Exogenous L-Tyrosine Motivates Diversities in Horsemint Essential Oil

Abstract

Horsemint essential oil has many biological properties, such as antimicrobial, insecticidal, antifungal and antibacterial, which makes it used for medicinal, pharmaceutical and food purposes. Amino acid L-tyrosine has an active role in the physiology and production of essential oils. Therefore, the aim of this investigation was to evaluate the composition of horsemint essential oil in response to L-tyrosine applications. Horsemint plants treated with different doses of L-tyrosine (0, 150, 300, 450 and 600 mg/L) as a foliar spray. The essential oil was isolated from the aerial parts by hydrodistillation and analyzed by GC and GC/MS. Plants treated with L-tyrosine at 450 mg/L resulted in the maximum amounts of dry aerial parts (65.8 g/plant), essential oil percentage (4.1%) and essential oil yield (1.7 g/plant) at first harvest. Carvone was the major component, while oxygenated monoterpenes were the major chemical class. The highest value of carvone (68.6%) was obtained with essential oil isolated from plants exposed to L-tyrosine at 150 mg/L during first harvest. Essential oil extracted from pants treated with 600 mg/L L-tyrosine gave the maximum amount of oxygenated monoterpenes (83.2%) at first harvest. This study ascertained that the subordination of horsemint plants to L-tyrosine doses led to variations in the content of its essential oil production and components, and this, in turn, affected its biological activity.