Echinacea

摘要

The plant commonly known as echinacea, used widely as an alternative medical technique in Europe, is becoming increasingly popular in the United States. It is native to the central United States and, historically, is one of the most important plants used medicinally by North American Indians. Today, echinacea is primarily used for its immune–stimulating and anti–inflammatory effects. Recent studies have indicated that several of its active components–high molecular weight polysaccharides, alkamides, and echinacoside–are very effective in mediating these effects. The polysaccharides have been shown to induce acute phase reactions in humans, activate phagocytes in humans and mice, and protect mice against lethal infection doses with Listeria monocytogenes and Candida albicans (3, 5). Inflammatory responses have been proven to be alleviated by alkamide inhibition of the enzymes 5–lipoxygenase and cyclooxygenase, both responsible for arachidonic acid metabolism to leukotrienes and prostaglandins respectively (2). Echinacoside was shown to strongly protect collagen from free radical attack, suggesting the use of echinacea extracts for the prevention of skin photodamage (1). Increasing concentrations of echinacea extracts given to normal individuals and patients with either chronic fatigue syndrome or AIDS caused increased antibody–dependent cellular cytotoxicity and natural killer cell function (4). The long history of successful echinacea use both in the United States and in Europe combined with the research which is now coming to light prove that it is deserving of continued attention by scientists and especially by clinicians seeking alternative ways to help their patients.