Ana S. Abreu

Nanoliposomes for encapsulation and delivery of the potential antitumoral methyl 6-methoxy-3-(4-methoxyphenyl)-1H

A potential antitumoral fluorescent indole derivative, methyl 6-methoxy-3-(4-methoxyphenyl)-1H-indole-2-carboxylate, was evaluated for the in vitro cell growth inhibition on three human tumor cell lines, MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), and NCI-H460 (non-small cell lung cancer), after a continuous exposure of 48 h, exhibiting very low GI50 values for all the cell lines tested (0.25 to 0.33 μM). This compound was encapsulated in different nanosized liposome formulations, containing egg lecithin (Egg-PC), dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylglycerol (DPPG), DSPC, cholesterol, dihexadecyl phosphate, and DSPE-PEG. Dynamic light scattering measurements showed that nanoliposomes with the encapsulated compound are generally monodisperse and with hydrodynamic diameters lower than 120 nm, good stability and zeta potential values lower than -18 mV. Dialysis experiments allowed to monitor compound diffusion through the lipid membrane, from DPPC/DPPG donor liposomes to NBD-labelled lipid/DPPC/DPPG acceptor liposomes.

Antimicrobial nanostructured starch based films for packaging

Montmorillonite modified with a quaternary ammonium salt C30B/starch nanocomposite (C30B/ST-NC), silver nanoparticles/starch nanocomposite (Ag-NPs/ST-NC) and both silver nanoparticles/C30B/starch nanocomposites (Ag-NPs/C30B/ST-NC) films were produced. The nanoclay (C30B) was dispersed in a starch solution using an ultrasonic probe. Different concentrations of Ag-NPs (0.3, 0.5, 0.8 and 1.0mM) were synthesized directly in starch and in clay/starch solutions via chemical reduction method. Dispersion of C30B silicate layers and Ag-NPs in ST films characterized by X-ray and scanning electron microscopy showed that the presence of Ag-NPs enhanced clay dispersion. Color and opacity measurements, barrier properties (water vapor and oxygen permeabilities), dynamic mechanical analysis and contact angle were evaluated and related with the incorporation of C30B and Ag-NPs. Films presented antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans without significant differences between Ag-NPs concentrations. The migration of components from the nanostructured starch films, assessed by food contact tests, was minor and under the legal limits. These results indicated that the starch films incorporated with C30B and Ag-NPs have potential to be used as packaging nanostructured material.

Synthesis of new heteroaryl and heteroannulated indoles from dehydrophenylalanines: Antitumor evaluation

A 3-(dibenzothien-4-yl)indole and a phenylbenzothienoindole or a 3-(dibenzofur-4-yl)indole and a phenylbenzofuroindole were prepared by a metal-assisted C-N intramolecular cyclization of the methyl esters of N-Boc-(E) or (Z)-beta-dibenzothien-4-yl or beta-dibenzofur-4-yl dehydrophenylalanines. The latter were obtained by Suzuki cross-coupling of the methyl esters of N-Boc-(E) or (Z)-beta-bromodehydrophenylalanines with dibenzothien-4-yl or dibenzofur-4-yl boronic acids, in high yields. The intramolecular cyclization from E or Z pure Suzuki-coupling products gave the corresponding heteroaryl and heteroannulated indoles, in different ratios, by either direct cyclization or cyclization after isomerisation. Three of the cyclized compounds, the two heteroarylindoles and the phenylbenzothienoindole, were evaluated for their capacity to inhibit the in vitro growth of three human tumor cell lines, MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), and SF-268 (CNS cancer). The methyl 3-(dibenzothien-4-yl)indole-2-carboxylate was the most potent compound with GI(50) values ranging from 11 to 17microM.

Synthesis and intramolecular cyclization of novel β, β-bis-(benzo[b]thienyl)dehydroalanine derivatives

Abstract The methyl ester of tert -butyloxycarbonyl-β,β-dibromodehydroalanine was obtained in a one-pot procedure from bis-( N - tert -butyloxycarbonyl)dehydroalanine. The former was reacted with several boronic benzo[ b ]thiophene acids under Suzuki cross coupling conditions, to give new β,β-bis-(benzo[ b ]thienyl)dehydroalanines in high yields. These compounds were cyclized to pyrrole derivatives by treatment with Pd(OAc) 2 and Cu(OAc) 2 in DMF.

Nanoliposomes for encapsulation and delivery of the potential antitumoral methyl 6-methoxy-3-(4-methoxyphenyl)-1H-indole-2-carboxylate

A potential antitumoral fluorescent indole derivative, methyl 6-methoxy-3-(4-methoxyphenyl)-1H-indole-2-carboxylate, was evaluated for the in vitro cell growth inhibition on three human tumor cell lines, MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), and NCI-H460 (non-small cell lung cancer), after a continuous exposure of 48 h, exhibiting very low GI50 values for all the cell lines tested (0.25 to 0.33 μM). This compound was encapsulated in different nanosized liposome formulations, containing egg lecithin (Egg-PC), dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylglycerol (DPPG), DSPC, cholesterol, dihexadecyl phosphate, and DSPE-PEG. Dynamic light scattering measurements showed that nanoliposomes with the encapsulated compound are generally monodisperse and with hydrodynamic diameters lower than 120 nm, good stability and zeta potential values lower than -18 mV. Dialysis experiments allowed to monitor compound diffusion through the lipid membrane, from DPPC/DPPG donor liposomes to NBD-labelled lipid/DPPC/DPPG acceptor liposomes.

Synthesis Using Suzuki Cross Couplings of Sulfur Analogues of Dehydrotryptophan with a Definite Stereochemistry

Sulfur analogues of dehydrotryptophan (5−7) were prepared in moderate to good yields (40−80%) by Suzuki cross coupling [Pd(PPh3)4, Na2CO3 or NaHCO3, DME/H2O, 90 °C] of several benzo[b]thiophene boronic acids with the methyl esters of N-tert-butyloxycarbonyl-β-bromodehydroalanine [Boc-ΔAla(β-Br)-OMe] or N-tert-butyloxycarbonyl-β-bromodehydroaminobutyric acid [Boc-ΔAbu(β-Br)-OMe]. The β-bromodehydroamino acid precursors 2 were, in turn, synthesized in high yields from the corresponding N,N-diacyldehydroamino acids 1 by treatment with trifluoroacetic acid (TFA) and N-bromosuccinimide (NBS) in two steps or in a one-pot procedure. Both procedures were stereoselective for the E-isomer of Boc-ΔAla(β-Br)-OMe. However, for Boc-ΔAbu(β-Br)-OMe, different ratios of E/Z isomers were obtained in each procedure. The stereoselectivity for the Z-isomer was increased greatly with the one-pot procedure. Pure isomers were used in the coupling reactions and the stereochemistry of the starting material was generally maintained. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Ultrasound enhances lipase-catalyzed synthesis of poly (ethylene glutarate)

The present work explores the best conditions for the enzymatic synthesis of poly (ethylene glutarate) for the first time. The start-up materials are the liquids; diethyl glutarate and ethylene glycol diacetate, without the need of addition of extra solvent. The reactions are catalyzed by lipase B from Candida antarctica immobilized on glycidyl methacrylate-ter-divinylbenzene-ter-ethylene glycol dimethacrylate at 40°C during 18h in water bath with mechanical stirring or 1h in ultrasonic bath followed by 6h in vacuum in both the cases for evaporation of ethyl acetate. The application of ultrasound significantly intensified the polyesterification reaction with reduction of the processing time from 24h to 7h. The same degree of polymerization was obtained for the same enzyme loading in less time of reaction when using the ultrasound treatment. The degree of polymerization for long-term polyesterification was improved approximately 8-fold due to the presence of sonication during the reaction. The highest degree of polymerization achieved was 31, with a monomer conversion of 96.77%. The ultrasound treatment demonstrated to be an effective green approach to intensify the polyesterification reaction with enhanced initial kinetics and high degree of polymerization.

Functionalized protein nanoemulsions by incorporation of chemically modified BSA

The incorporation of bioactive compounds in stealth nanoparticles or nanoemulsions enhances their half-life in systemic circulation and can overcome the problems associated with the free drug. Bovine serum albumin (BSA)–drug conjugates were produced with either methotrexate (MTX), a potent anticancer agent, or vancomycin (VCM), a potent antibiotic. Those conjugates were used to produce functionalized BSA nanoemulsions in a formulation composed of an aqueous phase and an organic phase. BSA–folic acid (FA) conjugates were also produced allowing specific folate receptor (FR) mediated targeting of cancer cells (KB cell line). All conjugates had similar effects either in solution or in the form of nanoemulsions: BSA–MTX as an anti-proliferative over the Caco-2 cell line and BSA–VCM with a lower minimum inhibitory concentration (MIC) compared to VCM solution on the Staphylococcus aureus strain Newman. The production of nanoemulsions using BSA–drug conjugates for obtaining vectors loaded with stabilized drugs offers a good, flexible template for a wide range of medical applications.

Palladium-catalyzed borylation and Suzuki coupling (BSC) to obtain β-substituted dehydroamino acid derivatives

Several benzo[b]thienyldehydroamino acids were prepared by one-pot palladium-catalyzed borylation and Suzuki coupling (BSC) from bromobenzo[b]thiophenes containing EDG (OMe or Me), as the component to be borylated with pinacolborane, and pure stereoisomers of β-bromodehydroamino acid derivatives. To our knowledge it is the first time that the BSC reaction involves a non aromatic system.

Size controlled protein nanoemulsions for active targeting of folate receptor positive cells

Bovine serum albumin (BSA) nanoemulsions were produced by high pressure homogenization with a tri-block copolymer (Poloxamer 407), which presents a central hydrophobic chain of polyoxypropylene (PPO) and two identical lateral hydrophilic chains of polyethylene glycol (PEG). We observed a linear correlation between tri-block copolymer concentration and size - the use of 5mg/mL of Poloxamer 407 yields nanoemulsions smaller than 100nm. Molecular dynamics and fluorescent tagging of the tri-block copolymer highlight their mechanistic role on the size of emulsions. This novel method enables the fabrication of highly stable albumin emulsions in the nano-size range, highly desirable for controlled drug delivery. Folic Acid (FA)-tagged protein nanoemulsions were shown to promote specific folate receptor (FR)-mediated targeting in FR positive cells. The novel strategy presented here enables the construction of size controlled, functionalized protein-based nanoemulsions with excellent characteristics for active targeting in cancer therapy.