Limonene is a major cyclic monoterpene hydrocarbon present in the essential oils of citrus fruits such as oranges and lemons. It contributes to their characteristic aroma and is widely used in fragrances, flavorings, solvents, and cleaning agents. Limonene exhibits antioxidant, anti-inflammatory, and antimicrobial activities. As a lipophilic volatile compound, it readily penetrates biological membranes and is rapidly absorbed and metabolized in humans. It is GRAS-approved by the FDA for use in food.