Annatto extract and β-carotene enhances antioxidant status and regulate gene expression in neutrophils of diabetic rats

Abstract

Annatto (Bixa orellana L.) contains a mixture of orange-yellowish pigments due to the presence of various carotenoids that have antioxidant effect. The immune system is especially vulnerable to oxidative damage because many immune cells, such as neutrophils, produce reactive oxygen and nitrogen species (ROS and RNS) as part of the body's defence mechanisms to destroy invading pathogens. It is well known that the function of neutrophils is altered in diabetes; one of the major functional changes in neutrophils in diabetes is the increased generation of extracellular superoxide via the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system. The purpose of this study is to evaluate the production of ROS and nitric oxide (NO) as well as the expression of NADPH oxidase subunits, inducible nitric oxide (iNOS), superoxide dismutase (SOD) and catalase (CAT) in neutrophils from diabetic rats treated with annatto extract and β-carotene. Forty-eight female Fisher rats were distributed into six groups according to the treatment received. All animals were sacrificed 7 days after treatment, and the neutrophils were isolated using two gradients of different densities. The ROS and NO were quantified by a chemiluminescence and spectrophotometric assays, respectively. Analyses of gene expression were performed using quantitative real time polymerase chain reaction (qRT-PCR). The results show that treatment with annatto extract and β-carotene was able to decrease ROS production and the mRNA levels of p22^phox and p47^phox and increase the mRNA levels of SOD and CAT in neutrophils from diabetic rats. These data suggest that annatto extract and β-carotene exerts antioxidant effect via inhibition of expression of the NADPH oxidase subunits and increase expression/activity of antioxidant enzymes.

Keywords::

• diabetes
• carotenoids
• qRT-PCR
• NADPH oxidase
• antioxidant enzymes

Acknowledgements

The authors thank Dr Maria Terezinha Bahia of the Laboratory of Doença de Chagas, Ouro Preto, MG, Brazil, for the use of the real time (ABI Prism 7300 Sequence Detector).

Declaration of interests

The authors declare have no conflict of interest. The authors alone are responsible for the content and writing of the article. This research was supported by the Fundação de Amparo Pesquisa do Estado de Minas Gerais (FAPEMIG), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível superior (CAPES – PNPD) and Universidade Federal de Ouro Preto (UFOP), Brazil.