The properties and mechanism of action of plant immunomodulators in regulation of immune response – A narrative review focusing on Curcuma longa L., Panax ginseng C. A. Meyer and Moringa oleifera Lam

Herbal treatments have been utilized for millennia to cure a variety of ailments. There are over 20, 000 herbal remedies available to treat cancer and other disease in humans. In Ayurveda, traditional plants having revitalizing and nourishing characteristics are known as "Rasayanas." They have anti-inflammatory, anticancer, anti-microbicidal, antiviral, and immunomodulatory effects on the immune system. Immunomodulation is a mechanism through which the body stimulates, suppresses, or boosts the immune system to maintain homeostasis. Plant-derived immunomodulators are typically phytocompounds, including carbohydrates, phenolics, lipids, alkaloids, terpenoids, organosulfur, and nitrogen-containing chemicals. Immunomodulation activity of phytocompounds from traditional plants is primarily mediated through macrophage activation, phagocytosis stimulation, peritoneal macrophage stimulation, lymphoid cell stimulation, and suppression or enhancement of specific and non-specific cellular immune systems via numerous signalling pathways. Despite extensive research, the precise mechanism of immunomodulation of most traditional plants has not yet been fully elucidated, justifying the need for further experimentation. Therefore, this review describes the immunomodulatory agents from traditional plants such as Curcuma longa L., Panax ginseng C.A. Meyer, and Moringa oleifera Lam, further highlighting the common molecular targets and immunomodulatory mechanism involved in eradicating diseases.