Shahrekord University of Medical Sciences Journal of Herbmed Pharmacology 2345-5004 9 3 2020 07 01 Battle between plants as antioxidants with free radicals in human body 191 199 10.34172/jhp.2020.25 EN Fatemeh Jamshidi-kia https://orcid.org/0000-0002-2103-2832 Joko Priyanto Wibowo https://orcid.org/0000-0003-4080-3724 Mostafa Elachouri https://orcid.org/0000-0002-4367-7770 Rohollah Masumi https://orcid.org/0000-0002-1545-0034 Alizamen Salehifard-Jouneghani https://orcid.org/0000-0001-6572-9394 Zohreh Abolhasanzadeh https://orcid.org/0000-0002-0709-1174 Zahra Lorigooini https://orcid.org/0000-0003-0844-7571 Journal Article 10.34172/jhp.2020.25 2019 12 09 2020 04 10 Free radicals are constructed by natural physiological activities in the human cells as well as in the environment. They may be produced as a result of diet, smoking, exercise, inflammation, exposure to sunlight, air pollutants, stress, alcohol and drugs. Imbalanced redox status may lead to cellular oxidative stress, which can damage the cells of the body, resulting in an incidence of various diseases. If the endogenous antioxidants do not stop the production of reactive metabolites, they will be needed to bring about a balance in redox status. Natural antioxidants, for example plants, play an important part in this context. This paper seeks to report the available evidence about oxidative stress and the application of plants as antioxidant agents to fight free radicals in the human body. For this purpose, to better understand oxidative stress, the principles of free radical production, the role of free radicals in diseases, antioxidant defense mechanisms, and the role of herbs and diet in oxidative stress are discussed.