A radioenzymatic method for S-adenosyl-l-methionine determination in biological fluids

doi:10.1016/0003-2697(84)90373-7

Analytical Biochemistry

Volume 137, Issue 1, 15 February 1984, Pages 217-220

https://doi.org/10.1016/0003-2697(84)90373-7 Get rights and content

Abstract

Current methods for the radioenzymatic assay of S-adenosyl-l-methionine (AdoMet) in biological fluids have been modified in order to increase sensitivity. The modified procedure has allowed to measure AdoMet content also in plasma and cerebrospinal fluid where the concentrations have been found to range between 17 and 72 ng/ml in the different animal species.

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Citation Excerpt :
The recommended oral dose is 20 mg/kg/d. SAMe has a high hepatic first-pass effect and a low bioavailability (approximately 3%). Measurable plasma and tissue concentrations are obtained, even within the cerebrospinal fluid in the cat and dog.33 Maximal plasma concentrations are variable but generally are achieved between 1 and 4 hours in dogs and 2 and 8 hours in cats.29,30
S-Adenosyl-L-methionine and alcoholic liver disease in animal models: Implications for early intervention in human beings
2002, Alcohol
In patients with severe alcoholic liver disease (i.e., cirrhosis), a deficiency of S-adenosylmethionine (SAMe) develops as a result of decreased SAMe synthetase activity. Whether a sizeable SAMe depletion occurs already at earlier stages of alcoholic liver disease has been the subject of debate. To address this issue, rats were fed alcohol (or isocaloric carbohydrate) in Lieber–DeCarli liquid diets containing adequate amounts of protein, vitamins, and lipotropic factors, including methionine. Alcohol feeding resulted in hepatic steatosis (without fibrosis) and unchanged SAMe synthetase activity, yet SAMe concentration was already greatly decreased. This most likely resulted from oxidative stress associated with the metabolism of alcohol and the induction of cytochrome P4502E1 (CYP2E1), which generates free radicals. Indeed, the decrease in hepatic SAMe correlated with parameters of oxidative stress, such as increased 4-hydroxynonenal (measured by gas chromatography–mass spectrometry) and diminished glutathione (GSH). Decreased GSH, occurring as a result of excessive GSH consumption caused by the oxidative stress, probably generated by enhanced utilization of SAMe, a precursor of GSH, thereby explaining the depletion of SAMe. In view of the known differences between rodents and primates in the metabolism of lipotropes, my colleagues and I have also studied the interaction between alcohol and SAMe in baboons and found again that, at early stages preceding the development of cirrhosis, there was already a significant lowering of hepatic SAMe concentration, associated with a striking oxidative stress documented by decreased levels and accelerated turnover of GSH. This was associated with increased lipid peroxidation and damage to cellular membranes, including those of the mitochondria, assessed by electron microscopy. Oral administration of SAMe resulted in its hepatic repletion with a corresponding attenuation of the ethanol-induced oxidative stress and liver injury, with significantly less GSH depletion, less increases in plasma aspartate aminotransferase (AST) levels, less leakage of mitochondrial glutamic dehydrogenase into the plasma, and fewer megamitochondria. In conclusion, (1) both in rodents and in non-human primates, significant SAMe depletion occurs already at early stages of alcoholic liver disease, despite the consumption of adequate diets; (2) the decreased hepatic SAMe concentration and the associated liver lesions, including mitochondrial injury, can be corrected with SAMe supplementation; and (3) accordingly, therapeutic administration of SAMe should be the subject of a comprehensive clinical trial to assess its capacity to attenuate early stages of alcoholic liver injury in human beings.
Alcoholic liver disease: New insights in pathogenesis lead to new treatments
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Much progress has been made in the understanding of the pathogenesis of alcoholic liver disease, resulting in improvement of prevention and therapy, with promising prospects for even more effective treatments. The most successful approaches that one can expect to evolve are those that deal with the fundamental cellular disturbances resulting from excessive alcohol consumption. Two pathologic concepts are emerging as particularly useful therapeutically. Whereas it continues to be important to replenish nutritional deficiencies, when present, it is crucial to recognize that because of the alcohol-induced disease process, some of the nutritional requirements change. This is exemplified by methionine, which normally is one of the essential amino acids for humans, but needs to be activated to S-adenosylmethionine (SAMe), a process impaired by the disease. Thus, SAMe rather than methionine is the compound that must be supplemented in the presence of significant liver disease. Indeed, SAMe was found to attenuate mitochondrial lesions in baboons, replenish glutathione, and significantly reduce mortality in patients with Child A or B cirrhosis. Similarly, polyenylphosphatidylcholine (PPC) corrects the ethanol-induced hepatic phospholipid depletion as well as the decreased phosphatidylethanolamine methyltransferase activity and opposes oxidative stress. It also deactivates hepatic stellate cells, whereas its dilinoleoyl species (DLPC) increases collagenase activity, resulting in prevention of ethanol-induced septal fibrosis and cirrhosis in the baboon. Clinical trials with PPC are ongoing in patients with alcoholic liver disease. Furthermore, enzymes useful for detoxification, such as CYP2E1, when excessively induced, become harmful and should be down-regulated. PPC is one of the substances with anti-CYP2E1 properties that is now emerging. Another important aspect is the association of alcoholic liver disease with hepatitis C: a quarter of all patients with alcoholic liver disease also have markers of HCV infection, with an even higher incidence in some urban areas but, at present, no specific therapy is available since interferon is contraindicated in that population. However, in addition to antiviral medications, agents that oppose oxidative stress and fibrosis should also be tested for hepatitis C treatment since these two processes contribute much to the pathology and mortality associated with the virus. In addition to antioxidants (such as PPC, silymarin, α-tocopherol and selenium), anti-inflammatory medications (corticosteroids, colchicine, anticytokines) are also being tested as antifibrotics. Transplantation is now accepted treatment in alcoholics who have brought their alcoholism under control and who benefit from adequate social support but organ availability is still the major limiting factor and should be expanded more aggressively. Finally, abstinence from excessive drinking is always indicated; it is difficult to achieve but agents that oppose alcohol craving are becoming available and they should be used more extensively.
Role of S-adenosyl-L-methionine in the treatment of liver diseases
1999, Journal of Hepatology
Measurement of plasma S-adenosylmethionine and S-adenosylhomocysteine as their fluorescent isoindoles
1998, Analytical Biochemistry
The low levels ofS-adenosylmethionine (AdoMet) andS-adenosylhomocysteine (AdoHcy) in plasma can be measured by formation of the fluorescent isoindole derivatives of these compounds. The procedure involves an initial separation of AdoMet and AdoHcy in deproteinized plasma by HPLC on a C-8 column followed by derivatization with naphthalenedialdehyde and cyanide for 10 min at pH 9.0. The fluorescent derivatives of AdoMet and AdoHcy are then chromatographed by HPLC on a C-18 column monitored with a fluorescence monitor. The formation of the isoindole goes to 85% completion and the overall recovery of standards added to plasma is about 65%. Correction for recovery is made by addition of known quantities of AdoMet and AdoHcy to plasma. Normal values (± SE) for AdoMet were 102.7 nM ± 9.9 and for AdoHcy were 22.7 ± 3.1.

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A radioenzymatic method for S-adenosyl-l-methionine determination in biological fluids

Abstract

J. Psychiatr. Res

Lancet

Anal. Biochem

Anal. Biochem

J. Chromatogr

Anal. Biochem

J. Biol. Chem

Lancet