| Fulvic acid (FA) is the portion of humic acid which can be dissolved sufficiently in a neutral aqueous solution such as acetone, ethanol and other organic reagents, and it has the smallest molecular weight and biggest medicinal value.The role of fulvic acid has been further confirmed in the last decades of researches and experiments, a large number of studies have shown that fulvic acid has properties such as anti-inflammatory, anti-pepticulcer, anti-bacterial, anti-viral, blood hemostasis, improving immune function and affecting liver function and lipid metabolism. The specific mechanism of these effects is not clear yet, but one of the important hypothesis about the mechanism is the free radical scavenging theory. This theory believes fulvic acid can effectively remove the oxygen free radicals both in animals and humans, and this has been confirmed preliminarily by protecting the biofilm component, preventing clinical disease and ischemic tissue injury. On the other hand, fulvic acid has been considered to be one of the incentives about Kashin-Beck disease (KBD). Studies have shown that the content of fulvic acid in KBD area increases both in water and soil, and this can produce free radicals, then result in oxidative stress (OS) which damages the articular cartilage and cartilage cells, and result in-KBD. These two different perspectives will seriously affect the applications of FA which is the oxidative degradation products from Yunnan young lignite in medicine. Taking these into account, we believe that studies about the antioxidant effects of FA has great significance.In this reseach, a conventional laboratory method-hydrogen peroxide degradation has been used to extract FA in young lignite from Eshan, Xundian and Zhaotong in Yunnan, and the fractions have been obtained after refined and dialysed. This reseach studied the effect of FA and free radicals from molecular level, evaluated the DPPH· scavenging capabilities and kinetic curves of FA and its fractions, and also studied the scavenging capabilities of the superoxide anion radical and hydroxyl radical. The protective effects of three fulvic acids on alcoholic liver injury has been studied by using the alcohol liver injury model in mice from overall animals level. Besides, the reseach studied the inhabitation of FA to mitochondrial swelling from organelles level. The main contents and findings of this study are as follows:(1) A total of15samples of FA and its fractions has obtained by using hydrogen peroxide to oxdative degradate the young lignite from Eshan, Xuandian and Zhaotong in Yunnan, they are refined fulvic acids (named ESFA, XDFA and ZTFA), relative molecular weight of less than7000fractions (named ES7K, XD7K, ZT7K), relative molecular weight of less than3500fractions (named ES3.5K, XD3.5K, ZT3.5K), relative molecular weight between1000and3500fractions (named ES1-3.5K, XD1～3.5K, ZT1～3.5K) and the relative molecular weight of less than1000fractions (named ES1K, XD1K, ZT1K).(2) In DPPH experiments, different concentrations of FA reacted with DPPH solution showed that all of15samples have varying degrees of scavenging capabilities on DPPH·, and the clearance rate increased with time and concentration increasing, and varied from the sample molecular weight and origin. Samples in the same origin, ES7K has the best role and its biggest clearance rate was85.85%, the maximum TAC is264.7783μg/mg; XDFA has the best role and the maximum clearance rate was88.83%, the maximum TAC is301.4797μg/mg; ZT7K has the best role, its biggest clearance rate was83.77%, the maximum TAC is251.0056μg/mg.(3) The scavenging effect of FA on two important oxygenated radicals has been studied by the reaction kit. The results show that15samples with different origins and molecular weights all have scavenging effect on both superoxide anion radical and hydroxyl radical, and the effects differ from the radical species. The strongest scavenging capacity of samples from different areas on the superoxide anion radical were ESFA32.87±3.86U/g, XD1K55.38±3.00U/g, ZT1K27.33±2.45U/g, while on the hydroxyl radical were ES1K2339.93±125.17U/mg, XD1K2165.96±121.58U/mg, ZT1K695.09±50.40U/mg.(4) Using three refined fulvic acids (ESFA, XDFA and ZTFA) to study the protective effect of FA on alcohol-induced liver injury, the results show that FA not only can significantly improve liver tissue SOD activity and reduce MDA content, but also can reduce serum ALT and AST activity. These indicate that three refined fulvic acids have a protective effect on alcoholic liver injury in mice.(5) Fe2+-Vc induced mitochondrial swelling model has been established successfully, and the role of FA to mitochondrial swelling has been studied. The results shows that ESFA can inhibit the mitochondrial swelling with a concentration-dependent manner.The findings above suggest that fulvic acids from young lignite in Yunnan have varying degrees of scavenging capabilities on DPPH·,superoxide anion radical and hydroxyl radical, the kinetics curves of different fulvic acid are not the same, these different effects are associated with the origin and molecular weight of fulvic acid. In addition, fulvic acid on alcoholic liver injury in mice has a significant protective effect, the mechanism may involve free radical mechanism. |
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