The investigation of protective effect of boron on formaldehyde-induced experimental oxidative stress in A549 lung epithelial cells by using biochemical and molecular biology techniques

Formaldehyde is a highly reactive aldehyde due to its electrophilic character, which is colourless, pungent, well soluble in water and it has a strong odour. Formaldehyde is used in many fields such as cosmetics industry, greenhouses, livestock, wood processing, production, environment, industry, dentistry and it is also used in the production of resin, laboratory materials, antiseptics, disinfectants. Besides, it is found in cigarette smoke, and it causes oxidative stress. With the development of technology and medicine, many substances are used as an alternative for diagnosis and treatment in various diseases. Turkey possesses rich boron mine sources. The increase in the usage of boron will provide positive economic benefits. Therefore, it is of utmost importance for performing researches and projects in this area. In this thesis, cell viability test (MTT), reduced glutathione (GSH), malondialdehyde (MDA) levels and activities of superoxide dismutase (SOD), catalase (CAT) were analysed to determine the effect of boric acid against formaldehyde-induced oxidative stress in A549 lung epithelial cells. Also, mRNA expression levels of β-actin, Tnf-α, caspase-3, Bcl-XL and NFκB genes were molecularly evaluated to determine the effect of boric acid in inflammation. For this purpose, A549 cell lines were exposed to 2.5, 5 and 10 mM boric acid for 12 hours. Then 100 μM formaldehyde was applied for 4 hours on cell lines. After application, it was determined that formaldehyde significantly reduced cell viability whereas increased MDA levels. However, it decreased GSH levels, SOD and CAT enzyme activities of cell lysates, and had no significant effect on NO levels of culture medium. Also, it was determined that formaldehyde administration increased Tnf-α, NFkB and caspase-3 mRNA expression levels, yet no significant change was observed in Bcl-XL mRNA expression levels. It was found that boric acid reversed lipid peroxidation, decreased antioxidant enzyme activity, increased mRNA expression levels of genes involved in inflammation and apoptosis which are caused by formaldehyde exposure. As a result, it was determined that boric acid, as a boron source, plays a significant role in formaldehyde-induced oxidative stress, inflammation and apoptosis in A549 cells and has positive effects on cell growth.