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Characterization and Quantification of Predominant Active Substances in Different Phenological Stages of Two Thymus daenensis Chemotypes through LC-MS/MS and GC
Hossein Ahmadi, Mohammad Reza Fatahi Moghadam, Zabihollah Zamani, Majid Shorpoor, Esfandyar Jahantab, Mohammadreza Morshedloo,
Volume 17, Issue 4 (2-2024)
Abstract
Background and objectives: Thymus daenensis, a thymol-rich thyme, is one of four endemic species of this genus in Iran, known for its pharmaceutical properties such as expectorant influence, antimicrobial, antifungal, and anti-inflammatory effects, primarily attributed to its metabolically active substances. This study aims to characterize and quantify the predominant active substances in different phenological stages of two Thymus daenensis chemotypes through LC-MS/MS and GC.
Methodology: Six genotypes from two phytochemically extreme Thymus daenensis Celak ecotypes (Zagheh and Malayer) were vegetatively propagated through stem cuttings (using 1000 ppm IBA hormone) in a greenhouse. Each clone consisted of at least eight individual plants. After well-rooted cuttings were transferred to eight-liter pots for further growth until cultivation in the farm. In the field, plants were adequately watered through drip irrigation and fertilized with 20:20:20 (N:K:P) fertilizer. Essential oil (EO) content, phenols, flavonoids, percentage of EO components, and antioxidant capacity of methanolic extracts were assessed in these clones at different phenological stages (vegetative, flower budding, early flowering, and full flowering) and in two organs (leaves and flowers). The data were analyzed using a two-factor full factorial experiment based on a completely randomized design (CRD).
Results: Malayer ecotype exhibited higher fresh weight, dry weight, vertical growth form, and significantly (65%) higher EO content than Zagheh ecotype. GC-MS analysis identified 24 constituents accounting for over 95% of essential oils, with thymol, carvacrol, carvacrol methyl ether, p-cymene, and γ-terpinene as the major components. Thymol content was 33% higher in Malayer ecotype (thymol chemotype) than Zagheh ecotype (thymol/carvacrol chemotype), while carvacrol content in Zagheh ecotype (~15%) was 13 times higher than Malayer ecotype. The highest amounts of thymol-carvacrol and p-cymene-γ-terpinene were observed in early flowering and vegetative stages, respectively. EO content and antioxidant properties peaked at the full flowering stage, with higher values in flower tissues than leaves. Regression analysis revealed negative and second-order relationships between p-cymene and thymol content, and between γ-terpinene and thymol content, as well as a significant linear relationship between p-cymene and γ-terpinene content. LC-MS/MS analysis identified 14 polyphenols and flavonoids, with rosmarinic acid and caffeic acid quantified through HPLC-PDA. Rosmarinic acid content was higher in Malayer samples, while Zagheh showed higher caffeic acid content, both peaking at early and full flowering stages.
Conclusion: Harvesting Thymus daenensis at the early flowering stage (~20% of flowers opened) is recommended for the highest biomass, EO, and thymol/carvacrol content. However, for higher antioxidant properties and phenols, harvesting at the full flowering stage (~90% of flowers opened) is advisable. Generally, the Malayer ecotype exhibited relative superiority in performance and essential oil production.
 
The effect of environmental factors on the quantity and quality of the essential oil (Thymus lancifolius Celak) in Hamadan province.
Mohamadreza Sadeghimanesh, Zeinab Jafarian Jeloudar, Jamshid Ghorbani, Razieh Azimi,
Volume 18, Issue 3 (1-2025)
Abstract
Background and objectives: Thymus lancifolius Celak is distributed in Hamedan Province, ranging from altitudes of 1450 to 3200 meters. This study aims to evaluate different ecotypes to identify those with the highest essential oil content and to determine the relationship between soil and climatic characteristics and the quantity and quality of essential oil for domestication purposes.
Methodology: Thymus lancifolius Celak variety in Hamedan province has five important habitats that are scattered in different regions of the province, which include Bahar, Razan, Tuyserkan, Hamedan and Malayra city. In this study, the branchs of the Thymus lancifolius was collected at the 50% flowering stage from its regions. Essential oil of plant samples extracted which collected from each region. After determining the essential oil yield, essential oil components and their amounts were determined by GC and GC / MS devices. The relationship between climatic and soil characteristics of the studied areas with the amount of essential oil and its components was investigated. From each habitat, 5 soil samples were collected from a depth of 30 cm and a total of 15 samples from five habitats were collected. Soil characteristics include soil texture by hydrometric method, soil moisture by weight method, acidity by saturated mud method, electrical conductivity by extraction method and EC meter, percentage of organic matter, lime, absorbable phosphorus by using spectrophotometer, potassium by using from the film photometer device and total soil analysis using the Kjeldal method were measured. The available climatic parameters including rainfall and temperature of different habitats in the statistical period of 2009 to 2020 were obtained from the nearest weather stations.
Results: The comparison of the soil properties of the studied habitats showed that in the areas where the amount of soil lime was higher, the plants had a higher percentage of essential oil. The results showed that the essential oil content of the studied samples ranged from 1.91% to 3.85%. The highest percentage of essential oil was observed in Asadabad ecotype and the lowest percentage of essential oil was obtained in Malayer ecotype. The highest amount of Thymol was observed in Hamedan ecotype (71.43%) and the lowest amount was observed in Razan ecotype (7.04%), while the highest amount of Carvacrol was observed in Malayer ecotype (23.52%) and the lowest amount was found in Razan ecotype (0.36%) was observed. The highest amount of Geraniol (53.15%) and linalool (7.04%) was observed in the resin ecotype, which is due to the optimal environmental conditions of this habitat due to its location in the Mediterranean climate. The results of the correlation between the percentage of essential oil with climatic characteristics showed that the percentage of essential oil of ecotypes had a positive and significant relationship with the average annual humidity and a positive relationship with the amount of rainfall, the temperature of the first six months of the year and the direction of the slope and a negative relationship with the altitude.
Conclusion: The largest thyme habitats were in areas with moderate to high slopes and northern and northwestern aspects. These correlations are useful for determining secondary cultivation environments. Identified chemotypes for cultivation include Thymol in Hamedan, Carvacrol in Malayer, Thymol/γ-terpinene in Asadabad, and Geraniol in Razan. These can be used in pharmaceutical and health industries while ensuring sustainable protection.
 
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