Plant-derived immunomodulators: an insight on their preclinical evaluation and clinical trials

Abstract

The phagocyte–microbe interactions in the immune system is a defense mechanism but when excessively or inappropriately deployed can harm host tissues and participate in the development of different non-immune and immune chronic inflammatory diseases such as autoimmune problems, allergies, some rheumatoid disorders, cancers and others. Immunodrugs include organic synthetics, biological agents such as cytokines and antibodies acting on single targets or pathways have been used to treat immune-related diseases but with limited success. Most of immunostimulants and immunosuppressants in clinical use are the cytotoxic drugs which possess serious side effects. There is a growing interest to use herbal medicines as multi-component agents to modulate the complex immune system in the prevention of infections rather than treating the immune-related diseases. Many therapeutic effects of plant extracts have been suggested to be due to their wide array of immunomodulatory effects and influence on the immune system of the human body. Phytochemicals such as flavonoids, polysaccharides, lactones, alkaloids, diterpenoids and glycosides, present in several plants, have been reported to be responsible for the plants immunomodulating properties. Thus the search for natural products of plant origin as new leads for development of potent and safe immunosuppressant and immunostimulant agents is gaining much major research interest. The present review will give an overview of widely investigated plant-derived compounds (curcumin, resveratrol, epigallocatechol-3-gallate, quercetin, colchicine, capsaicin, andrographolide, and genistein) which have exhibited potent effects on cellular and humoral immune functions in pre-clinical investigations and will highlight their clinical potential.

The potential role of some phytochemicals in recognition of mitochondrial damage-associated molecular patterns

“…1). At the same time, claims that some dietary agents can effectively improve immunity evoke serious doubts and suspicions (Jantan et al, 2015). Such skepticism can be only addressed by carefully designed research based on the vigorously expanding knowledge of the biological processes on the cellular level.…”

Intranasal treatment with a novel immunomodulator mediates innate immune protection against lethal pneumonia virus of mice

“…When used as adjuncts in combinational therapies, these can shorten the course of treatment and overall drug dosage. [83][84][85].…”

“…Immunomodulators can exert their function in either an antigen-specific or an antigen-independent manner [86,88]. In addition, they can be further subdivided into immunoadjuvants, immunostimulators, and immunosuppresants [85,88].…”

“…Immunomodulators are substances known to modify and correct the nature of host's immune responses [83][84][85]. These agents can be obtained from endogenous or exogenous sources.…”

Prolonged in vivo Stinging Nettle Treatment Impacts on Functional Capacity of Leukocytes in Immunologically Mature Chickens

“…3,4 Immunomodulation using medicinal plants may provide novel immunomodulatory agents to supplement the present conventional therapy for a variety of diseases. 1,5 Stinging nettle (Urtica dioica, Urticaceae family) is a wild-growing, widespread perennial plant with marked immunomodulatory, antimicrobial, antitumoral, anti-inflammatory, antioxidant, antiviral, activities. 6,7 The chemical composition of stinging nettle shows the presence of vitamins (A, B, B 12 ) acetylcholine, histamine, serotonine, minerals, chlorophyll, salicylic acid, lecithin, carotenoids, flavonoids, sterols and formic acid.…”