The increasing amount of contaminants in the environment raises growing concerns about the ecological and global impact on the environment and human and animal health. Today's trend is searching for preventive and therapeutic procedures to protect against the toxic and carcinogenic effects of these substances. The plant kingdom is considered one of the main sources of drugs. The use of herbal medicines and food supplements containing herbal extracts or their components is an integral part of therapy and prevention of various diseases. It is estimated that almost 80 % of the world's population uses a herbal medicine. Interest in the potential health benefits of plant extracts has been steadily increasing in the last few decades. Many of the effects are related to the presence of secondary metabolites (phytochemicals), which are a biologically active component of plants and, due to their complex effect, can reduce the risk of several animal and human diseases. For the plant itself, they are part of the defense mechanisms against environmental stress, and it is this defense capability that plants have great potential in protecting humans and animals from the harmful effects of pollutants in the environment. The aim of the work was the analysis of biological properties of selected plant extracts using model organisms in vitro and in vivo. We evaluated the potential ability of the extracts to protect organisms from oxidative stress and eliminate harmful effects by simultaneous exposure of living organisms to harmful substances occurring in the environment. The experiments were performed in vitro using selected model cell lines, in which we evaluated the cell response to exposure to tested substances in real time (xCELLigence system). The test substances were added either alone or in combination with toxic substances to determine the potential protective effect of the extracts. Using in vitro tests, we monitored the effect of substances on cell proliferation, metabolic activity, cytotoxicity of cells. In another part of the experimental work, substances of natural origin (extracts) were fed to broiler chickens alone or in combination and we evaluated the impact on growth and production parameters, antioxidant status and overall animal health.