Singlet Oxygen Generation and Fluorecsent Properties of New 9,10-anthraquinones

COMINI, L.R.; NUÑEZ MONTOYA, S.C.; SARMIENTO, M.; ARGÜELLO, GUSTAVO A.; CABRERA, J.L.

Viña del Mar. Chile.

Congreso; VII ENCUENTRO LATINOAMERICANO DE FOTOQUÍMICA Y FOTOBIOLOGÍA.; 2002

Fac. de Ciencias Químicas y Farmacéuticas, Universidad de Chile.

The 9,10 Anthraquinone (AQ) derivatives belong to an important class of biologically active and commercially valuable compounds.  They have been extensively studied in connection with their near UV-Vis absorbing characteristics and potential photosenzitizing properties. One of the basic mechanisms of photosensitization involves the generation of singlet oxygen generally via energy transfer from a long-lived triplet state of AQs derivatives. We present here the study of some new AQs isolated from Heterophyllaea pustulata Hook (Rubiaceae), a plant species that grows up in the north-western part of Argentina, Perú and Bolivia. This plant species causes severe skin lesions as well as temporary blindness to cattle when exposed to direct sunlight. Three out of the nine AQs isolated have not been described nor studied before and for the other six, only their structures have been reported. We have applied the direct measurement of singlet oxygen luminiscence at 1270 nm in order to determine the relative quantum yields of its production using CHCl3 as solvent and phenalen-1-one as the reference compound. The results are shown in the following Table: IUPAC Name Common name F(rel) 3-hydroxy-1-methoxy anthraquinone-2-aldehyde Danmacanthal 0.23 1,3-dihydroxy-2-methyl anthraquinone Rubiadin 0.21 1,6-dihydroxy-2-methyl anthraquinone Soranjidiol 0.31 3-hydroxy-2-hydroxymethyl-1-methoxy anthraquinone Danmacanthol 0.56 3-hydroxy-2-methyl-1-methoxy anthraquinone Rubiadin-1-methyl eter 0.00 1,6-dihydroxy-7-methoxy-2-methyl anthraquinone 0.42 6-hydroxy-2-methyl-1-methoxy anthraquinone Soranjidiol-1-methyl ether 0.11 2-hydroxy-7-methyl-3-methoxy anthraquinone 0.14 5,5-bis ( 1,6-dihydroxy-2-methyl anthraquinone) 0.00 In addition, the fluorescent properties of the nine AQs are studied and will be informed.