@article {6730, title = {Identification of 7,4 {\textquoteright}-dihydroxy-5-methoxyflavylium in "Dragon{\textquoteright}s blood": To be or not to be an anthocyanin}, journal = {Chemistry-a European Journal}, volume = {13}, year = {2007}, note = {

ISI Document Delivery No.: 136KGTimes Cited: 18
Cited Reference Count: 46
Melo, Maria J. Sousa, Micaela Parola, A. Jorge Seixas de Melo, J. Srgio Catarino, Fernando Marcalo, Joaquim Pina, Fernando
Melo, Maria Joao/C-8594-2011; Seixas de Melo, Sergio/A-5388-2008; Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010; REQUIMTE, AL/H-9106-2013; Marcalo, Joaquim/J-5476-2013
Seixas de Melo, Sergio/0000-0001-9708-5079; Parola, A. Jorge/0000-0002-1333-9076; Marcalo, Joaquim/0000-0001-7580-057X
Wiley-v c h verlag gmbh
Weinheim

}, month = {2007}, pages = {1417-1422}, abstract = {

The compound 7,4{\textquoteright}-dihydroxy-5-methoxyflavylium (dracoflavylium) was identified as the major red colorant in samples of the resin "dragon{\textquoteright}s blood", extracted from the tree Dracaena draco. The complex network of reversible chemical reactions that dracoflavylium undergoes in aqueous solution is fully described; for the first time, all the equilibrium constants that enable a complete characterisation of the system have been obtained (K{\textquoteright}(a)=1.6 x 10(-4), K-a1 = 1.0 x 10(-4), K-a2 = 3.2 x 10(-8), K-Ct1 = 1.0 x 10(-7), K-Ct2 = 1.3 x 10(-10)). It is concluded that the red colour is due to a stable quinoid base, A, which is the major species at pH 4-7. It is further shown that this compound does not fit the commonly accepted definitions of anthocyanidin nor 3-deoxyanthocyanidin. Similarly to synthetic flavylium salts, the natural compound 7,4{\textquoteright}-dihydroxy-5-methoxyflavylium gives rise to several species (multistate system) reversibly interconverted by external stimuli, such as pH.

}, isbn = {0947-6539}, url = {://WOS:000244220400007}, author = {Melo, MJ and M. Sousa and A. J. Parola and de Melo, JSS and Catarino, F. and Marcalo, J. and Pina, F} }