Chapter 4 - Comparative Studies in Relation to the Structure and Biochemical Properties of the Active Compounds in the Volatile and Nonvolatile Fractions of Turmeric (C. longa) and Ginger (Z. officinale)

Abstract

Abstract A wide variety of compounds present in spices that are extensively used as food seasoning agents possess potent antioxidant, antiinflammatory, antimutagenic, and cancer preventive activities. Turmeric ( Curcuma longa ) and ginger ( Zingiber officinale ) are rhizomes and they originate from the same family, Zingiberaceae. These two major natural products are known to have a variety of medicinal and biological properties. This review is a closer look at the structural parameters of the active compounds present in these two natural products that lead to common biological properties. The volatile oils and the nonvolatile oleoresins are the chief source for these active ingredients. The rhizomes of turmeric and ginger contain pungent vanillyl ketones and have been reported to possess strong antiinflammatory activity. The chemical composition of the components is similar yet different and shares a number of biological properties. The constituents of turmeric oil (TO) and ginger oil (GO) have sesquiterpene hydrocarbons and oxygenated sesquiterpenes. GO displays considerable diversity, yet it comprises of mostly sesquiterpenes such as zingiberene, ar -curcumene, β-bisabolene, and β-sesquiphellandrene. Many of these are in common with TO even though the major constituents in TO consist of turmerones. The common structural aspects will be discussed and this will also shed light in to the common biological properties. The oleoresins of turmeric and ginger containing the nonvolatile fractions consist of polyphenols. Wide arrays of phenolic substances in these natural products have been reported to possess substantial anticarcinogenic and antimutagenic activities along with antioxidative and antiinflammatory properties which appear to contribute to their chemopreventive or chemoprotective activity. Curcuminoids in turmeric contain curcumin, demethoxy curcumin, and bis-demethoxy curcumin. The active compounds in ginger are gingerols, shogaols, and zingerones. It was shown that 6-, 8-, and 10-gingerols and [6]-shogaol showed efficacy in antiinflammatory, antibacterial, antipyretic, antilipidemic, antitumorigenic, and antiangiogenic effects. They have structural similarities with curcuminoids which result in common biological properties and mechanism of action. The structural similarities and differences of these compounds will be discussed in relation to the biological and medicinal properties. Cyclo-oxygenase-2 is regulated by the eukaryotic transcription factor nuclear factor κB and it has been recognized as a molecular target of many antiinflammatory agents. This review will examine the molecular mechanisms underlying biological effects of the active compounds in these natural products in terms of their effects on intracellular signaling cascades. The structural correlation and biochemical properties of these compounds will help the design and development of drug targets and lead compounds for new drug discovery.