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Phenolic compounds, especially those with plant origin, constitute an essential part of the human diet due to their antioxidant properties. Antioxidants protect biological systems (nucleic acids, proteins, lipids, lipoproteins) against free radicals and reactive oxygen species. Some medicinal plants contain so high amounts of antioxidants that their use can be considerably effective for human health. The aim of this study was to evaluate the effect of flooding extraction method on phenolic compounds, flavonoids and the level of free radical scavenging properties of medicinal plants including Thyme, Hamadani Yarrow, Shirazi mountain thyme, Yarrow, Chamomile, Saffron corm hyssop Sagebrush, wormwood, Artemisia and Ziziphora clinopodioiedes, in four extraction solvents including water, methanol, acetone and ethanol. The results showed that methanol and water solvents had the highest and the lowest total phenolic, flavonoid and antioxidant activity, respectively. The results also showed that methanol extraction of Shirazi thyme and water extraction of Wormwood plant had the highest and the lowest phenol and flavonoids contents, respectively. The results of trapping the free radicals of DPPH indicated that the methanol extract of Shirazi thyme and aqueous extract of wormwood had the highest and the lowest inhibition activities, respectively. Therefore, the selection of solvent type can affect the rate of the extraction of phenolic compounds, flavonoids and antioxidant activity.
 

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Peroxidase catalyzes different oxidation of substrates using hydrogen peroxide, a reactive oxygen specie (ROS). ROS, at low concentrations, act as messenger to regulate intracellular signaling, whereas, at high concentrations, they can overcome the immune system by creating oxidative stress. Some common beverages such as coffee, tea and soft drinks contain high levels of xanthine alkaloids including theophylline and theobromine. In this study, the effect of theophylline and theobromine on peroxidase activity was kinetically studied by measuring the absorption of 4-aminoantipyrine, oxidized in the presence and absence of theophylline and theobromine at 510 nm for 3 minutes. The results showed that theobromine and theophylline acted as inhibitors with IC₅₀ of 0.50 and 0.55 mM, respectively. K_m and V_max values showed that both compounds are non-competitive inhibitors. The values of K_i were calculated as 0.03 and 0.045 mM for theobromine and theophylline, respectively. Lower values of K_i and IC₅₀ for theobromine compared to theophylline indicates that theobromine has a higher inhibition strength and binding tendency to the enzyme-substrate complex. Hence, it is concluded that theobromine has a stronger inhibitory effect on POD activity.
 
 

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Basil is an important medicinal plant, belonging to the Lamiaceae family. Basil is used for the treatment of different diseases such as stomachache, headache, constipation, fever and infections, as well as to reduce and regulate the blood sugar. Moreover, Basil is known for its antibacterial, antifungal and antioxidant properties. In this study, the impact of drought stress on phenols and flavonoids concentrations, as well as the antioxidant activities of leaf extract of three basil cultivars were investigated. Seeds of basil cultivars (mikhak, green, purple) were cultivated in sand-loamy soil and drought stresses (75%, 50% and 25% of the field capacity) were applied on six-leave plants. Experiments were conducted in a completely randomized design and three repeats. Total phenols, total flavonoids and flavonols concentrations of basil leaf extracts and their antioxidant activities were measured. The maximum values (with significant differences) of three groups of non-enzymatic antioxidants and the highest levels of antioxidant activities were observed for green cultivars under mild stresses (75% of the field capacity). It was observed that antioxidant activities were elevated by the increase of the concentration of the plant extract. Drought stress results in oxidative stress in basil plants. Phenols, flavonoids and flavonols are well-known as strong antioxidants have a role in the plant’s protection against the oxidative stress. In thrice cultivars of basil which were investigated, concentrations and abilities of these compounds to inhibit free radicals were decreased by the increase of the levels of drought stresses. It seems that both basil genotypes and drought stress levels affected the production of antioxidants studied and, consequently, have impacts on the plant inhibitory abilities against the oxidative stress.

 

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The increase of the entry of industrial effluents containing various types of heavy metals into water and soil leads to the ever-increasing spread of environmental problems. Therefore, it is necessary to find less expensive solutions to reduce the pollution. In this regard, in order to compare the effect of the removal of heavy elements on some of the morphological and physiological characteristics of C. alternifolius, Ch. zizanioides and Aloe vera plants, an experiment was conducted in the form of a randomized complete block design with three replications for 14 months at the University of Guilan. The results showed that under the treatment of industrial wastewater, the metal accumulation indices (MAI) of zinc, chromium, lead, copper, manganese, nickel, magnesium were higher in Ch. zizanioides and Aloe vera than those in C. alternifolius. In all three studied plants, the indices of root length, shoot length, total biomass and tolerance index (TI) had a significant decrease compared with those in the control plants, and Ch. zizanioides and A. vera plants had the lowest percentage of decrease. In addition, other investigated components including absorption index (UI), total soluble sugar, total phenol content, total flavonoid, total anthocyanin, total tannin, and DPPH free radical inhibition percentage increased in all three plants under industrial wastewater treatment. The highest percentage of increase in all investigated components, except DPPH free radical inhibition percentage, was observed in Ch. zizanioides. In general, it can be said that in terms of MAI and morphological and physiological characteristics, Ch. zizanioides and A. vera were more successful than the C. alternifolius. Therefore, it is recommended to plant the studied plants in the order of priority (Ch. zizanioides ˃ A. vera ˃ C. alternifolius) in soils contaminated with industrial effluents, in order to remediate the soil.