Multitargeted inhibition of key enzymes associated with diabetes and Alzheimer's disease by 1,3,4-oxadiazole derivatives: Synthesis, in vitro screening, and computational studies.

A library of 22 derivatives of 1,3,4-oxadiazole-2-thiol was synthesized, structurally characterized, and assessed for its potential to inhibit α-amylase, α-glucosidase, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and antioxidant activities. Most of the tested compounds demonstrated good to moderate inhibition potential; however, their activity was lower than that of the standard acarbose. Significantly, compound 3f exhibited the highest inhibition potential against α-glucosidase and α-amylase enzymes, with IC50 values of 18.52 ± 0.09 and 20.25 ± 1.05 µM, respectively, in comparison to the standard acarbose (12.29 ± 0.26; 15.98 ± 0.14 µM). Compounds also demonstrated varying degrees of inhibitory potential against AChE (IC50 = 9.25 ± 0.19 to 36.15 ± 0.12 µM) and BChE (IC50 = 10.06 ± 0.43 to 35.13 ± 0.12 µM) enzymes compared to the standard donepezil (IC50 = 2.01 ± 0.12; 3.12 ± 0.06 µM), as well as DPPH (IC50 = 20.98 ± 0.06 to 52.83 ± 0.12 µM) and ABTS radical scavenging activities (IC50 = 22.29 ± 0.18 to 47.98 ± 0.03 µM) in comparison to the standard ascorbic acid (IC50 = 18.12 ± 0.15; 19.19 ± 0.72). The kinetic investigations have demonstrated that the compounds exhibit competitive-type inhibition for α-amylase, noncompetitive-type inhibition for α-glucosidase and AChE, and mixed-type inhibition for BChE. Additionally, a molecular docking study was performed on all synthetic oxadiazoles to explore the interaction details of these compounds with the active sites of the enzymes.

Antioxidant enzymes and association of CAT SNP-21 A/T (rs7943316) with male infertility.

Infertility is a multifactorial and polygenic disease. A vast majority of infertility is still unexplained despite modern diagnostic techniques. Oxidative stress is considered a factor for male infertility but etiology in terms of functional gene polymorphism and experimental studies on human subjects is scarcely reported. The aim of the study was to investigate the status of three antioxidant enzymes; catalase, superoxide dismutase (SOD), and glutathione reduced (GSH) in clinically diagnosed infertile males and find the potential association of CAT gene variant in the promoter region -21 A/T (rs7943316). The study consisted of 55 clinically diagnosed infertile males and 50 non-infertile volunteers. The activity of antioxidant enzymes was measured through a spectrophotometer. Polymerase chain reaction-restriction fragment length polymorphism was performed for genotyping of single-nucleotide polymorphism. Catalase enzyme activity was significantly decreased while SOD and GSH were substantially increased (p ≤ 0.01) in infertile men in comparison to non-infertile. CAT gene variant rs7943316 had shown significant association in dominant, recessive model and allelic frequencies. The study concludes that rs7943316 has a substantial role in male infertility. The outcome of the study may help in resolving idiopathic infertility cases and may help in evolving novel diagnostic and therapeutic approaches. Other variants of CAT and antioxidant genes are suggested to ascertain further insight.

Protein Quantity and Quality of Safflower Seed Improved by NP Fertilizer and Rhizobacteria (Azospirillum and Azotobacter spp.).

HIGHLIGHTS Rhizobacteria (Azotobacter spp.) have improved the quality and quantity of safflower seed protein.Protein quality was confirmed by SDS-PAGE and new bands were found in response to different combinations of rhizobacteria and lower doses of fertilizers.The PGPR application has reduced the use of fertilizers upto 50%. Protein is an essential part of the human diet. The aim of this present study was to improve the protein quality of safflower seed by the application of plant growth promoting rhizobacteria (PGPR) in combination with conventional nitrogen and phosphate (NP) fertilizers. The seeds of two safflower cultivars Thori and Saif-32, were inoculated with Azospirillum and Azotobacter and grown under field conditions. Protein content and quality was assessed by crude protein, amino acid analysis, and SDS-PAGE. Seed crude protein and amino acids (methionine, phenylalanine, and glutamic acid) showed significant improvements (55-1250%) by Azotobacter supplemented with a quarter dose of fertilizers (BTQ) at P ≤ 0.05. Additional protein bands were induced in Thori and Saif-32 by BTQ and BTH (Azotobacter supplemented with a half dose of fertilizer) respectively. The Azospirillum in combination with half dose of fertilizer (SPH) and BTQ enhanced both indole acetic acid (IAA) (90%) and gibberellic acid (GA) (23-27%) content in safflower leaf. Taken together, these data suggest that Azospirillum and Azotobacter along with significantly reduced (up to 75%) use of NP fertilizers could improve the quality and quantity of safflower seed protein.

Structural basis for ion selectivity revealed by high-resolution crystal structure of Mg2+ channel MgtE.

Magnesium is the most abundant divalent cation in living cells and is crucial to several biological processes. MgtE is a Mg(2+) channel distributed in all domains of life that contributes to the maintenance of cellular Mg(2+) homeostasis. Here we report the high-resolution crystal structures of the transmembrane domain of MgtE, bound to Mg(2+), Mn(2+) and Ca(2+). The high-resolution Mg(2+)-bound crystal structure clearly visualized the hydrated Mg(2+) ion within its selectivity filter. Based on those structures and biochemical analyses, we propose a cation selectivity mechanism for MgtE in which the geometry of the hydration shell of the fully hydrated Mg(2+) ion is recognized by the side-chain carboxylate groups in the selectivity filter. This is in contrast to the K(+)-selective filter of KcsA, which recognizes a dehydrated K(+) ion. Our results further revealed a cation-binding site on the periplasmic side, which regulate channel opening and prevents conduction of near-cognate cations.

'Hit and run' serial femtosecond crystallography of a membrane kinase in the lipid cubic phase.

The lipid-based bicontinuous cubic mesophase is a nanoporous membrane mimetic with applications in areas that include medicine, personal care products, foods and the basic sciences. An application of particular note concerns it use as a medium in which to grow crystals of membrane proteins for structure determination by X-ray crystallography. At least two variations of the mesophase exist. One is the highly viscous cubic phase, which has well developed long-range order. The other so-called sponge phase is considerably more fluid and lacks long-range order. The sponge phase has recently been shown to be a convenient vehicle for delivering microcrystals of membrane proteins to an X-ray free-electron laser beam for serial femtosecond crystallography (SFX). Unfortunately, the sponge phase approach calls for large amounts of protein that are not always available in the case of membrane proteins. The cubic phase offers the advantage of requiring significantly less protein for SFX but comes with its own challenges. Here, we describe the physico-chemical bases for these challenges, solutions to them and prospects for future uses of lipidic mesophases in the SFX arena.

Structural basis for polyspecificity in the POT family of proton-coupled oligopeptide transporters.

An enigma in the field of peptide transport is the structural basis for ligand promiscuity, as exemplified by PepT1, the mammalian plasma membrane peptide transporter. Here, we present crystal structures of di- and tripeptide-bound complexes of a bacterial homologue of PepT1, which reveal at least two mechanisms for peptide recognition that operate within a single, centrally located binding site. The dipeptide was orientated laterally in the binding site, whereas the tripeptide revealed an alternative vertical binding mode. The co-crystal structures combined with functional studies reveal that biochemically distinct peptide-binding sites likely operate within the POT/PTR family of proton-coupled symporters and suggest that transport promiscuity has arisen in part through the ability of the binding site to accommodate peptides in multiple orientations for transport.

Crystallizing Membrane Proteins in the Lipidic Mesophase. Experience with Human Prostaglandin E2 Synthase 1 and an Evolving Strategy.

The lipidic mesophase or in meso method for crystallizing membrane proteins has several high profile targets to its credit and is growing in popularity. Despite its success, the method is in its infancy as far as rational crystallogenesis is concerned. Consequently, significant time, effort, and resources are still required to generate structure-grade crystals, especially with a new target type. Therefore, a need exists for crystallogenesis protocols that are effective with a broad range of membrane protein types. Recently, a strategy for crystallizing a prokaryotic α-helical membrane protein, diacylglycerol kinase (DgkA), by the in meso method was reported (Cryst. Growth. Des.2013, 14, 2846-2857). Here, we describe its application to the human α-helical microsomal prostaglandin E2 synthase 1 (mPGES1). While the DgkA strategy proved useful, significant modifications were needed to generate structure-quality crystals of this important therapeutic target. These included protein engineering, using an additive phospholipid in the hosting mesophase, performing multiple rounds of salt screening, and carrying out trials at 4 °C in the presence of a tight binding ligand. The crystallization strategy detailed here should prove useful for generating structures of other integral membrane proteins by the in meso method.

Lipidic cubic phase injector facilitates membrane protein serial femtosecond crystallography.

Lipidic cubic phase (LCP) crystallization has proven successful for high-resolution structure determination of challenging membrane proteins. Here we present a technique for extruding gel-like LCP with embedded membrane protein microcrystals, providing a continuously renewed source of material for serial femtosecond crystallography. Data collected from sub-10-µm-sized crystals produced with less than 0.5 mg of purified protein yield structural insights regarding cyclopamine binding to the Smoothened receptor.

Expression profiles of fetal membrane nicotinamide adenine dinucleotide phosphate oxidases (NOX) 2 and 3 differentiates spontaneous preterm birth and pPROM pathophysiologies.

INTRODUCTION: Nicotinamide adenine dinucleotide phosphate oxidases (NOX 1-5) are enzymes that generate cellular reactive oxygen species (ROS) besides mitochondria and might be important ROS sources associated with pregnancy complications, particularly preterm premature rupture of membranes (pPROM), that has been related to ROS. OBJECTIVE: To characterize NOX enzymes expression in human fetal membranes. METHODS: Differential expression and localization of NOX isoforms in human fetal membranes collected from women with uncomplicated pregnancies at term, preterm birth (PTB) or pPROM and in vitro in normal term membranes maintained in an organ explant system stimulated with water-soluble cigarette smoke extract (wsCSE) were documented by real time PCR and immunohistochemistry. RESULTS: Fetal membranes from term deliveries, PTB and pPROM expressed NOX 2, 3 and 4 mRNAs whereas NOX 1 and 5 were not detected. NOX 2 expression was 2.3-fold higher in PTB than pPROM (p = 0.005) whereas NOX 3 was 2.2-fold higher in pPROM compared to PTB (p = 0.04). NOX 2 and 3 expressions at term mimicked pPROM and PTB, respectively. No difference in NOX 4 expression was observed among the studied groups. NOX 2, 3 and 4 were localized to both amniotic and chorionic cells. Expression of NOX 2, 3 and 4 were not significant in wsCSE-stimulated membranes compared to untreated controls. DISCUSSION/CONCLUSIONS: NOX enzymes are present in the fetal membranes and are differentially expressed in PTB and pPROM. Absence of any changes in NOXs expression after wsCSE stimulation suggests ROS generation in the membranes does not always correlate with NOX expression.

Serial femtosecond crystallography of G protein-coupled receptors.

X-ray crystallography of G protein-coupled receptors and other membrane proteins is hampered by difficulties associated with growing sufficiently large crystals that withstand radiation damage and yield high-resolution data at synchrotron sources. We used an x-ray free-electron laser (XFEL) with individual 50-femtosecond-duration x-ray pulses to minimize radiation damage and obtained a high-resolution room-temperature structure of a human serotonin receptor using sub-10-micrometer microcrystals grown in a membrane mimetic matrix known as lipidic cubic phase. Compared with the structure solved by using traditional microcrystallography from cryo-cooled crystals of about two orders of magnitude larger volume, the room-temperature XFEL structure displays a distinct distribution of thermal motions and conformations of residues that likely more accurately represent the receptor structure and dynamics in a cellular environment.

Host Lipid and Temperature as Important Screening Variables for Crystallizing Integral Membrane Proteins in Lipidic Mesophases. Trials with Diacylglycerol Kinase.

A systematic study of the crystallization of an α-helical, integral membrane enzyme, diacylglycerol kinase, DgkA, using the lipidic cubic mesophase or in meso method is described. These trials have resulted in the production of blocky, rhombohedron-shaped crystals of diffraction quality currently in use for structure determination. Dramatic improvements in crystal quality were obtained when the identity of the lipid used to form the mesophase bilayer into which the protein was reconstituted as a prelude to crystallogenesis was varied. These monoacylglycerol lipids incorporated fatty acyl chains ranging from 14 to 18 carbon atoms long with cis olefinic bonds located toward the middle of the chain. Best crystals were obtained with a lipid that had an acyl chain 15 carbon atoms long with the double bond between carbons 7 and 8. It is speculated that the effectiveness of this lipid derives from hydrophobic mismatch between the target integral membrane protein and the bilayer of the host mesophase. Low temperature (4 °C) worked in concert with the short chain lipid to provide high quality crystals. Recommended screening strategies for crystallizing membrane proteins that include host lipid type and low temperature are made on the basis of this and related in meso crystallization trials.

Crystal structure of the integral membrane diacylglycerol kinase.

Diacylglycerol kinase catalyses the ATP-dependent phosphorylation of diacylglycerol to phosphatidic acid for use in shuttling water-soluble components to membrane-derived oligosaccharide and lipopolysaccharide in the cell envelope of Gram-negative bacteria. For half a century, this 121-residue kinase has served as a model for investigating membrane protein enzymology, folding, assembly and stability. Here we present crystal structures for three functional forms of this unique and paradigmatic kinase, one of which is wild type. These reveal a homo-trimeric enzyme with three transmembrane helices and an amino-terminal amphiphilic helix per monomer. Bound lipid substrate and docked ATP identify the putative active site that is of the composite, shared site type. The crystal structures rationalize extensive biochemical and biophysical data on the enzyme. They are, however, at variance with a published solution NMR model in that domain swapping, a key feature of the solution form, is not observed in the crystal structures.

Crystal structure of the ß2 adrenergic receptor-Gs protein complex.

G protein-coupled receptors (GPCRs) are responsible for the majority of cellular responses to hormones and neurotransmitters as well as the senses of sight, olfaction and taste. The paradigm of GPCR signalling is the activation of a heterotrimeric GTP binding protein (G protein) by an agonist-occupied receptor. The ß(2) adrenergic receptor (ß(2)AR) activation of Gs, the stimulatory G protein for adenylyl cyclase, has long been a model system for GPCR signalling. Here we present the crystal structure of the active state ternary complex composed of agonist-occupied monomeric ß(2)AR and nucleotide-free Gs heterotrimer. The principal interactions between the ß(2)AR and Gs involve the amino- and carboxy-terminal α-helices of Gs, with conformational changes propagating to the nucleotide-binding pocket. The largest conformational changes in the ß(2)AR include a 14 Å outward movement at the cytoplasmic end of transmembrane segment 6 (TM6) and an α-helical extension of the cytoplasmic end of TM5. The most surprising observation is a major displacement of the α-helical domain of Gαs relative to the Ras-like GTPase domain. This crystal structure represents the first high-resolution view of transmembrane signalling by a GPCR.

A review of the applications of imiquimod: a novel immune response modifier.

Imiquimod (1-(2-methylpropyl)-1 H-imidazo[4,5-c]quinolin-4-amine) and its analogues are a class of non-nucleoside imidazoquinolinamines (hetero-cyclic amine) that activate the immune system through localised induction of cytokines, such as IFN-alpha, -beta, and a number of endogenous interleukins. The exact mechanism of its actions are still unexplored, although when tested in a number of cell culture systems, imiquimod demonstrated no inherent antiviral or antiproliferative activity in vitro, whereas, due to its reported ability to produce onsite stimulation and secretion of cytokines in various in vivo studies, such types of immune response modifiers have been shown to cause diverse biological functions, involving immunoregulatory, antiviral, antiproliferative and antitumour activities. These data support a rational justification to consider imiquimod as an innovative topical agent to treat various cutaneous diseases. Since its synthesis in 1980,several studies using animal models and human subjects have been reported substantiating its usefulness as a treatment option for various skin disorders such as genital warts, genital herpes, molluscum contagiosum, basal cell carcinoma and psoriasis. Imiquimod is insoluble in water but in most of the clinical studies its incorporation from 1 - 5% by weight in an oil-into-water cream emulsion has been reported as being well-tolerated with mild-to-moderate drug-related side effects, such as itching, burning sensation, pain, erythema, erosion and oedema. As a potent immune response modifier and an agent stimulating cell-mediated immune responses, imiquimod appears to be a promising drug to treat many skin disorders, infections and neoplasms.

Management of psoriasis vulgaris with methotrexate 0.25% in a hydrophilic gel: a placebo-controlled, double-blind study.

BACKGROUND: Methotrexate has been used as one of the first and systemic therapies for psoriasis. In general, 70% of patients with psoriasis prefer topical therapy as the treatment of choice. OBJECTIVE: The purpose of this placebo-controlled double-blind study was to evaluate the clinical efficacy and tolerability of methotrexate 0.25% incorporated in a hydrophilic gel (hydroxyethylcellulose 1%) to treat patients afflicted with psoriasis vulgaris. METHODS: Sixty patients (37M/23F) ranging between 18 and 70 years of age, with slight to moderate chronic plaque-type psoriasis and PASI (Psoriasis Area and Severity Index) scores between 5.3 and 17.5 joined the study. The mean duration of the disease at entry was 9.6 years (range 1-24 years). The diagnosis of psoriasis was established by clinical and histopathologic methods. Patients were sequentially randomized into two parallel groups. Each patient was allocated a precoded 100-g tube (active or placebo) with instructions on how to self-administer the trial medication topically (without occlusion) to their lesions two times daily for 5 consecutive days per week. The study lasted for 12 weeks with 4 weeks of active treatment. Patients were examined on a weekly basis and those showing total clearing or remission of lesions were considered effectively treated. RESULTS: By the end of the treatment, breaking the code disclosed that methotrexate 0.25% gel had significantly treated more patients than placebo (83.3% vs. 6.7%; p < 0.0001), reduced the PASI score to a mean of 2.2, and cleared more plaques (82.2% vs. 4.3%; p < 0.0001). Laboratory evaluations, including CBC with differential and platelet count, renal function, liver chemistry [SGOT (aspartate transaminase) and SGPT (alanine transaminase)], and serum creatinine, were within the normal limits. The treatment was well-tolerated by all the patients, with no adverse drug-related symptoms and no dropouts. The study was followed up for 12 months from the first day of the treatment; two cured patients had relapsed after 8 months. CONCLUSION: The findings of this study demonstrate that methotrexate 0.25% in a hydrophilic gel is well tolerated and significantly more effective than placebo as a patient-applied topical medication to treat psoriasis vulgaris.

Treatment of external genital warts in men with imiquimod 2% in cream. A placebo-controlled, double-blind study.

OBJECTIVE: The purpose of this double-blind, placebo-controlled study was to evaluate the safety, clinical efficacy and tolerability of imiquimod (2%) in cream to cure external genital warts in males. METHODS: Preselected male patients (n=60) ranging between 18 and 50 years of age (mean 24.2) harbouring 558 lesions (mean 9.3) with clinical, histopathological and polymerase chain reaction (PCR) confirmed diagnosis of human papilloma virus (HPV) infection were randomized to two parallel groups. Each patient was allocated a precoded 25g tube, and instructions on how to apply the trial medication to their lesions at home once daily for three consecutive days per week (max. 12 application in 4 weeks). To evaluate the safety, clinical efficacy and tolerance, patients were exa-mined on a weekly basis. Cure was defined as the total elimination of treated warts with PCR, and Southern blot hybridization confirmed negative HPV DNA. RESULTS: By the end of the treatment, 40% (24/60) patients and 49.8% (278/558) warts were cured. Breaking the code revealed that imiquimod cream had cured 70% (21/30) patients and 86.8% of warts, while placebo healed three subjects and 28 warts (P=0.0001). Eleven patients (18.3%), predominantly in the imiquimod cream group, experienced mild to moderate, non-objective, drug-related side effects with no dropouts. The study was followed up for 18 months from the first day of the treatment, and among the 26 cured patients, one in the imiquimod cream group and two in the placebo had a relapse after 14 months. CONCLUSION: The study demonstrated that 2% imiquimod in cream with mild non-objective side effects is safe, tolerable and significantly more effective than placebo in curing external genital warts in males.

Management of intravaginal warts in women with 5-fluorouracil (1%) in vaginal hydrophilic gel: a placebo-controlled double-blind study.

The purpose of this placebo-controlled, double-blind study was to determine the safety, tolerability and clinical efficacy of 5-fluorouracil (1%) in a vaginal hydrophilic gel (hydroxyethylcellulose, 1%) to cure intravaginal papillomas in women. Pre-selected, 60 women ranging between 18 and 50 years of age (mean 24.6), having 312 vaginal condylomas (mean 5.2) joined the study. The diagnosis of human papillomavirus (HPV) was established with clinical, histopathological and polymerase chain reaction (PCR) techniques. Subjects were randomized into 2 parallel groups. Each patient was allocated a pre-coded tube 15 g (active or placebo) with graduated vaginal applicators (disposable), and instructions how to insert 4 g of the trial medication deep into the vagina once at bedtime on every other day (1, 3 and 5) per week, to visit the clinic on day 7 for clinical evaluations and to receive the same pre-coded replacement to continue the regimen for another week. A maximum 12 applications were to be used in 4 weeks. Cure was defined as absence of clinical signs of infection, re-confirmed by PCR and Southern blot hybridization negative HPV DNA. By the end of the treatment 48.4% patients and 51.9% lesions were cured. Breaking the code revealed that 5-fluorouracil (1%) gel had cured 83.3% patients and 87% intravaginal warts. Placebo resolved 13.3% patients and 14% condylomas; (active gel versus placebo; P < 0.001). Twelve patients (20%) mostly in the active gel experienced mild erythema, erosion and oedema, with no drop-outs. Among cured patients 3 had a relapse after 16 months. In conclusion, the clinical results of the study demonstrate that 5-fluorouracil (1%) in a vaginal hydrophilic gel is safe, tolerable and significantly more effective than placebo to cure intravaginal warts in women.

Butenafine hydrochloride: for the treatment of interdigital tinea pedis.

Butenafine, a derivative of benzylamine with potent fungicidal activity is a new generation of antimycotic compound that has shown to be extremely effective against experimentally-induced tinea pedis in the guinea-pig, a situation that resembles synergetic pathology similar to that of tinea pedis in humans. Butenafine, (N-4-tert-butylbenzyl-N-methyl-1-naphthalenemethyl-amine hydrochloride) with a chemical structure and mode of action similar to those of the allylamines, demonstrates superior fungicidal activity in vitro against dermatophytes and superior fungistatic activity toward Candida albicans that of naftifine and terbinafine. In vitro, pharmacodynamic data has shown that the geometric mean of minimum inhibitory concentration values for butenafine were comparatively lower than those of naftifine and clotrimazole against clinical isolates for many dermatophytes. It inhibits sterol synthesis by blocking the squalene epoxidation stage in fungi. In phramacokinetic assessments butenafine achieves and maintains high concentrations and long retention time in skin, with associated anti-inflammatory activity in vivo. In controlled clinical trials when applied topically, butenafine appears to be well tolerated with a subjective mild burning sensation at the application site. There were no withdrawals from the study. Butenafine is sparingly soluble in water but readily soluble in methanol, ethanol, dichloromethane and chloroform. If incorporated properly in semisolid topical preparations, with a balanced vehicle, butenafine hydrochloride potentially exhibits as a promising alternative antimycotic agent for the treatment of tinea pedis.

Treatment of toenail onychomycosis with 2% butenafine and 5% Melaleuca alternifolia (tea tree) oil in cream.

The prevalence of onychomycosis, a superficial fungal infection that destroys the entire nail unit, is rising, with no satisfactory cure. The objective of this randomized, double-blind, placebo-controlled study was to examine the clinical efficacy and tolerability of 2% butenafine hydrochloride and 5% Melaleuca alternifolia oil incorporated in a cream to manage toenail onychomycosis in a cohort. Sixty outpatients (39 M, 21 F) aged 18-80 years (mean 29.6) with 6-36 months duration of disease were randomized to two groups (40 and 20), active and placebo. After 16 weeks, 80% of patients using medicated cream were cured, as opposed to none in the placebo group. Four patients in the active treatment group experienced subjective mild inflammation without discontinuing treatment. During follow-up, no relapse occurred in cured patients and no improvement was seen in medication-resistant and placebo participants.

Management of toenail onychomycosis with 2% butenafine and 20% urea cream: a placebo-controlled, double-blind study.

Onychomycosis is an increasingly common and recalcitrant fungal nail infection world-wide. The purpose of this placebo-controlled, double-blind study was to determine the clinical efficacy, chemical avulsion, and tolerability of 2% butenafine hydrochloride and 20% urea incorporated in a cream to cure toenail onychomycosis in a preselected population. Sixty patients (38M, 22F), ranging between 18 and 60 years (mean 27.4), with more than 25% involvement of the big toenail were enrolled in the study. The diagnosis of onychomycosis was established by mycologic identification and reconfirmed by positive fungal culture. A precoded 25-g tube was randomly assigned to each patient (50 active and 10 placebo) with instructions to apply the trial medication to their infected toenail twice daily with an occlusive dressing for one week. The affected nail was removed with a nail clipper. No occlusive dressing was maintained after the initial one week regimen. To assess the chemical avulsion of the infected toenail, mycologic cure, clinical effectiveness of the treatment, and overall success, patients were examined twice a week for 16 weeks and thereafter on a weekly basis for a further 36 weeks. The treatment was well tolerated by all the patients throughout the study, with no dropouts. Marked improvement was seen in 73.3% patients after weeks 8, 16 and 24 with clinically and mycologically confirmed negative fungal culture. Code disclosure revealed that active butenafine and urea cream cured significantly more patients than placebo (88% versus 0%; p < 0.0001). Of the 60 patients 91.6% reported no drug-related adverse symptoms. Five patients reported non-objective mild inflammation without discontinuation of the treatment. During one year follow-up of the study phase, none of the cured patients had a relapse. In conclusion, the mycologic and overall assessment of this study demonstrate that 2% butenafine HCl and 20% urea incorporated in a cream for keratinolysis is safe to use and significantly more effective than placebo in curing big toenail onychomycosis.