Quality evaluation of snow lotus (Saussurea): quantitative chemical analysis and antioxidant activity assessment

Snow lotus is commonly used as a medicinal plant and has great pharmacological value. To protect these endangered plants, in vitro propagation and cell cultures have been established in order to meet the growing market demand. The phenolic composition, antioxidant activities, total phenolic content (TPC) and total flavonoid content (TFC) from three most commonly used species, in vitro propagated lines and the cell cultures were investigated to qualify their pharmacological value. Quantitative analysis showed that the phenolics varied greatly among different species and the same species at different habitats. From this it can be inferred that the phenolics were influenced by genetic background and the environmental conditions. Significant correlations were observed between the antioxidant activity and several phenolics/TPC/TFC, suggesting that the phenolics are a major contributor of the antioxidant activity and are important for quality evaluation of snow lotus. Based on the abundance of phenolics, TPC, TFC and antioxidant activity, the order of the quality for wild species would be Saussurea involucrata > Saussurea medusa > Saussurea gossypiphora. For S. medusa, its quality judged by origin would be Shigatse > Lhasa > Nagqu. For in vitro propagated plants, the matured plants could be a reliable substitute for wild plants, and the dynamics of phenolics is critical for quality control of this monocarpic species. We provide the first report of quality comparison between the wild plants and the cell cultures. The advantages of developing cell cultures as alternatives for plants collected from the wild are discussed.     

Effects of Light Regime on Antioxidant Content of Foliage in a Tropical Forest Community1

A basic tenet of plant ecology is that under high light and limiting nutrient levels, carbon becomes relatively more available for investment in anti-herbivore defense. Rarely considered in discussions of such defense investments, however, is the necessity for plants to defend themselves against oxidative damage caused by light exposure itself. To determine if the ability to respond to elevated levels of light exposure by increasing production of antioxidant compounds is a general characteristic of foliage in tropical plants, we conducted a broad survey of antioxidant content in foliage of 55 species in a tropical forest community by comparing individuals within forest gaps to conspecifics in the closed canopy forest. To do so, we devised a rapid assay to use under field conditions. Of the 41 species of shrubs, trees, and lianas demonstrating a discernible difference in antioxidant content under the two light regimes, 34 (68%) showed higher antioxidant content under high light conditions. In a quantitative laboratory-based study using four of these species, light was associated with a 15 to 45 percent increase in water-soluble antioxidants in three species; one species displayed a 118 percent increase in fat-soluble antioxidants as well. Thus, changes in the chemistry of plant foliage in response to light may reflect plant investments in defense against abiotic stress factors as well as investments in defense against biotic stress factors.     

Enzymatic and non-enzymatic antioxidant responses of Carrizo citrange,a salt-sensitive citrus rootstock,to different levels of salinity

In several plant species, oxidative stress has been shown to be one of the causes of damage produced by salinity. In order to assess the implication of oxidative stress in the reported sensitivity of the citrus rootstock Carrizo citrange to salt stress, 5-month-old seedlings were grown with increasing NaCl concentrations added to the watering solution. As an indicator of oxidative damage, malondialdehyde content was measured. The antioxidant capability of the plants was determined by measuring superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase activities together with the non-enzymatic antioxidant activity. As additional physiological responses to the stress, 1-aminocyclopropane-1-carboxilic acid and proline accumulation were assessed. Data indicate that Carrizo citrange responded to salt-induced oxidative stress by increasing enzymatic and non-enzymatic antioxidant defenses proportionally to the extent of the stress imposed, and that in all plants the malondialdehyde content remained at a moderate level. We suggest that the important deleterious effects reported in Carrizo citrange grown under high NaCl concentrations are mainly due to a cellular intoxication by Cl(-) ions and not to the salt-induced oxidative stress.     

Phytochemical Analysis and Total Antioxidant Capacity of Rhizome,Above‐Ground Vegetative Parts and Flower of Three Iris Species

This study was aimed at investigating the phytochemical composition and antioxidant capacity of rhizomes, above‐ground vegetative parts and flowers of three Iris species: Iris humilis Georgi , Iris pumila L. and Iris variegata L. UHPLC‐Orbitrap MS analysis was used for determination of phytochemical profile. Total pigments, phenolics, flavonoids, soluble sugars and starch content as well as ABTS antioxidant capacity were also determined. In total, 52 phenolics compounds were identified with 9 compounds (derivatives of iriflophenone, apigenin C‐glycosides, luteolin O‐glycoside, isoflavones derivatives of iristectorigenin, dichotomitin, nigracin and irilone) never reported before in Iris spp. Differences in phenolic composition profile, pigments, soluble sugar, starch, total phenolics and flavonoids content and total antioxidant capacity were found among Iris species and different part of plants. Significant correlation between total phenolic content and antioxidant capacity was determined. The obtained results are comparable with those obtained for medical plants. These findings could be useful for fingerprinting characterization of Iris species and estimation of possible use in pharmaceutical industries.     

Effects of nitrogen on the activity of antioxidant enzymes and gene expression in leaves of Populus plants subjected to cadmium stress

The research aimed to verify the important physiological effect of nitrogen (N) on plants exposed to cadmium (Cd). The poplar plants were grown in a Hoagland nutrient solution and treated with extra N, Cd, and N + Cd. After treatment, plant growth and chlorophyll content were recorded. The oxidative stress, the activity of antioxidant enzymes, and the expression of related genes were also examined. The results indicated the plants treated with sole Cd presented obvious toxicity symptoms, i.e. growth inhibition, reactive oxygen species accumulation, and chlorophyll content decrement. However, when N was added to the plants under Cd stress, plant growth was enhanced, chlorophyll synthesis was promoted, and the oxidative stress was alleviated. Further, the expression of antioxidant enzymes genes was upregulated by N. The results indicated that N partially reversed the toxic effect of Cd on poplar plants, which can provide new methodology to enhance the phytoremediation technology for heavy metal pollution soil.     

Irrigation of Solanum lycopersicum L. with magnetically treated water increases antioxidant properties of its tomato fruits

Antioxidant effects of tomatoes (Solanum lycopersicum L.) have been studied and an association between dietary intake of tomatoes and lowered risk of cancer, neurodegenerative, and cardiovascular diseases has been suggested. Here we used magnetically treated water (MTW; 0.03–0.15 T), which promotes better germination and productivity in tomatoes, and we investigated the effects of aqueous and ethanolic (10–400 μg/ml) extracts of S. lycopersicum as potential antioxidant against 10 μM Fe(II)-induced thiobarbituric acid reactive species (TBARS) in liver and brain homogenates from rats. The ethanolic extracts from magnetically treated plants were more effective than aqueous extracts in preventing TBARS formation in brain and liver. The protective effects of ethanolic extract can be associated with antioxidants (polyphenols and flavonoids), lycopene and other lipophilic components found in the extract. In effect, magnetically treated plants had higher content of polyphenolic and flavonoid compounds than nontreated plants and they can be a better source of antioxidants than nontreated plants. Consequently, MTW can be used to produce functional foods with high contents of antioxidant components and may have better beneficial health effects than traditionally produced foods.     

The Activities of Antioxidant Enzymes and the Glutathione Content of the Digestive Organs in Marine Invertebrates from Possiet Bay,Sea of Japan

The main components of the antioxidant (AO) system, that is, the activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, as well as the glutathione content of cells of the digestive organs, have been measured in 26 species of marine invertebrates that belong to four taxonomic groups from the Possiet Bay, Sea of Japan. It has been shown that the activities of antioxidant enzymes and glutathione content are species specific. In the digestive organs of echinoderms, the activities of antioxidant enzymes and the glutathione content are generally higher compared with those in mollusks. All the studied species exhibit the greatest variability in the activities of catalase and glutathione peroxidase; the lowest variability occurred in activities of superoxide dismutase and glutathione content. The possible causes of the differences in the levels of the investigated components of the AO system are discussed.     

Antioxidant activity and phenolic compounds of 112 traditional Chinese medicinal plants associated with anticancer

Cancer prevention and treatment using traditional Chinese medicines have attracted increasing interest. This study characterizes antioxidant activity and phenolic compounds of traditional Chinese medicinal plants associated with anticancer, comprising 112 species from 50 plant families. The improved ABTS(*+) method was used to systematically assess the total antioxidant capacity (Trolox equivalent antioxidant capacity, TEAC) of the medicinal extracts. The TEAC values and total phenolic content for methanolic extracts of herbs ranged from 46.7 to 17,323 micromol Trolox equivalent/100 g dry weight (DW), and from 0.22 to 50.3 g of gallic acid equivalent/100 g DW, respectively. A positive, significant linear relationship between antioxidant activity and total phenolic content (all R(2) values>/=0.95) showed that phenolic compounds were the dominant antioxidant components in the tested medicinal herbs. Major types of phenolic compounds from most of the tested herbs were preliminarily identified and analyzed, and mainly included phenolic acids, flavonoids, tannins, coumarins, lignans, quinones, stilbenes, and curcuminoids. These medicinal herbs exhibited far stronger antioxidant activity and contained significantly higher levels of phenolics than common vegetables and fruits. Traditional Chinese medicinal plants associated with anticancer might be potential sources of potent natural antioxidants and beneficial chemopreventive agents.     

Influence of nitric oxide in protection of tomato seedling against oxidative stress induced by osmotic stress

Osmotic stress associated with drought and salinity is a serious problem that inhibits the growth of plants mainly due to disturbance of the balance between production of ROS and antioxidant defense and causes oxidative stress. In this research, sodium nitroprusside (SNP) was used as NO donor in control and drought-stressed plants, and the role of NO in reduction of oxidative damages were investigated. In this study, we observed that SNP pretreatment prevented drought-induced decrease in RWC and membrane stability index, increase in lipid peroxidation and lipoxygenase activity and increase in hydrogen peroxide content. However, pretreatment of plants with SNP and phenyl 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (a NO scavenger) reversed the protective effects of SNP suggesting that protective effect by SNP is attributable to NO release. In addition, the relationship between these defense mechanisms and activity of antioxidant enzymes were checked. Results showed that in drought-stressed plants ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase activities were elevated over the controls, while GR decreased under drought condition. Activity of GPX was inhibited under SNP pretreatment in drought-stressed plants specially, while the activity of APX and GR increased under SNP pretreatment and it seems that under this condition APX had a key role of detoxification of ROS in tomato plants. This result corresponded well with ASA and total acid-soluble thiols content. Therefore, reduction of drought-induced oxidative damages by NO in tomato leaves is most likely mediated through either NO ability to scavenge active oxygen species or stimulation of antioxidant enzyme such as APX.     

Immune system and antioxidants,especially those derived from Indian medicinal plants

During the functioning of the immune system, such as in phagocytosis, reactive oxygen and nitrogen species are generated. If they are left unchecked they can affect the components of the immune system by inducing oxidative damage. This is more so in the elderly or during inflammation where there is excess generation of these reactive species than can be taken care of by the defenses in the form of antioxidants. Dietary supplementation with antioxidants may greatly help in such conditions. There are some indications of possible benefits of antioxidant supplementation. Natural compounds from medicinal plants having antioxidant and immunomodulatory activities have potential as therapeutic agents in this regard. Indian medicinal plants with these activities have been identified and their antioxidant and immunomodulatory effects reviewed. The possible future prospects in this regard are also outlined.     

Antioxidant activity of extracts from leaves and roots of Salvia miltiorrhiza Bunge, S. przewalskii Maxim., and S. verticillata L

Three Salvia species have been studied for antioxidant activity in methanol extracts from roots and leaves. The presence of the polyphenols and tanshinones was screened by HPLC and spectrophotometric assays and related to the antioxidant potential. The antioxidant capacity of the studied species is high, but differences between species and organs have been also revealed. Salvia przewalskii leaf extract was the strongest one in all tests, followed by Salvia miltiorrhiza root and Salvia verticillata leaf. Among the roots, the most active was S. miltiorrhiza extract, followed by S. verticillata. The antioxidant activity correlates to the total polyphenol and, depending on the assay, to the hydroxycinnamic acids content. The high content of tanshinones in both S. miltiorrhiza and S. przewalskii roots is unlikely to contribute to the antioxidant activity.     

Changes in hydrophilic antioxidant activity in Avena sativa and Triticum aestivum leaves of different age during de-etiolation and high-light treatment

The steady-state of reactive oxygen species (ROS) in plant cells is controlled by ROS-producing and scavenging agents. A large cellular pool of antioxidant metabolites is involved in their control. Variations in this antioxidant pool may be monitored by measuring changes in hydrophilic antioxidant activity (free radical-quenching activity of water-soluble components) and ascorbic acid levels. The de-etiolation process and induction of light stress in Avena sativa and Triticum aestivum leaves were used as physiological models to study the antioxidant status at different ages. The data showed that five-day-old green plants and de-etiolated plants of the same age have similar hydrophilic antioxidant activity (8 mol ASC equivalents g FW^–1), which increases during the de-etiolation process. In oat and wheat, young leaves (five days old) had higher antioxidant status (hydrophilic antioxidant activity and ascorbic acid level) than old leaves (10 and 20 days old). High-light treatment caused a decrease in antioxidant status, especially in young leaves. Hydrophilic antioxidant activity and ascorbic acid levels recovered totally or partially after 30 or 60 min in the dark. This capacity also depends on age and species. The ascorbic acid/hydrophilic antioxidant activity ratio is presented as an indicator of antioxidant variations in response to stress, but taking into account the absolute levels of antioxidants.     

Salt tolerance in <Emphasis Type="Italic">Solanum pennellii</Emphasis>: antioxidant response and related QTL

Background  

Excessive soil salinity is an important problem for agriculture, however, salt tolerance is a complex trait that is not easily bred into plants. Exposure of cultivated tomato to salt stress has been reported to result in increased antioxidant content and activity. Salt tolerance of the related wild species, Solanum pennellii, has also been associated with similar changes in antioxidants. In this work, S. lycopersicum M82, S. pennellii LA716 and a S. pennellii introgression line (IL) population were evaluated for growth and their levels of antioxidant activity (total water-soluble antioxidant activity), major antioxidant compounds (phenolic and flavonoid contents) and antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase and peroxidase) under both control and salt stress (150 mM NaCl) conditions. These data were then used to identify quantitative trait loci (QTL) responsible for controlling the antioxidant parameters under both stress and nonstress conditions.     

Production and detoxification of H2O2 in lettuce plants exposed to selenium

Selenium is considered an essential element for animals. Despite that it has not been demonstrated to be essential for higher plants, it has been attributed with a protective role against reactive oxygen species in plants subjected to stress. In this study, lettuce plants ( Lactuca sativa cv. Philipus) received different application rates (5, 10, 20, 40, 60, 80 and 120 μM) of selenite or selenate, with the aim of testing the effect of Se on the production and detoxification of H₂O₂ in non-stressed plants. The results indicate that the form selenate is less toxic than selenite; that is, the plants tolerated and responded positively to this element, and even increasing in growth up to a rate of 40 μM for the form selenate. On the contrary, the application of selenite triggered a higher foliar concentration of H₂O₂ and a higher induction of lipid peroxidation [malondialdehyde content and lipoxygenase activity] in comparison to that observed after the selenate application. Also, the plants treated with selenate induced higher increases in enzymes that detoxify H₂O₂, especially ascorbate peroxidase and glutathione (GSH) peroxidase, as well as an increase in the foliar concentration of antioxidant compounds such as ascorbate and GSH. These data indicate that an application of selenate at low rates can be used to prevent the induction in plants of the antioxidant system, thereby improving stress resistance.     

Specific features of oxidative stress in the chilled tobacco plants following transformation with the desC gene for acyl-lipid Δ9-desaturase from Synechococcus vulcanus

Tobacco plants (Nicotiana tabacum L.) transformed with the desC gene for acyl-lipid Δ9-desaturase from a thermophilic cyanobacterium Synechococcus vulcanus were cultivated on the agarized Murashige and Skoog medium at 22°C and a 16-h photoperiod. Tobacco plants transformed with an empty binary vector pGA482 served as the control. The investigations showed that, in contrast to the control, transgenic plants maintained a higher activity of antioxidant enzymes during 2-h incubation at 2°C; as a result, these plants resisted more efficiently the accumulation of reactive oxygen species and reduced the rate of the lipid peroxidation. The activity of antioxidant enzymes in the transformed plants is apparently related to the operation of the introduced desC gene for acyl-lipid Δ9-desaturase because the enhanced activity of the latter increased the relative content of polyunsaturated FAs in membrane lipids and in this way promoted the liquid state of membranes during the chilling period. These changes helped preserve the cellular homeostasis and thereby maintain the steady synthesis of antioxidant enzymes at hypothermic conditions; as a result, cold resistance of transformed tobacco plants increased.     

Overexpression of dehydroascorbate reductase, but not monodehydroascorbate reductase, confers tolerance to aluminum stress in transgenic tobacco

Aluminum (Al) inhibits plant growth partly by causing oxidative damage that is promoted by reactive oxygen species and can be prevented by improving antioxidant capacity. Ascorbic acid (AsA), the most abundant antioxidant in plants, is regenerated by the action of monodehydroascorbate reductase (MDAR) and dehydroascorbate reductase (DHAR). We investigated the role of MDAR and DHAR in AsA regeneration during Al stress using transgenic tobacco (Nicotiana tabacum) plants overexpressing Arabidopsis cytosolic MDAR (MDAR-OX) or DHAR (DHAR-OX). DHAR-OX plants showed better root growth than wild-type (SR-1) plants after exposure to Al for 2 weeks, but MDAR-OX plants did not. There was no difference in Al distribution and accumulation in the root tips among SR-1, DHAR-OX, and MDAR-OX plants after Al treatment for 24 h. However, DHAR-OX plants showed lower hydrogen peroxide content, less lipid peroxidation and lower level of oxidative DNA damage than SR-1 plants, whereas MDAR-OX plants showed the same extent of damage as SR-1 plants. Compared with SR-1 plants, DHAR-OX plants consistently maintained a higher AsA level both with and without Al exposure, while MDAR-OX plants maintained a higher AsA level only without Al exposure. Also, DHAR-OX plants maintained higher APX activity under Al stress. The higher AsA level and APX activity in DHAR-OX plants contributed to their higher antioxidant capacity and higher tolerance to Al stress. These findings show that the overexpression of DHAR, but not of MDAR, confers Al tolerance, and that maintenance of a high AsA level is important to Al tolerance.     

Phytomelatonin: a potential phytotherapeutic intervention on COVID-19-exposed individuals

Phytomelatonin is a pleiotropic molecule that originated in higher plants with many diverse actions and is primarily an antioxidant. The recent identification and advancement of phytomelatonin unraveled the potential of this modulatory molecule being considered a new plant hormone, suggesting its relevance in treating respiratory infections, including COVID-19. Besides, this molecule is also involved in multiple hormonal, physiological, and biological processes at different levels of cell organization and has been marked for its ability to cross the blood-brain barrier and prominent antioxidant effects, reducing mitochondrial electron leakage, up-regulating antioxidant enzymes, acting as a free radical scavenger, and interfering with pro-inflammatory signaling pathways as seen in mood swings, body temperature, sleep, cancer, cardiac rhythms, and immunological regulation modulators. However, due to its diversity, availability, affordability, convenience, and high safety profile, phytomelatonin has also been suggested as a natural adjuvant. This review discussed the origin, content in various plant species, processes of extraction, and detection and therapeutic potentials of phytomelatonin in treating COVID-19-exposed individuals.     

过表达ZmSKIP基因提高烟草抗低温胁迫的能力

以野生型和过表达ZmSKIP基因烟草为试材, 研究了低温胁迫下过表达ZmSKIP对烟草抗氧化能力的影响。测定了不同低温处理时间下过表达ZmSKIP转基因烟草T3代植株和野生型植株抗氧化酶如超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）活性和丙二醛（MDA）含量以及相对电导率, 结果表明, 低温下, 相对于野生型植株, 转基因烟草具有较高的抗氧化酶活性和较低的相对电导率和MDA含量, 说明过表达ZmSKIP提高了转基因植株的耐低温胁迫能力。