Effects of Foliar Applications of Various Zinc to Improve Estragol (Methyl Chavicol), Biological Activities and Introducing New Monoterpene Oxygenated of Horehound (Marrubium vulgare L.)

Marrubium vulgare (horehound) has been used to treat gastrointestinal disorders, inflammation. This plant has beneficial therapeutic properties and purifies the blood. In this research the changes in the composition of essential oils, aerial herb yield, and antioxidant activity of the aerial parts of Marrubium vulgare were determined at different treatments of zinc. An experiment was performed using completely randomized design (CRD) with five different treatments (T1= Control, T2= Zn sulfate, T3=Nano Zn, T4= EDTA- chelated Zn and T5= Citrate chelated- Zn) in three replications in Eram Garden greenhouse, Shiraz, Iran. The essential oil of air-dried samples was obtained by hydro distillation and analysed by gas chromatography/mass spectrometry (GC/MS). The result showed a significant difference between all zinc treatments for Estragol (methyl chavicol), biological activities and introducing new monoterpene oxygenated. The highest value of methyl chavicol was observed in zinc citrate (68.2%), followed by EDTA chelated Zn (51.2%), Zn sulfate (40.6%) and Nano Zn (18.5%), respectively. The highest essential oil (EO) content (w/w%) was obtained in the plants treated with Nano Zn (0.25%). The high antioxidant activity (735.3 mg/L) was found when Nano-Zn was applied. Results revealed that application of Zn to horehound may be very useful for the production of active natural compounds such as methyl chavicol for drug industries and medical materials.Abbreviations: DPPH: (2,2-diphenyl-1-picryl-hydrazyl-hydrate), EO: Essential oil, GC/MS: Gas chromatography/ mass spectrometry, HEO: Horehound essential oil.