Purification and properties of growth stage-dependent antiviral proteins from the leaves of Celosia cristata

Purification of an antiviral protein from the seeds of quinoa (Chenopodium quinoa Willd.) and characterization of its antiviral properties

Plant viral pathogens cause damaging diseases in many agriculture systems, and emerging viral infections are a serious threat for providing adequate food to a continuously growing population. Recent studies of biogenic substances have provided new opportunities for producing novel antiviral agents. The present work has been conducted to evaluate the antiviral activity of quinoa (Chenopodium quinoa Willd.) seeds crude extract. The antiviral activity was retained in different buffer solutions of various pH ranges (5.2-8.5) and remained after the diafiltration process. The putative virus inhibitor was sensitive to treatment with sodium dodecyl sulfate and trichloroacetic acid. An antiviral protein with ~ 25 kDa molecular weight was isolated from the seed quinoa extract using ammonium sulfate precipitation, anion and cation exchange chromatography. The purified protein (Quinoin-I) significantly inhibited TMV on tobacco leaves with an IC₅₀ value at a 6.81 μg/ml concentration. Enzyme activity assay revealed the RNase activity of Quinoin-I, and this feature was retained in the presence of β-mercaptoethanol and ethylene diamine tetraacetic acid. This antiviral protein has been shown as a promising leading molecule for further development as a novel antiviral agent.

Antiviral Activity of Ribosome-Inactivating Proteins

Ribosome-inactivating proteins (RIPs) are rRNA N-glycosylases from plants (EC 3.2.2.22) that inactivate ribosomes thus inhibiting protein synthesis. The antiviral properties of RIPs have been investigated for more than four decades. However, interest in these proteins is rising due to the emergence of infectious diseases caused by new viruses and the difficulty in treating viral infections. On the other hand, there is a growing need to control crop diseases without resorting to the use of phytosanitary products which are very harmful to the environment and in this respect, RIPs have been shown as a promising tool that can be used to obtain transgenic plants resistant to viruses. The way in which RIPs exert their antiviral effect continues to be the subject of intense research and several mechanisms of action have been proposed. The purpose of this review is to examine the research studies that deal with this matter, placing special emphasis on the most recent findings.

The role of enzymatic activities of antiviral proteins from plants for action against plant pathogens

Antiviral proteins (AVPs) from plants possess multiple activities, such as N-glycosidase, RNase, DNase enzymatic activity, and induce pathogenesis-related proteins, salicylic acid, superoxide dismutase, peroxidase, and catalase. The N-glycosidase activity releases the adenine residues from sarcin/ricin (S/R) loop of large subunit of ribosomes and interfere the host protein synthesis process and this activity has been attributed for antiviral activity in plant. It has been shown that AVP binds directly to viral genome-linked protein of plant viruses and interfere with protein synthesis of virus. AVPs also possess the RNase and DNase like activity and may be targeting nucleic acid of viruses directly. Recently, the antifungal, antibacterial, and antiinsect properties of AVPs have also been demonstrated. Gene encoding for AVPs has been used for the development of transgenic resistant crops to a broad range of plant pathogens and insect pests. However, the cytotoxicity has been observed in transgenic crops using AVP gene in some cases which can be a limiting factor for its application in agriculture. In this review, we have reviewed various aspects of AVPs particularly their characteristics, possible mode of action and application.

Role of primary metabolites in plant defense against pathogens

Plants under natural environment facing various pathogens, tend to produce defense to maintain their fitness and minimize pathogenic damage. Plant-pathogens interaction is gaining more importance by researches as, their means of the fight are primary metabolites. The ultimate result of either means of defense is pathogenesis or resistance. Plant defense mechanisms can be grouped either into inducible and constitutive defense or chemical, structural and morphological defense. Majority of defense mechanisms have a passive role, i.e. only defensive against pathogens, but a few are very active. Plant primary metabolites are catching interest in their immunity role. Deep information of molecular mechanisms involved during the plant-pathogen system is need of the day for future disease control. This review will highlight the role of primary metabolites and their mechanism of action in plant defense.

Purification of a ribosome-inactivating protein with antioxidation and root developer potencies from Celosia plumosa

Considering Celosia plumosa as a potent antiviral plant, the attempt was made to determine, purify and characterize its proteinaceous antiviral elements against tobacco mosaic virus hypersensitive response on Nicotiana glutinosa. By using 60% ammonium sulphate-precipitation, FPLC-based anion and cation-exchange chromatography in 10 and 50 mM NaCl, size-exclusion chromatography in 50 mM NaCl and SDS-PAGE 10%, a 25 kD antiviral protein with ribosome-inactivating/28S rRNase ability was purified from the leaves of C. plumosa at vegetative growth stage. The purified protein showed FRAP-based antioxidant activity in vitro and caused 1.7-fold and 1.4-fold increases in the growth rate of root system upon carborundum-based application on the root growth medium of N. glutinosa. The present work reports an antiviral protein with ribosome-inactivating, antioxidation and root developer potencies in C. plumosa as an edible or ornamental plant that may be useful in health and agricultural biotechnology in the future.

Study on Betalains in Celosia cristata Linn. Callus Culture and Identification of New Malonylated Amaranthins

Betacyanins and betaxanthins were characterized and determined in an intensely pigmented red-colored callus culture of Celosia cristata L. (Amaranthaceae). A new malonyl derivative, 6'- O-malonyl-amaranthin (celoscristatin) was isolated and identified by spectroscopic and mass spectrometric techniques. Its stereoisomer, 4'- O-malonyl-amaranthin (celoscristatin acyl-migrated), as well as its 15 R diastereomer were also detected in the callus as a result of the malonyl group migration in celoscristatin/isoceloscristatin, respectively. Amaranthin occurs in the callus as the major betacyanin, followed by celoscristatin, betanin, phyllocactin, and other minor betacyanins. The effect of different carbon sources on the growth rates of the Celosia callus as well as on betalains profiles in the callus cultures was studied. High dopamine content in the callus culture was determined and compared with the content in C. cristata inflorescences. The dopamine-based betalain (miraxanthin V) was detected as the main betaxanthin in the callus, however, at a concentration level much lower than that of the identified betacyanins. The studied callus culture of C. cristata can accumulate betalains in amounts which approach the quantities produced by most known high-yielding plant species.

Phyto-metabolites; An Impregnable Shield against Plant Viruses

Worldwide, economically important crops are under continuous threat from plant viruses as they reproduce within the host and spread via various biological and non biological means. The problem can be minimized via application of integrated management approaches involving utilization of resistant genotypes and reducing the insect vector population. But such strategies are rarely applied in developing countries and farmers prefer to use chemicals against all type of diseases. But increasing use of pesticides is a leading cause of disaster to our ecosystem so alternative means such as phyto-metabolites should be explored for eco friendly management of plant viruses. So here we have reviewed about different phyto-metabolites that can be effectively and potentially used against various plant virus diseases. We further explained about the various primary and secondary metabolites such as alkaloids, essential oils, flavonoids, polysaccharides and proteins. The review highlights the recent advances in the field of phyto-metabolites utilization against plant viruses and sums up via hoping through prospects that future drugs will be safer for human beings and our ecosystem.

Three new oleanane-type triterpenoid saponins from the seeds of Celosia cristata L

Phytochemical investigation of the 1-butanol soluble fraction of 60% ethanol extract of the seeds of Celosia cristata L. led to the identification of three new oleanane-type triterpenoid saponins. Using ¹D and ²D NMR experiment methods, ESI-MS analysis and acid hydrolysis, their structures were identified as 3-O-[β-D-xylopyranosyl-(1 → 3)-β-D-glucuronopyranosyl]-2β-hydroxy-oleanolic acid-28-O-β-D-glucopyranoside (1), 3-O-[β-D-xylopyranosyl-(1 → 3)-β-D-glucuronopyranosyl]-2β, 23-dihydroxy-oleanolic acid-28-O-β-D-glucopyranoside (2) and 3-O-[β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranosyl]-2-hydroxyl-medicagenic acid-28-O-β-D-glucopyranosyide (3), respectively.

Advances and prospects in biogenic substances against plant virus: A review

Plant virus diseases, known as 'plant cancer', are the second largest plant diseases after plant fungal diseases, which have caused great damage to agricultural industry. Since now, the most direct and effective method for controlling viruses is chemotherapeutics, except for screening of anti-disease species. As the occurrence and harm of plant diseases intensify, production and consumption of pesticides have increased year by year, and greatly contributed to the fertility of agriculture, but also brought a series of problems, such as the increase of drug resistance of plant pathogens and the excessive pesticide residues. In recent years, biopesticide, as characterized by environmentally safe due to low residual, safe to non-target organism due to better specificity and not as susceptible to produce drug resistance due to diverse work ways, has gained more attention than ever before and exhibited great development potential. Now much progress has been made about researches on new biogenic anti-plant-virus substances. The types of active components include proteins, polysaccharides and small molecules (alkaloids, flavonoids, phenols, essential oils) from plants, proteins and polysaccharides from microorganisms, polysaccharides from algae and oligochitosan from animals. This study summarized the research advance of biogenic anti-plant-virus substances in recent years and put forward their further development in the future.

Antinociceptive effect of methanol extract of Celosia cristata Linn. in mice

BACKGROUND

Celosia cristata Linn. (Amaranthaceae) is used in traditional medicine for the treatment of headache, sores, ulcers, eye inflammations, skin eruption, painful menstruation and carpal tunnel syndrome. This study was performed to evaluate the antinociceptive activity of methanol extract of the whole plant of C. cristata (MECC).

METHODS

The evaluation of the antinociceptive effect of MECC was performed using thermal (hot plate, tail immersion test) and chemical (acetic acid, formalin, and glutamate-induced nociception test) pain models in mice at four different doses (50, 100, 200, 400 mg/kg; p.o.). Involvement of opioid receptors mediated central antinociceptive mechanism of MECC was evaluated using naloxone. Furthermore, the association of ATP-sensitive K+ channel and cGMP pathway were evaluated using glibenclamide and methylene blue respectively.

RESULTS

Oral treatment of MECC produced significant, strong and dose-dependent central and peripheral antinociceptive effect in experimental pain models. MECC significantly increased the latency time of thermal threshold in both hot plate and tail immersion test. The inhibition of writhing syndrome by the extract in the acetic acid-induced writhing test was remarkable. MECC significantly reduced the formalin-induced neurogenic and inflammatory pain. In addition, the inhibition of glutamate-induced paw licking and edema by MECC was significant. The antinociceptive effect was significantly reversed by naloxone and glibenclamide, suggesting the association of opioid and ATP-sensitive K+ channel system respectively. In addition, MECC also demonstrated the involvement of cGMP pathway in the antinociceptive action.

CONCLUSION

The study suggests that C. cristata possess significant antinociceptive effect which is associated with both central and peripheral mechanisms and provides a rationale for its extensive use at different painful conditions in traditional medicine.

Digestion of chrysanthemum stunt viroid by leaf extracts of Capsicum chinense indicates strong RNA-digesting activity

KEY MESSAGE

CSVd could not infect Nicotiana benthamiana when the plants were pretreated with crude leaf extract of Capsicum chinense 'Sy-2'. C. chinense leaves were revealed to contain strong RNA-digesting activity. Several studies have identified active antiviral and antiviroid agents in plants. Capsicum plants are known to contain antiviral agents, but the mechanism of their activity has not been determined. We aimed to elucidate the mechanism of Capsicum extract's antiviroid activity. Chrysanthemum stunt viroid (CSVd) was inoculated into Nicotiana benthamiana plants before or after treating the plants with a leaf extract of Capsicum chinense 'Sy-2'. CSVd infection was determined using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) 3 weeks after inoculation. When Capsicum extract was sprayed or painted onto N. benthamiana before inoculation, it was effective in preventing infection by CSVd. To evaluate CSVd digestion activity in leaf extracts, CSVd was mixed with leaf extracts of Mirabilis, Phytolacca, Pelargonium and Capsicum. CSVd-digesting activities were examined by quantifying undigested CSVd using qRT-PCR, and RNA gel blotting permitted visualization of the digested CSVd. Only Capsicum leaf extract digested CSVd, and in the Capsicum treatment, small digested CSVd products were detected by RNA gel blot analysis. When the digesting experiment was performed for various cultivars and species of Capsicum, only cultivars of C. chinense showed strong CSVd-digesting activity. Our observations indicated that Capsicum extract contains strong RNA-digesting activity, leading to the conclusion that this activity is the main mechanism for protection from infection by CSVd through spraying or painting before inoculation. To our knowledge, this is the first report of a strong RNA-digesting activity by a plant extract.

Ribosome-inactivating and related proteins

Ribosome-inactivating proteins (RIPs) are toxins that act as N-glycosidases (EC 3.2.2.22). They are mainly produced by plants and classified as type 1 RIPs and type 2 RIPs. There are also RIPs and RIP related proteins that cannot be grouped into the classical type 1 and type 2 RIPs because of their different sizes, structures or functions. In addition, there is still not a uniform nomenclature or classification existing for RIPs. In this review, we give the current status of all known plant RIPs and we make a suggestion about how to unify those RIPs and RIP related proteins that cannot be classified as type 1 or type 2 RIPs.

Screening, isolation and optimization of anti-white spot syndrome virus drug derived from terrestrial plants

OBJECTIVE

To screen, isolate and optimize anti-white spot syndrome virus (WSSV) drug derived from various terrestrial plants and to evaluate the efficacy of the same in host-pathogen interaction model.

METHODS

Thirty plants were subjected to Soxhlet extraction using water, ethanol, methanol and hexane as solvents. The 120 plant isolates thus obtained were screened for their in vivo anti-WSSV property in Litopenaeus vannamei. The best anti-WSSV plant isolate, TP22C was isolated and further analyzed. The drug was optimized at various concentrations. Viral and immune genes were analysed using reverse transcriptase PCR to confirm the potency of the drug.

RESULTS

Seven plant isolates exhibited significant survivability in host. The drug TP22C thus formulated showed 86% survivability in host. The surviving shrimps were nested PCR negative at the end of the 15 d experimentation. The lowest concentration of TP22C required intramuscularly for virucidal property was 10 mg/mL. The oral dosage of 750 mg/kg body weight/day survived at the rate of 86%. Neither VP28 nor ie 1 was expressed in the test samples at 42nd hour and 84th hour post viral infection.

CONCLUSIONS

The drug TP22C derived from Momordica charantia is a potent anti-white spot syndrome virus drug.

Root secretion of defense-related proteins is development-dependent and correlated with flowering time

Proteins found in the root exudates are thought to play a role in the interactions between plants and soil organisms. To gain a better understanding of protein secretion by roots, we conducted a systematic proteomic analysis of the root exudates of Arabidopsis thaliana at different plant developmental stages. In total, we identified 111 proteins secreted by roots, the majority of which were exuded constitutively during all stages of development. However, defense-related proteins such as chitinases, glucanases, myrosinases, and others showed enhanced secretion during flowering. Defense-impaired mutants npr1-1 and NahG showed lower levels of secretion of defense proteins at flowering compared with the wild type. The flowering-defective mutants fca-1, stm-4, and co-1 showed almost undetectable levels of defense proteins in their root exudates at similar time points. In contrast, root secretions of defense-enhanced cpr5-2 mutants showed higher levels of defense proteins. The proteomics data were positively correlated with enzymatic activity assays for defense proteins and with in silico gene expression analysis of genes specifically expressed in roots of Arabidopsis. In conclusion, our results show a clear correlation between defense-related proteins secreted by roots and flowering time.

Isolation and characterization of ZH14 with antiviral activity againstTobacco mosaic virus

A large number of bacteria were isolated from plant samples and screened for antiviral activity against the Tobacco mosaic virus (TMV). The bacterium ZH14, which was isolated from Chinese Anxi oolong tea, secreted the antiviral substances, having 94.2% virus inhibition when the bacterial culture filtrate and TMV extract were mixed at a ratio of 1:1. The ZH14 strain is a gram-positive, spore-forming rod and has the ability to degrade ribonucleic acid. Based on its effectiveness on virus inhibition, ZH14 was selected for characterization and was identified as a strain of the Bacillus cereus group based on phenotypic tests and comparative analysis of its 16S rDNA sequence. At the same time, we determined the antiviral product of ZH14 as an extracellular protein with high molecular mass, having an optimum temperature of 15–60 °C and an optimum pH of 6–10. Hence, the ZH14 strain and its culture filtrate have potential application in controlling plant diseases caused by TMV.

Antiphytoviral activity of bruceine-D from Brucea javanica seeds

BACKGROUND

Brucea javanica (L.) Merr. is widely distributed throughout the southern parts of China and has been used in traditional medicine to treat a variety of diseases. The objective of the present study was to identify the active antiphytoviral compound in the seeds of B. javanica and evaluate the inhibitory activity of the compound against plant virus.

RESULTS

Bioassay-guided fractionation of the most active extract from the seeds led to the isolation of an antiphytoviral compound which was identified as bruceine-D by conventional spectroscopy methods. The compound exhibited significant inhibitory activity against the infection and replication of tobacco mosaic virus (TMV), with IC(50) values of 13.98 and 7.13 mg L(-1) respectively. The compound also showed a strong inhibitory effect on the infectivity of potato virus Y (PVY) and cucumber mosaic virus (CMV). Furthermore, the compound could effectively inhibit systemic TMV infection in the host tobacco plant under glasshouse conditions.

CONCLUSION

The results suggested that bruceine-D from Brucea javanica may have the potential to be used as a natural viricide, or a lead compound for new viricides.

Molecular cloning and functional identification of a ribosome inactivating/antiviral protein from leaves of post-flowering stage of Celosia cristata and its expression in E. coli

A full-length cDNA clone, encoding a ribosome inactivating/antiviral protein (RIP/AVP) was isolated from the cDNA library of post-flowering stage of Celosia cristata leaves. The full-length cDNA consisted of 1015 nucleotides, with an open reading frame encoding 283 amino acids. The deduced amino acid sequence had a putative active site domain conserved in other ribosome inactivating/antiviral proteins (RIPs/AVPs). The coding region of the cDNA was amplified by polymerase chain reaction (PCR), cloned and expressed in Escherichia coli as recombinant protein of 72 kDa. The expressed fusion product was confirmed by Western analysis and purification by affinity chromatography. Both the recombinant protein (reCCP-27) and purified expressed protein (eCCP-27) inhibited translation in rabbit reticulocytes showing IC50 values at 95 ng and 45 ng, respectively. The native purified nCCP-27 has IC50 at 25 ng. The purified product also showed N-glycosidase activity towards tobacco ribosomes and antiviral activity towards tobacco mosaic virus (TMV) and sunnhemp rosette virus (SRV).

Purification, characterization and cloning of antiviral/ribosome inactivating protein from Amaranthus tricolor leaves

An antiviral protein (AVP), imparting high level of resistance against sunnhemp rosette virus (SRV) was purified from the dried leaves of Amaranthus tricolor. The purified protein (AAP-27) exhibited approximately 98% inhibition of local lesion formation at a concentration range of approximately 30 microg ml(-1). The protein was found to be highly basic glycoprotein monomer (pI approximately 9.8) of Mr 27 kDa, with neutral sugar content of 4%. The purified protein exhibited N-glycosidase and RNase activities. We have also isolated full-length cDNA clone, encoding this protein designated as A. tricolor antiviral protein-1 (AAP-1). Two primers, one designed on the basis of N-terminal sequence of the purified protein and the other from the conserved active peptides of other AVPs/RIPs were used for PCR amplification of double stranded cDNA, isolated from the leaves of A. tricolor. The amplified fragment was used as a probe for library screening. The isolated full-length cDNA consisted of 1058 nucleotides with an open reading frame encoding a polypeptide of 297 amino acids. The deduced amino acid sequence of AAP-1 has a putative active domain conserved in other AVPs/RIPs and shows varying homology to the RIPs from other plant species.

Cloning and expression of small cDNA fragment encoding strong antiviral peptide from Celosia cristata in Escherichia coli

A small cDNA fragment containing a ribosome-inactivating site was isolated from the leaf cDNA population of Celosia cristata by polymerase chain reaction (PCR). PCR was conducted linearly using a degenerate primer designed from the partially conserved peptide of ribosome-inactivating/antiviral proteins. Sequence analysis showed that it is 150 bp in length. The cDNA fragment was then cloned in a bacterial expression vector and expressed in Escherichia coli as a ~57 kD fused protein, and its presence was further confirmed by Western blot analysis. The recombinant protein was purified by affinity chromatography. The purified product showed strong antiviral activity towards tobacco mosaic virus on host plant leaves, Nicotiana glutinosa, indicating the presence of a putative antiviral determinant in the isolated cDNA product. It is speculated that antiviral site is at, or is separate but very close to, the ribosome-inactivating site. We nominate this short cDNA fragment reported here as a good candidate to investigate further the location of the antiviral determinants. The isolated cDNA sequence was submitted to EMBL databases under accession number of AJ535714.

An antiviral protein having deoxyribonuclease and ribonuclease activity from leaves of the post-flowering stage of Celosia cristata

An antiviral protein named CCP-27 was purified from the leaves of Celosia cristata at the post-flowering stage by anion-exchange, cation-exchange, and gel-filtration chromatography. It exhibited resistance against sunnhemp rosette virus in its test host Cyamopsis tetragonoloba. It also exhibited deoxyribonuclease activity against supercoiled pBlueScript SK+ plasmid DNA. It was found to nick supercoiled DNA into nicked circular form at lower protein concentration followed by nicked to linear form conversion at higher protein concentration. CCP-27 also possesses strong ribonuclease activity against Torula yeast rRNA.