Antinociceptive effect of cyclic and linear diterpenoids as new atypical agonists of κ-opioid receptors obtained from four species of the Baccharis genus, and vehiculated in nanometric niosomes.

New natural analgesic compounds that act in KORs are important alternatives for potential therapeutical use in medicine. In this work, we report and compare here the antinociceptive activity displayed by cyclic and linear diterpenes, obtained from the genus Baccharis. The antinociceptive activities determined were relatively strong, in comparison whit morphine.

Preservation of the Antioxidant Capacity of Resveratrol via Encapsulation in Niosomes.

Resveratrol (RSV) is a natural polyphenol which produces several benefits to human health, being the isomer the most bioactive. However, its systemic absorption is limited due to its low water solubility, that reduces the oral bioavailability, and its chemical instability (owing to the - RSV isomer conversion upon light irradiation). Thus, encapsulation of this bioactive compound is required to protect it from destructive environmental conditions.

Recent Strategies in Resveratrol Delivery Systems.

Resveratrol, a natural polyphenolic stilbenoid widely found in grapes and wines, displays beneficial properties such as cardio-protective, antioxidant and anti-inflammatory activities. Trans-resveratrol (RSV) is the most bioactive and more abundant stereoisomer found in nature. Despite the positive properties of RSV, there are various factors that limit its effectiveness, including low aqueous solubility, low oral bioavailability and chemical instability.

Effect of drug molecular weight on niosomes size and encapsulation efficiency.

Encapsulation into nanocarriers, such as niosomes, is a promising way to protect them from degradation, and allow controll and target delivery of bioactive compounds. For biotechnological applications, a tight control of particle size with acceptable encapsulation efficiencies (EE) is a technological challenge, especially for hydrophilic compounds due to its capability to diffuse across biological barriers. Niosomes formulated with mixture of surfactants represent promising nanocarriers due to the advantages of non-ionic surfactants, such as low cost, versatility and enhanced physico-chemical properties.

Complex systems that incorporate cyclodextrins to get materials for some specific applications.

Cyclodextrins (CDs) are a family of biodegradable cyclic hydrocarbons composed of α-(1,4) linked glucopyranose subunits, the more common containing 6, 7 or 8 glucose units are named α, β and γ-cyclodextrins respectively. Since the discovery of CDs, they have attracted interest among scientists and the first studies were about the properties of the native compounds and in particular their use as catalysts of organic reactions. Characteristics features of different types of cyclodextrins stimulated investigation in different areas of research, due to its non-toxic and non-inmunogenic properties and also to the development of an improved industrial production.

Niosomes encapsulated in biohydrogels for tunable delivery of phytoalexin resveratrol.

A series of biohydrogels based on mixtures of kappa-carrageenan (κ-carrageenan, κ-C) and gelatin were evaluated as potential soft delivery vehicles for the encapsulation and subsequent release of non-ionic surfactant vesicles (niosomes) loaded with resveratrol (RSV). The niosomes were prepared using a mixture of amphiphilic lipids Tween 80 and Span 80 in water. The results showed that RSV-niosomes did not significantly affect the hydrogelation properties of the biopolymer mixture.

Cyclodextrin modified niosomes to encapsulate hydrophilic compounds.

Niosomes were prepared from equimolar mixtures of two non-ionic surfactants, Span 80 and Tween 80. The capability of the vesicular systems was studied through the encapsulation of two azo dyes as molecular probes of different hydrophobicity (methyl orange (MO) and methyl yellow (MY)). To improve the efficiency of the niosomes to encapsulate the dyes, we employed an additional modification of the vesicular system, adding β-cyclodextrin (β-CD) or a modified amphiphilic β-CD (Mod-β-CD) to the niosomes.

Synergism in the desorption of polycyclic aromatic hydrocarbons from soil models by mixed surfactant solutions.

This study investigates the effect of a mixed surfactant system on the desorption of polycyclic aromatic hydrocarbons (PAHs) from soil model systems. The interaction of a non-ionic surfactant, Tween 80, and an anionic one, sodium laurate, forming mixed micelles, produces several beneficial effects, including reduction of adsorption onto solid of the non-ionic surfactant, decrease in the precipitation of the fatty acid salt, and synergism to solubilize PAHs from solids compared with individual surfactants.

Supramolecular assemblies obtained by mixing different cyclodextrins and AOT or BHDC reverse micelles.

In this contribution we show the effect of the surfactant polar head and the external solvent on the incorporation of different cyclodextrins (CDs) {α-CD, β-CD, γ-CD, decenylsuccinyl-β-CD (Mod-β-CD), and hydroxypropyl-β-CD (hp-β-CD)} in different reverse micelles (RMs) {benzene/sodium 1,4-bis(2-ethylhexyl) sulfosuccinate(AOT)/water, and benzene/benzyl-n-hexadecyldimethylammonium chloride (BHDC)/water} and compare them with previous results obtained in n-heptane/AOT/water RMs. To investigate the different systems, we have used UV-vis spectrophotometry, induced circular dichroism spectroscopy (ICD), and the achiral molecular probe methyl orange (MO). The results show dramatic differences changing the external solvent and the surfactant, which are explained by considering the differences in the RMs interface composition, the water-surfactant interaction, and the CDs' location in the different media investigated.

Characterization of the hydrochlorothiazide: β-cyclodextrin inclusion complex. Experimental and theoretical methods.

Hydrochlorothiazide (HCT) is one of the most commonly prescribed antihypertensive drugs. In an attempt to gain an insight into the physicochemical and molecular aspects controlling the complex architecture of native β-cyclodextrin (β-CD) with HCT, we performed multiple-temperature-pH isothermal titration calorimetric measurements of the HCT:β-CD system, together with proton nuclear magnetic resonance spectroscopy ((1)H NMR), phase solubility analysis, and molecular modeling methods. The A(L)-type diagrams, obtained at different pH values and temperatures, suggested the formation of soluble 1:1 inclusion complexes of β-CD with HCT.

Inhibited phenol ionization in reverse micelles: confinement effect at the nanometer scale.

We found that the absorption spectra of 2-acetylphenol (2-HAP), 4-acetylphenol (4-HAP), and p-nitrophenol (p-NPh) in water/sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane reverse micelles (RMs) at various W(0) (W(0) = [H(2)O]/[surfactant]) values studied changed with time if (-)OH ions were present in the RM water pool. There is an evolution of ionized phenol (phenolate) bands to nonionized phenol absorption bands with time and this process is faster at low W(0) values and with phenols with higher bulk water pK(a) values. That is, in bulk water and at the hydroxide anion concentration used, only phenolate species are observed, whereas in AOT RMs at this fixed hydroxide anion concentration, ionized phenols convert into nonionized phenol species over time.

Different behaviours in the solubilization of polycyclic aromatic hydrocarbons in water induced by mixed surfactant solutions.

Water solubility of polycyclic aromatic hydrocarbons (PAHs), viz, naphthalene and phenanthrene, in micellar solutions at 25°C was investigated, using two series of different binary mixtures of anionic and nonionic surfactants. Tween 80 and Brij-35 were used as nonionic surfactants whereas fatty acids or amphiphilic cyclodextrins (Mod-β-CD) synthesized in our laboratory were used as anionic ones. Solubilization capacity has been quantified in terms of the molar solubilization ratio and the micelle-water partition coefficient, using UV-visible spectrophotometry.

Aggregation behavior of Brij-35/perfluorononanoic acid mixtures.

The mixed system of a nonionic hydrocarbon surfactant, polyoxyethylene (23) lauryl ether (Brij-35), and a perfluorinated surfactant, perfluorononanoic acid, was investigated by a combination of methods. The critical micelle concentrations (cmc's) have been determined over a wide range of sample compositions by fluorescence and UV-visible spectrophotometry using pyrene and N-(4-nitrophenyl) perfluorononanamide, respectively, as molecular probes. The values of the cmc's obtained were considerably different with the two techniques employed.

Investigation of the inclusion of the herbicide metobromuron in native cyclodextrins by powder X-ray diffraction and isothermal titration calorimetry.

We report the formation of inclusion complexes between the phenylurea herbicide metobromuron [3-(p-bromophenyl)-1-methoxy-1-methylurea] and beta- and gamma-cyclodextrin in the solid state. Formation of crystalline inclusion complexes by the kneading method was confirmed by powder X-ray diffraction and further structural characterization using the principles of isostructurality followed. In addition, DeltaH degrees , DeltaS degrees , DeltaG degrees and the association constants (K) at 298K were determined for complex formation in solution using isothermal titration calorimetry.

Synthesis and characterization of an amphiphilic cyclodextrin, a micelle with two recognition sites.

A cyclodextrin derivative (Mod-CD) was synthesized through the monoesterification of beta-cyclodextrin (beta-CD) with 3-((E)-dec-2-enyl)-dihydrofuran-2,5-dione. The compound is an interesting surfactant that can form large aggregates not only through the interaction of the hydrophobic tails as in common amphiphilic compounds but also through the inclusion of the alkenyl chain into the cavity of another Mod-CD molecule. The self-inclusion of the chain in the cavity of cyclodextrin as well as the intermolecular inclusion was demonstrated by 1H NMR measurements that were able to detect methyl groups in three different environments.

On the possibility that cyclodextrins' chiral cavities can be available on AOT n-heptane reverse micelles. A UV-visible and induced circular dichroism study.

The formation of reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) in n-heptane including two different beta-cyclodextrin (beta-CD) derivatives (hydroxypropyl-beta-CD, hp-beta-CD, and decenyl succinyl-beta-CD, Mod-beta-CD) is reported. Both cyclodextrins can be incorporated into AOT RMs in different zones within the aggregate, while beta-CD cannot. Using UV-vis and induced circular dichroism (ICD) spectroscopy and different achiral molecular probes (some azo dyes, p-nitroaniline and ferrocene), it was possible to determine that Mod-beta-CD is located with its cavity at the oil side of the AOT RM interface, while for hp-beta-CD the cavity is inside the RM water pool.

Competition between aggregation and hydrolysis in the reaction of arylperfluorooctanoates in micellar solutions.

The rate of hydrolysis of phenyl and p-nitrophenyl perfluorooctanoate (2a and 2b) was measured in water and in the presence of different cationic (dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, cetyltrimethylammonium bromide), anionic (sodium dodecyl sulfate (SDS) and perfluorooctanoate (PFO)) and neutral (Brij-35) surfactants. In water solution, the formation of phenol from 2a and p-nitro phenol from 2b takes place through two kinetic processes, both of which are much slower than the expected rate of hydrolysis for the monomeric compounds in water. The two kinetic processes are attributed to a coupling of the rates of hydrolysis and aggregation of the substrates.

Changing mechanisms in the beta-cyclodextrin-mediated hydrolysis of phenyl esters of perfluoroalkanoic acids.

The rate of hydrolysis of esters CF(3)(CF(2))(n)COOPh (1 (n = 1), 2 (n = 2), and 3 (n = 6)) was measured at pH 6.00 and at pH higher than 9.00 in the presence of beta-cyclodextrin (beta-CD).