4 hydroxyproline

HPLC-grade
methanol was purchased
from Merck (Darmstadt, Germany). Tridecanoic acid (internal standard) N-methyl-N-(trimethylsilyl)-trifluoroacetamide
(MSTFA), methoxyamine hydrochloride, pyridine, dichloromethane, linoleic
acid, glycerol-3-phosphate, 4-hydroxyproline, hypoxanthine, and l-aspartate were all supplied by Sigma-Aldrich (St. Louis, MO). l-Leucine and l-glutamate were provided by J&K
Scientific Ltd. (Beijing, China). 2-Ketoisocaproic acid and l-glutamine were purchased from AccuStandard (New Haven, CT) and LookChem
Chemicals (Shanghai, China), respectively.

Na₂CO₃, NaCl, and 20% HCl were obtained from Fluka, while 4-nitrobenzene sulfonyl chloride and 4-hydroxyproline were obtained from Sigma Aldrich (Bristol Scientific Nigeria). IR spectra were recorded on Bruker FT-IR spectrophotometer. The NMR peaks were recorded on Bruker DPX 300 spectrophotometer with ¹H at 400 MHz and 13 ℃ at 100 MHz. Chemical shifts δ are given in ppm and referenced to tetramethylsilane. Methanol was used as a solvent for crystallization. X-ray data of the single crystal were collected on an XtaLAB Synergy, Dualflex, Pilatus 200 K diffractometer using CuKα radiation at 105.4 (7)K. The pharmacokinetic properties were studied using SwissADME free online tool (https://www.swissadme.ch), while the Molecular docking was carried out using the Molecular operating environment (MOE) (AutoDock Vina, BIOVIA).