Fig. 1 The molecule of this study, chrozophoridin. Left: Close-up of C. tinctoria fruits (collected in Alentejo, Portugal) and clothlets prepared with the juice of the fruits following the instructions in the Book of all color paints. Light green fruits were used in this study shortly after collection. Right: Molecular structures of the blue colorants, hermidin (from M. perennis), and chrozophoridin (from C. tinctoria). Photo credit: Paula Nabais, Universidade NOVA de Lisboa.
Fig. 4 Analysis of the thermodynamically favored atropoisomers of chrozophoridin, in solution. Molecules are depicted as sticks and colored by atom type. (A) A ring, B ring, and glucose ring are colored in red, orange, and green, respectively. Both ω1 and ω2 dihedrals and hydrogen bonds are also indicated. (B) Superposition of the A ring of the two molecules. Colored by element (atropisomer 1) and green (atropisomer 2). (C) UV-VIS spectra (water, pH 7, blue) for chrozophoridin compared with the predicted spectra [Boese-Martin for kinetics (BMK) functional] for atropisomers 1 (black) and 2 (green).
- Table 1 API-LC-ESI-MS/MS data for the major and minor compounds extracted from C. tinctoria fruits.
Molecular ion and respective fragments MS2 and MS3 obtained by atmospheric pressure ionization (API)–LC–electrospray ionization (ESI)–MS/MS (positive ion mode) found in the blue extract of C. tinctoria fruits.
Rt (min) Identity [M+] [MS2] [MS3] 8.29 Hermidin-glycoside 334 172 157 15.63 Peonidin-3-glucoside 463 301 20.33 Hermidin-derivative (blue dye) 501 339 307; 279; 254 52.36 Delphinidin-3-
coumaroylglucoside611 303 52.67 Cyanidin-3-
coumaroylglucoside595 449 287 60.07 Pelargonidin-3-
coumaroylglucoside579 433 271 64.23 Peonidin-3-
coumaroylglucoside609 463 301 - Table 2 Essential NMR data for the identification of chrozophoridin.
1H and 13C chemical shifts of the blue dye present in C. tinctoria fruits, determined in DMSO-d6:D2O (9:1).
Position δ 1Η (ppm); J (Hz) δ 13C (ppm)* A ring 1-N-CH3 3.12; s 27.4/27.5 2 C═O – 164.0/163.7 3 – 88.5/88.4 4 – 156.0/156.1 4-OCH3 3.71; 3.78; s 59.2/59.4 5 – 122.0/122.3 6 – 159.0/158.8 B ring 7-N-CH3 3.12; s 27.3/27.5 8 C═O – 161.7/161.6 9 – 128.4/127.7 10 – 161.1/161.0 10-OCH3 3.75; 3.77; s 60.8/61.0 11 C═O – 172.6/172.3 12 C=O – 157.0/156.9 Glucose moiety 1′ 4.32; d, 7.7/4.20; d, 7.5 108.3/108.7 2′ 3.13;† 74.1/74.1 3′ 3.10;† 77.4/77.5 4′ 2.90;† 75.0/75.0 5′ 3.16;† 76.9/76.9 6a′ 3.45; 61.3/61.5 6b′ 3.63; 61.3/61.5 *The carbon signals are duplicated, which indicates that at least two isomers are present.
†Unresolved (superposition).
Supplementary Materials
Supplementary Materials for this article is available at http://advances.sciencemag.org/cgi/content/full/6/16/eaaz7772/DC1
Additional Files
Supplementary Materials
A 1000-year-old mystery solved: Unlocking the molecular structure for the medieval blue from Chrozophora tinctoria, also known as folium
P. Nabais, J. Oliveira, F. Pina, N. Teixeira, V. de Freitas, N. F. Brás, A. Clemente, M. Rangel, A. M. S. Silva, M. J. Melo
This PDF file includes:
- Supplementary Materials and Methods (detailed)
- Figs. S1 to S6
- Tables S1 and S2
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