Farmacja Polska (Jan 2021)
Trans-cinnamaldehyde: biological properties and applications in cosmetology
Abstract
Trans-cinnamaldehyde (cinnamic aldehyde; (2E)-3-phenylprop-2-enal) is an simple organic compound, an unsaturated aldehyde, naturally occurring in plant species of the genus Cinnamomum. The greatest quantities are found in essential oils obtained from Cinnamomum zeylanicum and Cinnamomum cassia. It is a tree of the laurel family (Lauraceae), native to Ceylon. It occurs in the form of a yellow liquid with a characteristic, intense cinnamon scent. In laboratory and industrial conditions, it is obtained using many patented methods. The most common of these is the condensation of benzaldehyde with acetaldehyde. Due to its interesting aromatic qualities and multidirectional biological activity, it is widely used in food products and household chemicals. In the pharmaceutical industry it is used to improve the odor and the taste of drugs, especially those containing bitter substances. However it is also an important ingredient of many cosmetic products. It has antimicrobial, anti-inflammatory and antioxidant properties. In addition, there are reports of its anti-cancer effect, a positive effect on the heart function and in the treatment of diabetes. Trans-cinnamaldehyde is generally recognized as Generally Recognized As Safe (GRAS) by the US Food and Drug Administration (FDA). However, despite the many positive aspects of trans-cinnamaldehyde, in the literature data on numerous side effects caused by its high concentrations can be found. This compound is described as a sensitizing agent and its irritating action is mainly directed at the skin. In cosmetics it is significant allergenic substance. Trans-cinnamaldehyde is an agonist of the TRPA1 receptor and can cause allergic contact dermatitis and non-immune contact urticaria, which are classified as contact eczema. Cinnamaldehyde is also used in patch tests, which are the basis for diagnosing allergies to cosmetic ingredients. Therefore, although it is considered a safe substance, due to its allergenic and irritating effects, its content in cosmetic products is subject to certain restrictions and it should not exceed 0.05%.
Keywords
