The photobiological differences of gilvocarcins V and M are not related to their transient intermediates and triplet yields
The photobiological differences of gilvocarcins V and M are not related to their transient intermediates and triplet yields
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DOI：
10.1111/j.1751-1097.1998.tb03248.x
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发表时间：
1998-07-01
影响因子：
3.3
通讯作者：
Alegría, AE
中科院分区：
文献类型：
--
作者：
Arce, R;Oyola, R;Alegría, AE
本文研究了在不同溶剂中，由355 nm激光激发gilvocarcin衍生物所产生的中间体的瞬态吸收光谱。光谱由可见光区的三重态-三重态吸收和在340 - 700 nm之间观察到的残留吸收组成，该残留吸收归因于长寿命物质，归属于自由基阳离子，在含有低DMSO/水体积比的溶液中以及在266 nm照射50%甲醇/水溶液时，也可以看到归因于溶剂化电子的在约700 nm处具有最大值的宽快速衰减带。水溶剂混合物。通过能量转移法测定的吉沃卡辛V（GV）和吉沃卡辛M（GM）三重态的摩尔吸收系数与溶剂性质无关，其值为3.0 x 10（4）/Mcm。两种药物的三重态衰减速率常数在1和5 × 10（4）/s之间。在3.4mM胸腺嘧啶存在下观察到GV的类似的初始产率和三重态衰减速率常数，因此，胸腺嘧啶对GV三重态的猝灭速率常数估计低于10（6）/Ms。通过使用比较方法测定的两种抗生素的三重态量子产率在二甲基亚砜（DMSO）中较高。（0.18）比对应于25%DMSO/水（0.06）的那些低。在水存在下phi（T）的降低可归因于从S-1状态的增强的内部转化速率常数或归因于光电离产率的增加。GV和GM的瞬时中间体和它们的产率的相似性表明它们的光生物学差异是由于其他因素，如DNA结合常数，药物在细胞中的优先定位或乙烯基对细胞组分的反应性增强。
The transient absorption spectra of the intermediates produced by the 355 nm laser excitation of gilvocarcin derivatives have been investigated in various solvents. The spectra consist of a triplet-triplet absorption in the visible region and a residual absorption observed between 340 and 700 nm due to a long-lived species, assigned to the radical cation, A broad-fast decaying band with a maximum at around 700 nm attributed to the solvated electron is also seen in solutions containing a low DMSO/water volume ratio and at 266 nm irradiation of a 50% methanol/water solvent mixture. The molar absorption coefficient of the triplet state of gilvocarcin V (GV) and gilvocarcin M (GM), determined by the energy transfer method, is independent of the solvent properties and has a value of 3.0 x 10(4)/Mcm. The triplet decay rate constants for both drugs are between 1 and 5 x 10(4)/s. A similar initial yield and triplet decay rate constant of GV were observed in the presence of 3.4 mM thymine, Thus, a quenching rate constant of the GV's triplet state by thymine is estimated to be lower than 10(6)/Ms. The triplet quantum yields of both antibiotics determined by using the comparative method are higher in dimethylsulfoxide (DMSO) (0.18) than are those corresponding to 25% DMSO/water (0,06), The decrease in phi(T) in the presence of water could be attributed to an enhanced internal conversion rate constant from the S-1 state or to an increase in the photoionization yield. The similarity of the transient intermediates and their yields for GV and GM suggest that their photobiological differences are due to other factors such as DNA binding constants, preferential localization of the drugs in the cell or the enhanced reactivity of the vinyl group toward cellular components.