Laila A. Abou-Zeid

Non-classical antifolates. Part 2: Synthesis, biological evaluation, and molecular modeling study of some new 2,6-substituted-quinazolin-4-ones

A new series of 2,6-substituted-quinazolin-4-ones was designed, synthesized, and evaluated for their in vitro DHFR inhibition, antimicrobial, and antitumor activities. Compounds 22, 33-37, 39-43, and 45 proved to be active DHFR inhibitors with IC(50) range of 0.4-1.0microM. Compound 18 showed broad-spectrum antimicrobial activity comparable to the known antibiotic gentamicin. Compounds 34 and 36 showed antitumor activity at GI(50) (MG-MID) concentrations of 11.2, and 24.2microM, respectively. Molecular modeling study including flexible alignment; electrostatic, hydrophobic mappings; and pharmacophore prediction were performed. A main featured pharmacophore model was developed which justifies the importance of the main pharmacophoric groups as well as of their relative distances. The substitution pattern and spatial considerations of the pi-systems in regard to the quinazoline nucleus proved critical for biological activity.

Synthesis and biological evaluation of new curcumin derivatives as antioxidant and antitumor agents

Twenty-four new compounds were prepared, taking curcumin as a lead, in order to explore their antioxidant and antitumor properties. The capacities of these derivatives to scavenge the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS.+), and to protect human red blood cells (RBCs) from oxidative haemolysis were investigated. In addition, the percentage viability of different cell lines (Hep G2, WI38, VERO and MCF-7) was tested. The result of the antitumor testing was generally in accordance with those of the antioxidant assays. Compounds which bear o-methoxy substitution to the 4-hydroxy function in the phenyl ring (7g, 5g and 3g) exhibited significantly higher ABTS.+-scavenging, antihaemolysis, and antitumor activities than other derivatives. In addition, molecular modelling studies were carried out for biologically active and inactive compounds, to study the structure–activity relationship, with the aim to elucidate which portions of the molecules are critical for the antioxidant and antitumor activity.

Recognition of resveratrol by the human estrogen receptor-alpha: a molecular modeling approach to understand its biological actions.

Objectives: Resveratrol (RSVL) is an edible phytoestrogen with multifaceted health benefits that may originate from binding to the estrogen receptors. Despite its structural similarity to the estrogen receptor-α (ERα) agonist diethylstilbestrol (DES), RSVL showed distinct biological profiles in estrogen-responsive biological systems. The molecular basis of such biological profiles has been undefined. Methods: We considered possible orientations for RSVL in ERα binding pocket. These conformations have been analyzed based on: (i) alignment with the key pharmacophoric elements of DES; (ii) computational energy of interaction, and (iii) pattern of accommodation at the ERα binding pocket. The characteristics of the most favored RSVL orientation have been compared with those of DES. Results: Both RSVL and DES interacted with the catalytic amino acid triad of the ERα pocket (His524, Arg394 and Glu 353). However, unlike the Erα agonists DES and estradiol (E2), RSVL formed three additional hydrogen bonds with Gly521 and Leu525, two paramount ligand recognition residues, and with Met343 at the ERα binding cavity. Lastly, RSVL displayed a more favorable energy of interaction with the ERα binding cavity. Conclusions: The present study suggests, for the first time, that RSVL is well recognized by the human ERα but in a manner distinct from the pure agonists DES and E2. These variations may well entail the unique biological responses of RSVL in ER-responsive systems.

Design, synthesis of 2,3-disubstitued 4(3H)-quinazolinone derivatives as anti-inflammatory and analgesic agents: COX-1/2 inhibitory activities and molecular docking studies.

A new series, 2-substituted mercapto-3-[2-(pyridin-2-yl)ethyl]-4(3H)-quinazolinone 1-21, was synthesized and evaluated for in vivo anti-inflammatory and analgesic activities and in vitro COX-1/COX-2 inhibition. Compounds 1, 4, 5, 6, 8, 10, 13, 14, 15, 16, and 17 exhibited potent anti-inflammatory and analgesic properties, with ED50 values of 50.3-112.1mg/kg and 12.3-111.3mg/kg, respectively. These values may be compared with those of diclofenac sodium (ED50=112.2 and 100.4mg/kg) and celecoxib (ED50=84.3 and 71.6mg/kg). Compounds 4 and 6 possessed strong COX-2 inhibitory activity with IC50 (0.33μM and 0.40μM, respectively) and selectivity index (SI>303.0 and >250.0, respectively) values that are similar to those of the reference drug celecoxib (IC50 0.30μM and COX-2 SI>333). Compounds 5, 8, and 13 demonstrated effective COX-2 inhibitory activity with IC50 values of 0.70-0.80μM and COX-2 SI>125-142. Potent COX-2 inhibitors, such as compounds 4, 6, and 13, were docked into the active site pockets of COX-1 and COX-2, with the greatest recognition occurring at the COX-2 binding site and insignificant interactions at the binding site of the COX-1 pocket.

Immune modulatory potentials of antineoplaston A-10 in breast cancer patients

Antineoplastons are naturally occurring cytodifferentiating agents. Chemically, they are medium and small sized peptides, amino acid derivatives and organic acids, which exist in blood, tissues and urine. Antineoplaston A-10 (3-phenylacetylamino-2,6-piperidinedione) is the first chemically identified antineoplaston. Previously we have shown a strong inverse association of urinary antineoplaston A-10 with breast cancer. This study is designed to evaluate neutrophil apoptosis in patients with breast cancer at time of diagnosis and to correlate urinary antineoplaston A-10 levels with neutrophil apoptosis and to describe the direct effect of A-10 in vitro on neutrophil apoptosis in breast cancer patients. The participants were patients with a histologically confirmed diagnosis of breast cancer. Only those cases without previous treatment for breast cancer were included. Neutrophil apoptosis was assessed in breast cancer patients both morphologically and by DNA fragmentation and studied relative to healthy controls. Antineoplaston A-10 was measured using high performance liquid chromatography in urine samples collected from the patients. Urine samples from normal women served as controls. Direct effect of antineoplaston A-10 on neutrophil apoptosis was tested in vitro after adding A-10 at a concentration of 10 ng/ml to the cellular suspensions of breast cancer patients. Non-treated samples served as controls. Significantly higher neutrophil apoptosis levels were detected among patients with breast cancer with a P value <0.001. Urinary antineoplaston A-10 level is significantly negatively correlated with high apoptosis levels (P<0.0001). In vitro, antineoplaston A-10 was found to inhibit significantly the neutrophil apoptosis with a P value <0.0001. These findings confirm the presence of immune defects among patients with breast cancer and such results should stimulate the development of new strategies to induce and augment immunity for the treatment of breast cancer. Antineoplaston A-10 may provide rational basis for designing trials to employ its immune modulatory potentials as adjuvant therapy in breast cancer patients.

Synthesis, spectroscopic characterization, stability assessment and DNA-binding of new 2,6-piperidinedione derivatives

This work reports on structural characterization of new antineoplaston (ANP) representatives, namely 3-(benzoylamino)-2,6-piperidinedione (BPD), 3-(4-methoxybenzoylamino)-2,6-piperidinedione (MPD) and 3-(p-nitrobenzoylamino)-2,6-piperidinedione (NPD). These compounds were prepared by reacting N-(4-substituted benzoyl)-glutamines with N-hydroxysuccinimide to afford the corresponding esters, which were heated to produce the corresponding 2,6-piperidinedione (PD) compounds. Non-destructive analytical procedures such as 1H NMR and NIR analyses confirmed the postulated chemical structures of these PD compounds. HPLC chromatograms at an ambient temperature or from solutions preheated at 30, 40 or 60 degrees C displayed only a single peak for each compound. Combination of heat with pH modification had virtually no effect on the obtained peaks, thus attesting to the stability and purity of these compounds. MS analysis displayed molecular mass ions indicative of BPD, MPD and NPD at m/z 233.4, 263.2 and 278.3, respectively. The fragmentation patterns using MS/MS analyses conformed to the structural and molecular formulae of the prepared compounds. Furthermore, preliminary biological assessments showed the capacity of these compounds to bind to the DNA. NPD, but not BMP or MPD, had a superior affinity to the DNA than the prototype ANP-A10.

Design, synthesis, molecular modeling and biological evaluation of novel diaryl heterocyclic analogs as potential selective cyclooxygenase-2 (COX-2) inhibitors

New series of 3,4-diaryl-2-thioxoimidazolidin-4-ones and 3-alkylthio-4,5-diaryl-4H-1,2,4-triazoles were designed, synthesized and evaluated for their activity as anti-inflammatory agents. Compounds 20, 21, 23 and 34 are highly selective inhibitors of COX-2 enzyme at a concentration of 100 mM relative to celecoxib, the standard reference. (±)-3-(4-Phenoxy-phenyl)-5-phenyl-2-thioxoimidazolidin-4-ones 23 exhibited the most active anti-inflammatory agent.

Combating oxidative stress as a hallmark of cancer and aging: Computational modeling and synthesis of phenylene diamine analogs as potential antioxidant.

The cross talk between the over expression of oxygen-free radicals is known as reactive oxygen species (ROS) that is associated with the excessive telomerase activity (TA). Telomerase activity is an invariable finding where human telomerase (hTERT) has been implicated in tumor oxidative stress and redox-mediated malignancy. The hTERT over expression is a novel tumor marker and is promising as a novel class of therapeutic weapons to fight against cancer. A new series of phenylene diamines were designed, synthesized, and evaluated for their in vitro antioxidant as an indicator of inhibiting the oxidative stress tumor. Compounds 3b and 7b proved to be the most active antioxidants with high percentage ABTS inhibition ranged from 89.40% to 88.59% respectively. Molecular modeling studies indicated that the crest configuration of phenylene diamine nucleus with substitutions of trimethoxy benzamido functional proved to be crucial for enhancing the free radical scavenging activity. Molecular modeling exploration indicated the proper binding selectivity of the 3b and 7b to the 3KYL pocket with promising hTERT inhibitors as a hallmark of cancer.

Synthesis, anticancer and apoptosis-inducing activities of quinazoline–isatin conjugates: epidermal growth factor receptor-tyrosine kinase assay and molecular docking studies

Abstract A new series of quinazolinone compounds 16–34 incorporating isatin moieties was synthesized. The antitumor efficacy of the compounds against MDA-MB-231, a breast cancer cell line, and LOVO, a colon cancer cell line, was assessed. Compounds 20, 21, 22, 23, 25, 27, 28, 29, 30, 31, 32, 33, and 34 displayed potent antitumor activity against MDA-MB-231 and LOVO cells (IC50: 10.38–38.67 μM and 9.91–15.77 μM, respectively); the comparative IC50 values for 5-fluorouracil and erlotinib in these cells lines were 70.28 μM, 22.24 μM and 15.23 μM, 25.31 μM respectively. The EGFR-TK assay and induction of apoptosis for compound 31 were investigated to assess its potential cytotoxic activity as a representative example of the novel synthesized compounds. At a concentration of 10 μM, compound 31 exhibited efficient inhibitory effect against EGFR-TK and induced apoptosis in MDA-MB-231 cells. Furthermore, a molecular docking study for compound 31 and erlotinib was performed to verify the binding mode toward the EGFR kinase enzyme, and showed a similar interaction as that with erlotinib alone. Graphical Abstract: Compound 31 showed potent antitumor activity and efficient inhibitory effect against EGFR-TK and induced apoptosis of MDA-MB-231 cells at a concentration of 10 μM. Graphical Abstract

Computational Modeling, Synthesis, and Antioxidant Potential of Novel Phenylcarbamoylbenzoic Acid Analogs in Combating Oxidative Stress

A new series of phenylcarbamoylbenzoic acid analogs were designed, synthesized, and evaluated for their in vitro antioxidant activity, aiming to find a lead for the treatment of oxidative stress. The target compounds were prepared by substituting the core phenylcarbamoylbenzoic acid moiety with certain functionalities via simple and efficient synthetic strategies. A molecular modeling study was performed to evaluate the recognition of target compounds at the 3MNG binding pocket. The docking data revealed that compounds 8c and 9a selectively bind to the crucial amino acid residues in the active site of 3MNG. The in vitro antioxidant activity was determined by ABTS antioxidant assay. Compounds 8c, 9a, and 9b showed high antioxidant activity and are thus promising as potent antioxidant leads.