Neurodegenerative diseases are a group of progressive neurological disorders that damage or destroy the function of neurons. Every year, more than 10 million people suffer from neurodegenerative diseases globally, and this figure is expected to grow by 20% over the next decade [1
]. The incidence of neurodegenerative diseases among people living in the Asian subcontinent is much lower than in North America. Why people from some countries are more prone to these diseases than from other countries is not fully understood. A report indicates that the market value for neurodegenerative diseases will be $30 billion in 2012 [1
] with approximately 150 compounds in clinical development [2
]. One of the major disadvantages of the currently available treatments for neurodegenerative disease is that they result in multiple side effects.
Although multiple factors are involved in the development of neurodegenerative diseases, dysregulation in the inflammatory network and oxidative imbalance are key components in the pathogenesis of diseases such as Alzheimer’s disease, Parkinson’s disease, brain tumors, and multiple sclerosis [3
]. The prevention of neurodegenerative diseases has been one of the primary goals of researchers, but to make prevention feasible, two objectives must be accomplished: (1) individuals at high risk for the disease must be identified before the symptoms become evident, and (2) compounds that are safe and effective in either reducing or slowing the disease progression need to be developed. Unfortunately, to date, no such safe preventive agents are available. Therefore, there is an urgent need for agents that are pharmacologically safe, cost-effective, and immediately available with minimal side effects.
Spices are one such source that has been used in cooking to add flavor and color to the food. A spice is a dried seed, fruit, root, bark, or flower of a plant. The use of spices has shaped a large part of the world’s history. For example, the ancient Egyptians pioneered maritime trade to fetch the incense of Arabia; Greco-Roman navigators found their way to India for pepper and ginger; Columbus sailed west for spices; Vasco de Gama sailed east for them; and Magellan sailed across the Pacific Ocean on the same quest. Despite globalization, persons in Asian countries are still the largest consumers of spices. In ancient times, many spices were used as medicines for treating several diseases such as rheumatism, body ache, intestinal worms, diarrhea, intermittent fevers, hepatic diseases, urinary discharges, dyspepsia, inflammation, constipation, and dental diseases [6
]. What was in such spices and how they exerted these activities remained obscure for ancient peoples. Modern molecular tools have shown that spices have active components, called nutraceuticals that contribute to the plethora of properties. Extensive research over the years has also identified the molecular targets of most nutraceuticals [7
]. During the past decade, a number of nutraceuticals have been identified from spices (). These nutraceuticals are chemically diverse () with a plethora of effects ().
Spices with potential against neurodegenerative diseases
Chemical structure of common nutraceuticals derived from spices
Effects of spice-derived nutraceuticals on neurodegenerative diseases
In the present review, we discuss how spice-derived nutraceuticals have been used against neurodegenerative diseases. The nutraceuticals have been shown to exert their effect against various neurodegenerative diseases by modulating multiple signaling pathways. For example, curcumin, the yellow curry spice, has been shown to exert its activity against Alzheimer’s disease through destabilization of fAbeta [10
], inhibition of NF-κB [11
], and inhibition of Egr-1 DNA-binding activity [12
]. Here, we focused on the most popular nutraceuticals such as curcumin, apigenin, kaempferol, capsaicin, eugenol, anethole, and gambogic acid and discussed how they have been used against neurodegenerative diseases.