Plants have the incredible ability, throughout their developmental cycle, to synthesize the active compounds on which today's drugs and therapies are based. They are also able to synthesize compounds that protect them from outside influences (enemies) and release them into individual plant particles to activate them. Many plants are found on European soil, including the European spruce (Picea abies). Among many other important active substances, spruce also contains limonene, which, along with α-and β-pinene, is the main group of natural monoterpenes. Limonene, which is mainly found in the peels of citrus fruits, is a useful and sought-after compound in various fields due to its properties. In addition to its use in fragrances, flavors, and beverage additives, it is also used in industry as a solvent and cleaning agent. Due to its ecological potential and a broad spectrum of biological activity, it is classified as an extremely promising active ingredient. Due to limonene's known anti-inflammatory and antiviral activity, it also appears to be of interest in the context of the search for potential agents in the fight against SARS-CoV-2.