Drug design and delivery最新文献

Degradable protein matrices containing chlorhexidine were tested as intra-pocket drug delivery systems in the treatment of periodontal diseases. The properties of the device were mainly dependent upon the degree of cross linking in the matrix, which could be varied according to the preparative conditions. The degree of cross linking was determined by amino acid analysis based on the amount of free lysine in the protein. The release of chlorhexidine and of the plasticizer used in the preparation of the matrix were determined. The release of chlorhexidine from the matrix was prolonged for a period of 300 hours, and the release of plasticizer ceased after four hours. Limited clinical trials suggest that one of the degradable devices--that containing the highest amount of cross-linking--causes a significant reduction in the amount of perio-pathogenic bacteria following its insertion into the periodontal pockets of patients with periodontal disease.

We describe an electronic and conformational study of histamine H2-receptor ligands of the imidazole series, in which the possibilities of configurational isomerism (the thiourea group) and N3H and N1H tautomerism (imidazole ring) were considered. The results suggest that the conformational flexibility of the molecules and the properties of the imidazole ring are of special importance in the display of H2-receptor activity. A theoretical model of histamine H2-receptor interactions is proposed on the basis of these and other results. A very important characteristic of our model is its ability to explain H2-receptor activation by compounds which differ structurally, and to explain antagonism at the same receptor. The stereospecificity of rigid analogues of cimetidine and tiotidine, and the importance of chain length in flexible histamine H2-antagonists are also accounted for.

Quantitative structure-activity relationship (QSAR) studies are reported on the benzodiazepine receptor binding of a series of substituted 9-benzyl-6-dimethylamino-9H-purines and N-(indol-3-ylglyoxylyl)amino acid derivatives. The nitrogen of the five membered heterocyclic ring and the polar substituent in the aromatic ring, present in both series of compounds, form important centres in the binding interaction. We conclude that the receptor must possess a strong nucleophilic centre and a polar site, and that a hydrophobic pocket exists to accommodate hydrophobic moieties.

The antirhinoviral activity of previously described 9-benzylpurines was quantitatively analysed using Huckel molecular orbital generated electronic parameters and physicochemical properties of substituents. Correlations with the activity against each of several serotypes of the virus were obtained but very few common requirements emerged. Our results emphasise the difficulties in identifying a compound with optimum structural features for broad spectrum antirhinovirus activity.

The synthesis and antinociceptive activity of 4-pyridylpiperdines (7 and 10) in which the phenyl group pf meperidine (1) or ketobemidone (3) is replaced by 2'-, 3'- or 4'-pyridyl is described. All were active in a rat writhing test, and the results showed that the point of attachment of the pyridyl ring to the 4-position was an important determinant of the activity; the relative potency order was 3'-pyridyl greater than 4'-pyridyl greater than 2'-pyridyl in each of the two series. The most potent compound (half the potency of meperidine) was 4-ethoxycarbonyl-4-(3'-pyridyl)-l-methylpiperidine (7b). This compound, and the corresponding 4'-isomer (7c), were further elaborated to provide 1'-phenyl, 1',6'-dihydropyridine (11), and 1'-phenyl, methyl or n-butyl. 1',2'-dihydropyridine (12) analogues containing an acyl function on the ring nitrogen. The most active compound in this series was 4-[4'-(1'-phenoxycarbonyl-2'-n-butyl-l',2'-dihydropyridyl)]- 4- ethoxycarbonyl-l-methylpiperdine (12k). Though less potent than the parent pyridyl compound (7c), it induced 70% inhibition in the writhing test at a dose of 8 mg/kg sc. [The ED50 for meperidine was 0.6 mg/kg sc.]

A number of Mannich bases 2 derived from alpha-arylidene-beta-ketoesters, some corresponding deaminated products 3, and a thiol adduct 5 were prepared. High resolution 1H NMR spectroscopy revealed that, in solution, most of the bases 2 existed principally in acyclic forms, but that all members of this series underwent some intramolecular cyclization. The compounds 2, 3 and 5 possessed activity against EMT6 mammary carcinoma cells. The Mannich bases 2a-e had the highest cytotoxicity. Topliss analysis of these compounds revealed an E4 parameter dependency, in which intramolecular cyclization was minimal. The Mannich base 2f--which existed principally in the cyclic forms 6 in deuterium oxide, the deamination products, and a thiol adduct had approximately one-sixth of the activity of 2a-e.

Ampicillin polymerizes in aqueous solution to produce antigenic polymers; the polymers were separated by anion-exchange chromatography and shown to consist of a dimer, trimer, tetramer and pentamer of ampicillin by the masses found in fast atom bombardment mass spectroscopy. The presence of an intact beta-lactam ring in each of the polymers was revealed by the characteristic positive Cotton effect near 230 nm in their circular dichroism spectra. beta-Cyclodextrin was found to inhibit this polymerization by complex formation involving equimolar quantities of the constituents. Formation of this complex was complete in 10% aqueous solution within 6 hr at 24 degrees C. The positive Cotton effect arising from the beta-lactam ring decreased as the degree of polymerization increased, but was unchanged by the complex formation with beta-cyclodextrin.

Glutaraldehyde treatment of dexamethasone-containing cylindrical fibrin gels (obtained by the thrombin-induced polymerization of fibrinogen in the presence of the drug) causes cross-linking of the gels and modification of the pore structure. The effect on the release of dexamethasone was assessed by measuring the diffusion coefficient of the drug across treated and untreated gels; diffusion across the treated gels was significantly decreased as compared with untreated gels, but was little affected by the concentration of glutaraldehyde used in the treatment. In biodegradable tests, the treated gels (all concentrations of glutaraldehyde) were resistant to digestion even in the presence of plasmin, but untreated gels were digested, and the digestion rate was accelerated by plasmin. The volume of the gels was progressively reduced as the concentration of glutaraldehyde was increased or the amount of fibrinogen was decreased, but the extent of the reduction did not correlate with the changes in the diffusion coefficient.

A series of unsymmetrical 3-arylethyl 5-isopropyl ester analogues of nifedipine, in which the 2'-nitrophenyl group at the 4 position is replaced by 2'- or 3'-pyridyl, were prepared and evaluated as calcium channel antagonists. The point of attachment of the pyridyl substituent was a determinant of activity, 2'-pyridyl analogues always being more potent than corresponding 3'-pyridyl analogues. The introduction of a substituent at the para-position of the phenethyl group in 3-phenethyl ester analogues usually enhanced the activity. The most potent compound was 3-(4'-bromophenethyl) 5-isopropyl 1,4-dihydro-2,6-dimethyl-4-(2'-pyridyl)-3,5-pyridinedicarboxylate. It was 82-fold more potent than nifedipine, and it did not exhibit a negative inotropic effect on guinea pig left atrium. Desirable features in 1,4-dihydropyridine calcium antagonists of the unsymmetrical 3,5-diester type are therefore a 4-(2-pyridyl) substituent in conjunction with a hydrophobic 3-(4-substituted-phenethyl) ester substituent. The arylethyl ester and the 4-(2'-pyridyl) substituents appear to provide important interdependent contributions to the calcium channel antagonist activity.

Electron density calculations were undertaken on several atoms in a series of 3-substituted-4-phenyl-3-buten-2-ones in order to gain insight into the molecular features which affect charge densities. The results indicate that substituents at position 3 alter the electron densities of the olefinic group but have little effect on the acetyl function. The compounds were tested against L1210 cells in vitro, and the results suggest that electronic--but not steric--factors are important in affecting cytotoxicity. The most active compound was 3-phenylmethylene-2,4-pentanedione (1c) with an ED50 value of 1.06 x 10(-8) M.