The short-lived paramagnetic particles formed during the UV irradiation of nonsteroidal anti-inflammatory drug - ketoprofen (KP) have been investigated using chemically induced dynamic nuclear polarization (CIDNP). This study answers the questions about the nature of paramagnetic particles which can be responsible for KP phototoxic effects. Phototoxic side effects of NSAIDs, according modern point of view, are associated with the action of free radicals, however, there is insufficient information regarding the nature of the radical species. In contrast, most ketoprofen photodegradation schemes include carbanion as a precursor of products. CIDNP effects analysis has shown that all the major products of KP photodegradation can form via radical pairs (RPs) involving benzyl (2′), ketyl (3′) and CO₂H or CO₂⁻ free radicals and solvated electron. Radical ways of KP photodegradation include: decarboxylation via RP with benzyl radical formation (I) in non-aqueous solution and both, (I) and photoreduction with formation of ketyl radicals in the presence of water. Moreover, it was found that the photoinduced radical decarboxylation of KP represents a reversible process.

已使用化学诱导动态核极化（CIDNP）研究了非甾体抗炎药-酮洛芬（KP）的紫外线照射过程中形成的短寿命顺磁性颗粒。这项研究回答了有关可能导致KP光毒效应的顺磁性粒子性质的问题。根据现代观点，NSAIDs的光毒副作用与自由基的作用有关，但是，关于自由基种类的性质的信息不足。相反，大多数酮洛芬的光降解方案包括碳负离子作为产品的前体。CIDNP效应分析表明，KP光降解的所有主要产物都可以通过涉及苄基（2'），酮基（3'）和CO ₂ H的自由基对（RP）形成或CO ₂ ^-自由基和溶剂化电子。KP光降解的自由基方式包括：通过RP脱羧，在非水溶液中形成苄基（I），以及两者（I），以及在水的存在下进行光还原，形成酮基。此外，发现KP的光诱导的自由基脱羧代表可逆过程。