Triethylamine

Methanol (HPLC gradient grade) and tetrachloroethylene (synthesis grade) were purchased from Scharlab (Barcelona, Spain). Triethylamine (analysis quality) and phenylisothiocyanate (PITC) of reagent grade were supplied by Panreac (Barcelona, Spain); 1,1-diphenyl-2-picrylhydrazyl (DPPH), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and anthrone (reagent grade) were supplied by Sigma-Aldrich (St. Louis, MO, USA). Formic acid (synthesis grade) and amino acids (aspartic acid, glutamic acid, histidine, arginine, proline, valine, lysine, methionine, isoleucine, and phenylalanine) were provided by Merck (Darmstadt, Germany). Phenolic compounds were supplied as follows: gallic acid, protocatechuic acid, (−) epicatechin, ferulic acid, p-coumaric acid, vanillic acid, syringic acid, and (+) catechin by Sigma–Aldrich Chemie (Steinheim, Germany), and rutin and gentisic acid by Merck (Darmstadt, Germany). Ultrapure water was obtained from a Milli-Q system from Millipore (Bedford, MA, USA).

MIL, LC-MS grade methanol and water were purchased from Sigma-Aldrich (Madrid, Spain). Acetonitrile (Scharlab, Barcelona, Spain), ammonia 25% and triethylamine (Panreac, Madrid, Spain) and glacial acetic acid (Fisher Scientific, Madrid, Spain) were of analytical grade. MIL for oral administration was Milteforan (Virbac, Carros, France) (20 mg/mL, Lot 7MD7A) and clindamycin was from Vétoquinol (Paris, France) (75 mg/capsule, Lot E36246/A).

Poly-l-lactide (PLLA) (Corbion, Amsterdam, The Netherlands) was used to prepare membranes. Chloroform (>98% Macron Fine Chemicals, Gliwice, Poland), tert-butanol (^tBuOH), ethanol (EtOH), methanol (MeOH, 98%), acetonitrinile (99%, Panreac, Darmstadt, Germany), dichloromethane (CH₂Cl₂, 98%, Macron Fine Chemicals), toluene (99%, Sigma Aldrich, St. Louis, MO, USA), N,N-dimethylformamide (DMF, 99%, Macron Fine Chemicals), acetic acid (Sigma Aldrich), deuterated chloroform (99.8% Sigma Aldrich) and Milli Q water were used as a solvents. Sodium hydroxide (99%, Panreac), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC·HCl, 98%), N-hydroxysuccinimide (NHS, 98%), triethylamine (<99.5%), propargylamine (97.5%), 3-bromopropylamine hydrobromide (98%), sodium azide (NaN₃, 99.5%), copper (II) sulphate pentahydrate (Cu₂SO₄·5H₂O, 98%), sodium ascorbate (98%), sodium sulphate anhydrous (Na₂SO₄, 96%, Panreac), N,N-diisopropylethylamine (DIPEA, 99%), N,N′-dicyclohexylcarbodiimide (DCC, 99%), 1-hydroxybenzotriazole hydrate (HOBT, 97%), O-toluidine blue (TBO, dye content 80%), dansyl chloride (>99%), indomethacin (>99%), thionyl chloride (>99%) from Sigma Aldrich were used as reactants. All the synthesized products spectra are summarized in Supplementary Information (Schemes S1–S4, Figures S1–S8).