Publications by authors named "Hassan Y Aboul-Enein"

318 Publications

Corrigendum to 'Poly(methyl methacrylate) with TiO2 nanoparticles inclusion for stereolithographic complete denture manufacturing the future in dental care for elderly edentulous patients?' [Journal of Dentistry 59 (2017) 68-77].

J Dent 2021 Sep 3;112:103739. Epub 2021 Jul 3.

Faculty of Midwifery and Medical Assisting, "Carol Davila" University of Medicine and Pharmacy, 8, Blvd Eroilor Sanitari, 050474, Bucharest, Romania,. Electronic address:

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http://dx.doi.org/10.1016/j.jdent.2021.103739DOI Listing
September 2021

Experimental design optimization of simultaneous enantiomeric separation of atenolol and chlorthalidone binary mixture by high-performance liquid chromatography using polysaccharide-based stationary phases.

Chirality 2021 07 8;33(7):397-408. Epub 2021 May 8.

Pharmaceutical Chemistry Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt.

In this work, enantiomeric separation of a drug combination of two chiral drugs, namely, atenolol and chlorthalidone, is described. Prior investigation of the effect of different variables on the resolution of the enantiomers' peaks and the total run time represented by the retention time of the last eluted peak was conducted using face-centered composite design. Twenty-two experiments were carried out by varying the chiral stationary phase type as a categorical factor and mobile phase composition including the percentage of ethanol and percentage of diethylamine as continuous factors. According to the optimization process, a mobile phase consisting of hexane:ethanol:DEA:TFA (60:40:0.2:0.1%, v/v/v/v) pumped at flow rate 1 ml min onto Lux-Cellulose 2 stationary phase was applied for the chiral separation and quantification of the drug combination at 230 nm. Application of the developed method to the pharmaceutical formulation of this combination was successfully performed, and satisfactory percentage of recoveries was obtained. The method was also fully validated following International Conference on Harmonization (ICH) guidelines. This method could be of high value and relevance for application in quality control laboratories.
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http://dx.doi.org/10.1002/chir.23315DOI Listing
July 2021

Synthesis and chiral separation of atropisomers of 4,5-Di methyl ∆ N-phenyl N-aryl imidazoline-2-thione derivatives.

Chirality 2021 06 26;33(6):264-273. Epub 2021 Mar 26.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Center, Dokki, Giza, Egypt.

Synthesis of three chiral 4,5-Di methyl ∆ N-phenyl N-aryl imidazole-2-thione derivatives was obtained by the condensation reaction of thiourea derivatives with α-hydroxy ketone. The structure of these compounds has been characterized by using spectroscopic methods (UV, IR, H NMR, and C NMR). The 4,5-Di methyl ∆ N-phenyl N-aryl imidazole-2-thiones display a chiral axis around the N-C bond linking between the nitrogen of the heterocyclic framework and the carbon of the aryl group. Screening on chiral analysis of the atropisomers of these derivatives was performed by high-performance liquid chromatography method on seven chiral selectors based on polysaccharides consisting of amylose and cellulose, namely, Chiralpak®AD, Chiralcel® OD, Chiralcel® OD-H, Chiralcel® OJ, Chiralcel® OD-3R, Chiralcel® OZ-3, and Chiralpak® AS-3R. The impact of ortho-substituent in the resolution of 4,5-Di methyl ∆ N-phenyl N-aryl imidazole-2-thione derivatives was also studied in this work.
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http://dx.doi.org/10.1002/chir.23306DOI Listing
June 2021

Application of nanoparticles in chiral analysis and chiral separation.

Chirality 2021 05 1;33(5):196-208. Epub 2021 Mar 1.

Pharmaceutical Chemistry Department, Faculty of Pharmacy, The British University in Egypt, Cairo, Egypt.

Chiral molecules in relation to particular biological roles are stereoselective. Enantiomers differ significantly in their biochemical responses in biological environment. Despite the current advancement in drug discovery and pharmaceutical biotechnology, the chiral separation of some racemic mixtures continues to be one of the greatest challenges, because the available techniques are too costly and time consuming for the assessment of therapeutic drugs in the early stages of development worldwide. Various nanoparticles became one of the most investigated and explored nanotechnology-derived nanostructures especially in chirality where several studies are reported to improve enantiomeric separation of different racemic mixtures. The production of surface-modified nanoparticles has contributed to these limitations in terms of sensitivity, accuracy, and enantioselectivity that can be optimized and therefore makes these surface-modified nanoparticles convenient for enantiomeric identification and separation.
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http://dx.doi.org/10.1002/chir.23303DOI Listing
May 2021

Synthesis and Chiral Separation of Some 4-thioflavones.

J Chromatogr Sci 2021 Feb 9. Epub 2021 Feb 9.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Center, 33 El Buhouth St, Ad Doqi, Dokki, Cairo Governorate, Giza 12622, Egypt.

A thionation reaction was performed on some chiral flavanones using Lawesson's reagent (LR) and leads to the formation of new chiral thiocarbonyl flavanes. LR in this thionation reaction with Hesperetin and Naringenin gives new flavan-4-thiones with yields ranged between 41 and 52%. Based on the Wittig reaction principle, LR is currently the most widely used reagent for this type of reaction. Enantiomeric separation by high-performance liquid chromatography methods was then set-up using three different polysaccharide-based chiral stationary phases (CSPs). Chiral separations were successfully accomplished with high resolution (1.22 ≤ Rs ≤ 5.23). The chiral discrimination mechanism(s) between the analytes under study, mobile phase, and the CSPs were discussed.
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http://dx.doi.org/10.1093/chromsci/bmab007DOI Listing
February 2021

Mass Spectrometry: A Powerful Method for Monitoring Various Type of Leukemia, Especially MALDI-TOF in Leukemia's Proteomics Studies Review.

Crit Rev Anal Chem 2021 Jan 26:1-28. Epub 2021 Jan 26.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Center, Cairo, Egypt.

Recent success in studying the proteome, as a source of biomarkers, has completely changed our understanding of leukemia (blood cancer). The identification of differentially expressed proteins, such as relapse and drug resistance proteins involved in leukemia by using various ionization sources and mass analyzers of mass spectrometry techniques, has helped scientists find better diagnosis, prognosis, and treatment strategies. With the aid of this powerful analytical technique, we can investigate the qualification/quantification of proteins, protein-protein interactions, post-translational modifications, and find the correlation between proteins and their genes with the hope of finding the missing parts of the successful therapy puzzle. In this review, we followed different MS sources and analyzers which used for monitoring various type of leukemia, then focused on MALDI-TOF MS as a quick and reliable method for studying proteins. Due to several review published for other techniques, the present review is the first work in this field. Also, by classifying more than 400 proteins, we have found 42 proteins are involved in two or three different stages of leukemia. Finally, we have suggested six specific biomarkers for AML, one for ALL, three biomarkers with a role in the etiology of leukemia and 13 markers with the potential for further studies.
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http://dx.doi.org/10.1080/10408347.2021.1871844DOI Listing
January 2021

Determination of Potential Genotoxic Impurity, 5-Amino-2-Chloropyridine, in Active Pharmaceutical Ingredient Using the HPLC-UV System.

J Chromatogr Sci 2021 Feb;59(3):241-245

Department of Medical Services and Techniques, Yunus Emre Vocational School of Health Services, Anadolu University, Eskişehir 26470, Turkey.

A novel analytical method, based on high-performance liquid chromatography with a UV (HPLC-UV) detection system for the sensitive detection of a genotoxic impurity (GTI) 5-amino-2-chloropyridine (5A2Cl) in a model active pharmaceutical ingredient (API) tenoxicam (TNX), has been developed and validated. The HPLC-UV method was used for the determination of GTI 5A2Cl in API TNX. The compounds were separated using a mobile phase composed of water (pH 3 adjusted with orthophosphoric acid): MeOH, (50:50: v/v) on a C18 column (150 × 4.6 mm i.d., 2.7 μm) at a flow rate of 0.7 mL min-1. Detection was carried out in the 254 nm wavelength. Column temperature was maintained at 40°C during the analyses and 10 μL volume was injected into the HPLC-UV system. The method was validated in the range of 1-40 μg mL-1. The obtained calibration curves for the GTI compound was found linear with equation, y = 40766x - 1125,6 (R2 = 0.999). The developed analytical method toward the target compounds was accurate, and the achieved limit of detection and limit of quantification values for the target compound 5A2Cl were 0.015 and 0.048 μg mL-1, respectively. The recovery values were calculated and found to be between 98.80 and 100.03%. The developed RP-HPLC-UV analytical method in this research is accurate, precise, rapid, simple and appropriate for the sensitive analysis of target GTI 5A2Cl in model API TNX.
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http://dx.doi.org/10.1093/chromsci/bmaa100DOI Listing
February 2021

Sources of outlier data in the bioanalytical and clinical part of a piroxicam bioequivalence study.

Int J Clin Pharmacol Ther 2020 Nov;58(11):652-663

Objective: This paper analyzes the potential outliers in the bioanalytical and clinical part of a bioequivalence study, the effect on bioequivalence decisions whether or not it is appropriate to eliminate them from the statistical evaluation of bioequivalence.

Materials And Methods: The clinical part was a cross-over, two periods, two sequences bioequivalence study concerning two piroxicam formulations, on healthy subjects. A simulation study evaluated the influence of 10% errors on the percent bias of calculated concentrations from nominal ones.

Results: In bioequivalence studies, it is not possible to distinguish between relevant types of outliers based only on statistical criteria. The "problem" is particularly acute when the omission of outliers leads to a bias in the decision concerning bioequivalence from rejection to acceptance. In such cases, there is the suspicion of subjective analysis and torture of data. The effect of analytical errors at high plasma levels was criticized for the calculated concentrations in the neighborhood of lower limit of quantification. Errors at low concentrations have a less significant effect. In the pharmacokinetic analysis, several types of outliers were shown: single points, curves, pairs of curves corresponding to the same subject, intrasubject ratios of areas under curves and maximum concentrations. These pharmacokinetic outliers could have had, at the same time, bioanalytical, physiological and physicochemical causes.

Conclusion: Considering the results, it was proposed the following algorithm in the analysis of outlier data and outlier subjects in bioequivalence studies: evaluation of the implications of the decision concerning elimination of outliers on the decision concerning bioequivalence; application of the statistic tests for detection of outliers data; evaluations from the point of view of physiological pharmacokinetics, final decision concerning elimination of outliers.
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http://dx.doi.org/10.5414/CP203794DOI Listing
November 2020

Application of Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection (CE-CD): 2017-2020.

Crit Rev Anal Chem 2020 Aug 24:1-9. Epub 2020 Aug 24.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Cairo, Egypt.

Capacitively coupled contactless conductivity detection (CD) has emerged as influential to detect analytes that do not have chromogenic or fluorogenic functional group. Since our last review several new capillary electrophoresis (CE) methods coupled with (CE-CD) have been communicated. The aim of this review is to give an update of the almost all the new applications of CE-CD in the field of pharmaceutical, food and biomedical analysis covering the period from 2017 to April 2020. The utilization of CE with CD in the areas of pharmaceutical, food and biomedical analysis is presented. Finally, concluding remarks and outlooks are discussed.
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http://dx.doi.org/10.1080/10408347.2020.1809340DOI Listing
August 2020

Discrimination between vegetable oil and animal fat by a metabolomics approach using gas chromatography-mass spectrometry combined with chemometrics.

J Food Sci Technol 2020 Sep 8;57(9):3415-3425. Epub 2020 Apr 8.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Giza, 12662 Egypt.

Adulteration of olive oil with the other cheap oils and fats plays an important role in economics and has nutritional benefits. In this work, metabolite profiling was performed using gas chromatography-mass spectrometry to identify and quantify animal fat (lard) adulteration in vegetable oil (olive oil). Principal component analysis could correctly identify and clustering olive oil, sunflower oil, sesame oil, lard, and adulterated samples through the changes in their fatty acid methyl esters (FAMEs) profile. A targeted metabolomics method was then optimized and validated through construction of calibration curves of known FAMSs in olive oil and lard. The method was presented high linearity (R > 0.96) and good intra and inter day accuracy and precision (79-101 and 86-102% and 2-7 and 3-7, respectively) for determination of FAMEs. Afterwards the absolute concentration and relative percentage of FAMEs were successfully determined in 12 commercial olive oils and 3 lards samples. Methyl myristate, methyl palmitate, methyl oleate, and methyl stearate were selected as discriminant markers to identify and quantify lard adulteration even at a low level of lard (5%w/w), with errors less than 2% in the comparison of the absolute or relative concentrations of FAMEs using several statistical methods. The proposed methodology allowed us to quantify the FAMEs simultaneously and also could predict small amount of lard in the adulterated olive oil samples.
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http://dx.doi.org/10.1007/s13197-020-04375-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7374695PMC
September 2020

Stochastic microsensors for the assessment of DNA damage in cancer.

Anal Biochem 2020 09 20;605:113839. Epub 2020 Jul 20.

Pharmaceutical and Medicinal Chemistry Department, The Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Cairo, 12622, Egypt.

Three stochastic microsensors based on graphite powder modified with three different oleamides: N-(2-piperidin-1-ylethyl)oleamide, N-(3,4-dihydroxyphenethyl)oleamide and N-(2-morpholinoethyl)oleamide, were designed, characterized, and used to assess DNA damage in cancer by assaying two biomarkers namely 8-nitroguanine and 8-hydroxy-2'-deoxyguanosine. The two biomarkers were determined from urine and whole blood samples. The characterization of the microsensors was done at two pHs 7.40 and 3.00. The best microsensor for the simultaneous determination of biomarkers in whole blood and urine samples was the one based on the graphite paste modified with N-(3,4-dihydroxyphenethyl)oleamide. The results indicated that the proposed microsensors can be reliably used for pattern recognition and quantitative determination of 8-nitroguanine and 8-hydroxy-2'-deoxyguanosine in whole blood and urine, and accordingly, for the assessment of DNA damage in cancer patients.
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http://dx.doi.org/10.1016/j.ab.2020.113839DOI Listing
September 2020

Development of a RP-HPLC method for simultaneous determination of reference markers used for in-situ rat intestinal permeability studies.

J Chromatogr B Analyt Technol Biomed Life Sci 2020 Jun 7;1147:122150. Epub 2020 May 7.

Department of Medical Services and Techniques, Yunus Emre Vocational School of Health Services, 26470 Eskişehir, Turkey; Department of Analytical Chemistry, Faculty of Pharmacy, Anadolu University, 26470 Eskişehir, Turkey.

One of the most common techniques for assessing the intestinal absorption characteristics of drugs is single-pass intestinal perfusion (SPIP) method. Metoprolol tartrate (MT, reference standard) and phenol red (PR, zero permeability marker) are the compounds that are normally used in SPIP studies. The aim of this study was to develop a reverse phase high-performance liquid chromatography (RP-HPLC) method combined with UV-detection for the simultaneous determination of MT and PR in the perfusion medium used in SPIP experiments. Elution was performed using a Restek Raptor C18 column (5 μm, 4.6 mm × 250) at a temperature of 25 °C. The mixture of the mobile phase consisted of (MeOH):(Phosphate buffer solution, PBS), (20 mM, pH 3.0 adjusted with ortho-phosphoric acid),(55:45, v/v). Flow rate and column temperature were set at 1.2 mL min and 25 °C, respectively. MT and PR were injected as 20 µL into the HPLC system. UV detection was performed at 227 nm. The obtained retention times were reported as 2.89 and 3.80 min for MT and PR, respectively. The developed RP-HPLC method was validated according to Q2(R1) guideline of The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). The method was linear within the range of 2-50 μg mL for PR and 10-75 μg mL for MT. The developed RP-HPLC method was successfully applied on determination of MT and PR in perfusion medium. The developed method could be helpful for researchers working on in-situ rat intestinal permeability studies and it could be easily modified on further studies.
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http://dx.doi.org/10.1016/j.jchromb.2020.122150DOI Listing
June 2020

Applications of shun shell column and nanocomposite sorbent for analysis of eleven anti-hypertensive in human plasma.

J Chromatogr B Analyt Technol Biomed Life Sci 2020 Jun 25;1146:122125. Epub 2020 Apr 25.

Department of Chemistry, College of Sciences, Taibah University, Al-Medina Al-Munawara 41477, Saudi Arabia; Department of Chemistry, Jamia Millia Islamia, (Central University), New Delhi 11025, India.

High-performance liquid chromatography (HPLC) and solid phase micro membrane tip extraction (SPMMTE) methods are developed for the simultaneous analysis of eleven cardiovascular drugs in human plasma. Iron nanoparticles were obtained by the green method, characterized by XRD, FT-IR, TEM, and EDS and utilized in SPMMTE for sample preparation. The mobile phase used was ammonium acetate buffer-methanol-acetonitrile (65:18:17) with a 1.0 mL/min flow rate at 260 nm detection. Column used was Sunshell C 150 × 4.6 mm, 2.6 µm. The values of k, α, and Rs were ranged from 040 to109.22, 1.20 to 2.67 and 1.0 to 26.18. SPMMTE and HPLC methods were fast, reproducible, precise, robust, economic and rugged for analysis of methyldopa, hydrochlorothiazide, prazosin hydrochloride, furosemide, labetalol, propranolol, valsartan, losartan potassium, diltiazem, irbesartan and spironolactone in human plasma. The recoveries (%) of methyldopa, hydrochlorothiazide, prazosin hydrochloride, furosemide, labetalol, propranolol, valsartan, losartan potassium, diltiazem, irbesartan, and spironolactone were 91.0, 85.2, 92.3, 90.4, 90.1, 85.6, 86.6, 86.2, 85.1, 86.6, and 85.7, respectively. These results showed that SPMMTE and HPLC methods can be applied to test the described drugs in several matrices.
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http://dx.doi.org/10.1016/j.jchromb.2020.122125DOI Listing
June 2020

Novel Application of Pentabromobenzyl Column for Simultaneous Determination of Eight Antifungal Drugs Using High-performance Liquid Chromatography.

Comb Chem High Throughput Screen 2020 ;23(10):991-1001

Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki 12622, Giza, Egypt.

Aim: A new, accurate and sensitive reversed-phase high-performance liquid chromatography (RP-HPLC) as an analytical method for the quantitative determination of eight antifungal drugs in spiked human plasma has been described optimized and validated.

Materials And Methods: The analyzed compounds were voriconazole (VOR), luliconazole (LUL), clotrimazole (CLO), tioconazole (TIO), posaconazole (POS), ketoconazole (KET), sertaconazole (SER) and terconazole (TER).

Results: The separation of the analyzed compounds was conducted using a novel pentabromobenzyl column known as COSMOSIL PBB-R (150 mm × 4.6 mm I.D., particle size 5 μm). The analysis of the studied drugs was determined within 14 min using a diode array detector and the mobile phase consisted of: 10 mM potassium dihydrogen phosphate buffer (pH 2.1): Methanol (2: 98 v/v). A linear response was observed for all compounds in the range of concentration studied. Sample preparation was done through liquid-liquid extraction using diethyl ether.

Conclusion: This proposed method was validated in terms of linearity, limit of quantification, limit of detection, accuracy, precision and selectivity. The method was successfully applied for the determination of these drugs in their pharmaceutical formulations and in human plasma samples.
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http://dx.doi.org/10.2174/1386207323666200220114818DOI Listing
June 2021

Preparation and in vitro antioxidant activity of some novel flavone analogues bearing piperazine moiety.

Bioorg Chem 2020 01 21;95:103513. Epub 2019 Dec 21.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Giza 12622, Egypt. Electronic address:

Background: A series of eight new flavone derivatives containing a piperazine chain with different substitution were synthesized and their structures were determined.

Methods: Their antiradical and antioxidant activities were evaluated using superoxide anion radical, hydroxyl radical, 2,2-diphenyl-1-picrylhydrazyl radical, 2,2'-azino-di(3-ethylbenzthiazoline sulphonate) radical cation (ABTS) scavenging (as measure total antioxidant status TAS), ferric reducing antioxidant power (TAC), and hydrogen peroxide decomposition. The antioxidant activities of the synthesized compounds were compared with standard antioxidants trolox, ascorbic acid, butylated hydroxytoluene (BHT) as positive controls, reference antibiotics (doxycycline, dicloxacillin), and medicinal plants (Menthae piperita, Cistus incanus). Chemiluminescence, spectrophotometry, electron spin resonance (ESR) spectroscopy in conjunction with 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) as the spin trap were the measurement techniques.

Results: The results show that the synthesized compounds exhibit weak, albeit a wide spectrum of antiradical and antioxidant activities. The TAS values were measured as trolox equivalents, ranging from 209.6 ± 6.1 to 391.1 ± 8.2 µM TE/g; the TAC values were in ranges from 10.8 ± 0.5 to 49.5 ± 0.5 µM TE/g being higher than that of dicloxacillin (241.0 ± 16.5 and 9.73 ± 0.8 µM TE/g, respectively), but lower than ascorbic acid, BHT, doxycycline, and medicinal plants. Best antioxidant activities were found for the piperazinyl analogues with methoxy group on phenyl piperazine ring.

Conclusion: We suggest that the synthesized compounds may be used as lead molecules for optimization of molecular structure to maximize the antioxidant potency.
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http://dx.doi.org/10.1016/j.bioorg.2019.103513DOI Listing
January 2020

Health risk assessment of neonicotinoid insecticide residues in pistachio using a QuEChERS-based method in combination with HPLC-UV.

Biomed Chromatogr 2020 Mar 17;34(3):e4747. Epub 2020 Jan 17.

Pharmaceutical and Drug Industries Research Division, Pharmaceutical and Medicinal Chemistry Department, National Research Centre, Cairo, Egypt.

There is an increasing need to address the potential risks arising from combined exposures to multiple residues from pesticides in the diet. Pesticide residue-related pollution is a problem that arises because of the increased use of pesticides in agriculture to meet the growing demands of food production. In this study, pesticide residue data were obtained based on an optimized extraction method. For this purpose, we established a method based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction for simultaneous determination of imidacloprid (IMI) and acetamiprid (ACT) in pistachio nuts. The parameters influencing the QuEChERS method were the sample-to-water ratio and adsorbent amounts. As a result, both were optimized to improve the recovery of the analytes as well as the clean-up efficiency of the pistachio matrix. Our results indicated that a freeze-out step and use of primary and secondary amines as an adsorbent led to much cleaner chromatograms with lower baseline drift, without using graphitized carbon black and C -based adsorbent, which reduced both cost and time of analysis. Following extraction, the pesticide residues were separated and quantified by reverse-phase HPLC. For validation purposes, recovery studies were carried out using a concentration range from 20 to 2500 μg/L at nine levels. The suitable linearity, precision, and accuracy were obtained with HPLC-UV with recoveries of 70.37%-89.80% for IMI and 81.05%-113.57% for ACT, with relative standard deviations <12%. The validated method was successfully applied to the analysis of pistachio samples collected from a field trial to estimate maximum residue limits. There was no significant health risk for consumers via pistachio consumption.
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http://dx.doi.org/10.1002/bmc.4747DOI Listing
March 2020

A Study on Synthesis and Antioxidant Activity Comparison of Novel Stilbenebenzamide Compounds.

Med Chem 2021 ;17(5):533-544

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Cairo 12622, Egypt.

Background: Stilbene phytalexis (1,2-diphenyloethylen) and benzamide are beneficial for human health. To increase the stilbene ring activity, a new series of its derivatives containing benzamide structure was synthesized and evaluated for their in vitro antioxidant power.

Methods: 1H nuclear magnetic resonance, mass spectroscopy, and chromatographic analyses were used to confirm the successful synthesis. The antioxidant properties were determined by the elimination of O˙-, HO˙ , DPPH˙ , ABTS+˙ radicals, total antioxidant status (TAS) and the ferric reducing antioxidant activities (TAC) measurements.

Results: Stilbenebenzamide compounds showed a wide spectrum of antioxidant ability; however, their total antioxidant power was weaker than those of butylated hydroxytoluene (BHT), ascorbic acid, and resveratrol. The highest antiradical activity towards O˙ and HO˙ was shown by the compounds with structures containing amine group (SBEBA, SBA) (O˙: 37.7 - 38.0% and 40.8 - 43.5%, HO˙ : 29.8%, 28.7% inhibition, respectively) at1.25 mM concentration. The antiradical power of SBEBA (0.29) in DPPH˙ assay was lower than those of resveratrol (1.83), ascorbic acid (3.63) and BHT (4.09). The TAS values of the synthesized compounds ranged from 152.9±5.3 to 240.2±6.7μM trolox equivalent/gram (TE/g) and were much lower than those of BHT (1304±43.0), reservatrol (1360±29.0) and ascorbic acid (2782±39.7) μM TE/g. Similarly, the TAC values ranging from 29.7±0.9 to 41.5±1.6 μM TE were weaker than that of resveratrol (239.2 ±6.7 μM TE/g).

Conclusion: The results suggest that the presence of the hydroxyl group in the stilbene ring should be considered in the further design of stilbenebenzamide compounds to enhance their antioxidant activity.
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http://dx.doi.org/10.2174/1573406415666191114123004DOI Listing
August 2021

Simultaneous determination of guaifenesin enantiomers and ambroxol HCl using 50-mm chiral column for a negligible environmental impact.

Chirality 2019 Oct 1;31(10):835-844. Epub 2019 Aug 1.

Medicinal and Pharmaceutical Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre (ID: 60014618), Giza, Egypt.

Chiral stationary phases are conveniently used for enantiomeric separation of drugs by liquid chromatography. Consumption of large volumes of hazardous solvents is considered as a common challenge for the sustainability of this technique. To this end, a columnar chromatography has been adopted using 50-mm-length stationary phases. The study comprised five Phenomenex Lux cellulose- and amylose-based columns for the separation of guaifenesin (GUA) enantiomers. In addition, an experimental design was used to optimize the gradient profile for the separation of racemic GUA and ambroxol HCl (AMB) binary mixture. The chromatographic method was achieved using Lux Cellulose-1 (50 × 4.6 mm) as a chiral stationary phase and ethanol/water as a mobile phase with linear gradient elution of 20% to 70% ethanol in 6 minutes at a flow rate of 1.0 mL min and UV detection at 270 nm. Linearity ranges were found to be 50 to 1000 μg mL and 15 to 450 μg mL for each GUA enantiomer and AMB, respectively. Environmental, health and safety tool was used to assess and compare greenness of the proposed and reported methods. Short column indeed reduces the environmental impact by decreasing waste by about 60% and utilizing only 1-mL ethanol in the mobile phase. The proposed method is a safer alternative for the simultaneous determination of drugs in their combined pharmaceutical formulation. The method has been validated and compared favorably with a reported one.
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http://dx.doi.org/10.1002/chir.23116DOI Listing
October 2019

A highly sensitive GC-MS method for simultaneous determination of anacardic acids in cashew (Anacardium occidentale) nut shell oil in the presence of other phenolic lipid derivatives.

Biomed Chromatogr 2019 Nov 20;33(11):e4659. Epub 2019 Aug 20.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre (NRC), Dokki, Cairo, Egypt.

The commercial value of cashew nut shell liquid (CNSL) has become a cornerstone of the agrowaste industry. It is the by-product of the cashew industry and has an 1/8 inch thickness of soft honeycomb structure. CNSL contains phenolic lipids with aliphatic chains such as anacardic acid, cardanol, cardol and methyl cardol, and their derivatives. The developed GC-MS method is rapid, accurate and selective using a selected derivatizing reagent, namely N-methyl-N-(trimethylsilyl)-trifluoroacetamide that was previously diluted 1:1% with anhydrous pyridine. The proposed GC-MS method was applied for the analysis of different CNSL samples. The results showed that all classes of CNSL compounds were detected. The four alkyl phenols were detected with their different alkyl sidechains without any interference. This method is also specified for the detection of fatty acids of saturated and unsaturated chains. Silylation did not cause any alteration in the chemical structure of CNSL compounds regardless of esterification action. Silylation is considered a safe derivatizing agent compatible with GC chromatography and specific for all volatile and nonvolatile polar and nonpolar CNSL compounds that could be detected in CNSL samples.
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http://dx.doi.org/10.1002/bmc.4659DOI Listing
November 2019

Oxidative stress in biological systems and its relation with pathophysiological functions: the effect of physical activity on cellular redox homeostasis.

Free Radic Res 2019 May 16;53(5):497-521. Epub 2019 May 16.

d John Hazen White College of Arts & Sciences , Johnson & Wales University , Providence , USA.

The body of evidence from the past three decades demonstrates that oxidative stress can be involved in several diseases. This study aims to summarise the current state of knowledge on the association between oxidative stress and the pathogenesis of some characteristic to the biological systems diseases and aging process. This review also presents the effect of physical activity on redox homeostasis. There is strong evidence from studies for participation of reactive oxygen and nitrogen species in pathogenesis of acute and chronic diseases based on animal models and human studies. Elevated levels of pro-oxidants and various markers of the oxidative stress and cells and tissues damage linked with pathogenesis of cancer, atherosclerosis, neurodegenerative diseases hypertension, diabetes mellitus, cardiovascular disease, atherosclerosis, reproductive system diseases, and aging were reported. Evidence confirmed that inflammation contributes widely to multiple chronic diseases and is closely linked with oxidative stress. Regular moderate physical activity regulates oxidative stress enhancing cellular antioxidant defence mechanisms, whereas acute exercise not preceded by training can alter cellular redox homeostasis towards higher level of oxidative stress. Future studies are needed to clarify the multifaceted effects of reactive oxygen/nitrogen species on cells and tissues and to continue study on the biochemical roles of antioxidants and physical activity in prevention of oxidative stress-related tissue injury.
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http://dx.doi.org/10.1080/10715762.2019.1612059DOI Listing
May 2019

Quick and Sensitive UPLC-ESI-MS/MS Method for Simultaneous Estimation of Sofosbuvir and Its Metabolite in Human Plasma.

Molecules 2019 Apr 3;24(7). Epub 2019 Apr 3.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, P.O. Box 12622, Dokki, Giza, Egypt.

A simple, fast and highly sensitive RP-UPLC-MS/MS method was developed and validated for the simultaneous determination of sofosbuvir (SR) and its metabolite GS331007 in human plasma using ketotifen as an internal standard (IS). The separation was achieved on Acquity UPLC BEH C (50 × 2.1 mm, i.d. 1.7 µm, Waters, USA) column using acetonitrile:5 mM ammonium formate:0.1% formic acid (85:15:0.1% //) as a mobile phase at a flow rate of 0.35 mL/min in an isocratic elution. The Xevo TQD UPLC-MS/MS was operated under the multiple-reaction monitoring mode using positive electrospray ionization. Extraction with dichloromethane was used in the sample preparation. Method validation was performed as per the Food and Drug Administration (FDA) guidelines and the calibration curves of the proposed method were found to be linear in the range of 1-1000 ng/mL for SR and in the range of 10-1500 ng/mL for its metabolite (GS331007) with an elution time of 1.83 min. All validation parameters were within the acceptable range according to the bioanalytical methods validation guidelines. Furthermore, the obtained results of matrix effects indicate that ion suppression or enhancement from human plasma components was negligible under the optimized conditions. The proposed method can be applied in high-throughput analysis required for pharmacokinetic and bioequivalence studies in human samples.
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http://dx.doi.org/10.3390/molecules24071302DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6480583PMC
April 2019

Surface Design of Enantiomeric HPLC Separation on Vancomycin and Teicoplanin-Based Stationary Phases, a Tool for Chiral Recognition of Model β-Blockers.

J Chromatogr Sci 2019 Jul;57(6):485-494

Department of Pharmaceutical Chemistry, German University in Cairo, Cairo, Egypt.

A quality-by-design approach was adopted for enantioseparation of atenolol on Vancomycin and Teicoplanin-based chiral stationary phases using reversed phase (RP) mode and polar ionic mode (PIM), respectively to account for major forces involved in enantiorecognition of β-blockers on macrocyclics. A fractional factorial screening design for the two modes; followed by a central composite optimization design and regression analysis were able to point out critical factors and chromatographic responses and robust surface of the design. Within the studied range of flow the optimal was 0.3 mL/min for Chirobiotic T and 1 mL/min for Chirobiotic V. In PIM, a composition of 100% methanol was mandatory to compromise between best separation and least retention with equal amounts of the acid and base modifiers for enantiomers of atenolol, as model drug in addition to metoprolol and pindolol as structurally related compounds for possible extrapolation of results on members of the same class. However, in RP mode, only triethylamine acetate was needed as buffer for atenolol enantiomers. Chiral recognition of atenolol in both elution modes, further confirmed via extrapolation of the models on the two other β-blockers showed that ionic interactions rather than any other forces governed chiral recognition on the two macrocyclic stationary phases in both modes.
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http://dx.doi.org/10.1093/chromsci/bmz018DOI Listing
July 2019

Quantitative Determination of Heavy Metal Contamination in Horse Mackerel and Whiting Caught in the Sea of Marmara.

Bull Environ Contam Toxicol 2019 Apr 14;102(4):498-503. Epub 2019 Mar 14.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Center, Dokki, Cairo, 12622, Egypt.

In this study, the concentrations of lead, cadmium and manganese were determined in horse mackerel (Trachurus mediterraneus) and whiting (Merlangius merlangus euxinus) that were caught in the Sea of Marmara. These are commonly consumed fish species in this region. Fish were provided by a fishermen quarterly between March 2013 and December 2013 and, separated according to size (small, medium and large). Pb(II), Cd(II) and Mn(II) levels were determined using the wet digestion method by Graphite furnace atomic atomic absorption spectrophotometer. According to this study, for horse mackerel, the highest concentration of lead, cadmium, and manganese was 6.69 µg kg (September), 5.24 µg kg (March) and 9.24 µg kg (June), respectively. For whiting, the highest concentration of lead, cadmium, and manganese was 2.25 µg kg (June), 0.263 µg kg (September) and 10.4 µg kg (June), respectively. These heavy metal levels in fish were found to be acceptable for human consumption according to World Health Organization border values.
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http://dx.doi.org/10.1007/s00128-019-02574-5DOI Listing
April 2019

A Chiral Generic Strategy for Enantioseparation of Acidic and Basic Drugs Using Short End Injection Capillary Electrophoresis: Application to Design of Experiment.

Methods Mol Biol 2019 ;1972:127-136

Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy and Pharmaceutical Manufacturing, Kafrelsheikh University, Kafrelsheikh City, Egypt.

The present work describes a capillary electrophoretic (CE) generic strategy used for chiral enantioseparation of Fluconazole (as an example of acidic drugs) and donepezil (as an example of basic drugs). Several modified cyclodextrins (CDs) were applied for enantioseparation of racemates such as highly sulfated α, γ CDs, hydroxyl propyl-β-CD, and sulfobutyl ether-β-CD. The starting screening conditions consist of 50 mM phosphate-triethanolamine buffer at pH 2.5, an applied voltage of 15 kV, and a temperature of 25 °C. The design of experiment (DOE) was based on a full factorial design of the crucial two factors (pH and %CD) at three levels, to make a total of nine (3) experiments with high, intermediate, and low values for both factors. Evaluation of the proposed strategy pointed out that best resolution was obtained at pH 2.5 for the investigated racemates using low percentages of HS-γ-CD, while SBE-β-CD was the most successful chiral selector offering acceptable resolution, with best separation at low pH values and at higher %CD within 10 min runtime. Regression study showed that the linear model shows a significant lack of fit for all chiral selectors, anticipating that higher orders of the factors are most likely to be present in the equation with possible interactions.
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http://dx.doi.org/10.1007/978-1-4939-9213-3_9DOI Listing
August 2019

Sensitive spectrofluorometric method for the determination of ascorbic acid in pharmaceutical nutritional supplements using acriflavine as a fluorescence reagent.

Luminescence 2019 Mar 13;34(2):168-174. Epub 2019 Jan 13.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Center, Dokki, Cairo, Egypt.

An easily performed, specific, sensitive, rapid, reliable and inexpensive procedure for the spectrofluorometric quantitation of ascorbic acid was proposed using acriflavine as a fluorescence quenching reagent. The procedure was based on the determined quenching effect of ascorbic acid on the natural fluorescence signal of acriflavine and the reaction between ascorbic acid and acriflavine in Britton-Robinson buffer solution (pH 6) to produce an ion-associated complex. The reduction in acriflavine fluorescence intensity was detected at 505 nm, while excitation occurred at 265 nm. The relationship between quenching fluorescence intensity (∆F) and concentration of ascorbic acid was linear (R  = 0.9967) within the range 2-10 μg/ml and with a detection limit of 0.08 μg/ml. No significant interference was detected from other materials often found in pharmaceutical nutritional tablets. The obtained results were compared with those from high-performance liquid chromatography and appeared in good agreement, with no important differences in precision or accuracy. The proposed spectrofluorimetric method was used to determine the amount of ascorbic acid in a number of commercial pharmaceutical nutritional supplement tablets with a 95% confidence performance.
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http://dx.doi.org/10.1002/bio.3589DOI Listing
March 2019

Retraction Note: RETRACTED CHAPTER: A Chiral Generic Strategy for Enantioseparation of Acidic and Basic Drugs using Short End Injection Capillary Electrophoresis: Application to Design of Experiment.

Methods Mol Biol 2019 ;1972:C1

Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy and Pharmaceutical Manufacturing, Kafrelsheikh University, Kafrelsheikh City, Egypt.

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http://dx.doi.org/10.1007/978-1-4939-9213-3_20DOI Listing
January 2019

Advances in immunosensors for clinical applications.

J Immunoassay Immunochem 2019 7;40(1):40-51. Epub 2018 Nov 7.

b Pharmaceutical and Medicinal Chemistry Department , The Pharmaceutical and Drug Industries Research Division, National Research Centre , Cairo , Egypt.

Immunoassay technique performs a fast, simple, reliable, and sensitive analysis of different compounds, being applied in several areas of interest such as clinical analysis for medical diagnosis, as well as in environmental analysis, and food quality control. The latest research activities in this field are represented by the attempts to achieve a low limit of detection by developing of new signal amplification strategies, eliminate the interferences, and decrease the cost of analysis.
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http://dx.doi.org/10.1080/15321819.2018.1543704DOI Listing
February 2019

Synthesis and in vitro antioxidant activity of new pyrimidin/benzothiazol-substituted piperazinyl flavones.

Future Med Chem 2018 10;10(19):2293-2308

Pharmaceutical & Medicinal Chemistry Department, Pharmaceutical & Drug Industries Research Division, National Research Centre, Dokki, Giza 12622, Egypt.

Aim: Synthesis of novel 2(2-hydroxyphenyl) pyrimidine/benzothiazole piperazinyl-substituted flavones end evaluate their antioxidant activity.

Results: Six novel 2-(2-hydroxyphenyl) pyrimidine/benzothiazole-substituted flavones were synthesized, their structures were confirmed by elementary and spectral analyses. The compounds were evaluated for their in vitro antioxidant potency by employing various antioxidant assays.

Conclusion: All tested compounds acted as scavengers of free radicals like hydroxyl (15-45%), 2,2-diphenyl-1-picrylhydrazyl (17-48%) at 1.25 and 0.5 mM concentrations respectively. The total antioxidant status activity values of the compounds ranged from 234.1 to 464.1 μm trolox equivalent/g, the total antioxidant capacity - from 24.9 to 52.7 μm trolox equivalent per gram. Compounds incorporating the benzothiazole group on the piperazine ring were more effective antioxidants than those with the 2-(2-hydroxyphenyl) pyrimidine group.
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http://dx.doi.org/10.4155/fmc-2018-0206DOI Listing
October 2018

Liquid Chromatographic Enantioseparation of Some Fluoroquinoline Drugs Using Several Polysaccharide-Based Chiral Stationary Phases.

J Chromatogr Sci 2018 Oct;56(9):835-845

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Center, Dokki, Giza, Egypt.

The enantioseparation of three fluoroquinoline antibacterial drugs, namely, flumequine, ofloxacin and lomefloxacin using high-performance liquid chromatography was optimized on seven polysaccharide-derived chiral stationary phases, namely, Chiralpak® IB, chiralpak® IA, Chiralpak® AD, Chiralcel® OJ, Chiralcel® OD, Chiralcel® OD-H and Chiralcel® OZ-3 and applying different mobile phases in isocratic mode is described. The role of addition of organic additives was also investigated. A baseline separation of flumequine, ofloxacin and lomefloxacin enantiomers was achieved. Parameters influencing enantioseparation including mobile phase, organic additive and chemical nature of the chiral selector found to be highly influencing on the enantiomeric separation were investigated. Chiral recognition mechanism(s) are also presented.
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http://dx.doi.org/10.1093/chromsci/bmy061DOI Listing
October 2018

Structure-retention relationship for enantioseparation of selected fluoroquinolones.

Chirality 2018 06 6;30(6):828-836. Epub 2018 Apr 6.

Medicinal and Pharmaceutical Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre (ID: 60014618), Giza, Egypt.

Fluoroquinolones are popular class of antibiotics with distinct chemical functionality. Most of them are ampholytes with one chiral center. Stereogeneic center is located either in the side ring of Gatifloxacin (GFLX) or in the quinolone core of Ofloxacin (OFLX). These two amphoteric fluoroquinolones have terminal amino groups in common. The unusual Nadifloxacin (NFLX) is an acidic fluoroquinolone with a core chiral center. Owing to chirality and functionality differences among GFLX, OFLX, and NFLX, we mapped these enantiomers onto structure-retention relationship. Amount of acetic acid modifier was studied in screened mobile phase and cellulose tris(3-chloro-4-methyl phenyl carbamate) (Lux cellulose-2) stationary phase. Experimental design of acetic acid% along with column temperature have been applied. Resolution and enantioselectivity have been related to structural features of the studied enantiomers. High amount of acid (0.4%) was optimum for the separation of either side chirality with a proximate amino group (GFLX) or core chirality without basic functionality (NFLX), while low amount (0.2%) is optimum for core chiral center with distal amino group (OFLX). Temperature has no significant effect on resolution and retention of enantiomers except for OFLX. Enantio-retention explains possible chiral selective and nonselective interactions. The proposed methods have been validated for pharmaceutical analyses.
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http://dx.doi.org/10.1002/chir.22861DOI Listing
June 2018
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