Phytochemical Antioxidants

**305**

**Chapter 15**

**Abstract**

phytochemical antioxidants.

**1. Introduction**

human health.

species (RNS), reactive sulfur species (RSS)

Phytochemical Antioxidants:

Most diseases that are difficult to prevent and cure are "syndromes" that are governed by multiple components with complicated interactions. Whatever the cause of such diseases, overproduction of harmful reactive oxygen species (ROS) can often be observed in progression of the disease. Under such conditions, the cells may be challenged by "oxidative stress" due to excessively generated oxidants. Antioxidants can be defined as chemical compounds that scavenge ROS or free radicals over-produced in the cells under oxidative stress conditions. The plant pigments flavonoids and betalains, rich in fruits and vegetables, are reactive not only with ROS but also with reactive nitrogen species (RNS) and possibly with reactive sulfur species (RSS). Here, we provide an overview of updates on the antioxidative functions of the plant pigments along with some prospects for future research on

**Keywords:** flavonoid, betalain, reactive oxygen species (ROS), reactive nitrogen

Fruits and vegetables are appreciated as "healthy foods" compared with beef or pork meat. Many epidemiological studies as well as clinical investigations have suggested that a vegetable-based diet is beneficial in preventing chronic diseases including cancer, coronary heart disease, stroke and hypertension [1, 2]. Meanwhile, traditional herbal medicines have used specific plant species that contain phytochemicals exhibiting pharmacological activities [3]. Novel compounds have been isolated from such plants and they have been chemically synthesized for pharmaceutical production [4]. Nobody doubts that edible plants are beneficial in

In "western" medicine, a disease can be defined as dysfunction of a physiological mechanism. Based on this concept, a drug in general is presumed to act on a specific component of a physiological mechanism. In many cases, these are inhibitors of enzymes or transporters, showing the "one-to-one" relationship between drug and target molecule. While recent drug designs have drastically changed due to a rapid development of computer technology [5] as well as gene therapy [6], the hunt for novel bioactive compounds contained in plants is still active for new drug discovery. The "one-to-one" philosophy in medicine and pharmacology works well, if the cause of a disease is ascribed to a single component such as a protein or an enzyme. However, most diseases that are difficult to prevent and cure are "syndromes" that

Past, Present and Future

*Yasuko Sakihama and Hideo Yamasaki*

## **Chapter 15**
