Analytical Procedure for Determination of S-Adenosylmethionine, S-Adenosyl-Homocysteine, and S-Adenosylethionine in Same Isocratic HPLC Run, with a Procedure for Preparation and Analysis of the Analog S-Adenosylhomocysteine Sulfoxide

Virtually all methyltransferase enzymes are regulated largely by the relative levels of S-adenosylmethionine (SAM) to its metabolic product, S-adenosylhomocysteine (SAH). Ethionine is the hepatocarcinogenic antimetabolite of methionine, and has been found to produce hypomethylation of hepatic DNA when fed to rats in acute doses. The hypomethylation apparently results from the accumulation in the liver of S-adenosylethionine (SAE), the sulfur activation product of ethionine, which is a competitive inhibitor of DNA methylase. Researchers seeking to measure SAM and SAH levels by HPLC in the past have experienced numerous analytical problems because of their separation characteristics. Previous methods have either required two separate HPLC runs or used gradient elution to measure the two compounds. The method outlined here, is an accurate and precise method, that measures SAM and SAH as well as SAE in a single isocratic HPLC run. S-Adenosyl-l-homocysteine sulfoxide (SAHO), the sulfoxide of SAH is known to be formed by spontaneous oxidation of SAH during sample preparation and storage. We have prepared the SAHO using a 4 hour process. Since SAHO is not readily available commercially, the present method could be very beneficial to researchers who need to verify whether SAH oxidation has occurred in analytical samples, or whether oxidation of the SAH has occurred in tissues.