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Saturday, 3 May 2014


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What are phytochemicals?
Phytochemicals are a large group of plant-derived compounds hypothesized to be responsible for much of the disease protection conferred from medicinal plants, diets high in fruits, vegetables, beans, cereals, and plant-based beverages such as tea and wine (Arts and Hollman, 2005).
 Phytochemicals are known to possess antioxidant (Wong et al., 2009), antibacterial (Nair et al., 2005), antifungal (Khan and Wassilew, 1987), antidiabetic (Singh and Gupta, 2007, Kumar et al. a, 2008), anti-cancer (Lawal et al., 2009) anti-inflammatory (Kumar et al. b, 2008), antiarthritic (Kumar et al., 2008), and radio-protective activity (Jagetia et al., 2005), and due to these properties they are largely used for medicinal purpose.
Phyto means plant, thus phytochemicals are plant chemicals that are use to find against diseases.
The development of drug resistance and the undesirable side effects of certain antibiotics have led to the search for new antimicrobial agents, mainly among plant kingdom, in order to find leads with unique chemical structures which may exert a hitherto unexploited mode of action. The phytochemical investigation of a plant may involve following steps:
  • Authentication and extraction of the plant material,
  • Separation and isolation of the constituents of interest,
  • Characterization of the isolated compounds and
  • Quantitative evaluation (Evans, 2008).
What are the various types of phytochemicals?
Text Box: PHYTOCHEMICALSBased on their chemical structure, phytochemicals can be broken into the following groups (Arts and Hollman, 2005).

Figure 1: Types of Phytochemicals (Arts and Hollman, 2005).
Phytomedicinal Actions
The beneficial medicinal effects of plants typically result from the combinations of secondary products present in the plant. The medicinal actions of plants are unique to particular plant species or group is consistent with this concept as the combinations of secondary products in a particular plant are often taxonomically distinct (Wink, 1999).
This is in contrast to primary products, such as carbohydrates, lipids, proteins, heme, chlorophyll, and nucleic acids, which are common to all plants and are involved in the primary metabolic processes of building and maintaining plant cells (Kaufman et al., 1999; Wink, 1999). Although plant secondary products have historically been defined as chemicals that do not appear to have a vital biochemical role in the process of building and maintaining plant cells, recent research has shown a pivotal role of these chemicals in the ecophysiology of plants. Plant secondary products have both a defensive role against herbivory, pathogen attack, and inter-plant competition and an attractant role toward beneficial organisms such as pollinators or symbionts (Kaufman et al., 1999; Wink and Schimmer, 1999).
Plant secondary products also have protective actions in relation to abiotic stresses such as those associated with changes in temperature, water status, light levels, UV exposure, and mineral nutrients (Kaufman et al., 1999). Furthermore, recent work has indicated potential roles of secondary products at the cellular level as plant growth regulators, modulators of gene expression, and in signal transduction (Kaufman et al., 1999).
Although secondary products can have a variety of functions in plants, it is likely that their ecological function may have some bearing on potential medicinal effects for humans. For example, secondary products involved in plant defense through cytotoxicity toward microbial pathogens could prove useful as antimicrobial medicines in humans, if not too toxic. Likewise, secondary products involved in defense against herbivores through neurotoxin activity could have beneficial effects in humans (i.e. as antidepressants, sedatives, muscle relaxants, or anesthetics) through their action on the central nervous system.
To promote the ecological survival of plants, structures of secondary products have evolved to interact with molecular targets affecting the cells, tissues, and physiological functions in competing microorganisms, plants, and animals (Wink and Schimmer, 1999). In this respect, some plant secondary products may exert their action by resembling endogenous metabolites, ligands, hormones, signal transduction molecules, or neurotransmitters and thus have beneficial medicinal effects on humans due to similarities in their potential target sites (e.g. central nervous system, endocrine system, etc.) (Kaufman et al., 1999). As noted by Wink (1999), the development of structural similarity between plant secondary products and the endogenous substances of other organisms could be termed “evolutionary molecular modeling.”

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