Cyheptamide and 3-hydroxy-3-phenacyloxindole: structural similarity to diphenylhydantoin as the basis for anticonvulsant activity

1-(3-Chlorobenzyl)-5-iodoindoline-2,3-dione

In the title compound, C₁₅H₉ClINO₂, which possesses anticonvulsant activity, the iodo­indoline ring system is essentially planar (maximum deviation 1.245 Å) and is oriented with respect to the 3-chloro­benzyl ring at a dihedral angle of 76.59 (3)°. In the crystal, there is a π–π contact between iodo­indoline ring systems [centroid–centroid distance = 3.8188 (4) Å].

Deducing the bioactive face of hydantoin anticonvulsant drugs using NMR spectroscopy

BACKGROUND

The general purpose of this study was to deduce the geometry of the bioactive face (pharmacophore) for the hydantoin class of anticonvulsants.

METHODS

Six hydantoin analogs, selected as probes of hydantoin structure, were synthesized. Nuclear magnetic resonance spectroscopy and molecular modelling calculations were used to determine the geometric relationship between the aromatic group and the amide group in the hydantoin pharmacophore.

RESULTS

In accord with both theoretical and experimental results, the biologically inactive hydantoin analogs containing a benzyl substituent existed in a folded conformation with the benzene flopped over the hydantoin ring. Conversely the biologically active hydantoins had a phenyl ring extended away from the hydantoin ring.

CONCLUSIONS

The bioactive face for hydantoins consists of a N(H)-C(=O)-X-phenyl molecular fragment, where X is a carbon or nitrogen atom and where the distance between the centre of the amide bond and the centroid of the phenyl ring is 4.3 A.

5'-Chloro-spiro-[1,3-dioxolane-2,3'-indolin]-2'-one: a potential anti-convulsant

The title compound, C₁₀H₈ClNO₃, is a significant anti­convulsant agent. The indolinone system is essentially planar, the dihedral angle between the rings being 2.24 (8)°. The dioxolane ring adopts an envelope conformation; the dihedral angle between the plane through its four coplanar atoms and the indolinone system is 89.8 (1)°. The crystal structure is stabilized by a three-dimensional network of inter­molecular N—H⋯O hydrogen bonds.

Anticonvulsant activity of phenylmethylenehydantoins: a structure-activity relationship study

Phenylmethylenehydantoins (PMHs) and their des-phenyl analogues were synthesized and evaluated for anticonvulsant activity using the maximal electroshock seizure (MES) assay. The phenyl rings of PMHs were substituted with a wide spectrum of groups, and the selection of substituents was guided by Craig's plot. Phenylmethylenehydantoins substituted with alkyl (2, 3, 5, 6, 12, 14), halogeno (35, 38, 41), trifluoromethyl (11), and alkoxyl (23) groups at the phenyl ring were found to exhibit good anticonvulsant activity with ED(MES(2.5)) ranging from 28 to 90 mg/kg. Substitution of polar groups such as -NO(2), -CN, and -OH was found to be less active or inactive on PMHs. Replacement of the phenyl ring with heteroaromatic rings reduced or caused the loss of anticonvulsant activity. The study identified two PMHs, 14 (ED(MES(2.5)) = 28 +/- 2 mg/kg) and 12 (ED(MES(2.5)) = 39 +/- 4 mg/kg), to be the most active candidates of the series, which are comparable to phenytoin (55, ED(MES(2.5)) = 30 +/- 2 mg/kg) in their protection against seizure. Multivariate analysis performed on the whole series of 54 PMHs further supported the finding that the alkylated phenylmethylenehydantoins are the best acting compounds. The SAR model derived on the basis of 12 of the most active phenylmethylenehydantoins demonstrated good predicting ability (root-mean-square error of prediction (RMSEP) = 0.134; RMSEE = 0.057) and identified LUMO energy and the log P as critical parameters for their anticonvulsant activity.

Mixed conformation in C alpha, alpha-disubstituted tripeptides: x-ray crystal structures of Z-Aib-Dph-Gly-OMe and Bz-Dph-Dph-Gly-OMe

We report here the synthesis and molecular structure in the solid state of fully protected tripeptides containing C alpha, alpha-diphenylglycine (Dph), namely Z-Aib-Dph-Gly-OMe (Aib: C alpha, alpha-dimethylglycine) and Bz-Dph-Dph-Gly-OMe. The molecular conformation around the Dph residue, containing two bulky substituents, is fully extended, while the Aib residue, containing two smaller groups on the C alpha atom, adopts the typical 3(10)/alpha-helical conformation. Gly residues, without substituents on the C alpha atom, show different conformational preferences. Each residue seems to behave, from a conformational point of view, independently from the presence of the other residues, and thus mixed local conformations (folded and extended) are present in the crystals. The nonconventional peptide synthesis, using the Ugi reaction, is also reported.

Use of molecular electrostatic potentials for analysis of anticonvulsant activities of phenylsuccinimides

The present study was performed on a group of 27 derivatives of phenylsuccinimides, of which only 12 were active against maximal electrical shock in spite of the structural similarities of these compounds. The work consisted of four main parts: 1. crystallographic investigations of a subset of chosen compounds; 2. conformational analysis of characteristic molecules from the investigated series, performed by means of molecular mechanics calculations; 3. molecular orbital optimization of all the molecules using the MNDO method starting with conformations obtained in 2; 4. molecular electrostatic potential (MEP) analysis which was performed on the semiempirical (MNDO) and ab initio levels. This research showed that MEP maps provide a signature that distinguishes between active and inactive compounds. There are MEP minima close to the two carbonyl oxygens of the imide ring, and although the magnitude of the difference between the two minima is approximately constant, the sign of the difference provides an activity index. The initial orientations of phenylsuccinimide molecules in relation to the receptor are not equivalent and they depend on the potential distribution around both the succinimide molecules and around the receptor. In the active compounds the negative potential difference at the discussed points most probably influences the initial set-up of the molecules in relation to the receptor and results in a considerably higher probability of the molecules being bound at the right place on the receptor.

Applications of molecular physics ‘biotechnology’ to the rational design of an improved phenytoin analogue

This study exploits molecular physics, in conjunction with a large scale computing environment, as a tool for understanding the clinical phenomenology of phenytoin (PHT) toxicology at a molecular level and for employing this understanding in an attempt to design improved drugs. The application of molecular physics techniques, such as quantum mechanics and molecular force field calculations, to the process of rational anticonvulsant drug design remains virtually unexplored. A 3-step strategy for applying these techniques to the design of an improved PHT molecule is presented. Step 1 employs quantitative structure-activity relationship calculations on 80 PHT analogues to ascertain the portion of the PHT molecule necessary for bioactivity (i.e. the 'bioactive face' of PHT); the N3-C4(O)-C5-R fragment of PHT was identified as the bioactive face. Step 2 employs molecular modelling studies to determine the portion of the PHT molecule necessary for the teratogenic, mutagenic and connective tissue toxicities of PHT (i.e. the 'biotoxic face'); the C2(O)-N3 fragment of PHT was identified as the biotoxic face. Step 3 experiments design an 'improved' PHT analogue, which maintains the bioactive face while eliminating the integrity of the biotoxic face; 2-deoxy-5,5-diphenylhydantoin was designed and synthesized as the improved PHT analogue. This compound had biological activity equivalent to PHT, but was unable to bind to nucleic acids or to chelate metals involved in connective tissue metabolism.

A pattern recognition study of acyclic ureide anticonvulsants

A pattern recognition structure-activity study employing topological, geometric and physicochemical descriptors was performed on 27 acyclic ureide anticonvulsants. Twelve numerical descriptors were used as variables in a discriminant function analysis which categorized the ureide analogues with respect to their bioactivity. The results from the discriminant function analysis were interpreted to support a model for antiepileptic activity.