Atallah F. Ahmed

Atallah F. Ahmed
King Saud University | KKUH · Department of Pharmacognosy

PhD
Looking for collaborators in the field of marine and terrestrial natural products

About

117
Publications
16,545
Reads
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Introduction
Professor of Pharmacognosy and Natural Products Chemistry. Research interests include 1. Isolation and structural identification of bioactive drug lead from terrestrial and marine organisms; 2. Preparation of fine chemicals, food supplements, and phytomedicines from biowastes; and 3. Evidence-based herbal medicine and standardization. It is our pleasure to interpersonal and inter-institutional collaborate on these themes and related publication activities (including reviews and book chapters).
Additional affiliations
February 2010 - February 2015
King Saud University, College of Pharmacy
Position
  • Professor
February 2008 - present
Mansoura University
Position
  • Professor of Pharmacognosy and Natural Products Chemistry
January 2001 - July 2006
National Sun Yat-sen University
Position
  • Research Associate

Publications

Publications (117)
Article
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Abstract A hydroacetone extract was prepared from seeds of Phoenix dactylifera L. var. Khalas, which is an industrial by-product of date processing. The proanthocyanidin nature of the extract (coded as DTX) was characterized by phytochemical and nuclear magnetic resonance (NMR) analyses. The total phenol/proanthocyanidin content and antioxidant act...
Article
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Three new polyoxygenated diterpenoids with a rare 4-isopropyl-1,5,8a-trimethylperhydrophenanthrane structure of the klysimplexane skeleton, briarols A‒C (1‒3), and one eunicellin-based diterpenoid, briarol D (4), were isolated from Briareum violaceum, a gorgonian inhabiting Taiwanese waters. The chemical structures of these compounds were determine...
Article
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Oxidative stress and chronic inflammation have a role in developing neurodegenerative diseases such as Parkinson’s disease (PD) and inflammatory movement disorders such as rheumatoid arthritis that affect millions of populations. In searching for antioxidant and anti-inflammatory molecules from natural sources that can counteract neurodegenerative...
Article
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A polyoxygenated and halogenated labdane, spongianol (1); a polyoxygenated steroid, 3β,5α,9α-trihydroxy-24S-ethylcholest-7-en-6-one (2); a rare seven-membered lactone B ring, (22E,24S)-ergosta-7,22-dien-3β,5α-diol-6,5-olide (3); and an α,β-unsaturated fatty acid, (Z)-3-methyl- 9-oxodec-2-enoic acid (4) as well as five known compounds, 10-hydroxykah...
Poster
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Dear Colleagues, The Middle East (ME) is the intersection region connecting Asia, Africa, and Europe with major bodies of marine waters including the East Mediterranean, Red Sea, Arabian Sea, Persian Gulf, Gulf of Oman, Gulf of Aden. The marine environment, whose biodiversity is in harmony with the geographical location, has been known to represen...
Article
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Three new 5,5,6,6,5-pentacyclic spongian diterpenes, spongenolactones A–C (1–3), were isolated from a Red Sea sponge Spongia sp. The structures of the new metabolites were elucidated by extensive spectroscopic analysis and the absolute configurations of 1–3 were determined on the basis of comparison of the experimental circular dichroism (CD) and c...
Article
The cytochalasan asporychalasin (1) was obtained from the marine fungus Aspergillus oryzae, isolated from the Red Sea sediments collected off Jeddah, Saudi Arabia. The chemical structure of 1 was elucidated by extensive spectroscopic analysis and quantum-mechanical calculations of ¹³C NMR resonances and ECD to possess an unprecedented 6/6/11-fused...
Article
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The new asperorlactone (1), along with the known illudalane sesquiterpene echinolactone D (2), two known pyrones, 4-(hydroxymethyl)-5-hydroxy-2H-pyran-2-one (3) and its acetate 4, and 4-hydroxybenzaldehyde (5), were isolated from a culture of Aspergillus oryzae, collected from Red Sea marine sediments. The structure of asperorlactone (1) was elucid...
Article
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Chemical investigation of a Red Sea Spongia sp. led to the isolation of four new compounds, i.e., 17-dehydroxysponalactone (1), a carboxylic acid, spongiafuranic acid A (2), one hydroxamic acid, spongiafuranohydroxamic acid A (3), and a furanyl trinorsesterpenoid 16-epi-irciformonin G (4), along with three known metabolites (−)-sponalisolide B (5),...
Article
Four new aromatic polyketides (1–4) were isolated from Penicillium sp. RO-11, obtained from the sediment of a hydrothermal spring in the southwestern region of Saudi Arabia. The new compounds are penipyranicins A–C (1–3), characterized by a 4-methyl-4H-pyran moiety, a structural motif unprecedented among fungal polyketides, and the naphthopyrone de...
Article
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The present investigation on chemical constituents of the soft coral Sarcophyton cherbonnieri resulted in the isolation of seven new cembranoids, cherbonolides F–L (1–7). The chemical structures of 1–7 were determined by spectroscopic methods, including infrared, one- and two-dimensional (1D and 2D) NMR (COSY, HSQC, HMBC, and NOESY), MS experiments...
Article
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Organic fractions and extracts of willow (Salix safsaf) leaves, produced by sequential solvent extraction as well as infusion and decoction, exhibited anticancer potencies in four cancerous cell lines, including breast (MCF-7), colorectal (HCT-116), cervical (HeLa) and liver (HepG2). Results of the MTT assay revealed that chloroform (CHCl3) and eth...
Article
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In the brain, propionic acid (PA) can cross cell membranes and accumulate within cells, leading to intracellular acidification, which may alter neurotransmitter release (NT), communication between neurons, and behavior. Such elevation in levels of PA constitutes a neurodevelopmental metabolic disorder called propionic acidemia, which could clinical...
Article
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Further chemical investigation of the EtOAc extract of the soft coral Lobophytum varium resulted in the discovery of eleven new diterpenoids lobovarols F–P (1–11) of lobane– and prenyleudesmane–types, along with two known metabolites (12 and 13). The structures of the new metabolites were established by spectroscopic analyses, including 2D NMR expe...
Article
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Two new capnosane-based diterpenoids, flaccidenol A (1) and 7-epi-pavidolide D (2), two new cembranoids, flaccidodioxide (3) and flaccidodiol (4), and three known compounds 5 to 7 were characterized from the marine soft coral Klyxum flaccidum, collected off the coast of the island of Pratas. The structures of the new compounds were determined by ex...
Article
Full-text available
Three new eunicellin-derived diterpenoids of briarellin type, briarenones A-C (1-3), were isolated from a Formosan gorgonian Briareum violaceum. The chemical structures of the compounds were elucidated on the basis of extensive spectroscopic analyses, including two-dimensional (2D) NMR. The absolute configuration of 1 was further confirmed by a sin...
Article
A phytochemical investigation of the leaves of Solanum capsicoides resulted in the isolation and characterization of five new withanolide-type steroids, capsisteroids G–K (1–5), along with three known analogues (6–8). Their structures were identified by interpretation of the NMR and HRESIMS data as well as by spectral data comparison with known ana...
Article
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Six new cembranoids, cherbonolides A−E (1–5) and bischerbolide peroxide (6), along with one known cembranoid, isosarcophine (7), were isolated from the Formosan soft coral Sarcophyton cherbonnieri. The structures of these compounds were elucidated by detailed spectroscopic analysis and chemical methods. Compound 6 was discovered to be the first exa...
Article
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Extensive phytochemical analysis of different root fractions of Jatropha pelargoniifolia Courb. (Euphorbiaceae) has resulted in the isolation and identification of 22 secondary metabolites. 6-hydroxy-8-methoxycoumarin-7-O-β-d-glycopyranoside (15) and 2-hydroxymethyl N-methyltryptamine (18) were isolated and identified as new compounds along with th...
Article
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Six new polyoxygenated cembrane-based diterpenoids, stellatumolides A–C (1–3), stellatumonins A and B (4 and 5), and stellatumonone (6), were isolated together with ten known related compounds (7–16) from the ethyl acetate (EtOAc) extract of soft coral Sarcophyton stellatum. The structures of the new compounds were established by extensive spectros...
Article
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Three new polyoxygenated steroids, michosterols A–C (1–3), and four known compounds (4–7) were isolated from the ethyl acetate (EtOAc) extract of the soft coral Lobophytum michaelae, collected off the coast of Taitung. The structures of the new compounds were elucidated on the basis of spectroscopic analyses and comparison of the nuclear magnetic r...
Article
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The Phytochemical investigation on MeOH extract on the bark of Aristolochia brasiliensis Mart. & Zucc (Aristolochiaceae) led to the isolation of major compound (1) as light brown grainy crystals. The compound was identified as 1-(4-hydroxybenzyl)-1,2,3,4-tetrahydroisoquinoline-6,7-diol (higenamine) on the basis of spectroscopic analysis, including...
Article
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In this study, we have developed a validated high-performance thin-layer chromatographic (HPTLC) method for the simultaneous quantification of two phenolic biomarkers, protocatechuic acid (compound 1) and quercetin 4?-O-?-d-glucopyranoside (compound 2) in antimicrobial and antioxidant active A. cepa ethyl acetate extract (ACEAE). The quantitative a...
Article
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Onion peel is a common bio-waste, occasionally used in traditional medicine in treatment of liver ailment and inflammation. However, a phytochemical and biological study is further required to provide the scientific evidence for this use. A phenolic-rich extract of red onion peels (coded as ACPE) was primarily prepared and then subjected to chromat...
Article
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New lobane-based diterpenoids lobovarols A–D (1–4) and a prenyleudesmane-typediterpenoid lobovarol E (5) along with seven known related diterpenoids (6–12) were isolatedfrom the ethyl acetate extract of a Taiwanese soft coralLobophytum varium. Their structureswere identified on the basis of multiple spectroscopic analyses and spectral comparison.Th...
Article
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The resistance and pathogenesis of bacteria could be related to their ability to sense and respond to population density, termed quorum-sensing (QS). Inhibition of the QS system is considered as a novel strategy for the development of antipathogenic agents, especially for combating drug-resistant bacterial infections. In the present study, the anti...
Article
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A new series of 3,4,5-trimethoxyphenyl bearing pyrazole (4a–g) and pyrazolo[3,4-d]pyridazine (5a–g) scaffolds were synthesized in good yield. The newly synthesized compounds were characterized on the basis of elemental and spectroscopic analyses. Their inhibitory activity against the pro-inflammatory inducible nitric oxide synthase and cyclooxygena...
Article
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Five new isoprenoids, 3,4,8,16-tetra-epi-lobocrasol (1), 1,15β-epoxy-deoxysarcophine (2), 3,4-dihydro-4α,7β,8α-trihydroxy-Δ2-sarcophine (3), ent-sarcophyolide E (4), and 16-deacetyl- halicrasterol B (5) and ten known compounds 6‒15, were characterized from the marine soft coral Sarcophyton glaucum, collected off Taitung coastline. Their structures...
Article
Continuing study of the ethyl acetate (EtOAc) extract of the cultured soft coral Sinularia brassica afforded five new withanolides, sinubrasolides H−L (1−5). The structures of the new compounds were elucidated on the basis of spectroscopic analysis. The cytotoxicities of new compounds 1–5 and a known compound sinubrasolide A (6) against the prolife...
Article
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New cembranoids klyflaccicembranols A–I (1–9), along with gibberosene D (10), have been isolated from the organic extract of a Formosan soft coral Klyxum flaccidum. Their structures were established by extensive spectroscopic analyses, including 2D NMR spectroscopy, and spectral data comparison with related structures. The cytotoxicity of the isola...
Article
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Medulloblastoma (MB) is the most common malignant brain tumor of childhood. The transcription factor NF-κB is overexpressed in human MB and is a critical factor for MB tumor growth. NF-κB is known to regulate the expression of interleukin-8 (IL-8), the chemokine that enhances cancer cell growth and resistance to chemotherapy. We have recently shown...
Article
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A series of new Schiff bases were synthesized by condensation of isatins with the nalidixic acid-L-amino acid hydrazides. Prior to hydrazide formation, a peptide linkage has been prepared via coupling of nalidixic acid with appropriate L-amino acid methyl esters to yield 3a-c. The chemical structures of the new Schiff bases (5b and 5d-h) were confi...
Article
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Despite progressive improvement in treating major depressive disorder (MDD), it remains mostly unresponsive to one antidepressant medication. Zinc is a brain highly abundant trace metal, a brain derived neurotrophic factor (BDNF) inducer, a modulator of synaptic plasticity and potent suppressor of the NMDA receptors. We proposed that co-administrat...
Article
Background: Antioxidant natural products and chemoprevention are considered nowadays as an effective approach against health various disorders and diseases induced by oxidative stress or free radicals. Objective: The aim of this study was to assess the hepato- and nephroprotective activity of a standardized red vine leaf aqueous extract AS195 (Anti...
Article
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A phytochemical investigation of the least polar organic extracts of Arnebia hispidissima (Lehm.) DC. roots has led to the isolation of two unique polycyclic geranylhydroquinone-derived metabolites, arnebacene (1) and arnebidin (2), along with some known phenolic metabolites viz., arnebin-7 (3) and vanillic acid (4). The chemical identification of...
Article
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A phytochemical investigation on the 5-lipoxygenase (5-LOX) inhibitory methanolic extract of Rudbeckia hirta L. flowers yielded 10 phenolic metabolites, including three phenolic acids, two phenolic acid esters, four flavonol glycosides and a trimethylated flavonol. The structures of the isolated metabolites were determined on the basis of spectrosc...
Article
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The flavonoid-rich hydro-acetone extract of red onion (Allium cepa peel, ACPE) was studied for its spasmolytic and bronchodilator activities using ex-vitro and in-vivo assays. In isolated rabbit jejunum preparations, ACPE produced a concentration-dependent (0.03-1 mg L-1) relaxation of spontaneous and high K+(80 mM)-induced contractions equipotentl...
Article
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The present study was undertaken to evaluate the crucial role of hepatocytes transplantation in experimental model of D-galactosamine-induced fulminating hepatic failure (FHF) in rat. Hepatocytes were isolated and grown from a group of apparently healthy rats. The isolated hepatocyte was characterized and cultured in vitro and transplanted in FHF r...
Article
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A new highly oxygenated pseudoguaianolide, rudbeckolide (1), was isolated from Rudbeckia hirta L. flowers. The structure of this terpenoid lactone was established on the basis of extensive 1D and 2D NMR spectroscopic analyses. The compound exhibited strong 5-lipoxygenase inhibitory activity (84.9% inhibition at 10 μg/mL) in vitro and the result pro...
Article
In the present study, in vitro antioxidant, antioxidative stress and hepatoprotective activity of Moringa oleifera Lam. seed oil (Ben oil; BO) was evaluated against carbon tetrachloride (CCl(4) ) induced lipid peroxidation and hepatic damage in rats. The oil at 0.2 and 0.4 mL/rat was administered orally for 21 consecutive days. The substantially el...
Article
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A novel phenanthrenoid symmetrical dimer 8,8'-bidehydrojuncusol [1,1',6,6'-tetramethyl-5,5'-divinyl-8,8'-biphenanthrene-2,2',7,7'-tetraol], a related phenanthrenoid monomer, a phenolic chromone, and five flavonoids derivatives have been isolated from the halophyte Juncus acutus L., Juncaceae. The structure of the dimeric phenanthrenoid was determin...
Article
From the roots of Bryonia cretica L. two new cucurbitacins, isocucurbitacins G (1) and H (2), along with three known cucrbitacins, cucurbitacins G (3), H (4), and J (5) were isolated. The structures of 1 and 2 were determined on the basis of 1D and 2D NMR spectroscopic analysis and X-ray crystallography. The relative stereochemistries of the side c...
Article
Six new sesquiterpene lactone esters, daucoguaianolactones A-F (1-6), and one new sesquiterpene lactone, daucoeudesmanolactone A (7) were isolated from the leaves and stems of Daucus glaber (FORSSK.) THELL., along with the known sesquiterpene lactones talasins A and B and badkhysin. The structures of 1-6 were established on the basis of extensive 1...
Article
Three new phenylpropanoid triesters, glaberins A–C (1–3), were isolated from the leaves and stems of Daucus glaber (Forssk.) Thell. (Apiaceae). Their gross structures were determined on the basis of 2D NMR experiments, and the absolute structure of 1 by X-ray crystallography and chemical methods. Glaberins A (1) and B (2) were evaluated for cytotox...
Article
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A novel skeletal norhumulene (1) and six xeniaphyllane-derived compounds, including norditerpenoids (2, 3) and diterpenoids (4-7), were isolated from the EtOAc extract of the Formosan soft coral Sinularia gibberosa. Their structures were elucidated by spectroscopic analysis. In vitro cytotoxic evaluation of the above metabolites revealed that 2 and...