Browsing by Author "Maneva K."

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    Antileukemic effect of epirubicin conjugated with chitosan against mouse p388 ascitic leukemia
    (2003-01-01) Todorova N.; Maneva K.; Ilarionova M.; Dudov A.; Todorov D.
    The antileukemic activity of the original conjugate of anthracycline antitumor antibiotic epirubicin, covalently bond to the biopolymer chitosan was studied. The ascitic form of lymphocytic leukemia P388 (transplantation dose 1 × 106 tumor cells/mouse), in hybrid mice BDF1 was used as leukemic model. A strong antileukemic activity of the studied conjugate was found, with a clear “dose-effect” correlation. The criterion “increase of life span”(ILS%) reached maximally 553.4% for the conjugate, in comparison with maximally 170.8% for the free epirubicin. The conjugate showed several advantages over the free antitumor antibiotic epirubicin: lower toxicity, stronger antileukemic activity and higher therapeutic index. © 2003 Taylor and Francis Group, LLC.
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    Preparation and antileukemic activity of epirubicin conjugate with chitosan
    (2004-01-01) Todorova N.; Maneva K.; Todorov D.
    Condensation of the antitumor antibiotic epirubicin with oxidized chitosan provided a new conjugated antibiotic. The resultant compound was characterized by IR and UV-Vis-spectra with support the conjugate structure. The amount of epirubicin bound to the matrix was 22.5% or 315 epirubicin residues. The biological activity of epirubicin-chitosan conjugate showed an antibacterial action against Bacillus Subtilis AT 6633 on the level of the initial antibiotic. The ascetic form of lymphocytic leukemia P 388 and lymphoid leukemia L1210 (transplantation dose 106 tumor cells) in hybrid mice BDF1 was used as leukemic model. Antileukemic activity of the studied conjugate was found with a clear “dose-effect” correlation. The criterion “increase of live span” is maximally 342.1% in P338 and 371.5% in L1210 for the conjugate in comparation with maximally 179.0% in P388 and 197.2% in L1210 for the free epirubicin. The conjugate showed lower toxicity and higher therapeutic index. © 2004 Taylor and Francis Group, LLC.
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    Preparation and antileukemic activity of the conjugate of doxorubicin with chitosan ax2
    (2005-01-01) Todorova N.; Maneva K.; Todorov D.
    Condensation of the antitumor antibiotic doxorubicin with oxidized chitosan in the presence of sodium borohydride provided a new conjugated antibiotic AC2.A ring involving a N-atom from the 31-amino group of the doxorubicin—sugar moiety and the residue of the oxidized glucosamine ring of chitosan was formed during reductive alkilation. The resulting conjugate was studied spectroscopicaly. The resultant compound was characterized by IR- and UV-Vis spectra which support the conjugate structure. The quantity of the bound antibiotic was evaluated using the spectra of doxorubicin-chitosan conjugate in 20% acetic acid. The bound doxorubicin was evaluated as 397.1 residues or 24.6%. The antibacterial activity of the conjugate was studied against Bacillus subtilis ATCC6633. Compared to unmodified doxorubicin the activity of the conjugate was 88.1%. The antileukemic activity of the conjugate AC2 of doxorubicin were studied against ascitic form of lymphocytic leukemia P388. A strong antileukemic activity of the conjugate AC2 was found and the criterion “increase of life span” (T/C) reached 412.8% in comparition with 167.6% at doxorubicin (at dose 0.25 mg/kg). © 2005 Taylor and Francis Group, LLC.