Studies On Pharmacological Mechanism Of EGCG And Honokiol On Molecular Lesions Of Aging

The amino-carbonyl cross-links induced by carbonyl stress are the central links in the molecular lesions of aging, which are the common process to form age pigments, such as lipofuscin, ceroid, AGEs and APFs. Moreover, the carbonyl-amino compounds have the highly active structures and can ceaselessly link and strangle the proteins, fats and nucleic acids around theirs, and the process can be more intense in the acidic microenvironment induced by the ischemia, hypoxia reductive damage in body. Therefore, the generation of drugs sharing both carbonyl-amino cross-links scavenger and reductive damages reverser properties represents a new therapeutic challenge in the treatment of carbonyl-stress-associated diseases such as the cardiovascular diseases and neurodegenerative diseases. The main research schemas of this thesis were, based on the analysis of structure-activity relationship, focus on exploring the multitarget-drugs pharmacological effects and mechanism of honokiol (HNK) and EGCG on the molecular lesions of aging from gene and protein levels. More details of the results are described as follows:1. Reaction between tea epicatechins and MDA-modified human serum albumin (HSA) had been investigated for the first time by using spectrofluorometry, HPLC, protein electrophoresis and FTIR spectrometer. The results showed that the ester-type catechins, especially EGCG, remarkably inhibited the formation of carbonyl-amino crosslinking products in MDA-modified HSA reaction system, while HNK had no effect in the model. The structure-activity relationship studies revealed that the binding of the galloyl-D ring tea catechins with protein was the key mechanism to neutralize the carbonyl stress process, that the galloyl-D ring increased the non-ionic active surface, and the antioxidative gallate-B ring could effectively eliminate MDA and other reactive carbonyl compounds when the galloyl-D ring binded with the target sites of protein.2. HNK had significant pharmacological activities under anoxic, acidic conditions in vitro biological models of cells and mitochondrial model. QSAR analysis revealed that the push-pull electronic structure composed of adjacent hydroxyl group, biphenyl rings and allyl, was the basic structure for HNK to play the multi-target pharmacological effects. Thus, HNK was one of the potential lead compounds for treating the reductive damages.3. Based on the D-galactose-induced aging mice model, HNK and EGCG could decrease the percentages of ischemic-like injuries, inhibit lipofuscin deposition and maintain mitochondrial integrity in cortex neurons to a large extent.4. Both Microarray and real-time PCR experiments revealed that the core molecular mechanism for HNK was to up-regulated genes about oxygen transport, hemopoiesis and removing the cross-linked products, such as Cartpt, Hbb-b2 and TTR, and down-regulated the express of the oncogene Zabtb7a. The immunohistochemical analysis showed that both HNK and EGCG could increase the protein expression of PI3K in cortex. All of the results suggested that EGCG, especially HNK, could delay the molecular lesions of aging process by scavenging protein cross-links and repairing reductive damages.