The Phytochemical Composition, Biological Effects and Biotechnological Approaches to the Production of High-Value Essential Oil from Geranium

Geraniaceae family plants are highly reputed aromatic and medicinal perennial branched herbs. The high economic value of these plants is due to their secondary metabolites, especially essential oil of foliage, which is a complex mixture of volatile phytochemicals, such as terpenes, esters, aldehydes, alcohols, ketones and phenols. The main phytoconstituents of the essential oil belong to the terpenoid group of metabolites, such as monoterpenes, sesquiterpenes, diterpenes and their esters. Of these, geraniol, linalool, citronellol and their esters (50–70%) generally constitute a major portion of essential oil, responsible for its fragrance. Essential oil is biosynthesized in specialized tissues known as glandular trichomes present in leaves, green branches and fresh flowers. Geraniaceae family plants have been highly useful in the perfumery, cosmetics, aromatherapy, pharmaceuticals and food industries. Several pharmacological properties such as antifungal, anti-inflammatory, anti-cancerous, anti-depressant, antibacterial, antioxidant, antiseptic, anti-dysentery, and antidiabetic properties are attributed to the presence of geranium oil. Further, it improves blood circulation, treats congestion, cleans the lymphatic system, strengthens the immune system, and is effective in combating nervousness, constipation, insomnia, anxiety and high blood pressure. The chapter discusses the phytochemical composition, pharmacological properties, genomics of essential oil biosynthetic pathway, enhancement of essential oil yield, and several biotechnological approaches to enhance the quantity as well as quality of essential oil in geranium.