Photoprotection of Mammalian Acid‐Soluble Collagen by Cuttlefish Sepia Melanin In Vitro
Photoprotection of Mammalian Acid‐Soluble Collagen by Cuttlefish Sepia Melanin In Vitro
复制标题
DOI：
10.1111/j.1751-1097.1998.tb02510.x
复制
发表时间：
1998-10
影响因子：
3.3
通讯作者：
J. Menter;A. Patta;Thomas D. Hollins;C. Moore;I. Willis
中科院分区：
文献类型：
--
作者：
J. Menter;A. Patta;Thomas D. Hollins;C. Moore;I. Willis
几种重要的临床条件可以导致黑色素和真皮胶原蛋白之间的密切联系。由于黑色素及其前体在基态和激发态下具有化学反应性，因此了解黑色素-胶原蛋白相互作用是否会导致光保护或光侵害非常重要。用0 -2.6倍104 J/m2 UVC或0 -83倍104 J/m2太阳模拟UV辐射（SSR）照射酸性和中性空气饱和胶原蛋白混悬液（0.033%）。在添加和不添加（0-100μg）乌贼真黑素的情况下，监测光不稳定胶原荧光团（δem 360 nm）的光化学破坏和胶原链降解作为照射时间的函数。黑色素延缓胶原蛋白的光损伤，但没有定性地改变荧光褪色动力学。H2 O2和O2都可以通过真黑素的UV照射产生。添加H202和K 02会破坏胶原蛋白荧光，并在摩尔过量约10 -20倍时导致50%链降解。先前的研究已经证明，真黑素有效地抑制02。我们证明了真黑素还有效地清除H2 O2，如其（a）与东莨菪内酯竞争过氧化物摄取和（B）通过透析袋直接摄取H2 O2的能力所证明的。后一种观察结果表明，过氧化物清除可以发生在体内的黑色素隔离在黑素噬菌体。因此，UV产生的O2和H2 O2都不可能以高到足以引起可测量的胶原蛋白损伤的浓度存在。激发辐射远离目标发色团的吸收和/或散射似乎是主要的光保护机制，尽管活性O2中间体的清除可能起重要的作用，如果微妙的话。
Several important clinical conditions can result in close association between the pigment melanin and dermal collagen. Because melanin and its precursors can be chemically reactive in ground and excited states, it is important to know whether the resulting melanin‐collagen interaction results in photoprotection or photoaggression. Acidic and neutral air‐saturated collagen suspensions (0.033%) were irradiated with0–2.6 times 104 J/m2 UVC or with0–83 times 104 J/m2 solar‐simulating UV radiation (SSR). Photochemical destruction of a photolabile collagen fluorophore (δem 360 nm) and collagen chain degradation were monitored as functions of irradiation time in the presence and absence of added (0–100μg) sepia eumelanin. Melanin retarded collagen photodamage but did not qualitatively alter the fluorescence fading kinetics. Both H202 and 02 can be produced by UV irradiation of eumelanin. Added H202 and K02 destroyed collagen fluorescence and caused 50% chain degradation at ca10–20‐fold molar excess. Previous studies have demonstrated that eumelanins efficiently scavenge 02 . We demonstrated that eumelanin also efficiently scavenges H202 as evidenced by its ability to (a) compete with scopoletin for peroxide uptake and (b) directly take up H202 through a dialysis bag. The latter observation suggests that peroxide scavenging could occur in vivo by melanin sequestered in melanophages. Thus, neither UV‐generated 02 nor H202 are likely to be present in concentrations high enough to cause measurable collagen damage. Absorption and/or scattering of excitation radiation away from the target chromophore appears to be the primary photoprotection mechanism, although scavenging of active 02 intermediates may play an important, if subtle role.