| چکیده انگلیسی مقاله |
Dill (Anethum graveolens L.) is an aromatic annual plant with strong medicinal properties, belonging to the Apiaceae family, and is widely cultivated in Iran and globally. This study focused on the phytochemical diversity of dill ecotypes from Arak, Jahrom, Malayer, Jolfa, and Kashmar to examine essential oil quantity and quality. Seeds from the studied ecotypes were collected, and their germination rates were determined. They were then cultivated and grown to the full flowering stage. At full bloom, the plant organs were harvested and dried in the shade. Essential oils were extracted using water distillation with a Clevenger apparatus, and the yield was calculated. The highest essential oil yield (0.34%) was obtained from the Kashmar accession, while the lowest (0.06%) was from the Arak accession. GC/MS analysis identified 71 compounds across the five ecotypes: 26 from Arak, 34 from Malayer, 26 from Jahrom, 42 from Jolfa, and 37 from Kashmar. Santolina triene had the highest concentration (0.591%) in the Jahrom accession, while cineole had the lowest (0.016%) in the Malayer accession. Compounds consistently present included α-phellandrene, D-limonene, limonene, p-cymenene, carvone, dihydrocarvone, trans-dihydrocarvone, dihydrocarveol, piperitenone oxide, myristicin, elemicin, apiol, and oleic acid. These findings provide valuable insights for conserving Iranian dill germplasm and for introducing these ecotypes to the food, pharmaceutical, and cosmetic industries.
Keywords: Essential oil, dill, phenylpropanoid, monoterpenoid
Introduction
The increasing demand for healthy and safe food products, driven by their impact on human health and environmental considerations is a significant concern. This is especially important for medicinal-edible plants that are directly related to human health (Rostaei et al., 2018). The climatic diversity of Iran has created unique natural habitats for medicinal plants, leading to a wide variety of these plants (Sarabi & Sefidkon, 2017; Nikrouz-Gharamaleki et al., 2019). Sustainable exploitation and conservation of these plants require awareness and management of their natural diversity. Dill (Anethum graveolens L.) is an edible-medicinal plant with essential oil that finds applications in various industries due to its valuable secondary metabolites (Setayesh-Mehr & Ganjeali. 2013; Pakravan et al., 2016). The reported medicinal effects of dill include anticancer, antifungal, antioxidant, antibacterial, cardioprotective, anti-diabetic, kidney protective, antidepressant, anti-inflammatory, analgesic, protective and antisecretory effects on gastric mucosa, increased progesterone concentration, and anti-diarrheal properties. This study examined the native ecotypes of dill from different regions of Iran and their phytochemical diversity in terms of essential oil to determine their variability in the quantity and quality of the extracted compounds. The results can be effective in the identification, management, and conservation of the natural germplasm of dill, and the selected ecotypes can be used in modern agricultural systems.
Materials & Methods
Fifty grams of dried samples of each variety were used for essential oil extraction using a Clevenger apparatus. To separate, identify, and quantify the compounds present in the extracted essential oil, a GC/MS device was utilized. Following preparation, 1 microliter of essential oil from each sample was injected into the device to determine the types of compounds present. After separation, the percentage of the essential oil components was calculated using the retention index. Finally, the proposed compounds were downloaded from the computer library connected to the device in separate files and compared with standard compounds from reputable sources (Adams, 1995; NIST WebBook). The gas chromatography device, equipped with a spectrophotometer detector, was manufactured by Agilent, USA. It featured the Agilent 7890B Series GC and Agilent 5977 Series MSD, which supports liquid sample injection with a Split/Splitless Inlet dilution. Additionally, the device offers the capability to perform qualitative and quantitative identification using a mass spectrometer detector (MSD).
Research Findings
The results of this study showed that the essential oil yield of the ecotypes varied from 0.06% to 0.34%. There were differences among the evaluated ecotypes in terms of the quantity and type of compounds. In total, 71 compounds were identified across the five ecotypes, with the highest amount (0.591%) related to Santolina triene in the Jahrom ecotype, and the lowest amount (0.016%) related to Cineole in the Malayer ecotype. Of the 71 identified compounds, 13 compounds—α-phellandrene, D-limonene, limonene, p-cymenene, carvone, dihydrocarvone, trans-dihydrocarvone, dihydrocarveol, piperitenone oxide, myristicin, elemicin, apiol, and oleic acid—were produced in all ecotypes in varying amounts. Among these 13 compounds, the first eight are cyclic monoterpenoids, and piperitenone oxide is biosynthesized through the methylerythritol phosphate (MEP) pathway in the plastid.
Discussion of Results & Conclusion
The yield of essential oil can be affected by environmental, genetic, and plant organ factors. When examining the impact of plant genetics on essential oil yield, a study on the essential oil of different ecotypes of dill reported that the essential oil content varies from 0.22% to 0.46% across ecotypes (Mohebodini and Farmanpour-Kalagh, 2021). This finding is consistent with the results of this study, which also observed variability in essential oil content among different ecotypes. Given that the ecotypes studied were collected from different regions of the country but cultivated under the same climatic conditions, the phytochemical diversity of the essential oil-based ecotypes showed significant differences in terms of yield and constituent compounds. Across all ecotypes, 13 compounds were produced, but their amounts varied among the five ecotypes. The compounds dihydrocarvone, trans-dihydrocarvone, carvone, elemicin, and apiol were identified as the dominant compounds in these ecotypes. These differences can be attributed to the genetic potential of the studied ecotypes under the climatic conditions of the cultivation site. This genetic potential has facilitated the production of various monoterpenoid and phenylpropanoid compounds. Thus, the information obtained from this study can be useful and effective in identifying and introducing specific ecotypes for the extraction and production of valuable compounds for the food and pharmaceutical industries. |