Clove trees (Eugenia aromatica) produces two cm long pink flowers that can be picked as buds and dried. These buds when dried turn brown, and at this point are referred to as cloves. Cloves are a common spice found throughout the World and have been historically recorded to be used by humans for thousands of years. Cloves are produced commercially mainly in Africa, but Brazil, India, Sri Lanka and Madagascar also export cloves. Cloves have been shown to possess medicinal properties in animals and humans, and this likely relates to the presence of essential oils in their flesh. The essential oil in cloves may possess antibacterial and antiseptic properties that make it useful in the treatment of infections. Some evidence also suggests that the essential oil is a mild anaesthetic, which is why it can be found in throat sprays and mouthwashes. The essential oil in cloves may also be beneficial to digestive function through the stimulation of acid secretion and peristalsis.
Eugenol is thought to be mainly responsible for the distinctive aroma and the warm taste of cloves. Many of the medicinal properties of the essential oil may relate to the presence of eugenol. However, other substances have been identified in cloves. The presence of methyl salicylate explains some of the pain relieving effects of cloves. Beta-caryophyllene is a sesquiterpene found in cloves, as well as the herb rosemary (Rosmarinus officinalis), hemp (Cannabis sativa) and black pepper (Piper nigrum), and may possess anti-inflammatory effects in animals. Measurements of the reducing power of cloves shows them to possess one of the highest antioxidant capacities of all spices. This may be explained by the presence of tannins, the flavonoids kaempferol, rhamnetin and eugenitin; as well as terpenes. However, it is likely other unidentified substances may also contribute to the reducing power of cloves. Cloves may also contain stigmasterol and campesterol, plant sterols that may affect plasma cholesterol levels.