Master Molecules of Spices

Spices are natural products of plant origin, used primarily for flavoring, for seasoning, or for adding pungency and color or all of them to foods and beverages. All spices are medicinal and are being used extensively in the traditional systems of medicine such as Ayurveda, Unani and Sidha and in the herbal medicines of the West. Some of the spices (pepper, long pepper, ginger, etc.) are among the most important and inevitable ingredients in the indigenous medicines. These three spices together constitute the “Trikatu,” the three acrids that cure the three discorded humors – vata, pitta, and kapha – and help to maintain normal health. The founder of Ayurveda in his lexicon Charaka Samhita lists 32 spices for the preparation of various formulations (see chapter “Spices: Definition, Classification, History, and Role in Indian Life” of this book). The spices become important in healthcare due to the presence of diverse types of secondary metabolites synthesized by the plants. Secondary metabolites are small organic molecules originated from primary metabolites during the metabolism of plant (hence they are termed secondary metabolites), and they characteristically have molecular masses of less than 3000 da. They are not directly involved in growth and development, another reason to christen them as secondary metabolites. In general, they are produced from biosynthesis modifications, such as methylation, glycosylation and hydroxylation. Though secondary metabolites are not essential for growth and development of plants, they are essential for the survival of plants in unfavorable environment and to overcome various stresses that the plants are subjected to. Secondary metabolites are important for contributing to the flower color, fragrance, and flavor and for attracting pollinators. They are also involved in the interaction of plants with symbiotic microorganisms and tolerance against insect pests and diseases. Secondary metabolites contribute to frost tolerance, nutrient storage, and protection from UV radiation, serve as chemical signals, and aid in the adaptation of plants to adverse environmental survival and growth conditions. Some of the secondary metabolites are playing significant roles in the prevention and protection of human health. Such health-promoting actions include antioxidant, cholesterol lowering, antibacterial, insecticidal, antifungal, antitumoral, antimicrobial, antibiotic, anticancer, and so on. Many secondary metabolites are being used as curative drugs. Though most spices have beneficial effects on human health, some are exceedingly useful both as curative medicines and as nutraceutical agents. Such spices include turmeric, ginger, black pepper, long pepper, garlic, black cumin, rosemary, wasabi, etc. Apart from the curative properties, spices are in fact more significant as nutraceuticals. Many spices can contribute to human wellness by avoiding many ailments including the lifestyle diseases. In the last few decades, several health beneficial effects of spices (both curative and preventive) have been experimentally documented, which suggest that the use of spices extends beyond taste and flavor for which they have been using universally from ancient times. The emerging research from in vitro and animal studies have given excellent positive indication that spices can be used as nutraceuticals for preventing many ailments inflicting the humans. Such preventive (as well as curative) benefits of spices include digestive-stimulant action, antiatherogenic and cardioprotective potential, antilithogenic property, antidiabetic influence, anti-inflammatory property, and cancer-preventive potential. Many spices possess strong anti-oxidative effect, which is of particular importance for preventing oxidative stress, thereby preventing the onset of degenerative diseases such as cardiovascular disease, neurodegenerative disease, inflammatory disease, and cancer. Spices deserve to be the essential ingredients of our daily diet. Especially worth mentioning are the cancer prevention properties of spices, and diverse mechanisms are proposed for such anticancer properties. Spices are taking on this new role as nutraceutical, going beyond their role of imparting taste, flavor, and color to our food. Spices and their phytochemicals fight chronic diseases of humans by influencing the actions of a variety of cellular molecules such as interleukins, cytokines, chemokines, enzyme proteins, effectors, transcription factors, signaling pathways, and so on, and they in turn led to the downregulating or upregulating the cellular functions. A summary of such events taking place in a cell facing a disease condition is in Fig. 2. Out of the many phytochemicals of spices, there are a few, which are often considered superior in their health benefits. This chapter looks at in depth four such health-giving and health-promoting nutraceutical phytomolecules, namely, (1) black pepper (Piper nigrum) and its master molecule piperine, (2) garlic (Allium sativum) and its key compounds diallyl sulfide and diallyl di-sulfide (DAS/DADS), (3) ginger (Zingiber officinale) and its major compounds gingerols, and (4) turmeric (Curcuma longa) and its key molecules, the curcumin and its derivatives, curcuminoids. The master molecules mentioned are discussed fairly in detail in the light of the current knowledge on the mechanisms involved in their actions and their mode of protection offered to the biological systems, cells, animals, and humans. The information presented here come from diverse sources, and the author has merely collected and collated the information for the benefit of the students, teachers, and general readers interested in spices. The chapter has an exhaustive list of references and also a list of abbreviations used in the text and their extended forms and meanings.