Toxicity of Selected Monoterpenes and Essential Oils Rich in These Compounds

Summary & key facts

This paper reviews what scientists know about a group of natural chemicals called monoterpenes, which are common in many plants and in essential oils. The authors say these chemicals can do useful things, like act as antioxidants, kill bacteria, calm the nervous system, and reduce inflammation. But the review also points out that some monoterpenes can be toxic in certain amounts or situations, for example during pregnancy. The paper looks specifically at six monoterpenes and the plants and essential oils that contain them, and it reports that some cause serious problems such as damage to developing embryos, harm to nerves, allergic reactions, and damage to DNA.

Key facts:

• Monoterpenes are a large family of natural chemicals made by plants, and they appear in many herbs and other plants.
• Researchers have found that some monoterpenes can act as antioxidants, kill bacteria, have calming (sedative) effects, and reduce inflammation, so they are used in medicines, foods, and cosmetics.
• The review warns that although many monoterpenes are safe for food and medical use, some can be harmful at certain doses or in special situations like pregnancy.
• The paper focuses on six specific monoterpenes: alpha-terpinene, camphor, citral, limonene, pulegone, and thujone, plus the essential oils and plants that contain them.
• Reported toxic effects include embryotoxicity (harm to developing embryos), neurotoxicity (harm to nerves), allergenic reactions, and genotoxicity (damage to genetic material).
• The authors note that popular essential oils made from common plants can sometimes have toxic properties that many people do not expect.

Abstract

Monoterpenes make up the largest group of plant secondary metabolites. They can be found in numerous plants, among others, the Lamiaceae family. The compounds demonstrate antioxidative, antibacterial, sedative and anti-inflammatory activity, hence, they are often employed in medicine and pharmaceuticals. Additionally, their fragrant character is often made use of, notably in the food and cosmetic industries. Nevertheless, long-lasting studies have revealed their toxic properties. This fact has led to a detailed analysis of the compounds towards their side effects on the human organism. Although most are safe for human food and medical applications, there are monoterpene compounds that, in certain amounts or under particular circumstances (e.g., pregnancy), can cause serious disorders. The presented review characterises in vitro and in vivo, the toxic character of selected monoterpenes (α-terpinene, camphor, citral, limonene, pulegone, thujone), as well as that of their original plant sources and their essential oils. The selected monoterpenes reveal various toxic properties among which are embryotoxic, neurotoxic, allergenic and genotoxic. It is also known that the essential oils of popular plants can also reveal toxic characteristics that many people are unaware of.

Topics

Allelopathy and phytotoxic interactions Essential Oils and Antimicrobial Activity Ethnobotanical and Medicinal Plants Studies

Categories

Agricultural and Biological Sciences Food Science Life Sciences

Tags

Camphor Chemistry Citral Essential oil Food science Generally recognized as safe Lamiaceae Limonene Medicine Menthone Monoterpene Organic chemistry Pulegone Traditional medicine

Substances

Other