Wang Xin-Xin, Lv Xia, Li Shi-Yang, Hou Jie, Ning Jing, Wang Jia-Yue, Cao Yun-Feng, Ge Guang-Bo, Guo Bin, Yang Ling
Liaoning Medical University, Jinzhou, Liaoning, China; Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Toxicol Appl Pharmacol. 2015 Nov 15;289(1):70-8. doi: 10.1016/j.taap.2015.09.003. Epub 2015 Sep 5.
As an edible traditional Chinese herb, Fructus psoraleae (FP) has been widely used in Asia for the treatment of vitiligo, bone fracture and osteoporosis. Several cases on markedly elevated bilirubin and acute liver injury following administration of FP and its related proprietary medicine have been reported, but the mechanism in FP-associated toxicity has not been well investigated yet. This study aimed to investigate the inhibitory effects of FP extract and its major constituents against human UDP-glucuronosyltransferase 1A1 (UGT1A1), the key enzyme responsible for metabolic elimination of bilirubin. To this end, N-(3-carboxy propyl)-4-hydroxy-1,8-naphthalimide (NCHN), a newly developed specific fluorescent probe for UGT1A1, was used to evaluate the inhibitory effects of FP extract or its fractions in human liver microsomes (HLM), while LC-UV fingerprint and UGT1A1 inhibition profile were combined to identity and characterize the naturally occurring inhibitors of UGT1A1 in FP. Our results demonstrated that both the extract of FP and five major components of FP displayed evident inhibitory effects on UGT1A1 in HLM. Among these five identified naturally occurring inhibitors, bavachin and corylifol A were found to be strong inhibitors of UGT1A1 with the inhibition kinetic parameters (Ki) values lower than 1 μM, while neobavaisoflavone, isobavachalcone, and bavachinin displayed moderate inhibitory effects against UGT1A1 in HLM, with the Ki values ranging from 1.61 to 9.86μM. These findings suggested that FP contains natural compounds with potent inhibitory effects against human UGT1A1, which may be one of the important reasons for triggering FP-associated toxicity, including elevated bilirubin levels and liver injury.
补骨脂作为一种可食用的传统中药，在亚洲已被广泛用于治疗白癜风、骨折和骨质疏松症。已有数例服用补骨脂及其相关成药后胆红素显著升高和急性肝损伤的病例报道，但补骨脂相关毒性的机制尚未得到充分研究。本研究旨在探讨补骨脂提取物及其主要成分对人尿苷二磷酸葡萄糖醛酸转移酶1A1（UGT1A1）的抑制作用，UGT1A1是负责胆红素代谢消除的关键酶。为此，使用一种新开发的UGT1A1特异性荧光探针N-(3-羧丙基)-4-羟基-1,8-萘二甲酰亚胺（NCHN）来评估补骨脂提取物或其组分在人肝微粒体（HLM）中的抑制作用，同时结合液相色谱-紫外指纹图谱和UGT1A1抑制谱来鉴定和表征补骨脂中天然存在的UGT1A1抑制剂。我们的结果表明，补骨脂提取物及其五个主要成分对HLM中的UGT1A1均表现出明显的抑制作用。在这五种鉴定出的天然抑制剂中，补骨脂二氢黄酮和补骨脂酚A被发现是UGT1A1的强抑制剂，其抑制动力学参数（Ki）值低于1 μM，而新补骨脂异黄酮、异补骨脂查尔酮和补骨脂宁对HLM中的UGT1A1表现出中等抑制作用，Ki值范围为1.61至9.86μM。这些发现表明，补骨脂含有对人UGT1A1具有强效抑制作用的天然化合物，这可能是引发补骨脂相关毒性（包括胆红素水平升高和肝损伤）的重要原因之一。
