Ahmed B. Abdelwahab

Natural and Synthetic Coumarins with Effects on Inflammation

In this review, we will present the different aspects of coumarins and derivatives, from natural origins or synthetically prepared, and their action on inflammation. Coumarins and also furo- and pyranocoumarins are found in many different plants. These compounds are very often investigated for antioxidant properties. Other biological properties are also possible and anti-inflammation activity is one of these. As coumarins are also available quite easily via synthesis, natural ones can be prepared this way but derivatives with special substituents are also feasible. A review on the same topic appeared in 2004 and our contribution will take into account everything published since then.

New pyranosyl cembranoid diterpenes from Sarcophyton trocheliophorum

Abstract During our continual searching programme for novel bioactive metabolites from Sarcophyton trocheliophorum, collected from Red Sea, we describe herein the isolation and structural elucidation of further two new pyrane-based cembranoid diterpenes: 9-hydroxy-7,8-dehydro-sarcotrocheliol (1) and 8,9-expoy-sarcotrocheliol acetate (2), along with the well-known sarcotrocheliol acetate (3), (+)-sarcophine (4), (+)-sarcophytoxide (5) and (-)-sarcophytoxide (6). The chemical structures of compounds 1 and 2 were determined on the basis of 1D and 2D NMR (1H, 13C, 1H–1H COSY, HMQC, HMBC and NOE), mass spectra (ESI and HR-ESIMS) and by comparison with related structures. The antimicrobial activities of the reported compounds 1–6 were investigated. According to the molecular docking study of compounds 1–6 using 3D structure of α,β tubulin in complex with taxol (PDB code 1JFF) and epothilone A (PDB code 1TVK), sarcophine (4) displayed the highest affinity towards both crystal structures, followed by 5 and 6, meanwhile pyrane-based cembranoid diterpenes (1–3) showed less affinity.

Design, synthesis and cytotoxic activity of vitamin E bearing selenium compounds against human breast cancer cell line (MCF-7)

GRAPHICAL ABSTRACT ABSTRACT A new series of vitamin E/selenated pyridine, vitamin E/selenated pyridazine, vitamin E/selenated coumarine and vitamin E/selenated nicotine moieties were synthesized and their cytotoxic activity is investigated using the human breast cancer cell line. The newly synthesized compounds were characterized using spectroscopic tools (IR, 1H NMR, 13C NMR, and mass spectroscopy) as well as microanalysis. Our study reveals that compound vitamin E/selenated nicotine moiety has the highest cytotoxic effect than the other synthesized compounds.

Naturally bioactive compounds from Hemimycale aff arabica: antimicrobial, antiglycation, cytotoxicity, and molecular docking studies

Two naturally new cyclic urea and amide derivatives, [1,3]-diazepan-2-one (1) and (S)-1,4-diaza-cyclododecane-2,3-dion (2), were isolated from the organic extract of the sponge Hemimycale aff arabica collected from the Red Sea. This was together with 4-acetamido-2,6-dibromo-4-hydroxy-1,1-dimethoxycyclohexa-2,5-diene (3), 2,4-bis(1-methyl-1-phenylethyl)-phenol (4), β-sitosterol (5), bis-[2-ethyl]-hexyl-phthylester, triglyceride fatty acid ester, and linoleic acid. The chemical structures of compounds 1 and 2 were determined based on 1D and 2D Nuclear Magnetic Resonance (NMR) and HR-ESIMS. Compounds 1 and 2 revealed high potency as antiglycated agents. The molecular docking study of compounds 1 and 2 using α-glucosidase, α-amylase, dipeptidyl peptidase-IV, and glycogen synthase kinase was performed to check their efficiency as hypoglycemic agents. Both the sponge extract and compound 1 showed no cytotoxicity vs. the RPE-1 as a model of normal cell line.

A cascade synthesis, in vitro cholinesterases inhibitory activity and docking studies of novel Tacrine-pyranopyrazole derivatives

In this work, we describe the preparation of some new Tacrine analogues modified with a pyranopyrazole moiety. A one-pot multicomponent reaction of 3-methyl-1H-pyrazol-5(4H)-one, aryl(or hetero)aldehydes, malononitrile and cyclohexanone involving a Friedländer condensation led to the title compounds. The synthesized heterocyclic analogues of this molecule were evaluated in vitro for their AChE and BChE inhibitory activities in search for potent cholinesterase enzyme inhibitors. Most of the synthesized compounds displayed remarkable AChE inhibitory activities with IC50 values ranging from 0.044 to 5.80 µM, wherein compounds 5e and 5j were found to be most active inhibitors against AChE with IC50 values of 0.058 and 0.044 µM respectively. Molecular modeling simulation on AChE and BChE receptors, showed good correlation between IC50 values and binding interaction template of the most active inhibitors docked into the active site of their relevant enzymes.

Secondary metabolites and biological activity of Pentas species: A minireview

Graphical abstract