Why do roses smell good? Before we answer that question, let's take a step back. Roses, a member of the Rosaceae family, are among the most beautiful and prized flowers. They are ancient flowers, with the earliest fossil evidence dating back about 35 million years. There are about 150 species and they are most common in the temperate zones of the Northern Hemisphere.
Love for roses dates back to ancient times
Already widely used by the ancient Romans, roses have always been symbols of beauty and love, but also of war and politics. In the 15th century, the rose was used as a symbol by rival factions during the "War of the Two Roses", fought for control of England between the Yorks, symbolized by the white rose, and the Lancasters, represented by the red rose.
Visually, there are many colors to choose from: from white to various shades of yellow and pink, without forgetting the classic and timeless red rose. Another distinctive feature is, of course, their scent. The scent of roses is made up of hundreds of volatile compounds, and in some species more than half of these compounds are organic in nature, called "monoterpenes".
What are terpenes?
Terpenes are a group of organic compounds widely found in nature, components of resins and essential oils extracted from many plants. They are generally volatile and have a distinctly pleasant odor. They are used in cosmetics, pharmaceuticals, paints and other areas of the chemical industry.
Chemically, their molecular structure is defined by multiples of a 5-carbon atom unit called isoprene (2-methyl-1,3-butadiene). The isoprene units are usually arranged in a head-to-tail pattern, and according to the number of units it is possible to distinguish: monoterpenes (2 isoprene units), sesquiterpenes (3 isoprene units), diterpenes (4 isoprene units), triterpenes (6 isoprene units), and polyterpenes (isoprene units greater than 6). In addition, when terpenes have oxygen-containing functional groups in their molecular structure, they are called terpenoids.
The main components of rose scent
In 2011, an article published in the Journal of Chemical Education by Albrecht Mannschreck and Erwin von Angerer of the University of Regensburg, Germany, identified the main molecules responsible for the enchanting scent of roses. Geraniol, citronellol and β-damascenone are the three molecules identified by the authors of the study.
Why do roses smell good? Thanks to geraniol, citronellol and β-damascenone.
Geraniol, which is very present in rose oil, is a monoterpene alcohol. Some important aspects about geraniol that have come to light in recent years are related to its possible applications in the pharmacological field.
There are numerous articles in the scientific literature highlighting the anti-inflammatory, anticancer, antioxidant, cardioprotective, neuroprotective and antimicrobial properties of geraniol. In short, geraniol not only contributes to the wonderful scent of roses, but is also emerging as a promising pharmacological candidate.
Citronellol, also a monoterpene alcohol, occurs naturally in the form of two isomers called (+) and (-). Of the two, the (-) isomer is the least abundant and is the one found in rose oil. β-Damascenone, unlike geraniol and citronellol, is not a monoterpene but belongs to the ketone family. It is a major contributor to the aroma of roses, although it is present in small amounts.
Why do roses smell and why do we like them so much? Brain and smell
The sense of smell is the sense for the perception of odors and it plays a major role in physiological effects. The mechanisms behind olfaction are both complex and fascinating. In general, the olfactory process begins with the attachment of odorant molecules to the cilia of olfactory receptors located in the nasal cavity. The activation of specific receptors then promotes the generation of electrical signals that are transmitted to the brain.
These signals can modulate brain functions, affecting thoughts, emotions and memory. In addition, several studies have shown that the inhalation of scented substances can significantly affect several physiological parameters such as: blood pressure, muscle tension, pupil dilation and heart rate.
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