Abstract: In this paper, luminol solution was used to measure the light intensity of plants. The purpose of this experiment was to determine if there was a direct correlation between the amount of reactive oxygen species present in Phaseolus vulgaris seedlings and the amount of chemiluminescence they emit. The plants that were soaked in hydrogen peroxide, had a light reaction that lasted the longest. Whereas, the plants that were soaked in water had a light reaction whose duration was the shortest. It was determined that the higher the amount of reactive oxygen species in an organism, the more chemiluminescence it emits. This demonstrated that a chemiluminescence assay can be used to determine the levels of reactive oxygen species produced by an organism. High levels of reactive oxygen species may be threatening to an organism if the levels are not monitored. .
Keywords: Oxidizing, Reduction, Luminol, Phaseolus vulgaris, ROS, Chemiluminescence
Introduction: The human body uses electrons during the electron transport chain which releases energy in the form of ATP. These electrons are derived from molecules such as fats, proteins, and carbohydrates and are transferred around the cells by molecules such as the coenzymes NADH and NADPH. The body requires a place to store the used electrons that drive energy requiring processes. When the electrons have given up their energy, they are combined with oxygen to form water. Since the electrons are given away to the oxygen molecules, it is said that the oxygen becomes “reduced”, which forms water (H2O), a completely harmless substance, in the process. In its normal state, oxygen has two unpaired electrons in separate orbitals of its outer shell. This indicates that two electrons are required for each water atom. When one of the electrons is lost or only one electron is given to each oxygen molecule, a free radical is created. These are known as reactive oxygen species.
Plants and other living organisms constantly produce reactive oxygen species in their mitochondria, chloroplasts, and other organelles because of their metabolic processes such as photosynthesis and respiration. These reactive oxygen species function as signaling molecules, which transmit information between cells. The most concerning radicals are those that are derived from oxygen. Overproduction of these oxygen radicals may cause a threat to the organism. When reactive oxygen species production exceeds the capacity for antioxidation, it can lead to cell damage and/ or cell death caused by toxicity. For instance, when cells are exposed to abnormal environments, they may generate dangerous amounts of damaging reactive oxygen species (Bowen, Free Radicals and Reactive Oxygen, colostate.edu). The body normally regulates the oxygen radicals, but if this system malfunctions having oxygen radicals in abundance may harm the cells around them. Many drugs that are used to cure infections and diseases today have oxidizing effects on cells which may lead to the production of oxygen radicals.
The materials that were used in this experiment were eighteen Phaseolus vulgaris seeds, distilled water, a vitamin E solution(which acted as the reducing agent) and a hydrogen peroxide solution (which acted as the oxidizing solution). Using reducing and oxidizing solutions caused the production of reactive oxygen species to either slow down, or speed up. Pieces of plastic were used to crush the plants. Luminol solution and a stopwatch were used to measure the light intensity resulting from the chemiluminescence reaction.
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