Belitz HD, Grosch W, Schieberle P (2008) Lehrbuch der Lebensmittelchemie, 6th edn. Springer, Berlin, Heidelberg
Google Scholar
Bouché N, Lacombe B, Fromm H (2003) GABA signaling: a conserved and ubiquitous mechanism. Trends Cell Biol 13:607–610
Article
PubMed
Google Scholar
Byun SM, Jeong SW, Cho DH, Kim YH (2015) Optimized conversion of l-lysine to l-pipecolic acid using recombinant lysine cyclodeaminase from Streptomyces pristinaespiralis. Biotechnol Bioprocess Eng 20:73–78
CAS
Article
Google Scholar
Choi SS, Song MJ, Kim OB, Kim Y (2013) Fragmentation patterns of protonated amino acids formed by atmospheric pressure chemical ionization. Rapid Commun Mass Spectrom 27:143–151
CAS
Article
PubMed
Google Scholar
Dengler WA, Schulte J, Berger DP, Mertelsmann R, Fiebig HH (1995) Development of a propidium Iodide fluorescence assay for proliferation and cytotoxicity assays. Anticancer Drugs 6:522–532
CAS
Article
PubMed
Google Scholar
Dirsch V, Lacaille-Dubois MA, Wagner H (1994) Dracoside, a new steroidal saponin from Helleborus purpurascens. Nat Prod Lett 4(1):29–33. doi:10.1080/10575639408043888
CAS
Article
Google Scholar
Dunn MS, Ross FJ (1938) Quantitative investigations of amino acids and peptides: IV. The solubility of amino acids in water–ethyl alcohol mixtures. J Biol Chem 125:309–332
CAS
Google Scholar
Fendler JH, Nome F, Nagyvary J (1975) Compartmentalization of amino acids in surfactant aggregates. J Mol Evol 6:215–232
CAS
Article
PubMed
Google Scholar
Fiebig HH, Berger DP, Dengler WA, Wallbrecher E, Winterhalter BR (1992) Combined in vitro/in vivo test procedure with human tumor xenografts. In: Fiebig HH, Berger DP (eds) Contributions to oncology: immunodeficient mice in oncology, vol 42. Karger, Basel, pp 321–351
Google Scholar
Fiebig HH, Dengler WA, Roth T (1999) Human tumor xenografts: predictivity, characterization, and discovery of new anticancer agents. In: Fiebig HH, Burger AM (eds) Contribution to oncology: relevance of tumor models for anticancer drug development, vol 54. Karger, Basel, pp 29–50
Google Scholar
Fringuelli R, Utrilla Navarro MP, Milanese L, Bruscoli S, Schiaffella F, Riccardi C, De Simone C (2004) Synthesis and evaluation of anti-apoptotic activity of l-carnitine cyclic analogues and amino acid derivatives. Il Farmaco 59:271–277
CAS
Article
PubMed
Google Scholar
Fujioka S, Sakurai A, Yamaguchi I, Murofushi N, Takahashi N, Kaihara S, Takimoto A (1987) Isolation and identification of l-pipecolic acid and nicotinamide as flower-inducing substances. Lemna Plant Cell Physiol 28:995–1003
CAS
Google Scholar
Germann UA, Shlyakhter D, Mason VS, Zelle RE, Duffy JP, Galullo V et al (1997) Cellular and biochemical characterization of VX-710 as a chemosensitizer: reversal of P-glycoprotein-mediated multidrug resistance in vitro. Anticancer Drugs 8:125–140
CAS
Article
PubMed
Google Scholar
Gopalakrishnan R, Kozany C, Gaali S, Kress C, Hoogeland B, Bracher A, Hausch F (2012) Evaluation of synthetic FK506 analogues as ligands for the FK506-binding proteins 51 and 52. J Med Chem 55:4114–4122
CAS
Article
PubMed
Google Scholar
Harper HA, Martin DW, Mayes PA, Rodwell VW (1986) Medizinische biochemie. Springer, Berlin, Heidelberg
Book
Google Scholar
Hill AE, Malisoff WM (1926) The mutual solubility of liquids. III. The mutual solubility of phenol and water. IV. The mutual solubility of normal Butyl alcohol and water. J Am Chem Soc 48:918–927
CAS
Article
Google Scholar
Karrer W (1943) Über Hellebrin, ein krystallisiertes glykosid aus radix Hellebori nigri. Helv Chim Acta 26:1353–1367
CAS
Article
Google Scholar
Kerek F (2000) The structure of the digitalislike and natriuretic factors identified as macrocyclic derivatives of the inorganic carbon suboxide. Hypertens Res 23:S33–S38
CAS
Article
PubMed
Google Scholar
Kerek F (2004) Peptides having a high cysteine content. WO Patent 2004/058813
Kerek F, Szegli G, Cremer L, Lupu AR, Durbaca S, Calugaru A, Herold A, Radu DL (2008) The novel arthritis-drug substance MCS-18 attenuates the antibody production in vivo. Acta Microbiol Immunol Hung 55:15–31
CAS
Article
PubMed
Google Scholar
Kißmer B, Wichtl M (1987) Ecdysone aus wurzeln und samen von helleborus-arten. Arch Pharm 320:541–546
Article
Google Scholar
Maftei CV, Fodor E, Jones PG, Freytag M, Franz MH, Kelter G, Fiebig HH, Tamm M, Neda I (2015) N-heterocyclic carbenes (NHC) with 1,2,4-oxadiazole-substituents related to natural products: synthesis, structure and potential antitumor activity of some corresponding gold(I) and silver(I) complexes. Eur J Med Chem 101:431–441
CAS
Article
PubMed
Google Scholar
Maftei CV, Fodor E, Jones PG, Freytag M, Franz MH, Kelter G, Fiebig HH, Tamm M, Neda I (2016a) Novel 1,2,4-oxadiazoles and trifluoromethylpyridines related to natural products: synthesis, structural analysis and investigation of their antitumor activity. Tetrahedron 72:1185–1199
CAS
Article
Google Scholar
Maftei E, Maftei CV, Jones PG, Freytag M, Franz MH, Kelter G, Fiebig HH, Tamm M, Neda I (2016b) Trifluoromethylpyridine-substituted N-heterocyclic carbenes related to natural products: synthesis, structure and potential antitumor activity of some corresponding gold(I), rhodium(I) and iridium(I) complexes. Helv Chim Acta 99:469–481
CAS
Article
Google Scholar
McPhee DJ, Ferreira ICFR (2016) Expression of Concern: Segneanu et al. Helleborus purpurascens—Amino acid and Peptide Analysis Linked to the Chemical and Antiproliferative Properties of the Extracted Compounds. Molecules 2015 20:22170–22187
Google Scholar
Miehl H (1957) Über freie aminosäuren im gifte der gelbbauchunke Bombina variegata L. Monatsh Chem 88:701–702
Article
Google Scholar
Milbradt AG, Kerek F, Moroder L, Renner C (2003) Structural characterization of hellethionins from Helleborus purpurascens. Biochemistry 42:2404–2411
CAS
Article
PubMed
Google Scholar
Morrison RI (1953) The isolation of l-pipecolinic acid from Trifolium repens. Biochem J 53:474–478
CAS
Article
PubMed
PubMed Central
Google Scholar
Muhr P, Kerek F, Dreveny D, Likussar W, Schubert-Zsilavecz M (1995) The structure of Hellebrin. Eur J Org Chem 1995(2):443–444
Google Scholar
Nagyvary J, Fendler JH (1974) Origin of the genetic code: a physical–chemical model of primitive codon assignments. Orig Life 5:357–362
CAS
Article
PubMed
Google Scholar
Návarová H, Bernsdorff F, Döring AC, Zeier J (2012) Pipecolic acid, an endogenous mediator of defence amplification and priming, is a critical regulator of inducible plant immunity. Plant Cell 24:5123–5141
Article
PubMed
PubMed Central
Google Scholar
Neacsu C, Ciobanu C, Barbu I, Toader O, Szegli G, Kerek F, Babes A (2010) Substance MCS-18 isolated from Helleborus purpurascens is a potent antagonist of the capsaicin receptor, TRPV1, in rat cultured sensory neurons. Physiol Res 59:289–298
CAS
PubMed
Google Scholar
Nernst W (1891) Verteilung eines Stoffes zwischen zwei Lösungsmitteln und zwischen Lösungsmittel und Dampfraum. Z Phys Chem 8:110–139
Article
Google Scholar
Nozaki Y, Tanford C (1971) The solubility of amino acids and two glycine peptides in aqueous ethanol and dioxane solutions establishment of a hydrophobicity scale. J Biol Chem 246:2211–2217
CAS
PubMed
Google Scholar
Otsuka H (2005) Purification by solvent extraction using partition coefficient. Nat Prod Isol Methods Biotech 20:269–273
CAS
Google Scholar
Ro KE, Keener CS, McPheron BA (1997) Molecular phylogenetic study of the Ranunculaceae; utility of the nuclear 26S ribosomal DNA in inferring intrafamilial relationships. Mol Phylogenet Evol 8:117–127
CAS
Article
PubMed
Google Scholar
Roth T, Burger AM, Dengler W, Willmann H, Fiebig HH (1999) Human tumor cell lines demonstrating the characteristics of the patient tumors as useful models for anticancer drug screening. In: Fiebig HH, Burger AM (eds) Contributions to oncology: relevance of tumor models for anticancer drug development, vol 54. Karger, Basel, pp 145–156
Google Scholar
Schmutz J (1947) Glycosides and aglycones. XXII. Hellebrin. Pharm Acta Hel 22:373–380
CAS
Google Scholar
Schmutz J (1949) Die konstitution des hellebrigenins: glykoside und aglykone. Helv Chim Acta 32:1442–1452
CAS
Article
Google Scholar
Segneanu AE, Grozescu I, Cziple F, Berki Damian D, Niculite CM, Florea A, Leabu M (2015) Helleborus purpurascens-amino acid and peptide analysis linked to the chemical and antiproliferative properties of the extracted compounds. Molecules 20:22170–22187
CAS
Article
PubMed
Google Scholar
Wissner W, Kating H (1974) Botanical and phytochemical investigations of species of the genus Helleborus growing in Europe and Asian Minor—III. The quantitative contents of hellebrin in plants of the natural biotops and in culture. Planta Med 26:364–374
CAS
Article
PubMed
Google Scholar
Zacharius RM, Thompson JF, Steward FC (1954) The detection, isolation and identification of l(−)-pipecolic acid in the non-protein fraction of beans (Phaseolus vulgaris). J Am Chem Soc 76:2908–2912
CAS
Article
Google Scholar
Zeier J (2013) New insights into the regulation of plant immunity by amino acid metabolic pathways. Plant, Cell Environ 36:2085–2103
CAS
Article
Google Scholar