); 0.83 (d, \(J\) = 6.6 Hz, 5 H).  
\({}^{13}\)C NMR (101 MHz, DMSO- \(d_{6}\)) \(\delta\) 174.39; 140.17; 138.36; 129.48 (2 C); 127.53 (2 C); 69.68; 66.40; 62.98; 44.64; 44.42; 30.03; 22.63 (2 C); 19.10.