Clove (Syzygium aromaticum) and eugenol toxicity
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2022
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Abstract
Clove (Syzygium aromaticum) is one of the most valuable spices that has been widely used for many medicinal purposes and as a food preservative in recent years. The major bioactive compound found both in clove spice and clove essential oil is eugenol (4-all-methoxyphenol C10H12O2) with a ratio of 85%-95%. However, side effects of this alkylphenol on human and animal health have been known for decades. Its cytotoxicity and genotoxicity are the most important factors that limit the consumption of both eugenol and clove by humans. World Health Organization (WHO) specified the acceptable daily intake (ADI) of eugenol which is a maximum of 2.5mg per kg body weight. Different mechanisms of action have been proposed to explain cytotoxicity of eugenol: (a) oxidation of eugenol by peroxidases generates quinone methide intermediate which is toxic to hepatocytes; (b) high affinity of eugenol to plasma membranes due to its highly lipophilic nature results in cell damage; (c) the influence of eugenol on uncoupling of oxidative phosphorylation in mitochondria; (d) the prooxidant activity of eugenol triggers the formation of oxygen-free radicals that contribute to tissue damage; and (e) protein deactivation and consequently toxicity due to binding of lysine to eugenol. Nevertheless, more detailed in vitro and in vivo studies are still required to clearly reveal the mechanism of action of clove’s toxicity on human health. Toxic effects of spices and their essential oils may occur depending on their areas of use and they are usually dose-dependent.Toxic constituents are generated in three classes as low toxicity compounds, components less harmless than first class, and high toxicity compounds, respectively. This chapter discusses the toxicity of clove spice and eugenol due to their antifungal, antibacterial, and pharmaceutical uses. © 2022 Elsevier Inc. All rights reserved.