Recent studies suggest that
Sirt inhibition may have beneficial effects on several human diseases such as
neurodegenerative diseases and
cancer.
Coffee is one of most popular beverages with several positive health effects. Therefore, in this paper, potential
Sirt inhibitors were screened using
coffee extract. First, HPLC was utilized to fractionate
coffee extract, then screened using a
Sirt1/2 inhibition assay. The screening led to the isolation of a potent
Sirt1/2 inhibitor, whose structure was determined as javamide-II (N-
caffeoyltryptophan) by NMR. For confirmation, the
amide was chemically synthesized and its capacity of inhibiting
Sirt1/2 was also compared with the isolated
amide. Javamide-II inhibited
Sirt2 (IC50; 8.7 μM) better than
Sirt1(IC50; 34μM). Since javamide-II is a stronger inhibitor for
Sirt2 than
Sirt1. The kinetic study was performed against
Sirt2. The
amide exhibited noncompetitive
Sirt2 inhibition against the NAD+ (Ki = 9.8 μM) and showed competitive inhibition against the
peptide substrate (Ki = 5.3 μM). Also, a docking simulation showed stronger binding pose of javamide-II to
Sirt2 than AGK2. In cellular levels, javamide-II was able to increase the acetylation of total
lysine,
cortactin and
histone H3 in neuronal NG108-15 cells. In the same cells, the
amide also increased the acetylation of
lysine (K382) in p53, but not (K305). This study suggests that Javamide-II found in
coffee may be a potent
Sirt1/2 inhibitor, probably with potential use in some conditions of human diseases.