The use of Maytenus ilicifolia to prevent cisplatin-induced ototoxicity.

UNLABELLED: Maytenus ilicifolia is a native plant from South America, with several medicinal properties including antioxidant effects. AIM: using an original cisplatin induced ototoxicity model, we evaluated a possible otoprotection caused by Maytenus ilicifolia extract. MATERIALS AND METHODS: clinical and experimental study design with female albino guinea pigs divided in groups as follows: 9 animals receiving cisplatin only (three doses of 7.5mg/kg/day), 4 animals receiving the plant extract only, 10 animals receiving the cisplatin protocol and 1g/kg/day of extract for 8 days, 5 animals with cisplatin and 3g/kg/day of extract for 8 days, and 5 animals receiving extract for 3 weeks and cisplatin in the last week. The tests were distortion product otoacoustic emissions, brainstem auditory response, before and after medication and scanning electron microscopy. RESULTS: the animals receiving cisplatin plus plant extract, had alterations in all the tests, showing lesions on the basal cochlear region under electron microscopy. CONCLUSIONS: Despite of the plant extract's antioxidant effect, it was not sufficient to protect the cochlea against cisplatin ototoxicity.

O uso de Maytenus ilicifolia na prevenção da ototoxicidade induzida pela cisplatina / The use of Maytenus ilicifolia to prevent cisplatin-induced ototoxicity

Maytenus ilicifolia é uma planta sul americana apresenta várias propriedades medicinais, entre elas, a ação antioxidante. OBJETIVO: Por meio de um modelo original de ototoxicidade induzida pela cisplatina, verificar uma possível ação otoprotetora do extrato aquoso desta planta. MATERIAL E MÉTODO: Estudo clínico e experimental com cobaias fêmeas, albinas divididas em 5 grupos: 9 animais recebendo somente 3 doses de 7,5mg/kg/d do protocolo de cisplatina, 4 animais somente com o extrato, 10 animais com cisplatina e 1g/kg/d de extrato por 8 dias, 5 animais com cisplatina e 3g/kg/d do extrato por 8 dias e 5 animais recebendo extrato por 3 semanas e cisplatina na última semana. Os exames foram emissões otoacústica por produtos de distorção, potencial de tronco encefálico pré e após administração de cisplatina e, microscopia eletrônica de varredura. RESULTADOS: Os animais que receberam a cisplatina com o extrato, independente da dose, obtiveram alterações em todos os testes, com lesões na região basal na microscopia eletrônica. CONCLUSÃO: Apesar do efeito antioxidante da Maytenus ilicifolia, ela não foi suficiente para bloquear o efeito ototóxico da cisplatina.

Maytenus ilicifolia is a native plant from South America, with several medicinal properties including antioxidant effects. AIM: using an original cisplatin induced ototoxicity model, we evaluated a possible otoprotection caused by Maytenus ilicifolia extract. MATERIALS AND METHODS: clinical and experimental study design with female albino guinea pigs divided in groups as follows: 9 animals receiving cisplatin only (three doses of 7.5mg/kg/day), 4 animals receiving the plant extract only, 10 animals receiving the cisplatin protocol and 1g/kg/day of extract for 8 days, 5 animals with cisplatin and 3g/kg/day of extract for 8 days, and 5 animals receiving extract for 3 weeks and cisplatin in the last week. The tests were distortion product otoacoustic emissions, brainstem auditory response, before and after medication and scanning electron microscopy. RESULTS: the animals receiving cisplatin plus plant extract, had alterations in all the tests, showing lesions on the basal cochlear region under electron microscopy. CONCLUSIONS: Despite of the plant extract's antioxidant effect, it was not sufficient to protect the cochlea against cisplatin ototoxicity.

Multistep adsorption of anionic dyes on silica/chitosan hybrid. 1. Comparative kinetic data from liquid- and solid-phase models.

In this work, a hybrid silica/chitosan was synthesized and characterized by nitrogen elemental analysis and thermal analysis (TG, DTG, DTA, and DSC) and BET surface area. The hybrid was used in adsorption studies of two anionic dyes from aqueous solutions. A rise of temperature accelerates mass transfer of dyes into the hybrid. However, the maximum adsorption capacities reach similar values from 25 to 55 degrees C. The kinetic data were first evaluated in relation to the decrease of the time-related residual concentration of the dyes in solution, where the second-order model has presented the best fitting. The solid-phase interaction of dye data presents a rough fitting to the traditional first-order Lagergren kinetic model. However, a modified Avrami kinetic equation was successfully fitted to the kinetic quantities, where from five to seven kinetic regions were found. A pore-diffusion model has also demonstrated that the diffusion is the rate-controlling interaction mechanism. However, the experimental-calculated comparative values are the best way to evaluate a specific aqueous- or solid-phase kinetic model.

Kinetics and equilibrium parameters of Hg(II) adsorption on silica-dithizone.

Sílica-dithizone (Sil-dtz) was synthesized and used to adsorb Hg(II) in solution at pH 6.0. Increasing the temperature accelerates the mass transfer of Hg(II) to the silica surface. The kinetic data were evaluated using the traditional pseudo-first-order Lagergren equation and an alternative Avrami kinetic equation. From the latter equation, two regions presenting distinct kinetic parameters were found, at 25 and 35 degrees C, and the use of the parameter n was also related to the determination of distinct kinetic orders. Variations of the adsorption kinetic rate in relation to the time and the temperature were also calculated and are discussed. The adsorption isotherms data were well fitted to the Freundlich model. Interestingly, good adsorption data correlation of the Langmuir model and experimental values was observed only at 45 and 50 degrees C, suggesting, for this temperature range, the formation of complexes with the proportion Hg:dithizone 1:1 on the silica surface.

An alternative Avrami equation to evaluate kinetic parameters of the interaction of Hg(II) with thin chitosan membranes.

In this work, thin chitosan membranes were utilized as an adsorbent for the removal of Hg(II) from aqueous solutions. A rise of temperature accelerates the mass transfer of Hg(II) to the membranes, surfaces. The kinetic data did not present a good fitting to the traditional Lagergren adsorption kinetic equations. An alternative Avrami kinetic equation was employed and successfully fitted to the kinetic adsorption quantities. From this new equation, two regions presenting distinct kinectic parameters were found, and the use of the parameter n was also relationed to the determination of the kinetic order. Variations of the adsorption kinetic rate in relation to the time, the initial Hg(II) concentration, and the temperature were also calculated and are discussed.