Browsing by Author "Zein, Nabila"

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    Aspergillus Niger thermostable Cytosine deaminase‑dextran conjugates with enhanced structure stability, proteolytic resistance, and Antiproliferative activity
    (BioMed Central Ltd, 2023-01) El‑Sayed, Ashraf S. A; Rady, Amgad M; Mohamed, Hossam Taha; Zein, Nabila; Yassin, Marwa A; Mohamed, Nabil Z; Hassan, Abdallah; Amer, MahmoudReyad El‑Sharakawy5 M; El‑Sharkawy, Aya Ali; El‑Sayed, Nesma; Ali, Mostafa G
    Cytosine deaminase (CDA) is a prodrug mediating enzyme converting 5-furocytosine into 5-furouracil with profound broad-range anticancer activity towards various cell lines. Availability, molecular stability, and catalytic efciency are the main limiting factors halting the clinical applications of this enzyme on prodrug and gene therapies, thus, screen‑ ing for CDA with unique biochemical and catalytic properties was the objective. Thermotolerant/ thermophilic fungi could be a distinctive repertoire for enzymes with afordable stability and catalytic efciency. Among the recovered thermotolerant isolates, Aspergillus niger with optimal growth at 45 °C had the highest CDA productivity. The enzyme was purifed, with purifcation 15.4 folds, molecular mass 48 kDa and 98 kDa, under denaturing and native PAGE, respectively. The purifed CDA was covalently conjugated with dextran with the highest immobilization yield of 75%. The free and CDA-dextran conjugates have the same optimum pH7.4, reaction temperature 37 °C, and pI 4.5, and similar response to the inhibitors and amino acids suicide analogues, ensuring the lack of efect of dextran conjuga‑ tion on the CDA conformational structure. CDA-Dextran conjugates had more resistance to proteolysis in response to proteinase K and trypsin by 2.9 and 1.5 folds, respectively. CDA-Dextran conjugates displayed a dramatic structural and thermal stability than the free enzyme, authenticating the acquired structural and catalytic stability upon dextran conjugation. The thermal stability of CDA was increased by about 1.5 folds, upon dextran conjugation, as revealed from the half-life time (T1/2). The afnity of CDA-conjugates (Km 0.15mM) and free CDA (Km 0.22mM) to deaminate 5-fuorocytosine was increased by 1.5 folds. Upon dextran conjugation, the antiproliferative activity of the CDA towards the diferent cell lines “MDA-MB, HepG-2, and PC-3” was signifcantly increased by mediating the prodrug 5-FC. The CDA-dextran conjugates strongly reduce the tumor size and weight of the Ehrlich cells (EAC), dramatically increase the titers of Caspase-independent apoptotic markers PARP-1 and AIF, with no cellular cytotoxic activity, as revealed from the hematological and biochemical parameters.
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    Exploiting the Biosynthetic Potency of Taxol from Fungal Endophytes of Conifers Plants; Genome Mining and Metabolic Manipulation
    (MDPI, 6/30/2020) El-Sayed, Ashraf S.A.; El-Sayed, Manal T.; Rady, Amgad M.; Zein, Nabila; Enan, Gamal; Shindia, Ahmed; El-Hefnawy, Sara; Sitohy, Mahmoud; Sitohy, Basel
    MDPI Open Access Journals zoom_out_map search menu Journals Molecules Volume 25 Issue 13 10.3390/molecules25133000 molecules-logo Submit to this Journal Review for this Journal Edit a Special Issue ► Article Menu Open AccessReview Exploiting the Biosynthetic Potency of Taxol from Fungal Endophytes of Conifers Plants; Genome Mining and Metabolic Manipulation by Ashraf S.A. El-Sayed 1,*,Manal T. El-Sayed 1,Amgad M. Rady 2,Nabila Zein 3,Gamal Enan 1,Ahmed Shindia 1,Sara El-Hefnawy 1,Mahmoud Sitohy 4OrcID andBasel Sitohy 5,6,*OrcID 1 Enzymology and Fungal Biotechnology Lab (EFBL), Botany and Microbiology Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt 2 Faculty of Biotechnology, October University for Modern Sciences and Arts, Cairo 12566, Egypt 3 Chemistry Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt 4 Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig 44519, Egypt 5 Department of Clinical Microbiology, Infection and Immunology, Umeå University, SE-90185 Umeå, Sweden 6 Department of Radiation Sciences, Oncology, Umeå University, SE-90185 Umeå, Sweden * Authors to whom correspondence should be addressed. Molecules 2020, 25(13), 3000; https://doi.org/10.3390/molecules25133000 Received: 24 May 2020 / Revised: 17 June 2020 / Accepted: 23 June 2020 / Published: 30 June 2020 (This article belongs to the Special Issue Drug Discovery and Development Based on Native/Engineered Microorganisms) View Full-Text Download PDF Browse Figures Cite This Paper Abstract Endophytic fungi have been considered as a repertoire for bioactive secondary metabolites with potential application in medicine, agriculture and food industry. The biosynthetic pathways by fungal endophytes raise the argument of acquisition of these machineries of such complex metabolites from the plant host. Diterpenoids “Taxol” is the most effective anticancer drug with highest annual sale, since its discovery in 1970 from the Pacific yew tree, Taxus brevifolia. However, the lower yield of Taxol from this natural source (bark of T. brevifolia), availability and vulnerability of this plant to unpredicted fluctuation with the ecological and environmental conditions are the challenges. Endophytic fungi from Taxus spp. opened a new avenue for industrial Taxol production due to their fast growth, cost effectiveness, independence on climatic changes, feasibility of genetic manipulation. However, the anticipation of endophytic fungi for industrial Taxol production has been challenged by the loss of its productivity, due to the metabolic reprograming of cells, downregulating the expression of its encoding genes with subculturing and storage. Thus, the objectives of this review were to (1) Nominate the endophytic fungal isolates with the Taxol producing potency from Taxaceae and Podocarpaceae; (2) Emphasize the different approaches such as molecular manipulation, cultural optimization, co-cultivation for enhancing the Taxol productivities; (3) Accentuate the genome mining of the rate-limiting enzymes for rapid screening the Taxol biosynthetic machinery; (4) Triggering the silenced rate-limiting genes and transcriptional factors to activates the biosynthetic gene cluster of Taxol.