Aromatherapy: The Science of Essential Oils

The history of aromatherapy begins over 3500 years BC. Aromatics were at the time for religious purposes, perfume, and medicine. Then, in 1910, René-Maurice Gattefossé, a chemical engineer from Lyon, discovered the therapeutic properties of pure lavender after an explosion in his laboratory, which left him with major burns. He treated them with lavender essential oil. Won over by that “miracle”, he founded the French Society of Aromatic Products and published around twenty works that are still considered references today. These works would give aromatherapy its reputation and its very name, as it was Gattefossé who coined the term “aromatherapy”, in 1935. He conducted many rewarding personal and scientific experiments on essential oils. Other scientists, such as Charles Chamberland, a biologist and assistant to Louis Pasteur, had already examined their spectacular antimicrobial action. In the 5th century BCE, Hippocrates was already treating patients with aromatic vapours. Aromatherapy is a branch of phytotherapy that uses the volatile active ingredients of aromatic plants. These are plants that have the ability to synthesize an essence. This science focusses on the use of essential oils for therapeutic, curative, or preventive purposes. For the most part, the essential oils are extracted by steam distillation of parts of the plant (such as leaves, flowers, or bark). Only the essences of citrus pericarp (such as orange or mandarin zest) tend to be obtained via mechanical cold pressing. In 1929, Sévelinge, a pharmacist from Lyon, demonstrated the antibacterial efficacy of certain essential oils.

Then, in the 1950s, a military physician used them to treat injured soldiers in Indochina. In 1975, Pierre Franchomme, a pharmacologist and aromatologist, brought about decisive progress by proposing that the concept of “chemotype”, the “plant’s true chemical ID card”, should be taken into account, listing the key aromatic compounds characterizing each plant and how they affect its properties. Today, aromatherapy is more frequently the focus of scientific studies. It is recognized as a fully-fledged branch of medicine. Over 17,000 articles on aromatherapy have appeared in an international high-level scientific publications.

The basis of healthcare has been medicinal plants from the dawn of humanity. For over 4000 years, people have carefully documented and passed down through generations the various ways in which these have been utilized. The Indian Vedic literature, which dates to roughly 2000 BC, contains a list of around 700 compounds. Cinnamon, spikenard, ginger, myrrh, coriander, and sandalwood are a few of these. Since ancient times, aromatic plant parts and oils have been used for their therapeutic and culinary characteristics, as well as to produce incense, perfumes, cosmetics, and for incense sticks. Ritual use was widespread in early cultures, where it served both sacred and therapeutic objectives that were intricately intertwined. Since prehistoric times, plant essential oils have been utilized in foods, aromatherapy, perfumes, cosmetics, spices, and alimentation. They have also been applied in other medical procedures and phytotherapy. In the current era of pharmaceutical science, interest in herbal medicines has grown relative to conventional or synthetic treatments because they are more affordable, more widely accepted, compatible with human physiology, and have fewer adverse effects. The medicinal properties and applications of an expanding number of emerging essential oils have been researched and documented by pharmacists. The interest in analysing their bioactivity has progressed owing to their widespread use, particularly the recently investigated antibacterial, antioxidant, anticancer, and antidiabetic effects. The traditional Indian or Ayurvedic system of medicine, as well as other ecumenical customary systems, would be transformed if plant predicated knowledge were to be incorporated. The uses of numerous plants for therapeutic, medical, aesthetic, psychological, olfactory, massage, aromatherapy, and other associated issues are examined in this chapter.

Essential oils which are complex blends of volatile compounds particularly present in a copious amount in aromatic plants, and are mainly composed of terpenes biochemically generated through the mevalonate pathway. In natural conditions, essential oils play a significant role in the defense mechanism of plants as antibacterial, antiviral, antifungal, insecticides and protect from herbivores by reducing their taste for such plants. Because of their chemical constituents, essential oil holds various biological activities such as antioxidants, antimicrobial, anti-inflammatory, etc. which finds important applications in food, cosmetic, agriculture, industrial, and medical fields. This chapter covers the chemical constituents and chemistry of essential oils on the one hand and their biological activities on the other hand.

Essential oils are natural plant products that have a wide range of applications in various fields like medicine, flavors, fragrance, etc. Their wide range of uses benefits people by exhibiting a variety of diverse properties like anti-allergic, antiinflammatory, antiviral, antibacterial, insect repellent, anticancer, anti-oxidant, and many more. They are also crucial to plants in terms of function. They are aromatic and are present in plants inside specialized cells or glands. Their biosynthesis occurs in the leaves and is present inside them until flowering. After the flowering of the plant, these oils get transferred to the flowers. These essential oils can be extracted using a variety of techniques, including solvent applications, steam distillation, and more. The quality and amount of essential oils in plants are affected by a variety of circumstances. These factors include the development stage of plants, the effect of UV radiation, the effect of Arbuscular mycorrhizal fungi, the effect of light quality, the effect of salt stress, and the effect of fertilizers.

The importance of medicinal plants in enhancing people's lives all around the world is undeniable. The primary metabolites of therapeutic plants are essential oils, which are widely used in a variety of businesses since their biological qualities were first identified in mythology. The biological effects of essential oils include insecticidal, antiviral, antibacterial, and antioxidant activities. These distinctive qualities raise their attraction and favourability in several international businesses. They are crucial as scent providers in the cosmetics business and have been employed as food preservatives in the food sector. Surprisingly, some components of essential oils are used in medicine since research has shown that some plant-based essential oils may be able to prevent, delay, or even reverse the growth of cancerous cells, the current focus is on investigating aromatherapy's potential in terms of Essential Oils biological qualities. This chapter's goal is to present a short and in-depth examination of Essential Oils’ cytotoxicity, activity, therapeutic and pharmacological potential, and common misunderstandings regarding these issues.

Some patients prefer complementary and alternative medicine treatments because they are under the impression that these methods are safer than conventional medication because of their “natural” origins. EOs can be used in a bath, during a massage, as a spray, a paste, a gel, or via inhalation. People think that these oils get into the skin through the upper dermis. There are different ideas about how aromatherapy could help people. The components of EOs are essential for the treatment and prevention of cancer; the processes responsible for EOs' antimutagenic capabilities are numerous. These EOs boost immunity, improve blood circulation, protect from respiratory and skin diseases, and improve digestion. These are also helpful in relieving pain in joints and muscular regions. Their importance in boosting brain functioning helps in the treatment of various neurological problems. They have a significant impact on resolving human reproductive issues. They play a significant role in modern medicine and are increasingly used to treat a wide range of illnesses. Their value as a natural remedy of last resort is universally acknowledged. Their increasing application to the treatment of human health issues has paved the path for natural aromatherapy to find widespread acceptance among the general public. 

When referring to a drug's active component as “Quinta essential,” Paracelsus von Hohenheim, a Swiss physician used the word “essential oil” for the very first time in the sixteenth century. Plant oils and extracts have been utilised for a variety of purposes for thousands of years. Essential oils have long been used in traditional medicine and by practitioners of alternative rejuvenation approaches. Because of their considerable immunomodulatory and antibacterial action, they have been used for many years to treat various ailments. Many volatile chemicals generated by plant secondary metabolism combine to make essential oils. Components of essential oil may be classified into two related types on a biosynthetic level. The two primary groups are terpene or terpenoid inchoation compounds, as well as aromatic and aliphatic components. Since the Middle Ages, essential oils have been utilized for antibacterial, biocidal, anti-fungal, antiprotozoal, and antifeedant purposes, as well as painkiller, calming, anti-inflammatory, anti-spasmodic, and locally anesthetic therapy.

However, little is understood about how essential oils function. Plant oils and extracts' antimicrobial characteristics have served as the foundation for a variety of enterprises, including pharmaceuticals, alternative medicine, and herbal treatments.

Essential oils have a direct influence on cancer cells along with an impact at a chemical level on the immune system. Essential oils work efficiently in getting rid of microorganisms and other foreign bodies from the human body by augmenting white blood cell activity. Many more small molecules change the way that the main components of many essential oils act. Furthermore, numerous components play an important part in various characteristics of essential oils like smell/fragrance, concentration, colour, texture, cell diffusion, lipophilicity/hydrophilicity, and fixation over cellular membranes and their distribution within the cell. Biologically, in the central nervous system disorders, volatile essential oils may affect synergistically along with the treatment drugs/chemicals. One of the important considerations is the specific time at which the plant possesses the highest quantity of volatile essential oils along with the chemical constituent mixture. Essential oils are a beneficial non-medicinal alternative and they could be included in routine conventional care for some particular health conditions when their protection and quality control issues have been calculated. Alternative medicine involving the usage of essential oils is hopeful to decrease the redundant effects of current medicine and if explored precisely, the therapy will benefit both the patients and the common man.