Journal of Medicinal Plants Biotechnology

Abstract The genus Thymus is one of the plants with a Mediterranean distribution. This plant has about 350 species and in Iran there are 14 species of aromatic and perennial plants that grow in mountainous areas and have an important impact on treatment, health and various industries due to having more than 20 types of major known chemical compounds. The percentage of thyme essential oil varies between 0.8 and 1.4 and most of its components include phenolic compounds, monoterpenes and sesquiterpenes. Thymol is the main component of phenolic compounds in the thyme plant. Thyme leaves are used in food products and the plant's essential oils is used in various beverages and pharmaceutical, health and cosmetic industries. Thyme oil has properties such as antispasmodic, carminative, antifungal, antibacterial, disinfectant, anthelmintic, antirheumatic, expectorant, antioxidant, natural food preservative and delaying the aging of mammals. Thyme essential oil is one of the ten famous essential oils that has a special place in global trade. This study provides a general overview of scientific research and findings, especially the species and morphological and phytochemical diversity of the Thyme genus. So far, much research has been conducted on this genus, but due to the high diversity of species in this genus, as well as diverse climatic and ecological effects and numerous subspecies, there is no appropriate conclusion in this regard. It is hoped that by summarizing the findings of the researchers, a new horizon can be opened in the study of endemic species of Iran and high-yielding varieties worldwide.

Abstract To investigate the effect of proline and gamma-aminobutyric acid on the quantitative and qualitative traits of medicinal plant chamomile (Matricaria chamomilla L.) under water deficit stress, an experiment was conducted according to split plots design with a completely randomized block arrangement with four replications during the spring and summer of 2024 in the research greenhouse at the University of Zanjan. The main factor consisted of two irrigation levels (70 and 100% of field capacity) and the subplots included foliar applications of two levels of proline (0.5 and 1 mM), gamma-aminobutyric acid (0.5 and 1 mM) and control treatment (distilled water).
The results showed that the highest chlorophyll a content (1.40 mg/g fresh weight) was achieved under 100% field capacity irrigation combined with 1 mM proline. Foliar application of 0.5 mM proline under 70% irrigation level resulted in the highest phenolic content (4.78 mg gallic acid/g dry weight) and the greatest total antioxidant activity (51.75%). The maximum flavonoid content (1.49 mg quercetin/g dry weight) was observed with 0.5 M GABA treatment. Additionally, the highest thousand-seed weight (148 mg) was recorded under full irrigation (100% field capacity) with 1 mM proline, compared to the control. Overall, the combined application of 0.5 mM proline and GABA was most effective in mitigating the adverse effects of drought stress on chamomile.

Abstract Taxanes are diterpenoid compounds with medicinal properties, obtained from various yew species (Taxus baccata). Among them, paclitaxel (Taxol) is the most important and is widely used in cancer chemotherapy. Due to the extremely low yield of taxol in yew plants, alternative production methods are necessary. Callus and plant cell culture present an environmentally friendly alternative for producing taxol and related taxanes. To enhance taxane production in cultured callus, various strategies such as elicitation can be employed. In this study, calli were treated with the elicitors chitosan (10, 30, and 50 mg/L) and jasmonic acid (50, 100, and 150 µM) in triplicate. The calli were maintained in B5 medium supplemented with 4 mg/L 2,4-D, 1 mg/L kinetin, 0.5 mg/L gibberellin, 10 mL/L antioxidant, 30 g/L sucrose, and 7 g/L agar, and incubated in darkness at 25°C for 21 days. The levels of five major taxanes: taxol, 10-deacetylbaccatin III, baccatin III, 10-deacetyltaxol, and cephalomannine were quantified using HPLC. The results indicated that the highest taxol and 10-deacetylbaccatin III contents were achieved with 100 µM jasmonic acid treatment. The maximum baccatin III yield was observed with 50 mg/L chitosan, while 10-deacetyltaxol production was highest with 50 µM jasmonic acid. Interestingly, the highest cephalomannine accumulation was found in the control (untreated) calli.