Immunomodulators Derived from Natural Products

The immune system (IS) is a complex integrated network of organs, tissues, cells, and chemicals that work together to protect the organism against any external factors, such as harmful pathogens, cancer cells, and environmental pollutants that can affect the integrity and homeostasis of the organism. Immunomodulators are substances that can modify or modulate the IS to assist the organism in responding to different diseases. Immunomodulators derived from natural products are extensively used in the treatment of many diseases, including autoimmune diseases, inflammatory disorders, and cancer. In the last decades, they have attracted the attention of researchers as therapeutic agents because they are inexpensive and exert less toxicity than synthetic chemotherapeutic agents. Immunomodulator agents can enhance or suppress the defense response of the host, and they can be used as a prophylaxis or with other therapeutic agents. Immunomodulators with anticancer activity exhibit their effects due to their anti-inflammatory, antioxidant, antiangiogenesis, and antimetastasis effects, as well as their ability to induce apoptosis. These natural immunomodulatory plants, which are rich in flavonoids, phenolic acids, tannins, and phenylpropanoids, can be used prophylactically to decrease the initiation of cancer, as well as to inhibit tumor growth and proliferation. However, immunostimulant agents can stimulate and activate humoral and cell-mediated immune responses against tumors, simplifying the destruction of the tumor already present. This chapter illustrates recent research on the efficacy of natural products as immunomodulators with anti-inflammatory effects. Moreover, we highlight the relationship between immunomodulatory mechanisms and the anti-inflammatory activity of different classes of phenolic compounds. In addition, the chemical nature of various classes of phenolic compounds is reviewed.