PHYTOCHEMICAL ANALYSIS OF SELECTED TOMATO PRODUCTS

CHAPTER ONE

1.0 INTRODUCTION

Intake of tomato and tomato basedproducts contributes to the absorption of a wide range of carotenoids in human serum and tissues. The prominent carotenoid in tomatoes is lycopene, a pigment principally responsible for the deepred colour of tomato fruits and tomato products. Fruits and vegetables contain in excess of 40 carotenoids that are routinely absorbed and metabolized by humans Khachik, 1992.

Tomatoes and tomato products are now being investigated for their potential role in prostate cancer prevention and therapy. This review summarizes the in vitro and invivo evidence as well as the molecular data that show the anticarcinogenic potential of tomatoes. Raw and processed tomatoes are among the most commonly consumed vegetables. They are rich in the phytochemicals, carotenoids and polyphenols. Lycopene and quercetin are the most abundant carotenoids and flavonols respectively. Canned tomato sauce is the primary source of lycopene whereas the tomato skin is enriched with flavonols. Most epidemiological studies suggest that the consumption of tomatoes and the products in associated with a reduced prostate cancer risk. The health professionals followsup study found that men who consumed 2 to 4 servings of raw tomatoes per week had a more than 20 reduction in prostate cancer risk compared to men who did not consume tomatoes. High lycopene plasma concentrations were associated with a low incidence of prostate cancer and aggressive prostate cancer in rested casecontrol study with the physicians health study. Invitro data show that the compounds found in tomatoes are potent anticarcinogens. Cancer cell growth is inhibited by the polyphenols quercetin, kaempferol and naringerin in a dose dependent manner. These compounds do not have cytotoxic effect. In a rat model of prostate cancer, tomato powder into but not lycopene intake by itself reduced prostate cancer related mortality. This suggests that the compounds in tomatoes have an additive influence on prostate cancer. Lycopenes exist as either the cis or trans isomer. The halflife of lycopene is approximately 10 to 14 days, so it remains in the body during washout period. The trans isomer dominates in tomatoes, between the cis isomer dominates in serum and tissues and during a washout period. Thus, recent intake of lycopenes is reflected in blood concentrations whereas longterm exposure is determined in the tissues.

Lycopene is a bioactive carotenoid found in many red fruits and vegetables, such as tomatoes, watermelon, pink grapefruits etc. Different fruits, vegetable and their products contain different concentrations of lycopene. This natural red pigment is synthesized exclusive by plants and microorganisms fungi, bacteria and algae. It facilitates the absorption of light during photosynthesis and also provides protection against photosensitization Adam et al., 1996 Animals including human being, cannot synthesize lycopene therefore, they obtain lycopene exclusively from diet Tapiero et al. 2004; Omoni and Aluko, 2005.

Although, tomato contain a lower concentration of nutrients compared to other commercially grow fruits species, they are a major source of lycopene. Lycopene comprises 83 of the total pigment present in tomatoes Shi et al., 1990. Therefore, the amount of lycopene present in tomatoes other fruits and vegetables vary with variety, degree of ripeness and other dimatic conditions and agricultural practices.