Complexation between oleanolic and maslinic acids with native and modified cyclodextrins

Oleanolic (OA) and maslinic (MA) acids are two natural triterpenoids with a wide range of beneficial effects for human health. However, their low solubility and permeability make their application in the food or pharmaceutical industry difficult. The complexation of OA and MA with alpha- beta-, gamma-, HP-alpha-, HP-beta- and HP-gamma-CDs under different pH and temperature conditions has been studied. Neither alpha- nor HP-alpha-CDs formed inclusion complexes, while beta-, HP-beta- and HP-gamma-CDs provided AL type and gamma-CDs BS phase solubility diagrams. Complexation was shown to be more stable in the case of MA but complexation efficiency was greater for OA. Increasing the pH and temperature of the complexation media tended to improve the complexation process with triterpenic acids.Project PFEseneca/06/10Ciencias de la Alimentació

Complexation of resveratrol by native and modified cyclodextrins: Determination of complexation constant by enzymatic, solubility and fluorimetric assays

The complexation of resveratrol with native a-, b- and c-cyclodextrins (CDs) and modified CDs (hydroxypropyl-b-(HP-b-CDs), maltosyl-b-(G2-b-CDs), methyl-b-, carboxymethyl-b- and acetyl-b-cyclodextrins) was studied, and the complexation constants (Kc) were compared. The complexation constant between resveratrol and each type of CD was calculated using three different methods: enzymatic, solubility and fluorimetric. The Kc values obtained showed that HP-b-CDs with their very high Kc of 18,048 ± 625 M 1, were the most effective for complexing resveratrol. Moreover, comparison of the results obtained by the three methods revealed that the fluorimetric method undervalued the Kc between resveratrol and all cyclodextrins, while the enzymatic and solubility methods were more precise for calculating the Kc between resveratrol and CDs, as demonstrated by the cyclodextrin-assay.This work was partially supported by Fundación Séneca (03025/PPC/05) and Ministerio de Educación y Ciencia (AGL2006-08702/ALI). C.L.A. is a holder of a research grant from the Programa Nacional de Formación de Personal Investigador (FPI), Ministerio de Educación y Ciencia (Spain) (BES-2007-16082).Ciencias de la Alimentació

Kinetic characterisation and thermal inactivation study of polyphenol oxidase and peroxidase from table grape (Crimson Seedless)

Polyphenol oxidase (PPO) and peroxidase (POD) were extracted from a table grape (Crimson Seedless) using Triton X-114 and characterized using spectrophotometric methods. Both PPO and POD were activated by acid shock. However, in the presence of the anionic detergent sodium dodecil sulphate (SDS), PPO was activated whereas POD was inactivated. The enzymes were kinetically characterized and both followed Michaelis–Menten kinetics, although with different values of their kinetic parameters. The Vm/Km ratio showed that Crimson Seedless grape PPO presents a similar affinity for 4-tert-butyl-catechol (TBC) whether activated by acid shock (0.018 min1 ) or SDS (0.023 min1 ). With regards to POD, the Km and Vm values for 2,20 -azinobis(3-ethylbenzothiazolinesulphonic acid) (ABTS) were 0.79 mM and 1.20 lM/min, respectively. In the case of H2O2, the Km and Vm value were 0.4 mM and 0.93 lM/min, respectively. PPO and POD showed similar thermostability, losing >90% of relative activity after only 5 min of incubation at 78 C and 75 C, respectively. In addition, PPO´ s activation energy was similar to that obtained for POD (295.5 kJ/mol and 271.9 kJ/mol, respectively).Ciencias de la Alimentació

Effect of HP-b-cyclodextrins complexation on the antioxidant activity of flavonols

The beneficial effects from phenolic compounds have been attributed to their antioxidant activity. Differences in the chemical structure of flavonols and their degree of substitution will influence phenoxyl radical stability and, thereby, their antioxidant properties. Cyclodextrins (CDs) can be used as a flavonol complexation agent, since they act as a substrate reservoir in a dose-controlled manner. In the present paper, the effect of complexing flavonols, kaempferol, quercetin and myricetin with HP-b-CDs on their antioxidant capacity is studied by means of the oxygen radical absorbance capacity-fluorescein (ORAC-FL) assay. This complexation phenomenon increased the antioxidant activity of the three flavonols, which reached a maximum level when each flavonol had been complexed in the hydrophobic cavity of CDs. The antioxidant activity increased because of the flavonol was protected against rapid oxidation by free radicals.Ciencias de la Alimentació

Comparative study of different methods to measure antioxidant activity of resveratrol in the presence of cyclodextrins

The antioxidant activity of resveratrol in the absence and presence of increasing concentrations of HPb- CDs was determined using three different methods: ORAC, ABTS and DPPH. The three methods were validated and compared for their linearity, precision and accuracy in measuring resveratrol antioxidant activity. The results indicated that the most sensitive method is the ORAC assay, which can measure the lowest resveratrol concentration (0.15–2 lM) with the highest precision. In the presence of increasing concentrations of HP-b-CDs, the antioxidant activity of resveratrol was seen to increase when it was measured by the ORAC and ABTS assays. However, no increase was observed when the DPPH assay was used. With the ORAC assay, the antioxidant activity increased until all the resveratrol had been included in HP-b-CDs (0.4 mM CDs), whereas in the case of ABTS assay the plateau in antioxidant activity was reached after 2 mM HP-b-CDs, suggesting that the CDs interferences in the measurement method. When the DPPH assay was used, no effect was observed when increasing concentrations of HP-b-CDs, indicating that in a methanolic medium resveratrol is free. Therefore, so this method cannot be used to measure the effect of resveratrol complexation with CDs on its antioxidant activity.Ciencias de la Alimentació

Effect of ripening on protein content and enzymatic activity of Crimson Seedless table grape

The evolution of Brix, protein content, polyphenoloxidase activity and peroxidase activity during the ripening of Crimson Seedless table grape was studied in three consecutive years (2006, 2007 and 2008). The total protein content was determined according to Bradford’s dye binding method, and polyphenoloxidase (PPO) and peroxidase (POD) were extracted using Triton X-114 and characterised using spectrophotometric methods. The year had a statistically significant effect on all the studied parameters and there was an interannual correlation in the evolution of protein, PPO, POD and Brix. All the studied parameters were statistically correlated, except POD activity with protein content. Weather conditions during the ripening period had a greater effect on protein content than PPO and POD activity.Ciencias de la Alimentació

Adsorption of Direct Blue 78 using chitosan and cyclodextrins as adsorbents

The dyeing industry is one of the most polluting in the world. The adsorption of dyes by polymeric matrixes can be used to minimize the discharge of dyes into the environment. In the present study, chitosan-NaOH and β-cyclodextrin-epichlorohydrin polymers were used to remove the dye Direct Blue 78 from a wastewater model. To understand the adsorption behavior of Direct Blue 78 onto the polymers, adsorption rate and maximum adsorption capacity were calculated using kinetic tests and isotherm curves respectively. The kinetic data and mechanism of the adsorption process were analyzed by three models and the equilibrium data by three adsorption isotherms; also the different thermodynamic parameters were calculated. Results showed that the adsorption process follows pseudo-second-order kinetics in both polymers and the Langmuir isotherm best-fitted data for chitosan-NaOH polymer and the Freundlich isotherm for the β-CDs-EPI polymer. The adsorption process is exothermic in both cases and spontaneous for the β-CDs-EPI polymer to a certain temperature and not spontaneous for the chitosan-NaOH polymer and β-CDs-EPI polymer at higher temperatures. The complementary action of an advanced oxidation process eliminated >99% of the dye from water. The coupled process seems to be suitable for reducing the environmental impact of the dyeing industry.Ciencias de la Alimentació

Optimization of a method for preparing solid complexes of essential clove oil with beta-cyclodextrins

BACKGROUND Clove oil (CO) is and aromatic oily liquid used in food, cosmetic and pharmaceutical industries due to their functional properties. However its disadvantages as pungent taste, volatility, light sensitivity and poor water solubility can be solved by applying microencapsulation or complexation techniques. RESULTS Essential CO was successfully solubilized in aqueous solution by forming inclusion complexes with -cyclodextrins (beta-CDs). Moreover, phase solubility studies demonstrated that essential CO also forms insoluble complexes with beta-CDs. Based on these results, essential CO-beta-CD solid complexes were prepared by the novel approach of microwave irradiation (MWI) followed by three different drying methods: vacuum oven drying (VO), freeze drying (FD) or spray drying (SD). Quantification of the solid complexes formed pointed to the treatment not involving heat, FD, as the best drying method, followed by VO and SD, which led to significantly lower amounts of encapsulated essential CO. CONCLUSION. MWI can be used efficiently to prepare essential CO-beta-CDs complexes with good yields on an industrial scale.Ciencias de la Alimentació

Stability of microencapsulated strawberry flavour by spray drying, freeze drying and fluid bed

The main goal of this paper was to study the stability of a microencapsulated strawberry flavour using different encapsulating agents and drying techniques: spray drying, freeze drying and fluid bed. According to the quantification of volatile compounds, the blend MDs/Hi-Cap (9/1) at a fixed concentration of CDs (1.7%) was the most appropriate for microencapsulating the strawberry flavour. The best drying yield was observed in the case of freeze drying. In the case of the moisture content, spray drying samples presented the lowest values, followed by freeze drying and fluid bed. The study of stability at different temperatures and times revealed that the presence of CDs in the blend enabled a higher presence of volatile compounds in the powder than in its absence. Microphotographs showed smooth spherical particles in the case of spray drying, whereas the structure of the powder was amorphous, like glass, with freeze drying and irregular in the case of fluid bed.Ciencias de la Alimentació

Development of lateral flow immunoassay for rapid detection of oxytetracycline in honey samples

[EN] A lateral flow immunoassay (LFIA) was developed in the competitive reaction format and applied to test residues of the antimicrobial oxyteracycline (OTC) in honey samples. To prepare the assay test, a nitrocellulose membrane was stripped with hapten OTC3 conjugate to ovoalbumin egg protein (OVA-OTC3) and goat anti-rabbit antisera (GAR) as capture and control reagents, respectively. Polyclonal antisera against oxyteracycline was conjugated to colloidal gold nanoparticles and used as the detection reagent. The visual detection limit (cut-off value) of the oxyteracycline LFIA was 20 ng/g, and qualitative results were obtained within 10 min without expensive equipment. The assay was evaluated with OTC spiked honey samples from different geographical origin (n = 25). The results were in good agreement with those obtained from liquid chromatography separation and mass spectroscopy detection (LC-MS), indicating that the LFIA test might be used as a semiquantitative method for the determination of oxyteracycline. The system was also highly specific, showing no cross-reactivity to other chemically similar antibiotics.This work was supported by a grant from Ministry of Education and Science of Spain. CIT-060000-2007-57.Guillen Guille, I.; Martínez Sanmartín, Á.; Gabaldón Hernández, JA.; Núñez Delicado, E.; Puchades Pla, R.; Maquieira Catala, Á. (2011). Development of lateral flow immunoassay for rapid detection of oxytetracycline in honey samples. Food and Environment Safety. X(1):5-12. http://hdl.handle.net/10251/78761S512X