Biphasic Effects of Phytochemicals and their Relevance to Cancer Therapeutics

Cancer is one of the most deadly diseases caused worldwide. Enormous active anti-cancer agents that are available in nature play an efficient role in therapies associated to cancer for different organ-specific cancers like breast, skin, pancreas, and thyroid. These anti-cancer agents which occur naturally are derived mostly from various sources such as herbs, plants, and microorganisms. However, spontaneous uses of these therapies have no proper data on their therapeutic benefits available, which might induce side effects or off-target toxicity on due course. This book chapter throws light on the effect of these natural compounds in a dose-dependent manner on various human cancer cells and how these compounds show biphasic effects at different concentrations. The naturally occurring compounds exhibit a biphasic nature depending on their dose, i.e., they show both stimulatory and inhibitory effects on tumor cells depending on their concentrations. There has been no study conducted which explains the reason behind the biphasic nature of these naturally occurring compounds. This book chapter summarizes the role of different naturally occurring compounds such as resveratrol, quercetin, falcarinol, genistein, kaempferol, berberine, daidzein, indole-3-carbinol, umbelliprenin, glabridin, and 12-O-tetradecanoylphorbol-13-acetate (TPA) used as chemotherapeutic agents based on their toxicity, dosage, and its exhibition of biphasic effects. This chapter also highlights the major signaling pathways involved in showing anti-cancer effects of the above compounds having a biphasic effect.