Ascorbic acid in the prevention and treatment of cancer / Ácido ascórbico na prevenção e no tratamento do câncer

Summary This review is aimed at the systematic mapping of ascorbic acid in the prevention and/or treatment of cancer in clinical and non-clinical studies from 2011 to 2015, in order to understand dose-response variations as well as its mechanisms of action as an antioxidant and antitumor agent. Seventy-eight articles were retrieved from the PubMed/Bireme database, of which only 30 included ascorbic acid in the prevention and/or treatment of cancer. However, there are controversies regarding doses and a lack of clinical studies featuring its mechanism of action more clearly. Other studies are needed to understand dose-response variations, as well as its targeting mechanisms of action, both as an antioxidant and antitumor agent, to assist treatment and prevention of cancer, aiming at better quality of life for both patients and the general population.

Resumo Este estudo de revisão teve como objetivo fazer o mapeamento sistemático do ácido ascórbico na prevenção e/ou no tratamento do câncer como antioxidante e/ou pró-oxidante em estudos clínicos e não clínicos, entre 2011 e 2015, para o entendimento das variações de dose-resposta, bem como dos seus mecanismos de ação como agente antioxidante e antitumoral. Nas bases de dados Pubmed e Bireme, foram identificados 78 artigos, dos quais apenas 30 apontavam o ácido ascórbico na prevenção e/ou no tratamento do câncer. Contudo, há controvérsias sobre as doses utilizadas e faltam estudos clínicos que caracterizem melhor o seu mecanismo de ação. Outros estudos devem ser realizados para o entendimento das variações de dose-resposta, bem como de seus mecanismos de ação, como agente antioxidante ou antitumoral, para auxiliar o tratamento e a prevenção do câncer, visando à melhor qualidade de vida dos pacientes e da população em geral.

Chemical composition and anxiolytic-like effects of the Bauhinia platypetala

The pantropical genus Bauhinia, Fabaceae, known popularly as cow's foot, is widely used in folk medicine as antidiabetic. Behavioral effects of the ethanolic extract and ethereal, aqueous and ethyl acetate fractions from B. platypetala Benth. ex Hemsl. leaves were studied in male Swiss mice. The ethanolic extract and fractions were administered intraperitoneally and its effects on spontaneous motor activity (total motility, locomotion, rearing and grooming behavior) were monitored. Anxiolytic-like properties were studied in the elevated plus-maze test and the possible antidepressant-like actions were evaluated in the forced swimming test. The results revealed that only the highest dose of the ethereal fraction (50 mg/kg, i.p.) caused a significant decrease in total motility, locomotion and rearing. Sole dose injected (50 mg/kg) of ethanolic extract and ethereal fractions increased the exploration of the elevated plus-maze open arms in a similar way to that of diazepam (2 mg/kg, i.p.). In the forced swimming test, the ethanolic extract and their fractions (12.5, 25 or 50 mg/kg) was not as effective as paroxetine (10 or 20 mg/kg, i.p.) and imipramine (25 or 50 mg/kg, i.p.) in reducing immobility. These results suggest that some of the components of the ethanolic extract and of the ethereal fraction from B. platypetala, such as p-cymene, phytol, D-lactic acid, hexadecanoic acid, among others, may have anxiolytic-like properties, which deserve further investigation. Furthermore, the results obtained indicate that ethanolic extract from B. platypetala and their fractions do not present antidepressive properties. However, these properties cannot be related to the chemical constituents identified in this specie.