Some reports have indicated that the use of anti-inflammatory compounds may modify the progression of Alzheimer’s disease, since inflammatory processes have been linked with Alzheimer’s disease pathology. Some studies have indicated that non-steroidal anti-inflammatory drugs (NSAIDs), which inhibit cyclo-oxygenase activity, may reduce the risk of developing Alzheimer’s disease, and patients with rheumatoid arthritis, who often use NSAIDs, are suggested to have a lower incidence of Alzheimer’s disease. In addition to inhibition of cyclo-oxygenase, it has also been suggested that NSAIDs may act via other mechanisms such as anti-amyloidogenic effects. In view of the adverse effects commonly associated with cyclo-oxygenase inhibitors currently in clinical use, new anti-inflammatory compounds may be developed, including those which are naturally derived, which may have potential in modifying the progression of cognitive disorders such as Alzheimer’s disease with fewer adverse effects.
There are numerous examples of plant extracts and their constituents which display anti-inflammatory effects. Consequently, there is some potential for novel anti-inflammatory agents to be identified from plant sources, although plants as a source of new anti-inflammatory drugs have not been extensively exploited to achieve this aim. Various flavonoids have been associated with anti-inflammatory activity and may have potential for use in some CNS disorders in which inflammatory processes are known to occur. Some structural features of flavonoid molecules required for cyclo-oxygenase inhibition are considered to be the presence of a pyro-catechol group in at least one of the flavonoid rings; however, flavones lacking these substituents can also inhibit cyclo-oxygenase. Other plant-derived compounds with potential for use in inflammatory disorders include ferulic acid, which is an antioxidant and anti-inflammatory compound. Ferulic acid is of interest since it ameliorated the reduction in acetylcholine levels in the cortex and the inflammatory responses in the hippocampus induced by beta-amyloid in mice and, significantly, it also improved cognitive function.