Tahia K Mohamed

National Research Center, Egypt, Al Qāhirah, Muḩāfaz̧at al Qāhirah, Egypt

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Publications (10)10.83 Total impact

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    ABSTRACT: Marine sponges have been considered as a gold mine, with respect to the diversity of their secondary metabolites. Many sponge extracts and isolated compounds are potential anticancer agents. In the present study, the antiproliferative activity of Negombata magnifica was investigated as petroleum ether extract (PE), total methanolic extract (ME) and two sub-fractions II and III, isolated pure compounds (palmitic acid and pregnanediol), sponge mesohyl and primmorphs ethyl acetate extract. Palmitic acid was used as a positive control. Cell viability was assessed via MTT assay, and apoptosis was investigated in terms of DNA fragmentation and BCl2 gene expression. Cell cycle analysis was performed via flow cytometry. GLC analysis of PE revealed that it contains 84.46 % hydrocarbons and 15.54 % sterols, whereas the fatty acids contain 38.62 % saturated and 61.38 % unsaturated fatty acids. Results revealed that except for pregnanediol and fraction II, all treatments exhibited cytotoxic activity. Primmorphs ethyl acetate extract and fraction III arrested cells in G0–G1, while fraction II arrested cell cycle in G2/M. PE extract arrested cells in G0–G1 and G2/M. Mesohyl, PE and fraction III could be apoptotic agents as indicated by DNA fragmentation independent on BCL2 expression, while ME and pregnanediol could exhibited pro-apoptotic effect through decreasing BCL2 expression although no DNA ladder was observed.
    Full-text · Article · Jan 2016 · Medicinal Chemistry Research
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    ABSTRACT: Further investigation of the methanol extract of the Egyptian Red Sea soft coral, Heteroxenia ghardaqensis (Family Xeniidae), led to the isolation of a new hydroxymethyl diacylglycerol namely, 1-(11’-hydroxymethyl-hexadecanoyl)-2-pentadecanoyl-3-propanol (1). The structure elucidation of the compound was deduced by 1D and 2D NMR as well as FAB-MS. Compound 1 as well as the methanol extract showed moderate antimicrobial activities against gram positive bacteria (Micrococcus luteus B-287), gram-negative bacteria, Klebsiella pneumonia, and fungi, Candida albicans ATCC 10321.
    Full-text · Article · Sep 2015
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    ABSTRACT: 2-Amino-3-cyanopyridine is a simple precursor for the synthesis of analogues of Egyptian natural products visnagin and khellin. Fused pyrido[2,3-d]pyrimidines were prepared under mild reaction conditions. The detailed syntheses and spectroscopic data of the synthesised compounds are reported. Some isolated compounds show antibacterial and antifungal activity.
    No preview · Article · Apr 2014
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    ABSTRACT: Cynara scolymus L. (Asteraseae) (artichoke) is commonly eaten as a vegetable; its leaves are frequently used in folk medicine in the treatment of hepatitis, hyperlipidaemia, obesity and dyspeptic disorders. The purpose of this study is to determine the chemical composition of the volatile oil and alcoholic extract of artichoke head scales. In addition, the role of the methanol extract as an anti-ulcer agent against ethanol-induced gastric ulcer in rats was evaluated. Six flavonoids and one phenolic acid were obtained from the methanol extract. Also, 37 compounds were identified in the volatile oil, the majority including mono- and sesquiterpenes. The artichoke extracts (200 and 400 mg kg−1) significantly (P < 0.05) reduced the ulcer index (55.33% and 72.14% inhibition). Histopathological examination of rat stomachs demonstrated that artichoke induced an increase in gastric mucus production, and a reduction of the depth and severity of mucosal lesions. Artichoke dose-dependently reduced the elevated ethanol gastric malonylaldehyde, and reduced glutathione levels and catalase activity. These results suggest that the head scales of artichoke possess potential anti-ulcer activity. The present paper describes the identification of volatile oil for the first time along with the isolation and identification of the constituents of the methanol extract. Moreover, the high anti-ulcerogenic potential of scales of C. scolymus heads was established here for the first time.
    Full-text · Article · Aug 2013 · Journal of the Science of Food and Agriculture
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    ABSTRACT: Albizia species are rich in phenolics and terpenes in the different plant organs. They are widely used in traditional Chinese medicine. So this study investigated the phytochemical and biological activities of Albizia Anthelmintica. Column chromatography has been performed for the isolation of compounds. Bioactivity studies of A. anthelmintica leaves were carried out on aqueous ethanol extract and some pure compounds were tested for their antioxidant activities. Eight compounds have been isolated for the first time from A. anthelmintica. The aqueous ethanol extract of A. anthelmintica showed moderate anti-inflammatory activity and significant for both analgesic and antioxidant activities. Quercetin-3-O-β-D-glucopyranoside, kaempferol-3-O-β-D-glucopyranoside, kaempferol-3-O-(6β-O-galloyl-β-D-glucopyranoside and quercetin-3-O-(6β-O-galloyl-β-D-glucopyranoside) exhibited potent antioxidant scavenging activity towards diphenyl-picrylhydrazine.
    Full-text · Article · Apr 2013
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    ABSTRACT: The methanolic extract of the leaves of Cassia roxburghii DC., was investigated for its anthraquinone glycosides and antioxidant activity. Two new anthraquinone glycosides named emodin 1-O-β-d-glucopyranosyl-(1→2)-glucopyranoside (1) and aloemodin 8-O-β-d-glucopyranosyl-(1→6)-glucopyranoside (2) along with aloemodin 8-O-β-d-glucopyranoside (3), emodin (4), aloemodin (5) and one flavonoid, quercetin-3-O-α-l-rhamnopyranoside, were isolated from the leaves of C. roxburghii. Structures of the isolated compounds were established by UV, HRESI-MS, and 1D/2D (1)H/(13)C NMR spectroscopy. The total extract and some isolated compounds were determined against DPPH (2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazinyl radical, for their free radical scavenging activity, the total alcoholic extract showed strong antioxidant activity while the two new compounds showed weak antioxidant activity.
    Full-text · Article · Oct 2012 · Carbohydrate research
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    ABSTRACT: Chemical investigation of the chloroform extract of the Egyptian Red Sea soft coral, Heteroxenia ghardaqensis (Family Xeniidae), led to the isolation of three gorgostane derivatives, namely gorgosten-5(E)-3β-ol (1), gorgostan-3β,5α,6β, 11α-tetraol (sarcoaldosterol A) (2) and gorgostan-3β,5α,6β-triol-11α-acetate (3). To our knowledge, sterol 3 is reported in this article for the first time. The structure elucidation of these compounds was deduced by 1-D and 2-D NMR as well as ESIMS. Sterol 1 showed moderate activity as growth inhibitor of human colon tumour cell lines.
    Full-text · Article · Sep 2012 · Natural product research
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    ABSTRACT: Investigation of the aqueous alcoholic extract of Pyruscalleryana Decne. leaves led to the isolation of two new phenolic acids glycosides, namely protocatechuoylcalleryanin-3-O-β-glucopyranoside (1) and 3'-hydroxybenzyl-4-hydroxybenzoate-4'-O-β-glucopyranoside (2), together with nine known compounds among them lanceoloside A and methylgallate, which have been isolated for the first time from the genus Pyrus. Structures of the isolated compounds were established by spectroscopic analysis, including UV, IR, HRESI-MS, and 1D/2D NMR. The total extract and some isolated compounds were determined against DPPH (2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazinyl radical, for their free radical scavenging activity, the total alcoholic extract showed strong antioxidant activity while the two new compounds showed weak antioxidant activity.
    Full-text · Article · Jan 2011 · Carbohydrate research
  • SA El-toumy · SS Mohamed · TK Mohamed · I Brouard · J Bermejo

    No preview · Article · Jul 2009 · Planta Medica
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    ABSTRACT: Water-distilled essential oil from leaves and flowers of Micromeria nubigena H.B.K. (Lamiaceae) were analyzed by GC and GC/MS systems. The major components identified were thymol (36.9%), carvacrol (16.7%), pulegone (10.8%), caryophyllene oxide (4.6%) and (E)-phytol (3.2%). The major volatiles released by β-glucosidase treatment of the aqueous plant residue were (Z)-3-hexenol (31.2%), (Z)-2-hexenol (18.3%) and δ—cadinene (3.4%). The oil showed significant antibacterial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa, and antifungal activity against Candida albicans, Botrytis cinerea and Aspergillus niger, while the β-glucosidase-liberated fraction was inactive.
    Full-text · Article · Sep 2008 · Journal of Essential Oil Research