Raltegravir monohydrate.

Area of Science:

• Medicinal Chemistry
• Structural Biology
• Crystallography

Background:

• The development of effective HIV treatments is a global health priority.
• HIV integrase inhibitors are a critical class of antiretroviral drugs.
• Understanding the molecular structure of inhibitors is key to optimizing their efficacy.

Purpose of the Study:

• To elucidate the three-dimensional crystal structure of the first identified HIV integrase inhibitor.
• To analyze the molecular conformation, including dihedral angles between key ring systems.
• To investigate the role of intra-molecular and inter-molecular hydrogen bonding in the compound's structure and packing.

Main Methods:

• Single-crystal X-ray diffraction was employed to determine the crystal structure.
• Analysis of dihedral angles to describe the relative orientation of planar groups (pyrimidine, phenyl, oxadiazole).
• Identification and characterization of hydrogen bonding networks (O-H⋯O, C-H⋯N, N-H⋯O) and water molecule interactions.

Main Results:

• The crystal structure of N-(4-fluoro-benzyl)-5-hydroxy-1-methyl-2-{1-methyl-1-[(5-methyl-1,3,4-oxadiazol-2-ylcarbonyl)amino]-ethyl}-6-oxo-1,6-dihydro-pyrimidine-4-carboxamide monohydrate (C20H21FN6O5·H2O) was determined.
• Significant dihedral angles were observed between the pyrimidine, phenyl, and oxadiazole rings, indicating a non-planar molecular conformation.
• Intra-molecular hydrogen bonds were identified within the molecule, and inter-molecular hydrogen bonds, including those involving the water molecule and amide groups, were found to link molecules into chains.

Conclusions:

• The determined crystal structure provides fundamental insights into the molecular architecture of this pioneering HIV integrase inhibitor.
• The observed conformation and hydrogen bonding patterns are likely critical for the compound's interaction with HIV integrase.
• This structural information can guide the design of novel and more potent HIV integrase inhibitors.