Antifungal, anti-biofilm, and anti-hyphal properties of N-substituted phthalimide derivatives against Candida species

Candida species comprise a ubiquitous pathogenic fungal genus responsible for causing candidiasis. They are one of the primary causatives of several mucosal and systemic infections in humans and can survive in various environments. In this study, we investigated the antifungal, anti-biofilm, and anti-hyphal effects of six N-substituted phthalimides against three Candida species. Of the derivatives, N-butylphthalimide (NBP) was the most potent, with a minimum inhibitory concentration (MIC) of 100 µg/ml and which dose-dependently inhibited biofilm at sub-inhibitory concentrations (10-50 µg/ml) in both the fluconazole-resistant and fluconazole-sensitive Candida albicans and Candida parapsilosis. NBP also effectively inhibited biofilm formation in other pathogens including uropathogenic Escherichia coli, Staphylococcus epidermidis, Staphylococcus aureus, and Vibrio parahaemolyticus, along with the polymicrobial biofilms of S. epidermidis and C. albicans. NBP markedly inhibited the hyphal formation and cell aggregation of C. albicans and altered its colony morphology in a dose-dependent manner. Gene expression analysis showed that NBP significantly downregulated the expression of important hyphal- and biofilm-associated genes, i.e., ECE1, HWP1, and UME6, upon treatment. NBP also exhibited mild toxicity at concentrations ranging from 2 to 20 µg/ml in a nematode model. Therefore, this study suggests that NBP has anti-biofilm and antifungal potential against various Candida strains.

An Oxidation Study of Phthalimide-Derived Hydroxylactams

A systematic study of the oxidation of 3-hydroxy-2-substituted isoindolin-1-ones (hydroxylactams) and their conversion to the corresponding phthalimides was undertaken using three oxidants. Of special interest was the introduction of nickel peroxide (NiO₂) as an oxidation system for hydroxylactams and comparison of its performance with the commonly used pyridinium chlorochromate (PCC) and iodoxybenzoic acid (IBX) reagents. Using a range of hydroxylactams, optimal conversions of these substrates to the corresponding imides was achieved with 50 equivalents of freshly prepared NiO₂ in refluxing toluene over 5–32 h reaction times. By comparison, oxidations of the same substrates using PCC/silica gel (three equivalents) and IBX (three equivalents) required oxidation times of 1–3 h for full conversion but required lengthier purification. While nominal amounts (~25 mg) of substrate hydroxylactams were used to ascertain conversion, scale-up procedures using all three methods gave good to excellent isolated yields of imides.

Efficient palladium-catalyzed double carbonylation of o-dibromobenzenes: synthesis of thalidomide

A convenient and mild procedure for double carbonylation of o-dibromobenzene with various 2-amino pyridines and naturally occurring amines has been developed. N-Substituted phthalimides were produced in good to excellent yields. Furthermore, thalidomide was produced in excellent yield under these conditions.

Synthesis and biological evaluation of some novel cyclic-imides as hypoglycaemic, anti-hyperlipidemic agents

Certain new halogenated cyclic-imides related to N-substituted phthalimide moiety were synthesized. Spacers of one or two carbon atom distances were inserted to connect the N-terminus of the cyclic-imide nuclei to the used heteroaryl groups to evaluate the effect of such alteration on biological activity. The synthesized compounds were subjected to hypoglycaemic and anti-hyperlipidemic evaluation. Some of the tested compounds proved to be more potent than the reference drugs glibenclamide and clofibrate. Compound 5e remarkably reduced serum glucose level by 55%; while 5c, 5e, 7d and 8e reduced total serum cholesterol by 58, 56, 54 and 53%, respectively. Those new cyclic-imides could be considered as useful template for future development to obtain more potent hypoglycaemic and anti-hyperlipidemic agents.