1,2,4-Oxadiazolidin-3,5-diones and 1,3,5-triazin-2,4,6-triones as cytosolic phospholipase A2α inhibitors

Design, Synthesis and Pharmacological Evaluation of Novel Antiinflammatory and Analgesic O-Benzyloxime Compounds Derived From Natural Eugenol

Background: :

A new series of O-benzyloximes derived from eugenol was synthesized and was evaluated for its antinociceptive and anti-inflammatory properties.

Methods: :

The target compounds were obtained in good global 25-28% yields over 6 steps, which led us to identify compounds (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-(4- (methylthio)benzyloxime (8b), (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-4- bromobenzyloxime (8d) and (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-4- (methylsulfonyl)benzyloxime (8f) as promising bioactive prototypes.

Results::

These compounds have significant analgesic and anti-inflammatory effects, as evidenced by formalin-induced mice paw edema and carrageenan-induced mice paw edema tests. In the formalin test, compounds 8b and 8f evidenced both anti-inflammatory and direct analgesic activities and in the carrageenan-induced paw edema, with compounds 8c, 8d, and 8f showing the best inhibitory effects, exceeding the standard drugs indomethacin and celecoxib.

Conclusion: :

Molecular docking studies have provided additional evidence that the pharmacological profile of these compounds may be related to inhibition of COX enzymes, with slight preference for COX-1. These results led us to identify the new O-benzyloxime ethers 8b, 8d and 8f as orally bioactive prototypes, with a novel structural pattern capable of being explored in further studies aiming at their optimization and development as drug candidates.

Binding conformation of 2-oxoamide inhibitors to group IVA cytosolic phospholipase A2 determined by molecular docking combined with molecular dynamics

The group IVA cytosolic phospholipase A(2) (GIVA cPLA(2)) plays a central role in inflammation. Long chain 2-oxoamides constitute a class of potent GIVA cPLA(2) inhibitors that exhibit potent in vivo anti-inflammatory and analgesic activity. We have now gained insight into the binding of 2-oxoamide inhibitors in the GIVA cPLA(2) active site through a combination of molecular docking calculations and molecular dynamics simulations. Recently, the location of the 2-oxoamide inhibitor AX007 within the active site of the GIVA cPLA(2) was determined using a combination of deuterium exchange mass spectrometry followed by molecular dynamics simulations. After the optimization of the AX007-GIVA cPLA(2) complex using the docking algorithm Surflex-Dock, a series of additional 2-oxoamide inhibitors have been docked in the enzyme active site. The calculated binding affinity presents a good statistical correlation with the experimental inhibitory activity (r(2) = 0.76, N = 11). A molecular dynamics simulation of the docking complex of the most active compound has revealed persistent interactions of the inhibitor with the enzyme active site and proves the stability of the docking complex and the validity of the binding suggested by the docking calculations. The combination of molecular docking calculations and molecular dynamics simulations is useful in defining the binding of small-molecule inhibitors and provides a valuable tool for the design of new compounds with improved inhibitory activity against GIVA cPLA(2).

Traceless solid-phase synthesis of 6-amino- and 6-hydroxyimino-1,3,5-triazine-2,4-diones and 1,3,5-triazine-2,4,6-triones

A traceless solid-phase synthesis of 6-amino- and 6-hydroxyimino-1,3,5-triazine-2,4-diones and 1,3,5-triazine-2,4,6-triones has been developed. The strategy comprises of linking a preformed N-carbamothioylcarbamate to bromomethyl resin to give a S-linked isothiourea, which then undergoes cyclization with isocynates to yield the resin-bound 1,3,5-triazine-2,4-diones. Subsequent cleavage was accomplished by either direct substitution with a suitable amine or by oxidative activation of the thioether functionality followed by nucleophilic substitution. Using this synthetic strategy, we prepared a representative set of 31 6-amino-1,3,5-triazine-2,4-diones, 10 6-hydroxyimino-1,3,5-triazine-2,4-diones, and 8 1,3,5-triazine-2,4,6-triones.

Location of inhibitors bound to group IVA phospholipase A2 determined by molecular dynamics and deuterium exchange mass spectrometry

An analysis of group IVA (GIVA) phospholipase A(2) (PLA(2)) inhibitor binding was conducted using a combination of deuterium exchange mass spectrometry (DXMS) and molecular dynamics (MD). Models of the GIVA PLA(2) inhibitors pyrrophenone and the 2-oxoamide AX007 docked into the protein were designed on the basis of deuterium exchange results, and extensive molecular dynamics simulations were run to determine protein-inhibitor contacts. The models show that both inhibitors interact with key residues that also exhibit changes in deuterium exchange upon inhibitor binding. Pyrrophenone is bound to the protein through numerous hydrophobic residues located distal from the active site, while the oxoamide is bound mainly through contacts near the active site. We also show differences in protein dynamics around the active site between the two inhibitor-bound complexes. This combination of computational and experimental methods is useful in defining more accurate inhibitor binding sites and can be used in the generation of better inhibitors against GIVA PLA(2).