DETERMINATION OF ANTIOXIDANT CAPACITY OF SELECTED BOROXINES

Abstract

Our previous in vitro and in vivo studies on standard tumor cell lines: mammary adenocarcinoma 4T1, melanoma B16F10, and squamous cell carcinoma SCCVII have demonstrated that dipotassium-trioxohydroxytetrafluorotriborate, K₂[B₃O₃F₄OH], affects the growth of cancer cells. Based on indicative results of its anticancer activity, that are comparable to the standard cytostatic 5-fluorouracil, we decided to analyze the antioxidant capacity of K₂[B₃O₃F₄OH]. In our research, we include two other simpler representatives of the boroxine family compounds: trimethoxyboroxine and trimethylboroxine, which are commercially available. The study objective is to explore the possibility of similar behavior within the same class of boron compounds, that is, to examine the activity of K₂[B₃O₃F₄OH] compared to simpler representatives of the same family of compounds. On the one hand, K₂[B₃O₃F₄OH], theoretically has the ability to exchange electrons in the extinction of reactive radicals, since two boron atoms are sp3-hybridized and use electrons from the inner shell. On the other hand, trimethoxyboroxine, and trimethylboroxine, in theory, should not exchange electrons. However, recent studies indicate the potential for the boron atom to act like carbon and participate in the exchange of protons. The study used the standard laboratory method of 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant assay. The selected boroxines were treated with a DPPH radical at a temperature of 35° C in various concentrations, and with a reaction time of one hour. Results of the DPPH test show an extremely weak antioxidant capacity exists for all investigated boroxines. When K₂[B₃O₃F₄OH] was tested at high concentrations, instead of decreased color in the DPPH radicals, there was an increase in absorbance readings, which could mean that this compound acts as a pro-oxidant at higher concentrations. Future research is recommended to examine the length of reaction times needed, and whether a change in the reaction conditions would boost the antioxidant capacity of K₂[B₃O₃F₄OH]. Finally, future research could test the hypothesis that K₂[B₃O₃F₄OH], in the absence of the expected antioxidant activity, acts as a pro-oxidant.