Metabolism of Phytochemicals

*Tanu Dixit, Akash Tiwari, Sneha Bose, Himani Kulkarni, Jitendra Suthar and Selvan Ravindran*

## **Abstract**

Several phytochemicals have been developed as medicinal compounds. Extensive research has recently been conducted on phytochemicals such as curcumin, resveratrol, catechin, gallic acid, humulone, quercetin, rutin, diosgenin, allicin, gingerenone-A, caffeic acid, ellagic acid, kaempferol, isorhamnetin, chlorogenic acid, and others. All of these phytochemicals are metabolized in the biological system. To study the metabolic pathways of phytochemicals, studies are done using both *in vitro* and *in vivo* techniques. Metabolism is critical in determining phytochemical bioavailability, pharmacokinetics, and effectiveness. Metabolism can occur in organs such as the intestine, liver, gut, and spleen. The metabolic process is aided by a variety of enzymes, including cytochrome P450 enzymes found in the organs. This study outlines a few phytochemicals metabolic pathways. Tannic acid, ellagic acid, curcumin, quercetin, and resveratrol are selected and explained as examples.

**Keywords:** metabolism, phytochemicals, biotransformation, natural products, metabolic pathways, medicinal compounds

#### **1. Introduction**

More phytochemicals are extensively researched in the past several years. Still, curiosity among researchers for medicinally important phytochemicals is increasing. Recently, during the outbreak of the coronavirus, several scientists around the world are in search of various modalities of treatment and one among them was through phytochemicals or naturally available compounds.

Formononetin, scutellarin, emodin, withanone, escin, quabin, tannic acid, genistein, and other naturally derived phytochemicals are being researched for their capacity to cure Middle East Respiratory Syndrome - Coronavirus (MERS-CoV), which causes Middle East respiratory syndrome. Pharmaceutical drugs developed based on the phytochemicals have been authorized by the Food and Drug Administration (FDA) for use in the treatment of different illnesses [1].

Phytochemicals derived from plants, marine-derived, and fungus are the source to discover drugs and prevent disease [2].

Several natural products exhibit antiviral effects against human CoVs, which will help to develop antiviral prophylactics. Phytochemicals such as dihydrotanshinone, quabin, and griffthsin suppress MERS-CoV by targeting the virus's S protein and preventing viral entrance [3–6]. Therefore, this chapter highlights few examples from the literature and the importance of metabolism study in drug discovery and development.

#### *Drug Metabolism*

Before a pharmaceutical drug is approved by the FDA, its metabolites are thoroughly researched and described, as well as related *in vitro* and *in vivo* investigations [7–11].

Similar rigorous studies are essential for phytochemicals, nanomedicine [12–15], monoclonal antibodies [16], formulation materials, and other new forms of therapeutics.

Upon successful completion of pharmacological and toxicological studies, the desired phytochemicals can be scaled up using bioreactors with the aid of microorganisms [17] or a methodology can be developed to synthesize the compounds by biological methods [18].
