Perilla alcohol is a naturally occurring monoterpene related to limonene. It is isolated from the essential oils of lavender, peppermint, spearmint, cherries, celery seeds, and several other plants. It has been used topically as a mosquito repellant and in toiletries and may be touted as a constituent of natural products such as tart cherry juice. Perillyl alcohol has demonstrated antiangiogenesis and anticancer effects in vitro. Purported mechanism of action is suppression of the synthesis of small G proteins, including RAS, thereby arresting tumor cells in the G1 phase of the cell cycle. Early clinical studies did not efficacy in prostate, ovarian or breast cancer, probably due to bad pharmacokinetic properties and toxicity after oral administration. More recent preliminary studies found intranasal delivery in patients with malignant gliomas to be well-tolerated and effective, with one study reporting tumor size regression, and another reporting increased overall survival and no side effects after long-term use.