Comparison of the hypolipidemic activity of cyclic vs. acyclic imides

Two series of nitrogen-substituted cyclic and acyclic imides were examined for hypolipidemic activity in mice after dosing for 16 days at a dose of 20 mg/kg per day. The hypolipidemic activity of the unsubstituted, N-butyl, N-3-oxobutyl, and N-2-carboxyethyl derivatives of diacetimide and succinimide were compared as well as the unsubstituted and N-substituted dibenzimide and diphenimide. It was shown that an imide functionality incorporated into a ring was not necessary for hypocholesterolemic activity. Good hypocholesterolemic activity was observed in both series of acyclic and cyclic imides. However, a cyclic imido structure was a necessary requirement for good hypotriglyceridemic activity. A decrease in hypotriglyceridemic activity was noted when comparing the cyclic imides to their respective acyclic congeners.     

Synthesis and antimicrobial activities of N-substituted imides

In the field of our research programs concerning novel antimicrobial agents, a series of N-substituted imides was synthesized. These compounds were obtained by cyclization of amido-acids in acetic anhydride/sodium acetate or hexamethyldisilazane/zinc bromide for the hydroxy-aromatic derivatives. The hydroxy-alkyl maleimides were directly prepared by condensation of the corresponding amino-alcohol with maleic anhydride in boiling toluene. Most of N-substituted maleimides showed an interesting antimicrobial activity towards bacteria from the ATCC collection (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) but the MIC values for P. aeruginosa were always high (128 microg/ml). The imides with alkyl substituents showed higher activities than aromatic analogues with MIC values in the range of 8-32 microg/ml. Comparatively, succinimides were practically inactive.     

Hypolipidemic activity of phthalimide derivatives V: Reduced and hydrolytic products of simple cyclic imides

A series of cyclic imides and related compounds have previously been shown to possess hypolipidemic activity at the low dose level of 20 mg/kg/d. Hydrolytic and reduced products of the cyclic imides were synthesized and examined to discern if possible metabolic products were the active chemical species of these hypolipidemic agents. Phthalimide proved to be the most active cyclic imide tested. Unfortunately, the new products did not, in general, improve hypolipidemic activity in rodents. The exceptions were piperidine which demonstrated improved hypotriglyceridemic activity, and 3,4,5,6-dibenzohomopiperidin-2-one, which demonstrated improved hypocholesterolemic activity compared to phthalimide.     

Analgesic activity of cyclic imides: 1,8-naphthalimide and 1,4,5,8-naphthalenediimide derivatives

In early studies, we have reported the synthesis and biological activities of several cyclic imides. The present study describes the analgesic activity of 1,8-naphthalimide and 1,4,5,8-naphthalenediimide derivatives in a standard murine model of analgesia. The pharmacological results show that all compounds studied, given intraperitoneally, produced significant inhibition of acetic acid-induced abdominal constrictions. At the ID50 (micromol/kg) level, these cyclic imide derivatives were about 40-270-fold more potent in this assay than aspirin and acetaminophen, two well-known and widely used analgesics. These results extend previous studies on the analgesic activity of cyclic imides.     

Development of a predictive statistical model for the analgesic activity of a family of imides.

Quantitative structure-activity relationship (QSAR) studies were done with a family of cyclic imides. Promising efforts to create a QSAR model with substantial predictive power for the design of novel cyclic imides with improved analgesic activity are reported.     

Antimicrobial activity and stability of tingenone derivatives.

Quinone-methide triterpenes of the tingenone series were evaluated for their antimicrobial activity. These compounds were effective against Bacillus cereus, B. subtilis, Sarcina lutea, Staphylococcus aureus, Microsporum gypseum and a Gram-negative bacterium, Klebsiella pneumoniae. Under acidic conditions, the quinone-methide part of these compounds rearranged into the divinyl-phenolic system, and the antimicrobial activity was thus lost.     

Convenient synthesis and antimicrobial activity of new 3-substituted 5-(benzofuran-2-yl)-pyrazole derivatives

The reaction of ethyl 4-(benzofuran-2-yl)-2,4-dioxobutanoate 2 with two moles of hydrazine hydrate afforded 5-(benzofuran-2-yl)-1H-pyrazole-3-carbohydrazide 4a, while its reaction with equimolar amount of phenylhydrazine gave ester 3b which then converted to 5-(benzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carbohydrazide 4b. Various new compounds such as imides 5 and 6, acyl hydrazones 7 and 8, bi-pyrazoles 9-12, and 1,3-thiazole derivatives 14 and 15 were prepared from carbohydrazide derivatives 4a, b. The new compounds are tested for their antimicrobial activity. Compounds 2, 5, 7, and 8 showed antifungal activities against C. albicans. Also, compounds 2, 6, 8, and 15 showed antibacterial activities.     

N-(Aminoalkyl)imide antineoplastic agents. Synthesis and biological activity

The similarity of the side-chain characteristics of 1,4-dihydroxy-5,8-bis[[2-[(2-hydroxyethyl)amino]ethyl]amino]- anthraquinone (DHAQ), discovered by us in 1978, and those of the N-substituted imides of 3-nitro-1,8-naphthalic acid, discovered by other investigators recently, led us to conduct a systematic study on the N-(aminoalkyl)-substituted derivatives of a variety of imides. Areas of study included (a) selection of the ring system, (b) modification of the side chain, (c) substitution on certain chosen ring systems, and (d) combinations of the aforementioned variants. Preliminary biological activity screening indicated that N-(dialkylaminoethyl)imides of the 3,6-dinitro- and 3,6-diamino-1,8-naphthalic acid system possessed prominent antileukemia and antimelanoma activity in both in vitro and in vivo experimental tumor systems.     

Oral absorption of cephalosporin antibiotics. 3. Synthesis and biological properties of 7 alpha-methoxy-7 beta-(arylacetamido)-3-chloro-3-cephem-4- carboxylic acids

A series of 7 alpha-methoxy-7 beta-amido-3-chloro-3-cephem-4-carboxylic acids was prepared and evaluated for biological activity. When compared with the parent 7-non-methoxy analogues, these new 7 alpha-methoxy-3-chloro cephalosporins displayed diminished antimicrobial activity.     

Synthesis and antimicrobial activity of certain novel quinoxalines

In this study, certain 3-methyl-2-[4-(substituted amino carbonyl)anilino] quinoxalines, (2a-d) and (3a-d), were synthesized from the new key compound 2-[4-(ethoxycarbonyl)anilino]-3-methyl quinoxaline (1). In addition, a series of 2-[4-(arylidene hydrazinocarbonyl)anilino]-3-methyl quinoxalines (5a-e), as well as their cyclized oxadiazolinyl derivatives (6a-e), and a series of 2-[4-N2-acylhydrazinocarbonyl) anilino]-3-methyl quinoxalines (7a-d), as well as their cyclized oxadiazoiyl derivatives (8a-d) were also prepared. Some of these derivatives were evaluated for antimicrobial activity in vitro. It was found that all the selected compounds exhibit antimicrobial activity and that compound 5b had a broad spectrum of activity.     

Design and synthesis of cationic antimicrobial peptides with improved activity and selectivity against Vibrio spp

Extensive use of classical antibiotics has led to the growing emergence of many resistant strains of pathogenic bacteria. Evidence has suggested that cationic antimicrobial peptides (AMPs) are of greatest potential to represent a new class of antibiotics. The largest group of AMPs comprises peptides that fold into an amphipathic alpha-helical conformation when interacting with the target microorganism. In the current study, a series of cationic AMPs of 20 amino acids was designed and synthesised based on four structural parameters, including charge, polar angle, hydrophobicity and hydrophobic moment. The effect of these parameters on antimicrobial activity and selectivity was assessed by structural and biological analyses. Our results indicated that high hydrophobicity and amphipathicity (hydrophobic moment) were correlated with increased haemolytic activity, whilst antimicrobial activity was found to be less dependent on these factors. Three of the synthetic AMPs (GW-Q4, GW-Q6 and GW-H1) showed higher antimicrobial activity and selectivity against a broad spectrum of Gram-positive and Gram-negative bacteria compared with the naturally occurring AMPs magainin 2a and pleurocidin. This study also demonstrates that these rationally designed cationic and amphipathic helical AMPs exhibited high selectivity against several Vibrio spp. and are potential agents for future use in the treatment of these marine pathogens.     

Synthesis and antimicrobial activity of novel quinazolone derivatives

Three novel series of 4-oxoquinazoline derivatives were prepared and evaluated as potential antimicrobial agents. Evaluation of the antimicrobial activity of a variety of 4-substituted-1-thiosemicarbazides, 3,4-disubstituted thiazolines, and 3-substituted-5-thiazolidones reveals that the majority possess significant in vitro activity against Gram-positive organisms. Some derivatives also exhibited antifungal activity.     

Antimicrobial activity of 9-O-acyl- and 9-O-alkylberberrubine derivatives

For the structure-activity relationship study on berberrubine derivatives, a series of compounds bearing 9-O-acyl- and 9-O-alkyl-substituents were synthesized and tested for antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. Octanoyl, decanoyl, lauroyl derivatives among the acyl analogs and hexyl, heptyl, octyl, nonyl, decyl, undecyl derivatives among the alkyl analogs showed strong antimicrobial activity against Gram-positive bacteria and fungi. As a whole, alkyl analogs were more active than acyl analogs for antimicrobial activity. Synthesized derivatives had no activity on Gram-negative bacteria. Too short or too long substituents decreased activity. These results suggest that the presence of lipophilic substituents with moderate sizes might be crucial for the optimal antimicrobial activity.     

Hypolipidemic activity of 4-phenyl-5,5-dicarbethoxy-2-pyrrolidinone in rodents

A series of pyrrolidinones have been reported to possess hypolipidemic activity in mice. The most active agent, 4-phenyl-5-5-dicarbethoxy-2-pyrrolidinone, effectively lowered both serum cholesterol and triglyceride levels at 20-30 mg/kg/d. The agent suppressed liver mitochondrial citrate exchange, phosphatidate phosphohydrolase, and sn-glycerol-3-phosphate acyl transferase activities. Lipid content of the liver, small intestine, and serum lipoprotein fractions was reduced by drug treatment, but lipid levels increased in the bile and fecal samples, suggesting the drug accelerated lipid excretion. The mode of action of the pyrrolidinone appears similar to that of the cyclic imides.     

Synthetic mimics of antimicrobial peptides from triaryl scaffolds

In this report, we describe the synthesis of a new series of small amphiphilic aromatic compounds that mimic the essential properties of cationic antimicrobial peptides using Suzuki-Miyaura coupling. The new design allowed the easy tuning of the conformational restriction, controlled by introduction of intramolecular hydrogen bonds, and the overall hydrophobicity by modifications to the central ring and the side chains. This approach allowed us to better understand the influence of these features on the antimicrobial activity and selectivity. We found that the overall hydrophobicity had a more significant impact on antimicrobial and hemolytic activity than the conformational stiffness. A novel compound was discovered which has MICs of 0.78 μg/mL against S. Aureus and 6.25 μg/mL against E. Coli, similar to the well-known antimicrobial peptide, MSI-78.     

Copper complexes of some amino acid derivatives of substituted coumarilic acid

A series of copper complexes of some amino acid derivatives of 6-methoxy-3-methyl-coumarilic acid were prepared. The infrared, visible spectra and magnetic sus-ceptibility of these compounds were reported. All copper complexes were found to have antimicrobial activity against gram-positive bacteria only.     

Hypobetalipoproteinemic agents. 2. Compounds related to 4-(1-adamantyloxy)aniline.

While the previously used displacement reaction of sodim 1-adamantyl oxide on 4-fluoronitrobenzene was applicable to the preparation of 4-(1-adamantyloxy)aniline and several related compounds, certain derivatives were not easily accessible by this route. Thus the recently reported ortho alkylation of anilines and the dicyclohexylcarbodiimide-promoted coupling of 1-adamantanol with phenols were useful in the preparation of aromatic-substituted derivatives. Furthermore, addition of phenylmagnesium bromide to 1-cyanoadamantane provided entry to the 4-(1-adamantylmethyl)aniline series. 4-(1-Adamantyloxy)aniline (3) is herein reported to be a more potent hypobetalipoproteinemic agent than the previously reported bicyclooctyloxy analogue. Replacement of the oxygen atom of 3 with sulfur (74) or methylene (62), but not nitrogen (71), results in active compounds. In the oxygen series derived from 3, the widest scope of substitution on nitrogen resulting in activity is found. The N-ethoxycarbonyl (5), acetyl (6), methyl (12), ethyl (13), N-methyl-N-(2-hydroxyethyl) (19), N-methyl-N-formyl (22), N,N-dimethyl (26), pyrrolidine (14), and piperidine (15) derivatives are active. Aromatic ring substitution also provided the active 3-chloro (44b), 2-fluoro (41b, 42, and 43), and 2-methylthiomethyl (48) compounds. Thus these active compounds are identified for further development as hypobetalipoproteinemic agents.     

Aromatic dienoyl tetramic acids. Novel antibacterial agents with activity against anaerobes and staphylococci

Streptolydigin (1) and tirandamycin A (2) are typical members of the naturally occurring class of 3-dienoyl tetramic acids. These compounds, which possess potent antibacterial activity particularly against anaerobes, have been shown to inhibit bacterial RNA polymerase. In contrast, tenuazonic acid (5), which lacks a complex dioxabicyclononane moiety and diene chromophore present in 1 and 2, exhibits essentially no antimicrobial activity and has no effect on bacterial RNA polymerase, suggesting that one or both of these structural features may be critical for antibacterial activity. In this paper, we report on a novel series of synthetic dienoyl tetramic acids that lack a complex dioxabicyclononane unit. Several of these compounds, particularly 8T-W, exhibit potent antimicrobial activity against Gram-positive and Gram-negative anaerobes as well as staphylococci. We will discuss the structure-activity relationship for this series of compounds which, in contrast to their natural counterparts, do not inhibit significantly RNA polymerase. We will also discuss preliminary results on the biochemical and microbiological properties of this series of compounds, several of which moderately inhibit supercoiling by DNA gyrase isolated from E. coli H560, although this enzyme has not been established as their target in whole cells. Compound 8W, which is not cross-resistant with DNA gyrase subunit A or B inhibitors or tirandamycin, has also been demonstrated to be rapidly bactericidal.     

Synthesis of the enantiomers of some disubstituted succinic imides

Synthesis of the Enantiomers of Some Disubstituted Succinic Imides The synthesis of the enantiomers of the disubstituted succinic imides 4a – 4d is described. It proceeds via the optically active cyanopropionates 2a – 2d which are synthesized from the succinic acid nitriles after resolution into the enantiomers. The enantiomers of the N-methyl succinic imides 5a – 5d and of the N-ethyl succinic imides 6a – 6d are obtained by alkylation of the chiral imides 4a – 4d .     

Anti-Helicobacter pylori agents. 3. 2-[(Arylalkyl)guanidino]-4-furylthiazoles.

A series of 2-[(arylalkyl)guanidino]-4-[(5-acetamidomethyl)furan-2-yl]thiazole s and some 4-acetamidomethyl positional isomers were synthesized and evaluated for antimicrobial activity against Helicobacter pylori. Among the compounds that had potent antimicrobial activity (MIC < 0. 1 microgram/mL), compounds 31 and 36 additionally possessed H2 antagonist and gastric antisecretory activities. Though compound 51, an analogue incorporating a methyl group onto the furan nucleus of 36, and compound 54, a positional isomer of 51, also showed potent anti-H. pylori activity, the H2 antagonism profile was eliminated from these compounds. Thus, two types of potent anti-H. pylori agents could be derived from the same scaffold.