Salt-Tolerant Plants, Halophytes, as Renewable Natural Resources for Cancer Prevention and Treatment: Roles of Phenolics and Flavonoids in Immunomodulation and Suppression of Oxidative Stress towards Cancer Management

Abstract

Halophytes and xerophytes, plants with adequate tolerance to high salinity with strong ability to survive in drought ecosystem, have been recognized for their nutritional and medicinal values owing to their comparatively higher productions of secondary metabolites, primarily the phenolics, and the flavonoids, as compared to the normal vegetation in other climatic regions. Given the consistent increases in desertification around the world, which are associated with increasing salinity, high temperature, and water scarcity, the survival of halophytes due to their secondary metabolic contents has prioritized these plant species, which have now become increasingly important for environmental protection, land reclamation, and food and animal-feed security, with their primary utility in traditional societies as sources of drugs. On the medicinal herbs front, because the fight against cancer is still ongoing, there is an urgent need for development of more efficient, safe, and novel chemotherapeutic agents, than those currently available. The current review describes these plants and their secondary-metabolite-based chemical products as promising candidates for developing newer cancer therapeutics. It further discusses the prophylactic roles of these plants, and their constituents in prevention and management of cancers, through an exploration of their phytochemical and pharmacological properties, with a view on immunomodulation. The important roles of various phenolics and structurally diverse flavonoids as major constituents of the halophytes in suppressing oxidative stress, immunomodulation, and anti-cancer effects are the subject matter of this review and these aspects are outlined in details.

Chrysin, The Flavonoid Molecule of Antioxidant Interest

“…Through their use throughout history, people have observed and documented what is helpful and dangerous, and their conviction in the role that plants play in preventing and treating diseases has been established. [5][6][7] Because of their secondary metabolite content, medicinal plants have proven to play an important role in the global health system, according to research and applications. [8,9] Several classes of secondary metabolites of the alkaloids, volatile oils, flavonoids, saponins, bitter principles, and others have been identified, examined, and applied for the management of diseases, and examples of such secondary metabolites are too numerous to be discussed.…”

“…[14,15] On the other hand, greens, colored fruits, and medicinal plants rich in flavonoids are recommended for human protection against hazards or oxidative stress and to enhance overall human health. [7] These recommendations have been based on the high levels of usefulness and lower risk potential associated with these greens and fruits for human consumption. Flavonoid as pure entities have also been recommended for the same purposes.…”

“…Plants and their metabolites are the most commonly used natural components in the world, and research into improving plant production and protecting their diversity is critical to reducing monopolies and compensating for mankind‘s daily consumption. Through their use throughout history, people have observed and documented what is helpful and dangerous, and their conviction in the role that plants play in preventing and treating diseases has been established [5–7] . Because of their secondary metabolite content, medicinal plants have proven to play an important role in the global health system, according to research and applications [8,9] .…”

“…Flavonoids have a defined role in plant physiological mechanisms, including protection against oxidative stress and microbial invasion [14,15] . On the other hand, greens, colored fruits, and medicinal plants rich in flavonoids are recommended for human protection against hazards or oxidative stress and to enhance overall human health [7] . These recommendations have been based on the high levels of usefulness and lower risk potential associated with these greens and fruits for human consumption.…”