Phenolics
Phenolics, also known as phenols, are a diverse class of aromatic compounds characterized by the presence of benzene rings and hydroxyl groups. These compounds are found abundantly in various plants and are recognized for their potential protective roles against several cancers, including breast, bladder, prostate, lung, and ovarian cancers. Key examples of phenolics include compounds like gallic acids, curcumin, resveratrol, and polyphenols from green tea. Their mechanisms of action are still being studied, but they are believed to exhibit antioxidant properties, inhibit cell growth, and induce apoptosis, which contributes to tumor shrinkage and reduced metastasis.
Phenolics are typically ingested through a diet rich in fruits and vegetables, or in supplement forms such as pills or capsules. They have shown promise in enhancing the effectiveness of conventional cancer treatments like radiation and chemotherapy. While laboratory studies have demonstrated their ability to inhibit cancer cell growth, results from live subjects have been less conclusive, potentially due to lifestyle or genetic variations. Additionally, individuals with phenol sulfotransferase deficiency may face toxicity from excessive phenolic intake, indicating a need for dietary adjustments in those cases. Overall, ongoing research continues to explore the anti-inflammatory, antioxidant, and anti-cancer properties of phenolics, highlighting their potential as a complementary approach in cancer therapy.
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Subject Terms
Phenolics
ATC CODE: D08AE
ALSO KNOWN AS: Phenols
DEFINITION: Phenolics are a class of compounds grouped together because of their chemical structure; they are aromatic compounds (containing benzene rings), usually with hydroxyl groups. Their function varies, however, and they may have a protective role against many cancers. Subclasses of this group are benzenediols, capsaicinoids, monolignols, and phenol ethers.
Cancers treated or prevented: Primarily breast cancer, also bladder, prostate, lung, and ovarian
Delivery routes: Oral in diet, pills, or capsules
How these compounds work: Phenolic acids have become the topic of much study for their protective role against many cancers. Examples of phenolics include gallic acids, curcumin, resveratrol, polyphenols from green tea, and ferulic acids. Found in abundance in many plants, phenolics in even low concentrations decrease cell proliferation, which makes them critically important in the shrinkage of cancer cells and concurrent reduction in the size of tumors. Though the exact mechanisms by which phenolics work as antiproliferative substances in the treatment of cancer is unclear, a diet consisting of many fruits and vegetables seems to play an important role in cancer prevention and aids in cancer treatment by reducing tumor size and spread. Further, phenolics can enhance the effectiveness of radiation and chemotherapy.
Proposed mechanisms by which these phenolic acids function include antioxidant effects, steroid receptor binding, direct interaction with intracellular elements and signaling systems, and aryl hydrocarbon receptor (AhR) binding and modification of subsequent pathways. Polyphenols and phenolic acids are rich in antioxidants, which reduce the concentration of harmful free radicals in the human body. Binding to receptor sites and inhibiting particular enzymes inhibits cell growth and prevents the inflammatory response of surrounding healthy tissues. As a result of their oxidation-reduction properties, they efficiently inactivate oxyl radicals and repair amino acid and deoxyribonucleic acid (DNA) base radicals. Phenols also induce apoptosis (scheduled cell death) and restrict the formation of new blood vessels. This active mechanism of phenolics is an important feature since both the growth and metastasis of a tumor depend heavily on angiogenesis (blood vessel formation) to provide oxygen and nutrients to the growing tumor cells.
Numerous laboratory studies have shown that phenolic acids inhibit the growth of cancerous cells in vitro. Unfortunately, studies performed in vivo do not show such clear benefits. Much of this may be attributable to differences in lifestyle or genetics. One promising study, however, showed that individuals who were prescribed low doses of aspirin had a decreased risk of developing colon cancer. The main metabolite of aspirin is a phenolic acid called salicylic acid. Salicylic acid is also found in plants, where it exists as a protective hormone. Its presence in fruits and vegetables may explain its oncoprotective role when made a staple in the human diet. Many more studies are currently being conducted on this matter.
In the mid-2020s, studies confirmed phenolics' anti-inflammatory, antioxidant, and anti-cancer properties and remained a key adjuvant therapy in cancer treatment. Phenolics were found to inhibit Nrf2 pathways, a main source of cancer spread, and allow for the increased effectiveness of traditional cancer treatments. Additionally, as medical researchers increasingly investigated the importance of gut microbiomes, phenolics were shown to increase the bioavailability of beneficial gut microbes, which increased the therapeutic effectiveness of traditional cancer treatments.
Side effects: There are no known side effects of phenolics in the diet, but phenolics can be toxic at excessive levels for those who have phenol sulfotransferase (PST) deficiency, a disease that results from difficulty in processing phenols into useful or at least nonharmful substances. In this case, phenols in the diet should be reduced, or an agent should be used to facilitate processing.
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