Letters
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10 3145
and purity for the target compounds. This material is available free
of ELVOL3 to ELOVL6) is ∼6-fold. Of them, compound 37
is a significantly more potent and selective inhibitor (Table 3).
Compound 37 was shown to be selective over human ELOVL1,
-2, and -5 enzymes and has a potent inhibitory activity for the
mouse ELOVL6 enzyme as well (Table 4). The selectivity
against mouse ELOVL3 is moderate where the ratio of mouse
ELOVL3 to ELOVL6 is ∼6-fold.
References
(1) Unger, R. H. Minireview: weapons of lean body mass destruction:
the role of ectopic lipids in the metabolic syndrome. Endocrinology
2003, 144, 5159–5165.
(2) Cao, H.; Gerhold, K.; Mayers, J. R.; Wiest, M. M.; Watkins, S. M.;
Hotamisligil, G. S. Identification of a lipokine, a lipid hormone linking
adipose tissue to systemic metabolism. Cell 2008, 134, 933–944.
(3) Matsuzaka, T.; Shimano, H.; Yahagi, N.; Kato, T.; Atsumi, A.;
Yamamoto, T.; Inoue, N.; Ishikawa, M.; Okada, S.; Ishigaki, N.;
Iwasaki, H.; Iwasaki, Y.; Karasawa, T.; Kumadaki, S.; Matsui, T.;
Sekiya, M.; Ohashi, K.; Hasty, A. H.; Nakagawa, Y.; Takahashi, A.;
Suzuki, H.; Yatoh, S.; Sone, H.; Toyoshima, H.; Osuga, J.; Yamada,
N. Crucial role of a long-chain fatty acid elongase, Elovl6, in obesity-
induced insulin resistance. Nat. Med. 2007, 13, 1193–1202.
(4) Nugteren, D. H. The enzymic chain elongation of fatty acids by rat-
liver microsomes. Biochim. Biophys. Acta 1965, 106, 280–290.
(5) Barrett, P. B.; Harwood, J. L. Characterization of fatty acid elongase
enzymes from germinating pea seeds. Phytochemistry 1998, 48, 1295–
1304.
(6) Matsuzaka, T.; Shimano, H.; Yahagi, N.; Yoshikawa, T.; Amemiya-
Kudo, M.; Hasty, A. H.; Okazaki, H.; Tamura, Y.; Iizuka, Y.; Ohashi,
K.; Osuga, J.; Takahashi, A.; Yato, S.; Sone, H.; Ishibashi, S.; Yamada,
N. Cloning and characterization of a mammalian fatty acyl-CoA
elongase as a lipogenic enzyme regulated by SREBPs. J. Lipid Res.
2002, 43, 911–920.
(7) Moon, Y. A.; Shah, N. A.; Mohapatra, S.; Warrington, J. A.; Horton,
J. D. Identification of a mammalian long chain fatty acyl elongase
regulated by sterol regulatory element-binding proteins. J. Biol. Chem.
2001, 276, 45358–45366.
(8) Tvrdik, P.; Westerberg, R.; Silve, S.; Asadi, A.; Jakobsson, A.; Cannon,
B.; Loison, G.; Jacobsson, A. Role of a new mammalian gene family
in the biosynthesis of very long chain fatty acids and sphingolipids.
J. Cell. Biol. 2000, 149, 707–718.
(9) Tvrdik, P.; Asadi, A.; Kozak, L. P.; Nedergaard, J.; Cannon, B.;
Jacobsson, A. Cig30, a mouse member of a novel membrane protein
gene family, is involved in the recruitment of brown adipose tissue.
J. Biol. Chem. 1997, 272, 31738–31746.
The plasma and liver levels 2 h following 10 mg/kg oral
administration of 37 in mice were determined to be 30 and 50
µM, respectively; therefore, 37 is demonstrated to be highly
liver penetrable (a liver-to-plasma ratio of 1.7). After oral dosing
at 1 mg/kg in mice, 37 exhibited sustained plasma exposure as
shown in Table 5.
Having demonstrated potent ELOVL6 activity and good
exposure, 37 was evaluated for its effects on the fatty acid profile
in the liver in mice. ELOVL6 is mainly responsible for the
elongation of palmitoyl-CoA. Enzymatic reactions of palmitoyl-
CoA involving ELVOL6 and SCD-1 are depicted in Scheme
3. When ELOVL6 elongation takes place first, palmitoyl-CoA
is elongated to give strearoyl-CoA followed by desaturation by
SCD-1 to give oleoyl-CoA. When the desaturation process by
SCD-1 takes place first, palmitoyl-CoA is converted to palmi-
toleoyl-CoA, which is elongated by ELVOL6 to yield cis-
vaccenoyl-CoA. We defined the elongation index as follows:
elongation index ) C18 fatty acids/C16 fatty acids ) [stearoyl
acid + oleic acid + cis-vaccenic acid]/[palmitic acid +
palmitoleic acid]. The elongation index was used as a surrogate
readout for ELOVL6 inhibitory activity in the liver using
[14C]palmitic acid as a radiotracer. After oral administration,
37 potently and dose-proportionally suppressed the elongation
index in the liver in mice (Figure 2).
In conclusion, new indoledione derivatives were synthesized
and evaluated as ELOVL6 inhibitors. After systematic SAR
studies of the R1-R5 substituents of the screen hit 1, several
para-substituted phenyl derivatives were identified as potent
ELOVL6 inhibitors. Representative potent inhibitor 37 was
selective for human ELOVL6 over human ELOVL1, -2, -3, and
-5 enzymes. Compound 37 displayed potent inhibitory activity
for mouse ELOVL6 as well; however, selectivity against mouse
ELOVL3 was moderate. Sustained plasma exposure and ap-
preciable liver penetration were observed after oral administra-
tion of 37 in mice. After oral dosing, 37 potently and dose-
proportionally suppressed the elongation index of fatty acids
in the liver in mice. The potent and selective inhibitor 37 would
be a powerful tool to probe the pharmacology of the ELOVL6
enzyme inhibition in vivo. The updated results will be reported
in due course.
(10) Zhang, K.; Kniazeva, M.; Han, M.; Li, W.; Yu, Z.; Yang, Z.; Li, Y.;
Metzker, M. L.; Allikmets, R.; Zack, D. J.; Kakuk, L. E.; Lagali, P. S.;
Wong, P. W.; MacDonald, I. M.; Sieving, P. A.; Figueroa, D. J.;
Austin, C. P.; Gould, R. J.; Ayyagari, R.; Petrukhin, K. A 5-bp deletion
in ELOVL4 is associated with two related forms of autosomal
dominant macular dystrophy. Nat. Genet. 2001, 27, 89–93.
(11) Leonard, A. E.; Bobik, E. G.; Dorado, J.; Kroeger, P. E.; Chuang,
L. T.; Thurmond, J. M.; Parker-Barnes, J. M.; Das, T.; Huang, Y. S.;
Mukerji, P. Cloning of a human cDNA encoding a novel enzyme
involved in the elongation of long-chain polyunsaturated fatty acids.
Biochem. J. 2000, 350 (Part 3), 765–770.
(12) Jakobsson, A.; Westerberg, R.; Jacobsson, A. Fatty acid elongases in
mammals: their regulation and roles in metabolism. Prog. Lipid Res.
2006, 45, 237–249.
(13) Miyazaki, M.; Dobrzyn, A.; Man, W. C.; Chu, K.; Sampath, H.; Kim,
H. J.; Ntambi, J. M. Stearoyl-CoA desaturase 1 gene expression is
necessary for fructose-mediated induction of lipogenic gene expression
by sterol regulatory element-binding protein-1c-dependent and -inde-
pendent mechanisms. J. Biol. Chem. 2004, 279, 25164–25171.
(14) Kumadaki, S.; Matsuzaka, T.; Kato, T.; Yahagi, N.; Yamamoto, T.;
Okada, S.; Kobayashi, K.; Takahashi, A.; Yatoh, S.; Suzuki, H.;
Yamada, N.; Shimano, H. Mouse Elovl-6 promoter is an SREBP target.
Biochem. Biophys. Res. Commun. 2008, 368, 261–266.
(15) Shimamura, K.; Miyamoto, Y.; Kobayashi, T.; Kotani, H.; Tokita, S.
Establishment of a high throughput assay for long chain fatty acyl-
CoA elongase using homogeneous scintillation proximity assay. Assay
Drug DeV. Technol., in press.
Acknowledgment. We thank Hirokazu Ohsawa for collect-
ing the high-resolution mass spectral data. We also thank Dr.
Peter T. Meinke (Merck Research Laboratories, Rahway, NJ)
for the editing of this manuscript.
Supporting Information Available: Synthetic procedures for
the preparation of 1-38, biological methods, HPLC retention times,
JM900391X