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  • 11
    Electronic Resource
    Electronic Resource
    Artemisia annua L.: a source of novel antimalarial drugs (1990)
    Springer
    Pharmacy world & science 12 (1990), S. 169-181 
    Details
    ISSN: 1573-739X
    Keywords: Artemisia annua L. ; Artemisinin ; Biosynthesis ; Chemistry, analytical ; Clinical trials ; Pharmacology ; Sesquiterpene lactones ; Structure—activity relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Artemisia annua L. contains artemisinin, an endoperoxide sesquiterpene lactone, mainly in its leaves and inflorescences. This compound and a series of derivatives have attracted attention because of their potential value as antimalarial drugs. In this review a survey of the currently available literature data is given. It includes phytochemical aspects, such as constituents ofA. annua, the artemisinin content during the development of the plant and its biosynthesis, isolation, analysis and stability. Total chemical synthesis of artemisinin is referred to, as well as structure—activity relationships of derivatives and simplified analogues. Pharmacological studies are summarized, including the mechanism of action, interaction of the antimalarial activity with other drugs, possible occurrence of resistance to artemisinin, clinical results, toxicological aspects, metabolism and pharmacokinetics. Finally, plant cell biotechnologyy is mentioned as a possible means to obtain plants and cell cultures with higher artemisinin contents, allowing an industrial production of pharmaceuticals containing this novel drug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01980041
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  • 12
    Electronic Resource
    Electronic Resource
    Production of the new antimalarial drug artemisinin in shoot cultures of Artemisia annua L. (1993)
    Springer
    Plant cell, tissue and organ culture 32 (1993), S. 247-257 
    Details
    ISSN: 1573-5044
    Keywords: antimalarial drugs ; Artemisa annua ; artemisinin ; sesquiterpene lactones ; shoot culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From aseptically grown Artemisia annua plantlets, shoot cultures were initiated. Using different concentrations of auxine, cytokinine and sucrose, a suitable culture medium was developed, with respect to the growth of the shoots and their artemisinin accumulation. Nitrate concentration and conductivity appeared to be suitable growth parameters. The artemisinin content was measured gas chromatographically. The shoot cultures were maintained in the developed standard medium, consisting of a half concentration of MS-salts with vitamins, 0.2 mg l-1 BAP, 0.05 mg l-1 NAA and 1% sucrose. The growth of the shoots and the artemisinin content remained stable for a longer period. They showed considerable photosynthetic activity and generally contained ca. 0.08% artemisinin on a dry weight basis. The highest artemisinin content found was 0.16% in the above mentioned standard medium, but also on the same medium with 0.5% sucrose. Attempts were made to further improve the artemisinin production by varying the medium composition through addition of gibberellic acid or casein hydroly-state; by omitting plant growth regulators; by precursor feeding, i.e. mevalonic acid; by influencing the biosynthesis routing through inhibition of the sterol synthesis by miconazole, naftifine or terbinafine; by changing gene expression with 5-azacytidine or colchicine; and by elicitation, using cellulase, chitosan, glutathione or nigeran. Enhanced artemisinin production was found with 10 mg l-1 gibberellic acid, 0.5 g l-1 casein hydrolysate, 10 mg l-1 or 20 mg l-1 naftifine. Relative increases of 154%, 169%, 140% and 120% were found, respectively. Other additions caused the growth to cease and the artemisinin contents to drop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029850
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  • 13
    Electronic Resource
    Electronic Resource
    Occurrence of L-DOPA and dopamine in plants and cell cultures ofMucuna pruriens and effects of 2,4-d and NaCl on these compounds (1993)
    Springer
    Plant cell, tissue and organ culture 33 (1993), S. 259-264 
    Details
    ISSN: 1573-5044
    Keywords: 2,4-d ; dopamine ; L-DOPA ; Mucuna pruriens ; plant cell culture ; salt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The development of the L-DOPA-content of roots, stems and leaves ofMucuna pruriens during growth of the plants is described. Besides L-DOPA, the leaves, but not the stems and the roots, also contain the related catechol dopamine. The time course of dopamine accumulation is compared to that of L-DOPA. In cell suspension cultures ofM. pruriens dopamine can be detected as well. Its level is strongly increased by addition of the growth regulator 2,4-d to the medium, a condition that suppresses cell growth and L-DOPA-accumulation. Dopamine induction appears to be a specific metabolic effect of 2,4-d. Salt stress, as caused by the addition of NaCl, gives no induction of dopamine formation, whereas L-DOPA is released into the medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319010
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  • 14
    Electronic Resource
    Electronic Resource
    Cyclodextrins as a useful tool for bioconversions in plant cell biotechnology (1994)
    Springer
    Plant cell, tissue and organ culture 38 (1994), S. 103-113 
    Details
    ISSN: 1573-5044
    Keywords: Bioconversion ; catechols ; cyclodextrins ; lignans ; plant cell cultures ; solubility enhancement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The application of cyclodextrins as precursor solubilizers in biotechnological processes, in which plant cells are involved, is new. In this paper the possibilities for cyclodextrin facilitated bioconversions by freely suspended and/or immobilized plant cells or plant enzymes are demonstrated. After complexation with β-cyclodextrin, the phenolic steroid 17β-estradiol could be ortho-hydroxylated into a catechol, mainly 4-hydroxyestradiol, by a phenoloxidase from in vitro grown cells of Mucuna pruriens. By complexation with β-cyclodextrin the solubility of the steroid increased from almost insoluble to 660 μM. In addition, by complexation with β-cyclodextrin, a solution of 3 mM coniferyl alcohol could be fed to cell cultures of Podophyllum hexandrum in order to enhance the accumulation of podophyllotoxin. Finally, the glucosylation of podophyllotoxin by cell cultures derived from Linum flavum was investigated. Four cyclodextrins: β-cyclodextrin, γ-cyclodextrin, hydroxypropyl-β-cyclodextrin and dimethyl-β-cyclodextrin were used to improve the solubility of podophyllotoxin. Dimethyl-β-cyclodextrin met our needs the best and the solubility of podophyllotoxin could be enhanced from 0.15 to 1.92 mM. Podophyllotoxin-β-d-glucoside was formed at a rate of 0.51 mmol l-1 suspension per day by the L. flavum cells growing in the presence of 1.35 mM podophyllotoxin, complexed with dimethyl-β-cyclodextrin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033867
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  • 15
    Electronic Resource
    Electronic Resource
    The production of podophyllotoxin and its 5-methoxy derivative through bioconversion of cyclodextrin-complexed desoxypodophyllotoxin by plant cell cultures (1995)
    Springer
    Plant cell, tissue and organ culture 42 (1995), S. 73-79 
    Details
    ISSN: 1573-5044
    Keywords: Glucosides ; Linum flavum ; 5-methoxypodophyllotoxin ; podophyllotoxin ; Podophyllum hexandrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The bioconversion of the lignan desoxypodophyllotoxin by cell suspensions of Linum flavum and of Podophyllum hexandrum was investigated. The apolar substrate could be easily dissolved in the culture medium at a concentration of 2 mM by complexation with dimethyl-β-cyclodextrin. Growth parameters of the cell suspensions were not affected by either the addition of cyclodextrin itself, or when cyclodextrin-complexed desoxypodophyllotoxin was present in the medium. The complexed lignan disappeared from the medium within 7 days for both cell cultures. Cellularly only small amounts of desoxypodophyllotoxin were found. After feeding of desoxypodophyllotoxin, the cell culture of L. flavum accumulated 5-methoxypodophyllotoxin and 5-methoxypodophyllotoxin-β-D-glucoside. After 7 days a total maximal content of 2.38% on a dry weight basis of 5-methoxypodophyllotoxin was formed, corresponding with 249 mg l-1 suspension. The highest bioconversion percentage of 52.3% was found at day 14. The desoxypodophyllotoxin-fed culture of P. hexandrum accumulated podophyllotoxin and its β-D-glucoside with a maximal content of 2.87% on a dry weight basis after 9 days, corresponding with 192 mg 1-1 suspension. The highest bioconversion percentage of 33.2% was also found at day 9.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037684
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  • 16
    Electronic Resource
    Electronic Resource
    Bioconversion of para-substituted monophenolic compounds into corresponding catechols by alginate entrapped cells ofMucuna pruriens (1988)
    Springer
    Plant cell, tissue and organ culture 13 (1988), S. 15-26 
    Details
    ISSN: 1573-5044
    Keywords: Mucuna pruriens ; entrapped plant cells ; bioconversions ; catechols ; isolation ; mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Alginate-entrapped cells ofM. pruriens were able to convert a number of parasubstituted monophenolic compounds into the corresponding catechols. All catechols produced were released into the medium, which offered the opportunity to isolate these products via a relatively simple procedure. Prepurification was performed on a Sephadex G10 gel and catechols were concentrated on Affigel 601. The identity of all products was confirmed with combined liquid chromatography/mass spectrometry (LC/MS) or MS using the desorption chemical ionization technique, depending on the catechol. For the entrapped cells and for a cell homogenate prepared of the same cell line ofM. pruriens the substrate specificities were qualitatively identical when judged on initial rates of synthesis calculated on protein basis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043043
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  • 17
    Electronic Resource
    Electronic Resource
    Bioconversion of bi- and tri-cyclic monophenols by alginate-entrapped cells of Mucuna pruriens L. and by the partially purified Mucuna-phenoloxidase (1990)
    Springer
    Plant cell, tissue and organ culture 21 (1990), S. 9-15 
    Details
    ISSN: 1573-5044
    Keywords: 3-aminotetralins ; bioconversions ; catechols ; entrapped plant cells ; mass spectrometry ; Mucuna pruriens L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although alginate-entrapped cells of Mucuna pruriens L. possess a low substrate specificity, only para-substituted monocyclic phenols have been ortho-hydroxylated into catechols so far. In this study, compounds with more complex chemical structures were found to be substrates using entrapped cells of M. pruriens as well as the partially purified Mucuna-phenoloxidase. Thus, 5-, 6- and 7-hydroxylated 2-aminotetralins and a tricyclic compound, 9-hydroxy N-n-propyl hexahydronaphthoxazine, were converted into catechols. After isolation using preparative HPLC, the identity of the products was confirmed by MS. In general, for the entrapped cells and the enzyme preparation identical substrate specificities were found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034485
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  • 18
    Electronic Resource
    Electronic Resource
    On the improvement of the podophyllotoxin production by phenylpropanoid precursor feeding to cell cultures of Podophyllum hexandrum Royle (1990)
    Springer
    Plant cell, tissue and organ culture 23 (1990), S. 217-224 
    Details
    ISSN: 1573-5044
    Keywords: coniferin ; lignan biosynthesis ; permeabilization ; phenylpropanoid precursors ; podophyllotoxin ; Podophyllum hexandrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to improve the production of the cytotoxic lignan podophyllotoxin, seven precursors from the phenylpropanoid-routing and one related compound were fed to cell suspension cultures derived from the rhizomes of Podophyllum hexandrum Royle. These cell cultures were able to convert only coniferin into podophyllotoxin, maximally a 12.8 fold increase in content was found. Permeabilization using isopropanol, in combination with coniferin as a substrate, did not result in an extra increase in podophyllotoxin accumulation. Concentrations of isopropanol exceeding 0.5% (v/v) were found to be rather toxic for suspension growth cells of P. hexandrum. When coniferin was fed in presence of such isopropanol concentrations, β-glucosidase activity was still present, resulting in the formation of the aglucon coniferyl alcohol. In addition, podophyllotoxin was released into the medium under these permeabilization conditions. Entrapment of P. hexandrum cells in calcium-alginate as such or in combination with the feeding of biosynthetic precursors, did not improve the podophyllotoxin production. Cell-free medium from suspension cultures at later growth stages incubated with coniferin, resulted in the synthesis of the lignan pinoresinol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034435
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  • 19
    Electronic Resource
    Electronic Resource
    Improvement of the production of 5-methoxypodophyllotoxin using a new selected root culture of Linum flavum L. (1991)
    Springer
    Plant cell, tissue and organ culture 27 (1991), S. 115-121 
    Details
    ISSN: 1573-5044
    Keywords: Linum flavum ; 5-methoxypodophyllotoxin ; optimization ; phenylpropanoids ; production ; root culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new, morphologically root-like cell line of Linum flavum was selected and used for the optimization of the production of 5-methoxypodophyllotoxin. The omittance of naphthaleneacetic acid from the medium resulted in further root formation, which was accompanied with a 2.6 fold increase of 5-methoxypodophyllotoxin levels. The feeding of the phenylpropanoids L-tyrosine and L-phenylalanine resulted in enhanced 5-methoxypodophyllotoxin contents. After the removal of vitamins together with the phytohormone from the medium, 5-methoxypodophyllotoxin levels were enhanced 6 times. The maximal content ever found using this production medium was 1.01% on a dry weight basis. The application of higher sucrose concentrations led to proportional biomass increase, cells grown on 6% sucrose resulted in the highest yield, 121.4 mg l-1 5-methoxypodophyllotoxin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041279
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  • 20
    Electronic Resource
    Electronic Resource
    Production of 5-methoxypodophyllotoxin in cell suspension cultures of Linum flavum L. (1990)
    Springer
    Plant cell, tissue and organ culture 20 (1990), S. 81-87 
    Details
    ISSN: 1573-5044
    Keywords: anti-tumour activity ; elicitation ; lignan biosynthesis ; 5-methoxypodophyllotoxin ; phenylalanine ammonia lyase ; phenylpropanoid pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell suspension cultures of Linum flavum L., routinely grown on a NAA-containing medium, accumulated low levels of the phenylpropanoid-derived lignan 5-methoxypodophyllotoxin (5-MPT), up to 0.004% on a dry weight basis. Feeding experiments with the precursor L-phenylalanine resulted in a 3–5-fold increase in 5-MPT levels, but caused the levels of PAL activity to fall. Treatment of the cultures with the elicitor Nigeran, either alone or in combination with phenylalanine, caused the 5-MPT production to cease, even though PAL activity was rapidly enhanced by these treatments. Transfer of the cultures to NAA-free medium resulted in a 40–50 fold higher level of 5-MPT accumulation, the PAL activity levels being lowered compared to the routinely grown cells. With these more differentiated cultures, phenylalanine feeding and elicitor treatment, both on its own and in combination with the precursor, had no effect on 5-MPT production, even though the PAL activity levels were higher than in the untreated cells. It can be concluded that in lignan-accumulating cultures of L. flavum, PAL activity is nearly always detectable and seems to show a reciprocal relationship with 5-MPT accumulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00114704
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