Several chemicals, including environmental toxicants and clinically useful drugs, cause severe cellular damage to different organs of our body through metabolic activation to highly reactive substances such as free radicals. Carbon tetrachloride is an organic compound of which chemical formula is CCl₄. CCl₄ is strong toxic in the kidney, testicle, brain, heart, lung, other tissues, and particularly in the liver. CCl₄ is a powerful hepatoxic, nephrotoxic and prooxidant agent which is widely used to induce hepatotoxicity in experimental animals and to create hepatocellular carcinoma, hepatic fibrosis/cirrhosis and liver injury, chemical hepatitis model, renal failure model, and nephrotoxicity model in recent years. The damage-causing mechanism of CCl₄ in tissues can be explained as oxidative damage caused by lipid peroxidation which starts after the conversion of CCl₄ to free radicals of highly toxic trichloromethyl radicals (•CCl₃) and trichloromethyl peroxyl radical (•CCl₃O₂) via cytochrome P450 enzyme. Complete disruption of lipids (i.e., peroxidation) is the hallmark of oxidative damage. Free radicals are structures that contain one or more unpaired electrons in atomic or molecular orbitals. These toxic free radicals induce a chain reaction and lipid peroxidation in membrane-like structures rich in phospholipids, such as mitochondria and endoplasmic reticulum. CCl₄-induced lipid peroxidation is the cause of oxidative stress, mitochondrial stress, endoplasmic reticulum stress. Free radicals trigger many biological processes, such as apoptosis, necrosis, ferroptosis and autophagy. Recent researches state that the way to reduce or eliminate these CCl₄-induced negative effects is the antioxidants originated from natural sources. For normal physiological function, there must be a balance between free radicals and antioxidants. If this balance is in favor of free radicals, various pathological conditions occur. Free radicals play a role in various pathological conditions including Pulmonary disease, ischemia / reperfusion rheumatological diseases, autoimmune disorders, cardiovascular diseases, cancer, kidney diseases, hypertension, eye diseases, neurological disorders, diabetes and aging. Free radicals are antagonized by antioxidants and quenched. Antioxidants do not only remove free radicals, but they also have anti-inflammatory, anti-allergic, antithrombotic, antiviral, and anti-carcinogenic activities. Antioxidants contain high phenol compounds and antioxidants have relatively low side effects compared to synthetic drugs. The antioxidants investigated in CCI₄ toxicity are usually antioxidants from plants and are promising because of their rich resources and low side effects. Data were investigated using PubMed, EBSCO, Embase, Web of Science, DOAJ, Scopus and Google Scholar, Carbon tetrachloride, carbon tetrachloride-induced toxicity, oxidative stress, and free radical keywords. This study aims to enlighten the damage-causing mechanism created by free radicals which are produced by CCl₄ on tissues/cells and to discuss the role of antioxidants in the prevention of tissue/cell damage. In the future, Antioxidants can be used as a therapeutic strategy to strengthen effective treatment against substances with high toxicity such as CCl₄ and increase the antioxidant capacity of cells.

Cadmium (Cd) is a significant ecotoxic heavy metal that adversely affects all biological processes of humans, animals and plants. Exposure to acute and chronic Cd damages many organs in humans and animals (e.g. lung, liver, brain, kidney, and testes). In humans, the Cd concentration at birth is zero, but because the biological half-life is long (about 30 years in humans), the concentration increases with age. The industrial developments of the last century have significantly increased the use of this metal. Especially in developing countries, this consumption is higher. Oxidative stress is the imbalance between antioxidants and oxidants. Cd increases reactive oxygen species (ROS) production and causes oxidative stress. Excess cellular levels of ROS cause damage to proteins, nucleic acids, lipids, membranes and organelles. This damage has been associated with various diseases. These include cancer, hypertension, ischemia/perfusion, cardiovascular diseases, chronic obstructive pulmonary disease, diabetes, insulin resistance, acute respiratory distress syndrome, idiopathic pulmonary fibrosis, asthma, skin diseases, chronic kidney disease, eye diseases, neurodegenerative diseases (amyotrophic lateral sclerosis, Parkinson’s disease, Alzheimer’s disease, and Huntington disease). Natural antioxidants are popular drugs that are used by the majority of people and have few side effects. Natural antioxidants play an important role in reducing free radicals caused by Cd toxicity. Our goal in this review is to establish the relationship between Cd and oxidative stress and to discuss the role of natural antioxidants in reducing Cd toxicity.

Heavy metals taken into the organism can make the toxic effects on the metabolism in various ways. For example, they may interact with proteins to alter and inhibit their enzymatic and structural functions. Mercury is one of the toxic elements that are widely distributed in nature. Mercury toxicity poses a serious threat to human health. It is an element that causes oxidative stress to increase in individuals, leading to tissue damage. Oxidative stress is the result of the imbalance between the production of oxidative species and cellular antioxidant defense. Phytotherapy continues to play an important role in health care. Natural phytotherapeutic antioxidants, exhibit a broad sequence of biological impacts, including anti-oxidative stress, anti-aging, anti-toxicicity and anticancer. Many studies have also shown that the phytotherapeutic agents play an important role in the removal of mercury from the tissue and in reducing oxidative stress. Our goal in this review was to investigate alternative ways of extracting the mercury in the tissue.

Hepatocellular carcinoma is one of the most common cancers in the world, and it is influenced by agents such as DEN, 2-AAF, phenobarbital, alcohol, aflatoxin B1 metabolite or hepatitis viruses (B and C). Oxidative stress is becoming recognized as a key factor in the progression of hepatocarcinogenesis. Reactive oxygen species can play a leading role in initiation and promotion of hepatic carcinogenesis. The metabolites of DEN Diethylnitrosamine (DEN) mediate the binding of tumour promoters by covalently binding to the DNA with one or two oxidation-providing electrons. 2-AAF is the inducer of DEN, and it is involved in tumour formation in the bladder and liver. Reactive Oxygen species (ROS); carbohydrates, lipids, DNA and enzymes, such as affect all important structures. Additionally, an excessive amount of ROS is highly toxic to cells. Antioxidants are protects against ROS, toxic substances, carcinogens. This review focuses on the literature on studies of Hepatic Carcinogenesis, oxidative stress and antioxidant therapy.