Ellagitannins isolated from various plant sources as well as newly synthesized n-alkyl (C
) esters of
hexahydroxydiphenyl (HHDP) dicarboxylic acid were evaluated as enzyme inhibitors of recombinant rat
squalene epoxidase, a rate-limiting enzyme of cholesterol biosynthesis. Among the ellagitannins tested,
pedunculagin (IC
50
) 2.0 íM) and eugeniin (IC
) 1.6 íM), both containing (S)-HHDP ester group(s),
showed remarkable inhibition, which was more potent than those of previously reported substrate analogue
inhibitors. Furthermore, ellagic acid (IC
50
50
) 2.0 íM), a bislactone formed by hydrolytic release of a HHDP
group from ellagitannins, was also a good inhibitor of the enzyme. On the other hand, the synthetic
HHDP esters with C
6
(IC
50
) 0.93 íM) and C
) 0.83 íM) showed potent enzyme
inhibition at the submicromolar concentration range, while esters with shorter chain lengths (C
8
alkyl side chains (IC
50
)
andaC
18
ester exhibited moderate inhibition (IC
50
) 8-47 íM).
1
-C
18
1
-C
4