Development of a liposomal nanoparticle formulation of 5-fluorouracil for parenteral administration: formulation design, pharmacokinetics and efficacy.

5-Fluorouracil (5-FU) is a small, very membrane permeable drug that is poorly retained within the aqueous compartment of liposomal nanoparticles (LNP). To address this problem a novel method relying on formation of a ternary complex comprising copper, low molecular weight polyethylenimine (PEI) and 5-FU has been developed. More specifically, in the presence of entrapped copper and PEI, externally added 5-FU can be efficiently encapsulated (>95%) in DSPC/Chol (1,2-Distearoyl-sn-Glycero-3-Phosphocholine/cholesterol; 55:45 mol%) liposomes (130-170 nm) to achieve drug-to-lipid ratios of 0.1 (mol:mol). Drug release studies completed using this LNP formulation of 5-FU demonstrated significant improvements in drug retention in vitro and in vivo. Plasma concentrations of 5-FU were 7- to 23-fold higher when the drug was administered intravenously to mice as the LNP 5-FU formulation compared to free 5-FU. Further, the therapeutic effects of the LNP 5-FU formulation, as determined in a HT-29 subcutaneous colorectal cancer model where treatment was given QDx5, was greater than that which could be achieved with free 5-FU when compared at equivalent doses. This is the first time an active loading method has been described for 5-FU. The use of ternary metal complexation strategy to encapsulate therapeutic agents may define a unique platform for preparation of LNP drug formulations.

Different modes of DNA cleavage activity of dihydroxo-bridged dicopper(II) complexes having phenanthroline bases.

Dihydroxo-bridged dicopper(II) complexes [(Cu(phen))(2)(mu-OH)(2)](ClO(4))(2) (1), [(Cu(dpq))(2)(mu-OH)(2)](ClO(4))(2) (2) and [(Cu(dppz)(DMF))(2)(mu-OH)(2)](PF(6))(2) (3), where phen, dpq and dppz are 1,10-phenanthroline, dipyridoquinoxaline and dipyridophenazine, respectively, are prepared and their DNA binding and cleavage properties studied. Complex 3 has been structurally characterized by X-ray crystallography. The complexes have a (Cu(2)(mu-OH)(2))(2+) core with an essentially planar arrangement of two CuN(2)O(2) basal planes. The complexes are avid binder to calf thymus DNA (K(app) value of 4.8 x 10(6) and 5.9 x 10(6) M(-1) for 2 and 3, respectively, from ethidium displacement assay) and exhibits significant cleavage of supercoiled (SC) pUC19 DNA in dark in presence of mercaptopropionic acid. Besides, the dpq and dppz complexes display photo-induced DNA cleavage on UV (312 nm) and red light (632.8 nm) irradiations in absence of any additives. Mechanistic investigations reveal minor groove binding for the phen and dpq complexes, and major groove preference for the dppz species. The oxidative DNA cleavage reactions in presence of mercaptopropionic acid as a reducing agent involve hydroxyl radicals. The photo-cleavage reactions at UV light involve singlet oxygen as the reactive species, while similar reactions on red light irradiation (632.8 nm) proceed through the formation of hydroxyl radical. The complexes show significant DNA hydrolase activity in absence of any additives under dark reaction conditions.

Synthesis, crystal structure, and nuclease activity of planar mono-heterocyclic base copper(II) complexes.

A series of mononuclear copper(II) complexes having a 1:1 molar ratio of copper and the planar heterocyclic base like 1,10-phenanthroline (phen), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) and dipyrido[3,2-a:2',3'-c]phenazine (dppz) are prepared from a reaction of copper(II) nitrate.trihydrate and the base (L) in ethanol or aqueous ethanol at different temperatures. The complexes [Cu(dpq)(NO(3))(2)] (2), [Cu(dpq)(NO(3))(H(2)O)(2)](NO(3)) (3), [Cu(dpq)(NO(3))(2)(H(2)O)(2)].2H(2)O (4.2H(2)O) and [Cu(dppz)(NO(3))(2)(H(2)O)].H(2)O (5.H(2)O) have been characterized by X-ray crystallography. The crystal structures show the presence of the heterocyclic base in the basal plane. The coordination geometries of the copper(II) centers are axially elongated square-pyramidal (4+1) in 2, 3 and 5, and octahedral (4+2) in 4. The nitrate anion in the coordination sphere displays unidentate and bidentate chelating bonding modes. The axial ligand is either H(2)O or NO(3) in these structures giving a Cu-L(ax) distance of approximately 2.4 A. The one-electron paramagnetic complexes (mu approximately 1.8 mu(B)) exhibit axial EPR spectra in DMF glass at 77 K giving g(parallel)>g( perpendicular ) with an A(parallel) value of approximately 170G indicating a [d(x)2(-y)2](1) ground state. The complexes are redox active and display a quasireversible cyclic voltammetric response for the Cu(II)/Cu(I) couple near 0.0 V vs. SCE giving an order of the E(1/2) values as 5(dppz)>2-4 (dpq)>[Cu(phen)(2)(H(2)O)](2+)>1 (phen). The complexes bind to calf thymus DNA giving an order 5 (dppz)>2 (dpq)>[Cu(phen)(2)(H(2)O)](2+)>1 (phen). An effect of the extended planar ring in dpq and dppz is observed in the DNA binding. The complexes show nuclease activity with pUC19 supercoiled DNA in DMF/Tris-HCl buffer containing NaCl in presence of mercaptopropanoic acid as a reducing agent. The extent of cleavage follows the order: [Cu(phen)(2)(H(2)O)](ClO(4))(2)>5>2 approximately 3 approximately 4>1. The bis-phen complex is a better cleaver of SC DNA than 1-5 having mono-heterocyclic base. Mechanistic investigations using distamycin reveal minor groove biding for the phen, dpq complexes, and a major groove binding for the dppz complex 5. The cleavage reactions are found to be inhibited in the presence of hydroxyl radical scavenger DMSO and the reactions are proposed to proceed via sugar hydrogen abstraction pathway. The ancillary ligand is found to have less effect in DNA binding but are of importance in DNA cleavage reactions.