Document Type : Research Paper
Authors
Research Institute of Forests and Rangelands, Tehran, Iran
Abstract
The genus of Thymus presents 14 species in Iran, some of them are endemic (1). In this project some of the endemic and non-endemic Thymus species, named: T. pubescens Boiss. et Kotschy ex Celak, T. carnosus Boiss, T. kotschyanus Boiss and Hohen, T. persicus (Ronniger ex Rech. F.) Jalas and T. serpyllum L. were collected from different regions at before flowering and full flowering stage. The air-dried aerial parts of these species were steam distilled for obtaning their essential oils. The oil yields are as follow respectively: at before flowering (0.66%, 0.28%, 0.26%, 0.55% and 0.57%) and at full flowering stage (0.86%, 2.1%, 0.43%, 1.45% and 0.90%).
Totally the oil yields were lower for theses Thymus species before flowering. The highest oil yields were obtained from T. kotschyanus and T. pubescens.
Analysis and identification of chemical composition of the oils were performed by GC and GC/MS.
Thirty-seven components (representing 93.1%-98.3% of the oils) at before flowering stage and thirty-nine components (representing 88.2%-99.3% of the oils) at full flowering stage were identified.
The main components of the oils were as follow, before and full flowering stage, respectively:
T. carnosus, thymol (27.2% and 36.1%), g-terpinene (19.6% and 19.1%), p-cymene (26.2% and 21.3%), b-caryophyllene (2.5% and 2.8%), carvacrol (2.2% and 2.5%) and borneol (1.6% and 1.6%).
T. kotschyanus carvacrol (40.7% and 41.4%), thymol (26.9% and 19.5%), g-terpinene (7.3% and 10.3%), p-cymene (3.9% and 5.3%), b-caryophyllene (1.8% and 2.5%) and borneol (1.3% and 2.4%)
T. persicus (39.0% and 27.1%), thymol (6.5% and 11.9%), g-terpinene (6.1% and 6.5%), p-cymene (7.5% and 10.2%), b-caryophyllene (2.0% and 3.0%) and borneol (1.6% and 2.9%).
T. pubescens carvacrol (64.8% and 48.8%), thymol (11.9% and 13.9%), g-terpinene (6.1% and trace), p-cymene (2.9% and 12.7%), b-caryophyllene (1.5% and 1.3%) and borneol (0.7% and 3.8%).
T. serpyllum, thymol (18.7% and 18.7%), g-terpinene (21.9% and 22.7%), p-cymene (21.1% and 20.7%), b-caryophyllene (7.1% and 0.1%) and borneol (3.9% and 3.1%)
Geraniol (15.7% and 9.4%), Geranyl acetate (5.3% and 5.3%) and a-terpineol (0 and 9.5%) were found just in T. persicus oil before and full flowering stage, respectively. Germacrene D was also found in T. serpyllum oil (6.0% and 5.1%).
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