Glutarimide

(−)-Epicatechin
of ≥90% and (+)-catechin hydrate of ≥96% purities were
purchased from Sigma-Aldrich (Saint Louis, MO) and recrystallized
from ethanol. Barbituric acid, 5-methylo-1H-benzotriazole,
4-(methyloamino)-pyridine, 5-methylbenzimidazole, acetamide, salicylamide,
niacinamide, isonicotinamide, caffeine, glutarimide, and the solvents
purchased from Sigma-Aldrich were of analytical grade.
The cocrystal
synthesis: Catechins and the BTA coformer in 1:1 and 2:1 molar ratios
were dissolved in ethanol at 30 °C. Colorless crystals were obtained
by slow evaporation of the solvent. The procedure lasted for 2 days
at room temperature. Crystals were collected from the crystallization
vessels.

Racemic thalidomide was purchased from Tocris Biosciences. (S)- and (R)-thalidomides and their deuterated (D-thalidomide) enantiomers were synthesized as previously described^{30 (link),57 (link)}. Enantiomeric purities were monitored by HPLC (DAICEL Chiralpak IA, 4.6 × 250 mm, MeOH = 100%, flow rate 1.0 ml/min, λ = 254 nm) and are summarized in Supplementary Table 1. Thalidomide and D-thalidomide enantiomers were dissolved in dimethylsulphoxide (DMSO) at room temperature to generate a 100 mM stock solution. Similarly, glutarimide, phthalimide, glutaric anhydride, δ-valerolactam and cycloheximide (Sigma Aldrich) were each dissolved in DMSO.

Xanthohumol purchased from Sigma-Aldrich (Darmstadt, Germany) with purity of >98% was recrystallized from acetonitrile. Nicotinamide, glutarimide, acetamide, caffeine, and all used solvents were of analytical grade and were purchased from Sigma-Aldrich. The compounds used as coformers are included in the list of compounds authorized for the safe use as additives to food products, pharmaceutical preparations, and dietary supplements (so-called GRAS list (“Generally Recognized as Safe”) created by the FDA-American Food and Drug Agency).
Synthesis of the cocrystals. Xanthohumol and coformers at the 1:1 molar ratio were dissolved in acetonitrile at 30 °C. The concentrated solution was kept for 2 days at room temperature to obtain yellow crystals (with a plate and prismatic shapes) using the slow evaporation solution growth technique. Then crystals were collected from the crystallization vessels.