Discovery of 5-Benzylidene-2-phenyl-1,3-dioxane-4,6-diones as Highly Potent and Selective SIRT1 Inhibitors

Highly Potent and Selective SIRT1 Inhibitors

Letter

Discovery of 5‑Benzylidene-2-phenyl-1,3-dioxane-4,6-diones as

⊥

Chunpu Li, Sha-Sha Hu, Lisheng Yang, Min Wang, Jian-Dong Long, Bing Wang, Haozhen Han,

Haoran Zhu, Sen Zhao, Jing-Gen Liu,* Dongxiang Liu,* and Hong Liu*

Cite This: ACS Med. Chem. Lett. 2021, 12, 397 −403

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sı Supporting Information

ABSTRACT: SIRT1, a member of the sirtuin family, catalyzes the

deacetylation of proteins with the transformation of NAD into

nicotinamide and 2′-O-acetyl-ADP-ribose. Selective SIRT1/2

inhibitors have potential application in the chemotherapy of

colorectal carcinoma, prostate cancer, and myelogenous leukemia.

Here we identiﬁed novel SIRT1 inhibitors with the scaﬀold of 5-

benzylidene-2-phenyl-1,3-dioxane-4,6-dione. The most potent

inhibitor 12n displayed an IC₅₀of 460 nM and a selectivity for

SIRT1 over SIRT2, SIRT3, and SIRT5 of 113.5-, 254.3-, and

0.83-fold, respectively. It did not aﬀect the activity of SIRT6. To

elucidate the inhibitory mechanism, we determined the inhibition

type of the inhibitor by enzyme kinetic analysis, showing that the

inhibitor was competitive to the acetyl peptide and noncompetitive

to NAD . Further, the interaction of the inhibitor in SIRT1 was studied by using molecular docking, which was validated by the

structure−activity relationship analysis of the inhibitors and the site-directed mutagenesis of SIRT1. Consistent with the in vitro

assays, the inhibitors increased the acetylation level of p53 in a concentration-dependent manner in cells.

KEYWORDS: SIRT1, inhibitor, structure−activity relationship, interaction, deacetylase

he acetylation state of proteins regulates diverse biological

processes and is related with age-related diseases. Sirtuins

are a family of NAD -dependent deacetylases that catalyze the

deacetylation of proteins with the transformation of NAD into

nicotinamide and 2′-O-acetyl-ADP-ribose. Human sirtuins

include seven family members, SIRT1−7. They have diﬀerent

subcellular localizations and functions. SIRT1, mostly present in

the nucleus, is associated with a variety of metabolic pathways

and involved in diseases including metabolic syndrome and

insulin resistance. Activation of SIRT1 was found to mediate

the progesterone resistance, which is believed to contribute to

the infertility and progression of endometriosis. Besides, SIRT1

suppresses intestinal tumorigenesis and colon cancer growth

through deacetylation of β-catenin but functions as a tumor

promoter in colorectal carcinoma, prostate cancer, and

−11

myelogenous leukemia.

Selective SIRT1/2 inhibitors have

2−16

potential application in the chemotherapy of these cancers.

To date, several SIRT1 inhibitors have been discovered. For

instance, Cambinol (1), a SIRT1/2 inhibitor, exhibits antitumor

activity in the Daudi Burkitt lymphoma xenograft model (Figure

Figure 1. Representative SIRT1 inhibitors.

Received: October 18, 2020

Accepted: February 22, 2021

Published: March 1, 2021

). EX-527 (Selisistat, 2), a selective SIRT1 inhibitor, was

entered into clinical trials for Huntington’s disease and

18,19

endometrial receptivity.

In a double-blind, randomized

phase II clinical trial involving Huntington’s disease patients,

EX-527 was found to be safe and well-tolerated. However, no

2021 American Chemical Society

ACS Med. Chem. Lett. 2021, 12, 397−403

ACS Medicinal Chemistry Letters

Letter

clinical beneﬁt was observed after 2 weeks’ treatment.

Recently, a SAFER trial for EX-527 was started in the clinical

setting of in vitro fertilization and embryo transfer (clinical trial

number NCT04184323). Besides, Lu et al. disclosed a small

molecule, Inauhzin (3), that promotes the p53-dependent

apoptosis of cancer cells by inhibiting SIRT1. Some

benzylidene compounds such as 3-benzylideneindolin-2-one

(

GW 5074, 4) have also been described as sirtuin

4−26

inhibitors.

A screen for sirtuin activators identiﬁed suramin

27,28

(5) as a SIRT1 inhibitor.

Further, Jung et al. developed a

suramin analogue, NF675 (6), with an improved inhibitory

potency. Even so, the road of SIRT1 inhibitors to the clinical

applications remains challenging. Structurally diverse and highly

active SIRT1 inhibitors are still in urgent need, which highlights

the signiﬁcance of developing a novel chemotype of selective

SIRT1 inhibitors.

To identify novel SIRT1 inhibitors, a ﬂuorescent assay that

detects the deacetylation of an Abz-labeled acetyl peptide by

SIRT1 was employed to screen our in-house compound library

(

Figure 2A). We found that compound 7 (Figure 2B)

inhibited the activity of SIRT1 with an IC₅₀of 13.63 μM

Figure 2C). To conﬁrm the inhibitory eﬀect, we purchased 14

(

derivatives of the compound from SPECS company (https://

www.specs.net ) and determined their IC . The assay showed

that 13 derivatives possessed the inhibitory eﬀect with IC₅₀

lower than 20 μM (Figure 2D). Among them, compound 8m is

the most active with an IC of 1.9 μM. In order to develop more

potent SIRT1 inhibitors, we synthesized the derivatives of the

compound and studied their structure−activity relationship

(

SAR).

The synthesis of compounds 11a−11j and 12a−12s is

outlined in Scheme 1. Benzaldehyde (9) reacts with malonic

acid to obtain the 2-phenyl-1,3-dioxane-4,6-dione (10) in

moderate yield. The condensation of 2-phenyl-1,3-dioxane-

,6-dione (10) and various substituted benzaldehydes gives the

target compounds 11a−11j and 12a−12s.

We evaluated the inhibitory eﬀect of the synthesized

derivatives. EX-527, a selective SIRT1 inhibitor whose IC₅₀

was originally determined with the substrate of RHKKac-

AMC, was used as the positive control. Herein, we used the

peptide of Abz-GVLKacAY_N_O₂GY-NH as the substrate of the

enzyme assay. As summarized in Table 1, compound 11a (R =

F) exhibited a potent eﬀect against SIRT1 in low micromolar

concentration (IC : 3.76 μM). Replacement of ﬂuorine with

bromide (11b) maintains the activity. Both compounds

displayed better activities than compound 8k, indicating that

small substituent at R may enhance the interaction of the

Figure 2. (A) Fluorescent assay that detects the deacetylation of an

Abz-labeled acetyl peptide by SIRT1. (B) Chemical structure of

compound 7. (C) Inhibition curve of compound 7. (D) Chemical

structures and inhibitory activities of 14 derivatives from SPECS.

compound in SIRT1. Similar result may be obtained by

comparing the activities of compounds 11c and 11i. Meanwhile,

derivatives with various substituents (such as methyl, halogens,

Scheme 1. Synthesis of Compounds 11a−11j and 12a−12s

alkoxyl) at the ortho position (i.e., R ) of hydroxy (11c−11h)

showed the inhibitory potency in the low micromolar range.

Interestingly, the chlorine-substituted analogue 11e exhibits a

better activity than ﬂuorine-substituted analogue 11d. The

bromide-substituted analogue 11f exhibited an improved

potency compared with 11e with an IC₅₀of 1.40 μM. In

addition, the atom linked to the ortho position has a marked

impact on the activity. Halogens and oxygen seem more

Reagents and conditions: (a) malonic acid, Ac O, H SO (conc), rt;

(b) the appropriate benzaldehyde, NaOAc, DMSO, rt.

favorable than carbon. Beyond that, introducing an alkyl at R

may improve the activity (comparing compound 11b to 11j,

compound 11g to 11h). This suggests that the space in SIRT1 to

accommodate R and R should be limited. Substitution at these

positions with appropriate chemical groups would enhance the

interaction of the compound with SIRT1.

ACS Med. Chem. Lett. 2021, 12, 397−403

ACS Medicinal Chemistry Letters

Letter

Table 1. Chemical Structures and Inhibitory Activities of

Derivatives 11a−11j

compounds with more steric hindrance were decreased (12c vs

12a). Compound 12d was much less potent than 12a likely due

to the electro-donating property of the methoxy group. In

contrast, introduction of electro-withdrawing groups (such as

ester, nitro, bromide) at R led to enhanced inhibitory activities

(

2.4−8.0-fold) compared to compound 12d. Notably, com-

pounds 12i and 12j potently inhibited SIRT1 with IC values of

.31 and 1.14 μM, respectively. In addition, diiodo-substituted

analogue 12n exhibited improved potency with IC of 0.46 μM,

whereas dichloro-substituted and dibromo-substituted ana-

logues 12l and 12m showed slightly weaker potency. The IC₅₀

of the compounds displayed a decreasing trend of F > Cl > Br > I.

Besides, compounds 12o−12q containing halogens and

benzyloxy/methoxy at the phenol group showed the IC of

.68, 0.61, and 0.89 μM, respectively, suggesting that

introduction of halogens at the ortho position of pheno is

essential for the activity. Moreover, replacement of hydroxy by

amino group reduced the potency dramatically (compounds 12r

and 12s), indicating that the hydroxy is important for the

interaction of the compounds with SIRT1.

As each sirtuin has its distinct roles in the physiological

process, selectivity among the sirtuins should be considered

when developing SIRT1 inhibitors. Thus, we determined the

inhibitory potencies of our compounds against SIRT2, SIRT3,

SIRT5, and SIRT6. As shown in Table 3, 12i, 12l, 12n, and 12q

exhibited signiﬁcant selectivity for SIRT1 over SIRT2, SIRT3,

SIRT5, and SIRT6. The most potent inhibitor 12n displayed a

SIRT1 selectivity over SIRT2, SIRT3, or SIRT5 of 113.5-,

In light of the above SAR analysis, 19 new compounds were

designed and synthesized to improve the potency of 11f (Table

54.3-, or 10.83-fold, respectively. All compounds did not aﬀect

). Compounds 12a−12c contain the same alkyl substituents at

the activity of SIRT6. In comparison, EX-527 displayed a SIRT1

selectivity over SIRT2 of only 8.78-fold and over SIRT3 of

1 2

R and R on the phenyl group, but the lengths of the

substituents are diﬀerent (methyl, ethyl, and tert-butyl). Clearly,

the enzymatic assay showed that the inhibitory activities of

29.47-fold, indicating that compound 12n is a very potent

SIRT1 inhibitor with high selectivity.

As known, the deacetylation catalyzed by SIRT1 is a

Table 2. Chemical Structures and Inhibitory Activities of

Derivatives 12a−12s

bisubstrates reaction (i.e., the acetyl lysine and NAD ). The

acetyl lysine binds to the D-site whereas NAD occupies the A-,

B-, and C-sites in SIRT1. To unveil the inhibitory mechanism,

we determined the inhibition type of compound 12i and

examined how the inhibitor aﬀects the binding of acetyl

substrate and NAD in SIRT1.

From the Lineweaver−Burk plot of the acetyl substrate at

various concentrations of 12i (Figure 3B), we may see that the

lines intersect in the third quadrant, indicating that the initial

velocity V and the apparent Michaelis−Menten constant K of

Compound

R¹

R²

^I^C⁵0 (μM)

3.07 ± 0.17

3.10 ± 0.15

18.96 ± 0.10

11.90 ± 2.62

2.47 ± 0.10

2.66 ± 0.09

3.69 ± 0.10

3.49 ± 0.11

1.31 ± 0.26

1.14 ± 0.08

4.54 ± 0.03

1.20 ± 0.09

0.70 ± 0.03

0.46 ± 0.09

0.68 ± 0.07

0.61 ± 0.06

0.89 ± 0.01

7.63 ± 0.11

10.21 ± 0.17

the acetyl substrate decrease with the increasing concentration

of 12i. Thus, compound 12i is a mix-type competitive inhibitor

for the acetyl lysine. It may occupy the D-site, which is the

binding site of the acetyl lysine in SIRT1. Meanwhile, the

t-Bu

OMe

t-Bu

OMe

OEt

OMe

OEt

Lineweaver−Burk plot of NAD shows that the lines intersect at

COOBn

the horizontal axis (Figure 3D), indicating that the initial

^N^O2

velocity V decreases but the apparent Michaelis−Menten

^N^O2

constant K of NAD remains unchanged with the increasing

OBn

OMe

concentration of 12i. Therefore, compound 12i did not aﬀect

the interaction of NAD in SIRT1. It is a noncompetitive

inhibitor for NAD and should not occupy the binding sites of

NAD .

To elucidate the inhibitory mechanism, we simulated the

interaction of 12i in SIRT1 (PDB ID: 4I5I) by using swissdock

(

http://www.swissdock.ch). SIRT1 contains a catalytic core

constituted by a Rossmann-fold domain and a Zn -binding

domain. The acetyl lysine binds to the cleft enclosed by two

domains (i.e., D-site). As shown in Figure 4, compound 12i

occupies the binding site of acetyl lysine. A hydrophobic

^N^H2

ACS Med. Chem. Lett. 2021, 12, 397−403

ACS Medicinal Chemistry Letters

Letter

Table 3. Inhibitory Activities of Our Compounds and EX-527 against SIRT1, SIRT2, SIRT3, SIRT5, and SIRT6 (IC : μM)

SIRT1

SIRT2

SIRT3

SIRT5

SIRT6

1.31 ± 0.26

1.20 ± 0.09

0.46 ± 0.09

0.89 ± 0.01

0.99 ± 0.10

54.04 ± 6.3

56.44 ± 0.44

52.24 ± 2.88

49.45 ± 5.95

8.69 ± 0.08

136.70 ± 14.30

171.80 ± 13.60

117.0 ± 1.60

135.80 ± 14.70

29.18 ± 1.60

19.84 ± 1.24

37.42 ± 1.47

4.98 ± 0.88

22.45 ± 0.78

EX-527

NA means “not active ”.

explain the positive correlation between halogen substitution at

the benzylidene and the inhibitory potency of inhibitors. In

addition, the hydroxy at the benzene ring of benzylidene forms

hydrogen-bonds with the side-chains of Asn346 and Asp348.

Substitution of the hydroxy with amino dramatically reduced the

inhibitory activity (Table 2).

To validate the binding mode of 12i in SIRT1, the residues

Phe273, Asn346, Ile347, Asp348, and Phe414 of SIRT1 were

selected for single-site mutation. The dissociation equilibrium

F273L

constant K of compound 12i with SIRT1, SIRT1

N346A

I347A

D348A

F414A

SIRT1

, SIRT1

, or SIRT1

mutant

was determined by the secondary plots of the kinetics data of 12i

Figure 5 ). We may see that the K of 12i for wild type SIRT1 is

various concentrations of 12i .

Figure 3. Enzyme kinetic study of compound 12i. (A) Michaelis−

Menten plot of the Abz-labeled acetyl peptide at various concentrations

of 12i and 1 mM of NAD . (B) Lineweaver−Burk plot of the Abz-

labeled acetyl peptide at various concentrations of 12i. (C) Michaelis−

Menten plot of NAD at various concentrations of 12i and 30 μM of the

Abz-labeled acetyl peptide. (D) Lineweaver−Burk plot of NAD at

Figure 5. Secondary plots for determining K of 12i for wild-type SIRT1

and its mutants. The slopes of the Lineweaver−Burk plot of NAD for

wild-type SIRT1 (Figure 3D) and the mutants (Figure S3) were plotted

versus the concentration of 12i. The values of K were calculated from

the x intercepts of the lines.

.10 μM whereas the K values for SIRT1^F²⁷³^L, SIRT1^N³⁴⁶^A

I347A

D348A

F414A

SIRT1

, SIRT1

, and SIRT1

mutants are 0.65, 1.94,

.71, 7.06, and 18.17 μM, respectively. These demonstrated that

Phe273, Asn346, Ile347, Asp348, and Phe414 did interact with

compound 12i, among which Phe414 had the greatest

contribution to the interaction with the compound.

All-trans retinoic acid (ATRA) had been shown to induce the

diﬀerentiation of SH-SY5Y cells through activation of SIRT1.

As p53 is a substrate of SIRT1, modulation of SIRT1 activity

may change the acetylation state of p53. To examine whether

our inhibitors are active in cells, we treated SH-SY5Y cells with

ATRA and the inhibitors and detected the expression of acetyl

p53 by Western blot. As shown in Figure 6A, treatment of SH-

SY5Y cells with ATRA alone (lane: control) decreased the

expression level of acetyl p53 (compared to the lane of blank),

while incubation of the cells with ATRA and 10 μM of

compounds 12i, 12q, 8m, 12l, or 12n for 72 h signiﬁcantly

increased the acetyl-p53 level. To further conﬁrm the result, we

examined the inhibitory activity of 12n through a titration assay

with the concentrations of 0.1, 1, 10, and 50 μM. The result

showed that 12n increased the ratio of acetyl-p53 to p53 in a

Figure 4. Interaction of compound 12i in SIRT1 (dash line: H-bond).

interaction was formed between the phenyl at the C2 position of

2i and the residues Phe413, Phe414, and Val445 of SIRT1. The

benzylidene at the C5 position of the inhibitor is in the vicinity of

Ile347 and forms an edge-to-face π−π interaction with Phe273.

Substitution with bromine atom may cause electron deﬁciency

of the benzene ring of benzylidene and enhance the π−π

interaction between compound 12i and Phe273, which may

ACS Medicinal Chemistry Letters

ACS Med. Chem. Lett. 2021, 12, 397−403

The Supporting Information is available free of charge at

Letter

inhibitor, 12n. The enzyme kinetic analysis showed that the

inhibitor was competitive to the acetyl peptide and non-

competitive to NAD . We also simulated the interaction of the

inhibitor in SIRT1 by molecular docking, which was supported

by the SAR analysis of the derivatives and the SIRT1

mutagenesis studies. In line with the in vitro assays, the inhibitor

signiﬁcantly increased the acetylation of p53 in cells.

ASSOCIATED CONTENT

sı Supporting Information

■

https://pubs.acs.org/doi/10.1021/acsmedchemlett.0c00559.

Experimental details, characterization of all compounds,

and the Lineweaver−Burke plots of NAD for SIRT1 and

its mutants (PDF)

AUTHOR INFORMATION

■

Corresponding Authors

Jing-Gen Liu − Key Laboratory of Receptor Research, Shanghai

Institute of Materia Medica, Chinese Academy of Sciences,

Shanghai 201203, China; Email: jgliu@simm.ac.cn

Dongxiang Liu − Department of Pharmacology III, Shanghai

Institute of Materia Medica, Chinese Academy of Sciences,

Shanghai 201203, China; University of Chinese Academy of

Sciences, Beijing 100049, China; orcid.org/0000-0002-

7639-5497 ; Email: dxl@mail.shcnc.ac.cn

Hong Liu − State Key Laboratory of Drug Research and Key

Laboratory of Receptor Research, Shanghai Institute of

Materia Medica, Chinese Academy of Sciences, Shanghai

01203, China; University of Chinese Academy of Sciences,

Beijing 100049, China; School of Pharmaceutical Science and

Technology, Hangzhou Institute for Advanced Study, UCAS,

Hangzhou 310024, China; orcid.org/0000-0003-3685-

6268 ; Phone: +86-21-50806600; Email: hliu@simm.ac.cn;

Fax: +86-21-50807088

Authors

Chunpu Li − State Key Laboratory of Drug Research and Key

Laboratory of Receptor Research, Shanghai Institute of

Materia Medica, Chinese Academy of Sciences, Shanghai

01203, China; School of Pharmaceutical Science and

Technology, Hangzhou Institute for Advanced Study, UCAS,

Hangzhou 310024, China

Sha-Sha Hu − Department of Pharmacology III, Shanghai

Institute of Materia Medica, Chinese Academy of Sciences,

Shanghai 201203, China; University of Chinese Academy of

Sciences, Beijing 100049, China

Lisheng Yang − State Key Laboratory of Drug Research and Key

Laboratory of Receptor Research, Shanghai Institute of

Materia Medica, Chinese Academy of Sciences, Shanghai

Figure 6. Eﬀects of inhibitors on acetylation of p53. (A) The control

group was treated with 10 μM of ATRA while the blank was untreated.

The other groups were cotreated with 10 μM of ATRA and inhibitor

(

EX-527, 12i, 12q, 8m, 12l or 12n). (B) 12n showed a dose-dependent

eﬀect on the acetylation level of p53. Error bars represent mean ± SEM

201203, China

(N = 5). *p < 0.05, ***p < 0.001, compared with the control group.

Min Wang − Department of Pharmacology III, Shanghai

Institute of Materia Medica, Chinese Academy of Sciences,

Shanghai 201203, China

One-way ANOVA with Newman-Keuls post hoc test.

dose-dependent manner (Figure 6B). It displayed a comparable

activity as EX-527 in cells.

In summary, here we identiﬁed novel SIRT1 inhibitors with

the scaﬀold of 5-benzylidene-2-phenyl-1,3-dioxane-4,6-dione.

The derivatives of the inhibitor were synthesized and evaluated

for their SIRT1 inhibitory activity. Based on the SAR of the

derivatives, we developed a highly potent and selective SIRT1

Jian-Dong Long − Key Laboratory of Receptor Research,

Shanghai Institute of Materia Medica, Chinese Academy of

Sciences, Shanghai 201203, China

Bing Wang − Department of Pharmacology III, Shanghai

Institute of Materia Medica, Chinese Academy of Sciences,

Shanghai 201203, China; University of Chinese Academy of

Sciences, Beijing 100049, China

ACS Med. Chem. Lett. 2021, 12, 397−403

ACS Medicinal Chemistry Letters

D. A.; Drayson, M. T.; Craddock, C.; Turner, B. M. Histone

Letter

Haozhen Han − Department of Pharmacology III, Shanghai

Institute of Materia Medica, Chinese Academy of Sciences,

Shanghai 201203, China; University of Chinese Academy of

Sciences, Beijing 100049, China

Haoran Zhu − State Key Laboratory of Drug Research and Key

Laboratory of Receptor Research, Shanghai Institute of

Materia Medica, Chinese Academy of Sciences, Shanghai

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deacetylases in acute myeloid leukaemia show a distinctive pattern of

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Eltoum, I. A.; Elgavish, A.; Nagy, T. R. SIRT1 is significantly elevated in

mouse and human prostate cancer. Cancer Res. 2007, 67, 6612−6618.

01203, China; University of Chinese Academy of Sciences,

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enhances elimination of CML leukemia stem cells in combination with

imatinib. Cancer Cell 2012, 21, 266−281.

Sen Zhao − State Key Laboratory of Drug Research and Key

Laboratory of Receptor Research, Shanghai Institute of

Materia Medica, Chinese Academy of Sciences, Shanghai

(10) Stunkel, W.; Peh, B. K.; Tan, Y. C.; Nayagam, V. M.; Wang, X.;

01203, China

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Complete contact information is available at:

https://pubs.acs.org/10.1021/acsmedchemlett.0c00559

Leppänen, J.; Jarho, E.; Lahtela-Kakkonen, M. Structure-based design

11) Yamakuchi, M.; Ferlito, M.; Lowenstein, C. J. MiR-34a

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(

Author Contributions

C.L., S.-S.H., and L.Y. contributed equally. The manuscript was

written through contributions of all authors.

⊥

of pseudopeptidic inhibitors for SIRT1 and SIRT2. J. Med. Chem. 2011,

13) Kumar, A.; Chauhan, S. How much successful are the medicinal

4 (13), 6456−6468.

chemists in modulation of SIRT1: A critical review. Eur. J. Med. Chem.

016, 119, 45−69.

Funding

The work was supported by National Natural Science Fund of

China (Grants 21672233, 81973239, 81620108027, and

1632008), the Strategic Priority Research Program of the

Chinese Academy of Sciences (XDA12020375 and

XDA12050411), SA-SIBS Scholarship Program, and the

Youth Innovation Promotion Association CAS.

(14) Monaldi, D.; Rotili, D.; Lancelot, J.; Marek, M.; Wossner, N.;

Lucidi, A.; Tomaselli, D.; Ramos-Morales, E.; Romier, C.; Pierce, R. J.;

Mai, A.; Jung, M. Structure-Reactivity relationships on substrates and

inhibitors of the lysine deacylase sirtuin 2 from schistosoma mansoni

Coombes, R. C.; Fuchter, M. J.; Hsiao, C. D.; Lam, E. W. SIRT inhibi-

SmSirt2). J. Med. Chem. 2019, 62, 8733−8759.

Notes

(

15) Peck, B.; Chen, C. Y.; Ho, K. K.; Di Fruscia, P.; Myatt, S. S.;

The authors declare no competing ﬁnancial interest.

tors induce cell death and p53 acetylation through targeting both

SIRT1 and SIRT2. Mol. Cancer Ther. 2010, 9, 844−855.

ABBREVIATIONS

■

(16) Rotili, D.; Tarantino, D.; Nebbioso, A.; Paolini, C.; Huidobro, C.;

SIRT1, silent mating type information regulation 2 homologue-

Lara, E.; Mellini, P.; Lenoci, A.; Pezzi, R.; Botta, G.; Lahtela-Kakkonen,

M.; Poso, A.; Steinkuhler, C.; Gallinari, P.; De Maria, R.; Fraga, M.;

; NAD , nicotinamide adenine dinucleotide; Ac O, acetic

anhydride; SAR, structure−activity relationship; ATRA, all-

trans retinoic acid

Esteller, M.; Altucci, L.; Mai, A. Discovery of salermide-related sirtuin

inhibitors: binding mode studies and antiproliferative effects in cancer

cells. J. Med. Chem. 2012, 55 (24), 10937−10947.

(17) Heltweg, B.; Gatbonton, T.; Schuler, A. D.; Posakony, J.; Li, H.;

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