Photo Reaction of 4,5‘,8‐trimethylpsoralen With Adenosine

Abstract

The near-UV induced photoreaction of 4,5',8-trimethylpsoralen (TMP) with adenosine was investigated in a dry film state. Four major photoadducts were isolated and purified by reverse-phase liquid chromatography. The structures of the photoproducts were elucidated on the basis of spectroscopic methods, including UV, FT-IR, mass spectrometry (FAB and EI methods) and 1H-NMR analysis. These photoproducts were characterized to be TMP-adenosine 1:1 adducts, which resulted from the covalent bond formation between the carbon C(4) of TMP and ribose 1' or 5' carbon of adenosine. Of the photoadducts, one photoadduct (V) was the major product, reflecting some selectivity in the photoreaction of TMP with adenosine in the solid state.

A Novel Photoadduct of 4,5',8‐trimethylpsoralen and Adenosine

“…In the other photoadducts previously reported, photobinding occurred between C(4) of TMP and ribose 1'or 5'-position (Shim and Choi, 1990).…”

“…followed by the photoproducts, and then the less polar TMP appeared. The photoproducts corresponding to five peaks labeled a-e are previously characterized and reported (Shim and Choi, 1990). The photobinding of TMP occurs to adenosine through covalent bond formation between C(4) of TMP and 1'-carbon of osidic moiety in photoadducts a and b.…”

“…The disappearance of the absorption band around 335 nm indicates loss of conjugation in the pyrone ring of photoproduct I, suggesting involvement of the 3,4-double bond of TMP in the photoaddition reaction. Irradiation of the photoproduct with 254 nm UV light does not produce TMP and adenosine, the starting materials, indicating that the photoproduct is not a C4-cycloaddition product (Shim et al, 1986;Cadet et al, 1988;Shim and Choi, 1990).…”

“…Psoralens, however, show a strong affinity to purine bases as well (Krauch et al, 1967;Ou and Song, 1978;Decout and Lhomme, 1983), but the photoreaction of psoralens with purine bases has not attracted as much attention as the reaction with pyrimidine bases. Recently, photoreactions of psoralens with adenosine or 2'deoxyadenosine were investigated in a dry film state and the photoadducts of psoralens and adenosine or 2'-deoxyadenosine were isolated and characterized (Shim et al, 1986;Cho et al, 1987;Cadet et al, 1988;Shim and Choi, 1990).…”

“…We have isolated and characterized four major TMP-adenosine 1: 1 photoadducts resulting from the covalent bond formation between the carbon C(4) of TMP and ribose 1'-or 5'-carbon of adenosine (Shim and Choi, 1990). The same type of photoreactions took place in 5,7-dimethoxycoumarin (DMC)-adenosine and 8-MOP-2'-deoxyadenosine systems, forming the covalent bond at the 'To whom correspondence should be addressed.…”