Study On Physicochemical Properties And Biological Activity Of Melanin From Lachnum YM156

In this study,the intracellular melanin?LIM?of Lachnum YM156 was obtained by fermentation,extraction and purification.The physicochemical properties of LIM and its antioxidant activity in vitro were studied.The nephroprotective effects of LIM against acute kidney injury?AKI?induced by cisplatin in mice and the hepatoprotective effects in Cd-exposure mice were also investigated.Studies have shown that LIM had better thermostability and light resistance,and its solubility was relatively high under alkaline conditions.Cu²⁺and Fe³⁺may cause melanin precipitation.Moreover,LIM has significant antioxidant activity,including good scavenging ability to·OH and O2^-·free radicals,reducing power and total antioxidant capacity.The model of AKI was induced by cisplatin,and the nephroprotective effects of LIM on AKI mice was evaluated.The results showed that different doses of LIM effectively counteracted weight loss,and effectively decreased kidney index,serum creatinine?Cr?and urea nitrogen?BUN?levels,and renal platinum content in mice.At the same time,LIM also significantly reduced the content of malondialdehyde?MDA?and increased superoxide dismutase?SOD?,catalase?CAT?,glutathione peroxidase?GSH-Px?and glutathione?GSH?levels in kidneys.Compared with the model group,LIM significantly decreased the mRNA expression levels of tumor necrosis factor-??TNF-??and interleukin-1??IL-1??in kidneys.In addition,western blot analysis showed that LIM reduced nuclear factor-?B?NF-?B?p65,cyclooxygenase-2?COX-2?,inducible nitric oxide synthase?iNOS?,p-p38 MAPK,p53,caspase 3,cleaved caspase 3 and p38MAPK protein expression levels in kidneys,indicating that it has a protective effect on cisplatin-induced renal injury.The Cd exposure model was established and the hepatoprotective effects of LIM was investigated.The results showed that LIM could effectively inhibit the decreased body weight growth rate,increased liver index,elevated serum alanine aminotransferase?ALT?and aspartate aminotransferase?AST?levels as well as the increased Cd accumulation in livers caused by Cd exposure.LIM also significantly reduced the content of MDA and increased levels of SOD,CAT,GSH-Px and GSH in livers.At the same time,LIM increased mRNA levels of NF-E2-related factor 2?Nrf2?,heme oxygenase?HO-1?,NADPH quinone oxidoreductase 1?NQO-1?in livers,and decreased TNF-?,IL-1?levels as well as the mRNA levels of NF-?B p65,iNOS in livers.Therefore,LIM can be used as a potential liver damage protector in Cd exposure.