Perillyl alcohol and its precursor limonene are naturally occurring monocyclic terpenes derived from the mevalonate pathway in plants. Perillyl alcohol can be found in the essential oils of various botanicals, such as lavender, lemongrass, sage, and peppermint. It has a number of manufacturing, household, and medical applications. For example, perillyl alcohol may be used as an ingredient in cleaning products and cosmetics, and it has shown promise for inhalation therapy of patients with brain cancer. Perillyl alcohol is only produced by certain botanicals, not by animals or humans. It is a metabolite of limonene, which itself is formed from geranyl pyrophosphate in the mevalonate pathway. Conversion of limonene to perillyl alcohol is accomplished via hydroxylation by enzymes that belong to the superfamily of cytochrome P450 proteins. Perillyl alcohol can be metabolized further to perillaldehyde (perillyl aldehyde) and perillic acid.
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