Self-assembled squalenoyl-cytarabine nanostructures as a potent nanomedicine for treatment of leukemic diseases.

Background: In this investigation, the antileukemic activity of a new nanomedicine based on the conjugation of 1,1',2-tris-nor-squalenic acid with cytarabine (Ara-C) was evaluated.

Methods: Squalenoyl-Ara-C conjugate (Sq-Ara-C) self-assembled nanosystems were obtained by the nanoprecipitation method and characterized in vitro and in vivo.

Results: This new nanomedicine, which had a mean diameter of approximately 150 nm, improved the in vitro antitumoral activity of Ara-C in different cancer cell lines (L1210, K562, and MCF-7).

Synthesis of n-squalenoyl cytarabine and evaluation of its affinity with phospholipid bilayers and monolayers.

Cytarabine (1-β-D-arabinofuranosylcytosine, Ara-C), a pyrimidine nucleoside analogue, is an attractive therapeutic agent for the treatment of both acute and chronic myeloblastic leukemias. 1,1',2-tris-nor-Squalene acid (squaleneCOOH) has been conjugated to cytarabine with the formation of the squalenoyl-cytarabine prodrug, in order to improve the drug lipophilicity and, consequently, the affinity towards the environment of biological membranes, as well as of lipophilic carriers. The interaction of cytarabine and its prodrug with dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles and monolayers has been studied by the differential scanning calorimetry and the Langmuir-Blodgett techniques.

Interaction of acyclovir and its squalenoyl-acyclovir prodrug with DMPC in monolayers at the air/water interface.

Acyclovir has been conjugated to the acyclic isoprenoid chain of squalene to form the squalenoyl-acyclovir prodrug. Its interaction with biomembrane models constituted by dimyristoylphosphatidylcholine (DMPC) monolayers has been studied by employing the Langmuir-Blodgett technique. The aim of the work was to gain information on the interaction of these compounds with phospholipid membranes.

Conjugation of squalene to acyclovir improves the affinity for biomembrane models.

Differential scanning calorimetry was used to study the interaction of acyclovir and its prodrug squalenoyl-acyclovir (obtained by conjugation of 1,1',2-tris-nor-squalene acid (squaleneCOOH) with acyclovir) with biomembrane models made of DMPC multilamellar vesicles with the aim to verify whether a stronger interaction of the prodrug with respect to the free drug can be obtained. Multilamellar vesicles were prepared in the presence of increasing molar fractions of acyclovir, squaleneCOOH or prodrug and the effect of the compounds on the thermotropic behavior of vesicles was researched, revealing no effect of acyclovir but a strong effect of squaleneCOOH and prodrug. To evaluate if acyclovir, squaleneCOOH and prodrug can be absorbed by the biomembrane model, an experiment was carried out in which the considered compounds were left in contact with the biomembrane model and their eventual uptake was evaluated analyzing the effect on the thermotropic behavior of the biomembrane model.

Antifungal activity of bis-azasqualenes, inhibitors of oxidosqualene cyclase.

The antifungal activity and in vitro toxicity toward animal cells of two inhibitors of oxidosqualene cyclase, squalene bis-diethylamine (SBD) and squalene bis-diethylmethylammonium iodide (SBDI) were studied. Minimum inhibitory concentration (MIC) against dermatophytes and other fungi involved in cutaneous and systemic infections (12 isolates from seven species) were determined by the broth microdilution method based on the reference documents M38-A and M27-A2 of Clinical and Laboratory Standards Institute (CLSI). Both compounds exerted fungistatic activities, although with different action.

Interaction of lipophilic gemcitabine prodrugs with biomembrane models studied by Langmuir-Blodgett technique.

The stability and bioavailability of anticancer agents, such as gemcitabine, can be increased by forming prodrugs. Gemcitabine is rapidly deaminated to the inactive metabolite (2('),2(')-difluorodeoxyuridine), thus to improve its stability a series of increasingly lipophilic gemcitabine prodrugs linked through the 4-amino group to valeroyl, lauroyl, and stearoyl acyl chains were synthesized. Studies of monolayer properties are important to improve understanding of biological phenomena involving lipid/gemcitabine or lipid/gemcitabine derivative interactions.

Characterization of lipophilic gemcitabine prodrug-liposomal membrane interaction by differential scanning calorimetry.

Gemcitabine is an anticancer agent rapidly deaminated to the inactive metabolite 2',2'-difluorodeoxyuridine. Its stability as well as bioavailability can be increased by making prodrugs. A series of lipophilic prodrugs of gemcitabine were synthesized by linking the 4-amino group with valeroyl, lauroyl, and stearoyl linear acyl derivatives.

Analogs of squalene and oxidosqualene inhibit oxidosqualene cyclase of Trypanosoma cruzi expressed in Saccharomyces cerevisiae.

Recently, a number of inhibitors of the enzyme oxidosqualene cyclase (OSC; EC 5.4.99.

Synthesis and biological activity of new iodoacetamide derivatives on mutants of squalene-hopene cyclase.

New iodoacetamide derivatives, containing a dodecyl or a squalenyl moiety, were synthesized. The effect of these new thiol-reacting molecules was studied on two mutants of Alicyclobacillus acidocaldarius squalene-hopene cyclase constructed especially for this purpose. In the quintuple mutant, all five cysteine residues of the enzyme are substituted with serine; in the sextuple mutant, this quintuple substitution is accompanied by the substitution of aspartate D376, located at the enzyme's active site, with a cysteine.

Structure and reactivity of the dammarenyl cation: configurational transmission in triterpene synthesis.

[reaction: see text] The dammarenyl cation (13) is the last common intermediate in the cyclization of oxidosqualene to a diverse array of secondary triterpene metabolites in plants. We studied the structure and reactivity of 13 to understand the factors governing the regio- and stereospecificity of triterpene synthesis. First, we demonstrated that 13 has a 17beta side chain in Arabidopsis thaliana lupeol synthase (LUP1) by incubating the substrate analogue (18E)-22,23-dihydro-20-oxaoxidosqualene (21) with LUP1 from a recombinant yeast strain devoid of other cyclases and showing that the sole product of 21 was 3beta-hydroxy-22,23,24,25,26,27-hexanor-17beta-dammaran-20-one.

1,5-Benzodiazepines XIV. Synthesis of new substituted 9H-bis-[1,2,4]triazolo[4,3-a:3',4'-d] [1,5]benzodiazepines and relate compounds endowed with in vitro cytotoxic properties.

A series of 11 new 9H-bis-[1,2,4]triazolo[4,3-a:3',4'-d] [1,5]benzodiazepine derivatives 8e-o was synthesized. Ten of these compounds (8e-m,o), along with four analogues (8a-d) (previously synthesized by us) were tested in vitro in order to evaluate their cytotoxic and anti-HIV-1 properties. In this connection other six original compounds, i.

Preparation, characterization, cytotoxicity and pharmacokinetics of liposomes containing lipophilic gemcitabine prodrugs.

Gemcitabine is a known anticancer agent rapidly deaminated to the inactive metabolite 2',2'-difluorodeoxyuridine; it must therefore be administered at very high dose. Many different approaches have been tried to improve the metabolic stability; we synthesized a series of increasingly lipophilic prodrugs of gemcitabine by linking the 4-amino group with valeroyl, heptanoyl, lauroyl and stearoyl linear acyl derivatives. We studied their stability at storage, in plasma and with the lysosomal intracellular enzyme cathepsins.

Synthesis, characterization and transfection activity of new saturated and unsaturated cationic lipids.

We synthesized new cationic lipids, analogue to N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) and 1,2-dimyristyloxypropyl-3-dimethyl-hydroxyethylammonium bromide (DMRIE), in order to compare those containing a dodecyl chain with those having a relatively long chain with two or five double bonds, such as squalenyl and dihydrofarnesyl derivatives, or complex saturated structures, such as squalane derivatives. The fusogenic helper lipid dioleoylphosphatidylethanolamine (DOPE) was added to cationic lipids to form a stable complex. Liposomes composed of 50:50 w/w cationic lipid/DOPE were prepared and incubated with plasmidic DNA at various charge ratios and the diameter and zeta potential of the complexes were measured.

From conventional to stealth liposomes: a new frontier in cancer chemotherapy.

Many attempts have been made to achieve good selectivity to targeted tumor cells by preparing specialized carrier agents that are therapeutically profitable for anticancer therapy. Among these, liposomes are the most studied colloidal particles thus far applied in medicine and in particular in antitumor therapy. Although they were first described in the 1960s, only at the beginning of 1990s did the first therapeutic liposomes appear on the market.

Conjugated methyl sulfide and phenyl sulfide derivatives of oxidosqualene as inhibitors of oxidosqualene and squalene-hopene cyclases.

Various (1E,3E)- and (1Z,3E)-conjugated methylthio derivatives of oxidosqualene (OS) and conjugated and non-conjugated phenylthio derivatives of OS were obtained. These compounds, designed as inhibitors of pig liver and Saccharomyces cerevisiae 2,3-oxidosqualene-lanosterol cyclases (OSC) (EC 5.4.

Novel poly(ethylene glycol) derivatives for preparation of ribosome-inactivating protein conjugates.

This study describes the synthesis, characterization, and reactivity of new methoxypoly(ethylene glycol) (mPEG) derivatives containing a thioimidoester reactive group. These activated polymers are able to react with the lysyl epsilon-amino groups of suitable proteins, generating an amidinated linkage and thereby preserving the protein's positive charge. mPEG derivatives of molecular weight 2000 and 5000 Da were used, and two spacer arms were prepared, introducing chains of different lengths between the hydroxyl group of the polymer and the thioimidate group.