CHAPTER ONE

1.0                                                             INTRODUCTION

Toward the end of the 20th century, epidemiological studies and associated meta-analyses suggested strongly that long-term consumption of diets rich in plant foods offered some protection against chronic diseases, especially cancer (Wallstromet al., 2000).Because uncontrolled production of free radicals was thought to be significantly implicated in the etiology of cancer (Guyton and Kensler 1993),these observations focused attention on the possible role of radical scavenging and radical suppressing nutrients and non-nutrients in explaining the apparent benefit of such diets (Weisburger, 1991).

The realization that free radicals were similarly implicated in the etiology of many other chronic diseases (Kehrer, 1993 and Stohs, 1995), immediately focused attention on flavonoids and the foods and beverages rich therein. An unfortunate, but unintended side effect of some research works and papers was the misleading tendency of many investigators to think of dietary phenols, polyphenols, and tannins (PPT)as encompassing only the flavonoids, flavonols, and flavones. More recent epidemiological studies have supported the association between better health and long-term consumption of diets rich in foods of plant origin(Hung et al., 2004 and Jansen et al., 2004).However, whether this is because such diets minimize exposure to deleterious substances (example oxidized cholesterol, pyrolysis mutagens, salt, saturated fat, etc.), or maximize intake of certain beneficial nutrients (example isothiocyanates and other sulfur-containing plant constituents, mono-unsaturated fatty

acids, and poly-unsaturated fatty acids, PPT, polyacetylenes, selenium, terpenes, etc.) or some combination as advocated in the ‘‘Polymeal’’ concept, remains unknown (Franco et al., 2004 and Johnson, 2004).An in vitro study indicates that there may be mechanistic basis for true synergy between PPT and isothiocyanates. In contrast, more recent studies seeking to assess the suggested link between the consumption of flavonols and flavones, or other flavonoids, have given much less consistent results. Some studies have suggested a possible protective effect of flavonoids against vascular diseases (Hirvonen et al., 2001 and Mennen et al., 2004) or certain (but not all) cancers(Knekt et al., 1997 and Sun et al., 2002).Interestingly, an investigation of the relationship between the consumption of Hibiscus sabdariffa (zobo) and other cruciferous vegetables and the risk of breast cancer in premenopausal women has to be carried out in order to ascertain the beneficial effects to isothiocyanates and/or the phenolic components of the plants (like the dietary phenols including flavonoids) in the management of cancer growth and initiation of various types of diabetes.

In the same time period, various studies have suggested beneficial effect associated with raised consumption of other classes of dietary phenols. For example, increased coffee consumption has been linked with reduced incidence of type II diabetes (van Dam et al., 2002 and Saremi et al., 2003).Similarly, increased consumption of lignans (or at least greater plasma concentrations of their metabolites)has been linked with reduced incidence of estrogen-related cancers in some (Boccardo et al., 2004 and McCann et al., 2004) but not all studies (Kilkkinen et al., 2004 and Zeleniuch –Jacquotte et al., 2004),and a prospective study was equivocal.

1.1       SUGGESTIONS FOR FURTHER RESEARCH

The flavonoids in the water extract of Hibiscus sabdariffa should be extracted for further experimental and clinical research in the management of certain ailments and disorders like cancer, diabetes mellitus etc.

The mechanisms of flavonoid-protein interactions have been determined; it is my suggestion that such mechanisms should be carried to the in-vivo metabolic and physiological processes aimed at determining the detailed mechanisms involved in cells aging processes and the progression of diseases.

1.2       OBJECTIVE OF STUDY

    The objective of this study is to determine the physico chemical (biochemical) and water constituent of Zobo produced from dried calyces of Hibiscus sabdariffa (Linn Roselle). Using atomic absorption spectrophotometer (AAS). The biochemical content of the zobo has undesirable effects on human health when consumed.

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