Journal of Medicinal Plants Biotechnology

Abstract Artichoke (Cynara scolymus L.), is a perennial herbaceous plant belonging to the Asteraceae family, which has both medicinal and nutritional properties. It seems that harvesting time has an important effect on the quantity and quality of plant products especially on secondary metabolites. In order to analysis of plant or field age on some physiological, biochemical and secondary metabolites characteristics of artichoke, a research project was carried out in a completely randomized design at the research field of medicinal plants at the University of Zanjan. One-year old and two-year old artichoke farms were selected as experimental treatments, and then three plots were randomly selected from each farm in which the plant specimens were taken and the desired traits were measured. According to the results: some traits such as: leaf dry weight, leaf length and width, amount of chlorophylls and carotenoids, root soluble proteins and carbohydrates increased at second year old plants. However; shoot soluble proteins and carbohydrate and also the total number of extracted secondary metabolites were decreased by increasing of plant age. D-methyl Buta Dienil (26.18 %), Pentacosadiynoic acid (21.24%), Inositol (10.97%) and Tetramethyl-octahydronaphthalen (9.61%) were the major compounds of one-year old artichoke plants and scyllo inositol (59.01%), methyl-hexadecatetra enoate (20.46%), isopropenyl-methanol (5.2%) and glucopyranose (4.71%) were the major components two-year old artichoke plant leaf extract.  It can be concluded that plant age has noticeable effects on growth and biochemical and specially on secondary metabolites properties of artichoke.

Abstract Saffron (Crocus sativus L.) is one of the oldest medicinal and spice plants in the world. In order to investigate the effects of plant age on secondary metabolites and some physiological factors of saffron, a research project was conducted in a completely randomized design with three replications at the research field of medicinal plants of the University of Zanjan. Three saffron farms with different biological ages of one, two and five years old were selected as experimental treatments, and then three plots were randomly selected from each farm and the desired traits were measured. Results showed that, increasing of the age of saffron plants in this experiment increased fresh weight of plant and dry weight of stigma. 5-yraes old plants showed the highest amounts of these traits. Whereas, the contents of soluble proteins and sugars and photosynthetic pigments were higher at first year and decreased by increasing of plant age. Number of secondary metabolites decreased when the age of plants increased as in one–year old saffron plants 26 metabolites and in 5-year old plants only 15 metabolites were detected. Loliolid (18%) and thymol (17%) in 1-year old plants and thymol (19%) and camphor (14%) in 5-year old plants showed the highest level among all detected secondary compounds. Generally according to these results, plant age has an important effect on the number and kinds of secondary metabolites in saffron which should be considered at the time of saffron harvesting.

Abstract Thyme is one of the most important medicinal plants which grows naturally in wide areas of range lands in Iran and simultaneously is cultured widely in Iran and other parts of the world. As Iran has placed in arid and semi-arid regions of the world, with actually low precipitation, doing projects in order to reveal the mechanisms or increase the drought tolerance of crop and medicinal plants has great value. Drought stress decreases the yield and quality of medicinal plants as well as crops. To investigate the mechanisms of drought tolerance of thyme plants and to evaluate the possibility of increasing of drought tolerance in these valuable medicinal plants, activity of some antioxidant enzymes and total soluble proteins were been analyzed in Thymus vulgaris L.in a complete randomized design experiment. After reaching to the adequate stage of growth, seedlings were grown in pots containing suitable soil, were subjected to different levels of drought stress (80% as control, 60% and 40% irrigation of field capacity(FC) as treatments). Results show that, drought stress had significant effect on total protein content as well as the activity of antioxidant enzymes. At 60% FC treatment and especially at 40% FC the amount of total soluble proteins drastically decreased. However; the activity of catalase increased at 60% FC treatment. The activity of peroxidase did not change significantly at 60% treatment but its activity decreased at 40% treatment. As a conclusion; it can be suggested that, one of the drought tolerance mechanisms of thyme is increasing of the activity of antioxidant enzymes especially the activity of catalase.  

Abstract Thyme is one of the high consuming medicinal plant in Iran and Thymus persicus is an Iran endemic thyme species which grows in heavy metal contaminated areas of Zanjan province. In order to study of the effect of Nickel and Cadmium on the secondary compounds of Thymus persicus, seedlings were cultured in different concentrations of Ni and Cd: 0 (control), 0.2, .04 and 0.6 mM in a hydroponic culture system. Three weeks after treatment, the N-Hexane extract of aerial parts of plants at control and heavy metal stress treatments were analyzed using GC/MS. According to the results; thymol, thymoquinone, linalool and formic acid were the main components of the extract at the control treatment. The percentage of thymol increased at all Ni and Cd concentrations except for the 0.4 mM Ni, however; the amount of thymoquinone, linalool and formic acid decreased at all heavy metal treatments comparing to control. It can be suggested that Ni and Cd had different effects on extract composition in this plant. Some major compounds of extract increased and some decreased which showed unpredictable consequences.