Phytochemical analysis and gastroprotective effect of Stellaria media (L.) Vill. methanolic extract on piroxicam-induced gastric ulcer in Wistar rats.

Stellaria media L. has traditionally been used to treat inflammatory and gastrointestinal ailments. This study aimed to phytochemically characterize the S. media extract and explore its anti-ulcer efficacy against piroxicam-induced stomach lesions in Wistar rats. Phytochemical analysis was performed and antioxidant capacity of extract was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. In vivo, piroxicam (30mg/kg) was administered to induce gastric ulceration. Gastro protective effect of S. media extract was observed at 150, 300 and 450mg/kg, respectively. While omeprazole (20mg/kg) was used as a conventional anti-ulcer drug. After oral treatment for 14 days, stomach acidic secretions, ulcerogenic indices, hematological markers and oxidative stress parameters were assessed along with histological examination. The existence of polyphenol contents in S. media extract was confirmed in correlation to a marked DPPH inhibition (IC50 27.94µg/mL). S. media extract resulted in a dose-dependent elevation in gastric pH while a decrease in acid volume, acidity and ulceration. Also, S. media extract administration restored the impaired hematological markers (RBCs, Hb, WBCs and PLTs) and decreased oxidative stress by reducing oxidants (TOS and MDA) while raising antioxidants (TAC and CAT). Furthermore, gastric histological results corroborated the aforementioned findings. Conclusively, S. media could provide a promising protective effect against drug-induced gastric ulceration.

Molecular networking-guided isolation strategy of a new C-glycosyl flavone rotamer from Stellaria alsine and evaluation of anti-inflammatory and antioxidant activities.

INTRODUCTION: Stellaria alsine has traditionally been used as both a famine relief food and an alternative medicine in East Asia. Modern pharmacological studies have revealed that S. alsine has various biological effects such as anticancer, anti-hepatoma, anti-inflammatory, and antioxidative effects. However, the anti-inflammatory properties of chemical constituents derived from this plant have not been studied well. OBJECTIVES: To identify potential therapeutic candidate for treating inflammatory diseases such as inflammatory bowel disease (IBD). METHODS: The distribution of chemical compounds was investigated by Global Natural Product Social (GNPS)-based molecular networking (MN) analysis using UPLC-Orbitrap tandem mass spectrometry. The anti-inflammatory and antioxidative effects of S. alsine extracts and fractions were evaluated by measuring interleukin (IL)-8 and reactive oxygen species (ROS) productions. RESULTS: The active EA layer of S. alsine showed the highest percentage of major compounds by feature-based molecular networking. The top candidate structures of EA fraction were rapidly annotated as flavone C- or O-glycosides via an advanced analysis tool, Network Annotation Propagation (NAP). With the GNPS molecular networking-guided isolation strategy, a new C-glycosyl flavone rotamer (1) was isolated. The structures of the major (1a) and minor (1b) rotational isomers were determined by extensive NMR analysis and MS/MS fragmentation. Finally, the anti-inflammatory activity of 1 was predicted by molecular docking simulations with IL-8 protein. CONCLUSION: These results suggested that the compound 1 is a potential therapeutic candidate for inflammatory bowel disease (IBD).

The complete genome sequence of Stellaria aquatica virus A, a new member of the genus Alphacarmovirus, family Tombusviridae.

A new member of the genus Alphacarmovirus was detected in Stellaria aquatica using high-throughput RNA sequencing analysis. The complete genome sequence of this new virus isolate, tentatively named "Stellaria aquatica virus A" (StAV-A), comprises 4,017 nucleotides with five predicted open reading frames (ORFs) and has a typical alphacarmovirus genome organization. Pairwise comparison of StAV-A with selected members of family Tombusviridae showed 44-58%, 32-64%, and 19-49% sequence identity for the overall nucleotide sequence, polymerase, and coat protein, respectively. Phylogenetic analysis of polymerase sequences places StAV-A alongside other members of the genus Alphacarmovirus in the family Tombusviridae.

Complete genome sequence of Stellaria aquatica virus B, a novel polerovirus that infects Stellaria aquatica.

The complete genome sequence of Stellaria aquatica virus B (StAVB), a new member of the genus Polerovirus that infects Stellaria aquatica, was determined using high-throughput RNA sequencing with confirmation by Sanger sequencing. The complete StAVB genome (GenBank accession no. OP389993) is 5,900 nucleotide (nt) long with seven open reading frames (ORF0-5 and ORF3a) that encode putative proteins (P0-P5 and P3a) in a similar configuration to that of other typical poleroviruses. Pairwise sequence comparisons with other poleroviruses showed 38-50% nt sequence identity in the complete genome and 13-24%, 36-45%, 7-68%, and 6-50% amino acid sequence identity in (aa), for the P0, P1-2, P3, and P4 protein, respectively. These data, together with the results of phylogenetic analysis, indicate that StAVB should be classified as a new member of the genus Polerovirus, family Solemoviridae.

Evolution of apetaly in the cosmopolitan genus Stellaria.

PREMISE: Apetaly is widespread across distantly related lineages of flowering plants and is associated with abiotic (or self-) pollination. It is particularly prevalent in the carnation family, and the cosmopolitan genus Stellaria contains many lineages that are hypothesized to have lost petals from showy petalous ancestors. But the pollination biology of apetalous species of Stellaria remains unclear. METHODS: Using a substantial species-level sampling (~92% of known taxonomic diversity), we describe the pattern of petal evolution within Stellaria using ancestral character state reconstructions. To help shed light on the reproductive biology of apetalous Stellaria, we conducted a field experiment at an alpine tundra site in the southern Rocky Mountains to test whether an apetalous species (S. irrigua) exhibits higher levels of selfing than a sympatric, showy petalous congener (S. longipes). RESULTS: Analyses indicated that the ancestor of Stellaria was likely showy petalous and that repeated, parallel reductions of petals occurred in clades across much of the world, with uncommon reversal back to showy petals. Field experiments supported high rates of selfing in the apetalous species and high rates of outcrossing in the petalous species. CONCLUSIONS: Petal loss is rampant across major clades of Stellaria and is potentially linked with self-pollination worldwide. Self-pollination occurs within the buds in S. irrigua, and high propensities for this and other forms of selfing known in many other taxa of arctic-alpine habitats may reflect erratic availability of pollinators.

A Synthetic Strong and Constitutive Promoter Derived from the Stellaria media pro-SmAMP1 and pro-SmAMP2 Promoters for Effective Transgene Expression in Plants.

Synthetic promoters are vital for genetic engineering-based strategies for crop improvement, but effective methodologies for their creation and systematic testing are lacking. We report here on the comparative analysis of the promoters pro-SmAMP1 and pro-SmAMP2 from Stellaria media ANTIMICROBIAL PEPTIDE1 (AMP1) and ANTIMICROBIAL PEPTIDE2 (AMP2). These promoters are more effective than the well-known Cauliflower mosaic virus 35S promoter. Although these promoters share about 94% identity, the pro-SmAMP1 promoter demonstrated stronger transient expression of a reporter gene in Agrobacterium infiltration of Nicotiana benthamiana leaves, while the pro-SmAMP2 promoter was more effective for the selection of transgenic tobacco (Nicotiana tabacum) cells when driving a selectable marker. Using the cap analysis of gene expression method, we detected no differences in the structure of the transcription start sites for either promoter in transgenic plants. For both promoters, we used fine-scale deletion analysis to identify 160 bp-long sequences that retain the unique properties of each promoter. With the use of chimeric promoters and directed mutagenesis, we demonstrated that the superiority of the pro-SmAMP1 promoter for Agrobacterium-mediated infiltration is caused by the proline-inducible ACTCAT cis-element strictly positioned relative to the TATA box in the core promoter. Surprisingly, the ACTCAT cis-element not only activated but also suppressed the efficiency of the pro-SmAMP1 promoter under proline stress. The absence of the ACTCAT cis-element and CAANNNNATC motif (negative regulator) in the pro-SmAMP2 promoter provided a more constitutive gene expression profile and better selection of transgenic cells on selective medium. We created a new synthetic promoter that enjoys high effectiveness both in transient expression and in selection of transgenic cells. Intact promoters with differing properties and high degrees of sequence identity may thus be used as a basis for the creation of new synthetic promoters for precise and coordinated gene expression.

Stress responses and nickel and zinc accumulation in different accessions of Stellaria media (L.) Vill. in response to solution pH variation in hydroponic culture.

In most non-hyperaccumulating plants, Ni and Zn uptake is negatively correlated with soil pH, however, few studies so far have investigated how pH influences the activity and uptake of Ni and Zn in plants grown in a hydroponic system, which generally allows culture variables to be singularly manipulated. In this study, the non-accumulator Stellaria media (L.) Vill. (Caryophyllaceae) had opposite trends of Ni and Zn uptake along a pH gradient (between 5 and 8 for Zn and between 5 and 6.5 for Ni), when grown in hydroponics. In all treatments, the solution metal concentration was fixed at 0.1 mM Ni or 0.55 mM Zn. Nickel accumulation increased with increasing pH with an average concentration in shoots of 167 µg/gDW at pH 5 and of 250 µg/gDW at pH 6.5. In contrast, Zn accumulation decreased with increasing pH, with an average concentration in shoots varying from 1640 µg/gDW, at pH 5, to 435 µg/gDW at pH 8. Assessment of total polyphenol and flavonoid contents and of antioxidant activity showed that these parameters were positively correlated with Ni or Zn accumulation in S. media shoots, while photosynthetic pigments content and root and shoot biomass were negatively correlated with Ni and Zn accumulation. The study was carried out on five different S. media populations, which did not show differences in relation to the accumulation of metals and synthesis of antioxidant compounds, nonetheless showing a different biomass production under control conditions.

Protective effects of a traditional herbal extract from Stellaria dichotoma var. lanceolata against Mycobacterium abscessus infections.

Stellaria dichotoma var. lanceolata (SdLv), a member of the Caryophyllaceae, is a traditional herbal medicine that has been used to treat fever, night sweats, and malaria in East Asia. Inflammation plays an essential role in both host defense and pathogenesis during infection by diverse intracellular pathogens. Herein, we showed that an herbal extract from SdLv effectively attenuated inflammatory responses from infection of Mycobacterium abscessus (Mab), but not Toxoplasma gondii (T. gondii). In primary murine macrophages, Mab infection resulted in the rapid activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK), as well as in the generation of proinflammatory cytokines, such as tumor necrosis factor α and interleukin-6, which were all significantly inhibited by pretreatment with SdLv. However, herbal extracts from Bupleurum chinense DC. (Buch) or Bupleurum falcatum L. (Bufa) did not affect M. abs-induced activation of proinflammatory responses. Importantly, we demonstrated that generation of intracellular reactive oxygen species, which are important signaling intermediaries in the activation of NF-κB and the MAPK signaling pathway, was rapidly increased in Mab-infected macrophages, and this was effectively suppressed by pretreatment with SdLv, but not Buch and Bufa. We further found that the treatment of Buch and Bufa, but not SdLv, led to the activation of NF-κB and the MAPK signaling pathway and the generation of intracellular reactive oxygen species. Moreover, oral administration of SdLv significantly reduced lethality in Mab-infected mice. Collectively, these results suggest the possible use of SdLv as an effective treatment for Mab infection.

Effects of mutual intercropping on the cadmium accumulation in accumulator plants Stellaria media, Malachium aquaticum, and Galium aparine.

Intercropping affects heavy-metal uptake in plants. In this study, three cadmium (Cd)-accumulator species (Stellaria media, Malachium aquaticum, and Galium aparine) were intercropped together in Cd-contaminated soil to study the effects of intercropping on co-remediation. Mutual intercropping significantly increased the biomasses of S. media, M. aquaticum, and G. aparine compared with their respective monocultures. The photosynthetic pigment contents of three species were not significantly affected by mutual intercropping. Mutual intercropping did not increase the Cd contents in roots and shoots of G. aparine, but it increased the Cd contents in roots of S. media and M. aquaticum. It also decreased the Cd contents in shoots of S. media and M. aquaticum. Only G. aparine intercropped with M. aquaticum and three-species intercropping increased Cd-accumulation levels in whole plants of each species. Only S. media intercropped with M. aquaticum and three-species intercropping increased the Cd accumulation at the whole plant level in every plant in a single pot, with S. media intercropped with M. aquaticum showing the greatest increase. Therefore, S. media intercropped with M. aquaticum and three-species intercropping may improve the efficiency of phytoremediation of Cd-contaminated soil, with S. media intercropped with M. aquaticum representing the best combination.

Defense peptide repertoire of Stellaria media predicted by high throughput next generation sequencing.

Being perfectly adapted to diverse environments, chickweed (Stellaria media (L.) Vill), a ubiquitous garden weed, grows widely in Europe and North America. As opposed to the model plants, many weeds, and S. media in particular, have been poorly studied, although they are likely to contain promising components of immunity and novel resistance genes. In this study, for the first time RNA-seq analysis of healthy and infected with Fusarium oxysporum chickweed seedlings, as well as de novo transcriptome assembly and annotation, are presented. Note, this research is focused on antimicrobial peptides (AMPs), the major components of plant immune system. Using custom software developed earlier, 145 unique putative AMPs (pAMPs) including defensins, thionins, hevein-like peptides, snakins, alpha-hairpinins, LTPs, and cysteine-rich peptides with novel cysteine motifs were predicted. Furthermore, changes in AMP expression profile in response to fungal infection were traced. In addition, the comparison of chickweed AMP repertoire with those of other Caryophyllaceae plants whose transcriptomes are presently available is made. As a result, alpha-hairpinins and hevein-like peptides which display characteristic modular structure appear to be specific AMPs distinguishing S. media from Dianthus caryophyllus, Silene vulgaris, and Silene latifolia. Finally, revealing several AMPs with proven antimicrobial activity gives opportunity to conclude that the presented method of AMP repertoire analysis reveals highly active AMPs playing vital role in plant immunity.

Taxonomy and Phylogeny of Peronospora Species (Oomycota) Parasitic to Stellaria and Pseudostellaria in Korea, with the Introduction of Peronospora casparyi sp. nov

The genus Peronospora, an obligate biotrophic group belonging to Oomycota, causes serious damage to a variety of wild and ornamental plants, as well as cultivated crops, such as beet, rose, spinach, and tobacco. To investigate the diversity of Peronospora species parasitic to Stellaria and Pseudostellaria (Caryophyllaceae) plants in Korea, we performed a morphological analysis on dried herbarium specimens and molecular phylogenetic inferences based on internal transcribed spacer rDNA and cox2 mitochondrial DNA sequences. As a result, it was confirmed that there are four species of Peronospora parasitic to specific species of Stellaria and Pseudostellaria, all of which were hitherto unrecorded in Korea: P. alsinearum (ex Stellaria media), P. stellariae-aquaticae (ex Stellaria aquatica), P. stellariae-uliginosae (ex Stellaria alsine), and P. pseudostellariae (ex Pseudostellaria palibiniana). In addition, Peronospora specimens parasitic to Pseudostellaria davidii differed morphologically from P. pseudostellariae owing to the large and ellipsoidal conidia; this morphological discrepancy was also validated by the high genetic divergence between the two species. Peronospora casparyi sp. nov. is described and illustrated here.

Novel strong promoter of antimicrobial peptides gene pro-SmAMP2 from chickweed (Stellaria media).

BACKGROUND: In a previous study we found that in chickweed the expression level of the pro-SmAMP2 gene was comparable or even higher to that of the ß-actin gene. This high level of the gene expression has attracted our attention as an opportunity for the identification of novel strong promoters of plant origin, which could find its application in plant biotechnology. Therefore, in the present study we focused on the nucleotide sequence identification and the functional characteristics of the pro-SmAMP2 promoter in transgenic plants. RESULTS: In chickweed (Stellaria media), a 2120 bp promoter region of the pro-SmAMP2 gene encoding antifungal peptides was sequenced. Six 5'-deletion variants -2120, -1504, -1149, -822, -455, and -290 bp of pro-SmAMP2 gene promoter were fused with the coding region of the reporter gene gusA in the plant expression vector pCambia1381Z. Independent transgenic plants of tobacco Nicotiana tabacum were obtained with each genetic structure. GUS protein activity assay in extracts from transgenic plants showed that all deletion variants of the promoter, except -290 bp, expressed the gusA gene. In most transgenic plants, the GUS activity level was comparable or higher than in plants with the viral promoter CaMV 35S. GUS activity remains high in progenies and its level correlates positively with the amount of gusA gene mRNA in T3 homozygous plants. The activity of the рro-SmAMP2 promoter was detected in all organs of the transgenic plants studied, during meiosis and in pollen as well. CONCLUSION: Our results show that the рro-SmAMP2 promoter can be used for target genes expression control in transgenic plants.

[Expression of plant antimicrobial peptide pro-SmAMP2 gene increases resistance of transgenic potato plants to Alternaria and Fusarium pathogens].

The chickweed (Stellaria media L.) pro-SmAMP2 gene encodes the hevein-like peptides that have in vitro antimicrobial activity against certain harmful microorganisms. These peptides play an important role in protecting the chickweed plants from infection, and the pro-SmAMP2 gene was previously used to protect transgenic tobacco and Arabidopsis plants from phytopathogens. In this study, the pro-SmAMP2 gene under control of viral CaMV35S promoter or under control of its own pro-SmAMP2 promoter was transformed into cultivated potato plants of two cultivars, differing in the resistance to Alternaria: Yubiley Zhukova (resistant) and Skoroplodny (susceptible). With the help of quantitative real-time PCR, it was demonstrated that transgenic potato plants expressed the pro-SmAMP2 gene under control of both promoters at the level comparable to or exceeding the level of the potato actin gene. Assessment of the immune status of the transformants demonstrated that expression of antimicrobial peptide pro-SmAMP2 gene was able to increase the resistance to a complex of Alternaria sp. and Fusarium sp. phytopathogens only in potato plants of the Yubiley Zhukova cultivar. The possible role of the pro-SmAMP2 products in protecting potatoes from Alternaria sp. and Fusarium sp. is discussed.

A novel antifungal peptide from leaves of the weed Stellaria media L.

A novel peptide named SmAMP3 was isolated from leaves of common chickweed (Stellaria media L.) by a combination of acidic extraction and a single-step reversed-phase HPLC and sequenced. The peptide is basic and cysteine-rich, consists of 35 amino acids, and contains three disulphide bridges. Homology search revealed that SmAMP3 belongs to the family of hevein-like antimicrobial peptides carrying a conserved chitin-binding site. Efficient binding of chitin by SmAMP3 was proved by in vitro assays. Molecular modeling confirmed conservation of the chitin-binding module in SmAMP3 locating the variable amino acid residues to the solvent-exposed loops of the molecule. The peptide exhibits potent antifungal activity against important plant pathogens in the micromolar range, although it is devoid of antibacterial activity at concentrations below 10 µM. As judged by chromatographic behavior and mass spectrometric data, the peptide is constitutively expressed in above-ground organs and seeds of S. media plants, thus representing an important player in the preformed branch of the plant immune system.

Phenotypic plasticity of sun and shade ecotypes of Stellaria longipes in response to light quality signaling, gibberellins and auxin.

Stellaria longipes plant communities (ecotypes) occur in several environmentally distinct habitats along the eastern slopes of southern Alberta's Rocky Mountains. One ecotype occurs in a prairie habitat at ∼1000 m elevation where Stellaria plants grow in an environment in which the light is filtered by taller neighbouring vegetation, i.e. sunlight with a low red to far-red (R/FR) ratio. This ecotype exhibits a high degree of phenotypic plasticity by increasing stem elongation in response to the low R/FR ratio light signal. Another Stellaria ecotype occurs nearby at ∼2400 m elevation in a much cooler alpine habitat, one where plants rarely experience low R/FR ratio shade light. Stem elongation of plants is largely regulated by gibberellins (GAs) and auxin, indole-3-acetic acid (IAA). Shoots of the prairie ecotype plants show increased IAA levels under low R/FR ratio light and they also increase their stem growth in response to applied IAA. The alpine ecotype plants show neither response. Plants from both ecotypes produce high levels of growth-active GA1 under low R/FR ratio light, though they differ appreciably in their catabolism of GA1. The alpine ecotype plants exhibit very high levels of GA8, the inactive product of GA1 metabolism, under both normal and low R/FR ratio light. Alpine origin plants may de-activate GA1 by conversion to GA8 via a constitutively high level of expression of the GA2ox gene, thereby maintaining their dwarf phenotype and exhibiting a reduced phenotypic plasticity in terms of shoot elongation. In contrast, prairie plants exhibit a high degree of phenotypic plasticity, using low R/FR ratio light-mediated changes in GA and IAA concentrations to increase shoot elongation, thereby accessing direct sunlight to optimize photosynthesis. There thus appear to be complex adaptation strategies for the two ecotypes, ones which involve modifications in the homeostasis of endogenous hormones.

Flavonoids from Stellaria nemorum and Stellaria holostea.

Stellaria nemorum L. and S. holostea L. (Caryophyllaceae) were investigated for their flavonoids. The new flavonoid 6-C-[(α-arabinopyranosyl)-( 1-->2)-O-ß- xylopyranosyl]apigenin (1) and the four known C-glycosides, 6-C-[(α-arabinopyranosyl)-(1-->2)-O-ß-glucopyranosyl]apigenin (2), apigenin 6-C-ß- galactopyranoside-8-C-ß-glucopyranoside (3), apigenin 6-C-ß-glucopyranoside-8-C-α-arabinopyranoside (4), and apigenin 6-C-ß-glucopyranoside-8-C-ß- xylopyranoside (5) were isolated from the aerial parts of S. nemorum for the first time. Furthemore, five known flavonoids, 3,5,7-trihydroxy-3',5'- dimethoxyflavone (9), diosmetin 6-C-ß-glucopyranoside (8), schaftoside (4), isoorientin (6) and orientin (7) were obtained from the aerial parts of S. holostea. Compounds 4, 8 and 9 are reported for the first time from this species. The structures of all isolated compounds were unambiguously elucidated by one- and two- dimensional NMR and mass spectral analysis, by acid hydrolysis, as well as by comparison with literature data. The crude extracts of the investigated species exhibited antimicrobial activity against Staphylococcus aureus, while none of the isolated compounds was found to be active.

[Effect of drought stress on growth and physiological-biochemical characteristics of Stellaria dichotoma].

A pot experiment was conducted to study effect of drought stress on leaf physiological characteristics and growth of one year old Stellaria dichotoma seedlings. The result showed that plant height and shoot dry weight significantly decreased with decrease in soil water content; however, root length and root dry weight increased at light drought stress and decreased at severe drought stress. The result also showed that with the decrease of soil water content, proline content in S. dichotoma leaves decreased then increase, while solube protein content decreased. Activities of SOD and POD in S. dichotoma leaves significantly decreased as soil water content decreased, while activity of CAT significantly decreased at severe drought stress. Membrane permeability in S. dichotoma leaves increased, while MDA content decreased then increased as soil water decreased. These results suggest that S. dichotoma had osmotic stress resistance ability and reactive oxygen scavenging capacity at light drought stress, which caused S. dichotoma growth was no inhibited at a certain extent drought stress.

Novel antifungal α-hairpinin peptide from Stellaria media seeds: structure, biosynthesis, gene structure and evolution.

Plant defense against disease is a complex multistage system involving initial recognition of the invading pathogen, signal transduction and activation of specialized genes. An important role in pathogen deterrence belongs to so-called plant defense peptides, small polypeptide molecules that present antimicrobial properties. Using multidimensional liquid chromatography, we isolated a novel antifungal peptide named Sm-AMP-X (33 residues) from the common chickweed (Stellaria media) seeds. The peptide sequence shows no homology to any previously described proteins. The peculiar cysteine arrangement (C(1)X3C(2)XnC(3)X3C(4)), however, allocates Sm-AMP-X to the recently acknowledged α-hairpinin family of plant defense peptides that share the helix-loop-helix fold stabilized by two disulfide bridges C(1)-C(4) and C(2)-C(3). Sm-AMP-X exhibits high broad-spectrum activity against fungal phytopathogens. We further showed that the N- and C-terminal "tail" regions of the peptide are important for both its structure and activity. The truncated variants Sm-AMP-X1 with both disulfide bonds preserved and Sm-AMP-X2 with only the internal S-S-bond left were progressively less active against fungi and presented largely disordered structure as opposed to the predominantly helical conformation of the full-length antifungal peptide. cDNA and gene cloning revealed that Sm-AMP-X is processed from a unique multimodular precursor protein that contains as many as 12 tandem repeats of α-hairpinin-like peptides. Structure of the sm-amp-x gene and two related pseudogenes sm-amp-x-ψ1 and sm-amp-x-ψ2 allows tracing the evolutionary scenario that led to generation of such a sophisticated precursor protein. Sm-AMP-X is a new promising candidate for engineering disease resistance in plants.

Effect of drought stress on growth and physiological-biochemical characteristics of Stellaria dichotoma / 中国中药杂志

A pot experiment was conducted to study effect of drought stress on leaf physiological characteristics and growth of one year old Stellaria dichotoma seedlings. The result showed that plant height and shoot dry weight significantly decreased with decrease in soil water content; however, root length and root dry weight increased at light drought stress and decreased at severe drought stress. The result also showed that with the decrease of soil water content, proline content in S. dichotoma leaves decreased then increase, while solube protein content decreased. Activities of SOD and POD in S. dichotoma leaves significantly decreased as soil water content decreased, while activity of CAT significantly decreased at severe drought stress. Membrane permeability in S. dichotoma leaves increased, while MDA content decreased then increased as soil water decreased. These results suggest that S. dichotoma had osmotic stress resistance ability and reactive oxygen scavenging capacity at light drought stress, which caused S. dichotoma growth was no inhibited at a certain extent drought stress.

Purification and characterization of a novel anti-HSV-2 protein with antiproliferative and peroxidase activities from Stellaria media.

A novel antiviral protein, designated as Stellarmedin A, was purified from Stellaria media (L.) Vill. (Caryophyllaceae) by using ammonium sulfate precipitation, cation-exchange chromatography system. Gel electrophoresis analysis showed that Stellarmedin A is a highly basic glycoprotein with a molecular weight of 35.1 kDa and an isoelectric point of ∼8.7. The N-terminal 14-amino acid sequence, MGNTGVLTGERNDR, is similar to those of other plant peroxidases. This protein inhibited herpes simplex virus type 2 (HSV-2) replication in vitro with an IC50 of 13.18 µg/ml and a therapeutic index exceeding 75.9. It was demonstrated that Stellarmedin A affects the initial stage of HSV-2 infection and is able to inhibit the proliferation of promyelocytic leukemia HL-60 and colon carcinoma LoVo cells with an IC50 of 9.09 and 12.32 µM, respectively. Moreover, Stellarmedin A has a peroxidase activity of 36.6 µmol/min/mg protein, when guaiacol was used as substrate. To our knowledge, this is the first report about an anti-HSV-2 protein with antiproliferative and peroxidase activities from S. media.