Biomimetic Synthesis of Rhytidenone A and Mode of Action of Cytotoxic Rhytidenone F

Article abstract of DOI:10.1002/anie.201914257

The rhytidenone family comprises spirobisnaphthalene natural products isolated from the mangrove endophytic fungus Rhytidhysteron rufulum AS21B. The biomimetic synthesis of rhytidenone A was achieved by a Michael reaction/aldol/lactonization cascade in a single step from the proposed biosynthetic precursor rhytidenone F. Moreover, the mode of action of the highly cytotoxic rhytidenone F was investigated. The pulldown assay coupled with mass spectrometry analysis revealed the target protein PA28γ is covalently attached to rhytidenone F at the Cys92 residue. The interactions of rhytidenone F with PA28γ lead to the accumulation of p53, which is an essential tumor suppressor in humans. Consequently, the Fas-dependent signaling pathway is activated to initiate cellular apoptosis. These studies have identified the first small-molecule inhibitor targeting PA28γ, suggesting rhytidenone F may serve as a promising natural product lead for future anticancer drug development.

Full text of DOI:10.1002/anie.201914257

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
International Edition Chemie
www.angewandte.org
Accepted Article
Title: Biomimetic synthesis of rhytidenone A and elucidation of mode of
action of the cytotoxic rhytidenone F
Authors: Xiaoguang Lei, Zongwei Yue, Hiuchun Lam, Kaiqi Chen,
Ittipon Siridechakorn, Yaxi Liu, and Khanitha Pudhom
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201914257
Angew. Chem. 10.1002/ange.201914257
Link to VoR: http://dx.doi.org/10.1002/anie.201914257
http://dx.doi.org/10.1002/ange.201914257

Angewandte Chemie International Edition
10.1002/anie.201914257
RESEARCH ARTICLE
Biomimetic synthesis of rhytidenone A and elucidation of mode
of action of the cytotoxic rhytidenone F
Zongwei Yue,a,b,+ Hiu C. Lam,b,+ Kaiqi Chen, Ittipon Siridechakorn, Yaxi Liu, Khanitha Pudhom,
b
b
b
c
b
Xiaoguang Lei *
Abstract: Rhytidenones family are spirobisnaphthalene natural
products isolated from mangrove endophytic fungus Rhytidhysteron
rufulum AS21B. The biomimetic synthesis of complex rhytidenone A
was achieved via a sequence of Michael reaction, aldol and
lactonization cascade in a single step, from the proposed biosynthetic
precursor rhytidenone F. Moreover, the mode of action of the highly
cytotoxic rhytidenone F has been investigated. The pulldown assay
coupled with mass spectrometry analysis revealed the target protein
PA28γ is covalently attached to rhytidenone F at the Cys92 residue.
The interactions of rhytidenone F with PA28γ would lead to the
accumulation of p53 which is an essential tumor suppressor in
humans. Consequently, the Fas-dependent signalling pathway will be
activated to initiate cellular apoptosis. Our studies have identified the
first small molecule inhibitor targeting PA28γ, suggesting rhytidenone
F may serve as a promising natural product lead for future anticancer
drug development.
coworkers identified a family of novel spirobisnaphthalene
compounds from endophytic fungi Rhytidhysteron rufulum AS21B,
namely rhytidenones A-F (Scheme 1).[13] Rhytidenone F (2)
shows excellent cytotoxic activity against Ramos (Burkitt’s
lymphoma) and H1975 (non-small cell lung cancer) cells,[14] but
the mode of action remains elusive. Moreover, rhytidenone A (6)
bears the most complex structure in the rhytidenone family
containing 6 contiguous stereocenters and a spirocycle, which
could be biogenetically derived from rhytidenone F (2).
Introduction
p53 is an essential tumor suppressor in humans.[1] Loss or
mutation of p53 is strongly associated with various cancers.[2]
Extensive studies to develop drugs that could activate or restore
the
p53
pathway
have
now
reached
clinical
trials.[ Fundamentally, discovery of small molecules targeting
p53 pathway with new mode of action may further stimulate many
exciting new approaches to cancer drug discovery.
Spirobisnaphthalenes consist of two naphthalene-derived C10
units joining together through a spiroketal linkage, belong to a
novel family of natural products isolated from fungi.[4-5] They
3]
possess
antimicrobial,
a
variety of biological properties,[6] including
[
7-8]
[9]
[10]
antiplasmodial,
antileishmanial,
nematicidal,[ and antitumor activities. In 2014, Pudhom and
11]
[12]
[
[
a]
b]
Z. Yue+
School of Life Sciences, Peking University, Beijing 100871,
People’s Republic of China
+
+
Z. Yue , Dr. H. C. Lam , K. Chen, Dr. I. Siridechakorn, Y. Liu,
Prof. Dr. X. Lei
Scheme 1. Proposed biosynthetic connections of rhytidenones A-F and
MK3018 from Rhytidhysteron rufulum AS21B.[13, 15]
Beijing National Laboratory for Molecular Sciences, State Key
Laboratory of Natural and Biomimetic Drugs, Key Laboratory of
Bioorganic Chemistry and Molecular Engineering of Ministry of
Education, Department of Chemical Biology, College of
Chemistry and Molecular Engineering, Synthetic and
Functional Biomolecules Center, and Peking-Tsinghua Center
for Life Sciences, Peking University, Beijing 100871, People’s
Republic of China
Email: xglei@pku.edu.cn
Prof. Dr. K. Pudhom
Department of Chemistry, Faculty of Science, Chulalongkorn
University, Bangkok 10330 Thailand
These authors contributed equally to this work
We postulate the biosynthesis of rhytidenones natural products
could be derived from MK3018 (1), a natural product which is co-
isolated from Rhytidhysteron rufulum AS21B (Scheme 1).[
Dehydration of MK3018 (1) would afford rhytidenone F (2). Union
of rhytidenone F (2) with hydroxyketone 3 via a series of cascade
reaction could give rhytidenone A (6). Hydroxyketone 3 is a
secondary metabolite which is derived from α-ketoglutarate and
acetaldehyde, common intermediates from citric acid cycle and
ethanol metabolism respectively.[17-19] Our proposed biosynthesis
of rhytidenone A (6) first involves a Michael reaction of the
15-16]
[c]
[+]
Supporting information for this article is given via a link at the
end of the document.
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201914257
RESEARCH ARTICLE
secondary alcohol 3 to the unsaturated ketone of rhytidenone F
in reflux PhMe afforded rhytidenone F (2), which matches the
spectroscopic data from the isolated 2.
(
2). The resulting enolate 4 would then attack the ketone to give
alkoxide 5, followed by lactonization to afford rhytidenone A (6)
6
,7
(
Scheme 1). Similarly, selective hydrogenation of Δ -alkene of
rhytidenone F (2) could give rhytidenone B (7), while Michael
reaction by water or methanol could deliver rhytidenones C-E (8
With rhytidenone F (2) and 14 in hand, we began our investigation
on the biomimetic cascade transformation towards rhytidenone A
(6). After screening both acidic and basic conditions (Scheme 2D),
–
10) respectively.
2 3
we have discovered stirring 2 and 14 in pTSA·H O in PhCF at
room temperature gave rhytidenone A (6) in 39% yield along with
diastereoisomer 15 (Scheme 2B). 15 is presumably derived from
the non-stereoselective aldol reaction where enolate 4 could
attack either side of the ketone. Our DFT calculation suggested
rhytidenone A (6) is thermodynamically more stable than epi-9-
rhytidneone A 15 by 2.85 kcal mol-1 which is consistent to our
experimental results (Scheme 2C). To our surprise, the optical
rotation of rhytidenone A (6) is opposite to the reported value from
the isolation. Our single crystal X-ray crystallography has
unambiguously confirmed the absolute configuration of
rhytidenone A (6). Unfortunately, we were unable to obtain natural
rhytidenone A (6) for comparison despite multiple isolation
attempts from Rhytidhysteron rufulum AS21B. After discussion
with the authors of the original natural product isolation paper, we
Results and Discussion
Herein, we report a biomimetic synthesis of rhytidenone A (6).
First, hydroxyketone 14 can be obtained from 12 which can be
accessed from a 3-step transformation of acetylfuran 11.[20-21]
Hydrogenation of 12 by Zn and AcOH afforded 13,[22] followed by
ring opening of lactone by NaOH and MeOH to give 14 (Scheme
2A). In this study, rhytidenone F (2) was obtained either from
isolation of Rhytidhysteron rufulum AS21B or dehydration of the
more naturally abundant MK3018 (1).[14] After screening a few
conditions, we found heating 1 with PhB(OH)
[
23]
2
and acetic acid
Scheme 2. A) Synthesis of the methyl ester 14; B) Biomimetic synthesis of rhytidenone A (6) and rhytidenone E (10); C) Relative Gibbs free energies of 6
and 15 calculated at DFT/m06-2x-6-311G(d,p) level of theory; D) Selected screened conditions for the biomimetic cascade reaction.
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201914257
RESEARCH ARTICLE
believe that the previous optical rotation was wrongly measured
due to the small amount of natural product sample.
rhytidenone F (2) for 24 h or 72 h. Subsequently, cell viability was
assessed using the cell-titer Glo kit. Rhytidenone F (2) shows
potent anticancer activity against the tumor cell lines with IC50
values of 0.01 ~ 0.82 μM (Table 1B). In addition, rhytidenone F
(2) is more toxic towards leukemia and lymphoma cell lines than
solid tumors. These results suggest rhytidenone F (2) might be a
promising agent for anticancer drug development.
Next, subjecting rhytidenone F (2) in pTSA in the presence of
MeOH gave rise to rhytidenone E (10) in 86% yield. Interestingly,
only a single diastereoisomer was observed in the reaction
suggesting the Michael reaction with methanol is stereoselective.
The spectroscopic data of rhytidenone E (10) matches the
reported literature data.[13] Furthermore, we have observed an
interesting dimerization product 16 when rhytidenone E (10) was
heated at 35 °C during evaporation of solvent in the presence of
acid (Scheme 2B), presumably via a double Michael reactions.
The structure of dimer 16 was confirmed by single crystal X-ray
crystallography. The biomimetic synthesis of rhytidenone A (6)
from rhytidenone F (2) has provided insights towards the
biosynthesis of the rhytidenones family. Although the biomimetic
transformation of rhytidenone F (2) to rhytidenone A (6) is not fully
diastereoselective in the aldol step, considering both 2 and 3 are
natural products and the reaction took place in relative mild
conditions, we speculate 15 might be an “undiscovered natural
product”.
Cell death occurs in four major manners: apoptosis (type I cell
death), autophagic cell death (type II), necrosis (type III) and
ferroptosis.[
24-25]
Apoptosis, a programmed cell death, is regarded
as a caspase-dependent process, characterized by cell shrinkage
and DNA fragmentation.[26] To determine if rhytidenone F (2)
induces apoptosis or other types of cell death, we treated HeLa
cells with rhytidenone F (2) for 24 h, and subsequently observed
the effects of morphological features. Upon the treatment of
rhytidenone F (2), HeLa cells appeared shrinkage and lost the
capacity of adherence (Figure S1a). Moreover, the activation of
caspase 3 and poly ADP-ribose polymerase (PARP) proteolysis
were clearly noticeable in western blot when exposed to
rhytidenone F (2) (Figure S1b), suggesting rhytidenone F (2)
triggers caspase-dependent cell apoptosis. Additionally,
rhytidenone F (2) can induce genomic DNA fragmentation which
is another hallmark of apoptosis (Figure S1c.). We also observed
that rhytidenone F (2) has no significant effect on cell cycle
comparing to the control group by by flow cytometry analysis
(Figure S1d).
Table 1A. IC50 of compounds against HeLa cells.
Compound
IC50 (μM)
MK3018 (1)
0.97 (±0.08)
0.21 (±0.10)
1.38 (±0.01)
19.8 (±3.90)
9.35 (±1.91)
1.51 (±0.19)
rhytidenone F (2)
rhytidenone E (10)
dimer 16
rhytidenone A (6)
epi-9-rhytidenone A (15)
Table 1B. The anti-proliferation effects of rhytidenone F (2) against different
cancer cell lines.
Cell line
IC50 (μM)
HEK293T (non-pathological cell)
K562 (leukemia)
0.51 (±0.23)
0.30 (±0.06)
HL-60 (leukemia)
0.05 (±0.03)
0.07 (±0.02)
0.01 (±0.01)
0.13 (±0.01)
0.07 (±0.06)
0.21 (±0.10)
0.44 (±0.18)
0.20 (±0.05)
0.39 (±0.17)
0.81 (±0.32)
0.41 (±0.13)
0.82 (±0.36)
NB4 (leukemia)
Ramos (lymphoma)
Hut-78 (lymphoma)
HCT-116 (colon cancer)
HeLa (cervical cancer)
HEPG2 (liver cancer)
KB (oral cancer)
A549 (lung cancer)
MCF-7 (breast cancer)
MDA-MB-231 (breast cancer)
SK-MEL-28 (melanoma)
Scheme 3. Syntheses and biological evaluation of both positive and negative
rhytidenone F probes for target identification. Biological activity was evaluated
against Ramos cells.
After total synthesis, we then investigated the preliminary
cytotoxicity of the natural products and two derivatives towards
HeLa cells, where rhytidenone F (2) is the most potent one (Table
Our next objective is to identify the cellular target proteins that
directly interacts with rhytidenone F (2) in order to further
elucidate its mode of action. Since the electrophilic unsaturated
ketones moieties of rhytidenone F (2) could be good Michael
acceptors to form covalent bonds with nucleophilic residues of
proteins (e.g. cysteines) to give rise to the biological activity,[27] we
1A). We observed 2 can trigger cancer cells death in low dose
through inducing cell apoptosis. We have further investigated the
anticancer efficacy of rhytidenone F (2) to 13 different human
tumor cell lines representing 9 different cancer types. (Table 1B)
The tumor cells were treated with increasing concentration of
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201914257
RESEARCH ARTICLE
Figure 1. Rhytidenone F (2) directly targets PA28γ and induces p53 accumulation. A) HeLa cell lysates were incubated with negative 19 or positive probe 18
followed by pulldown with streptavidin-agarose beads and analyzed by SDS-PAGE with sliver staining. B) The recombinant PA28γ was incubated with biotin-
labeled rhytidenone F in the absence or presence of unlabeled rhytidenone F for 30 min, and the mixtures were blotted for biotin or PA28γ. C) Rhytidenone F
(2) treatment (10 μM) increased the thermal stability of PA28γ in HeLa cells as measured by the temperature-dependent cellular thermal shift assay (n = 3).
D) Trypsin-digest LC-MS/MS analysis indicated modification of PA28γ with rhytidenone F (2) at residue cys92. E) PA28γ was knocked down in HeLa cells,
and the knockdown efficiency was confirmed by qPCR (left). HeLa cells were treated with different concentration of rhytidenone F (2) and the cell viability was
measured. HeLa cells with PA28γ knockdown were more resistant to rhytidenone F (2). F) HeLa cells (above) and MDA-MB-231 (below) were treated with
rhytidenone F (2) for 24 h, followed by Western blot analysis of expression level of the indicated proteins. KD, knockdown.
have designed and synthesized the biotin-tagged positive probe
8 and the negative probe 19 for affinity purification (Scheme 3).
The biological activity of the positive probe 18 is comparable to
rhytidenone F (2), whereas the negative probe 19 is not active
competitively inhibited by higher concentrations of the unlabeled
rhytidenone F (Figure 1B). To reveal the binding sites, the
recombinant PA28γ was incubated with rhytidenone F (2),
followed by LC-MS/MS analysis. The results showed a mass shift
(320 Da) on the peptide RLDECEEAFQGTK, which is consistent
with the addition of one molecule of rhytidenone F (2). Tandem
mass spectrometry results revealed that Cys92 was the binding
site for the covalent interaction of PA28γ and rhytidenone F (2)
(Figure 1D).
1
(
Scheme 3). These two probes were used for the target
identification studies.
We have performed pulldown assay using both probes 18 and 19
for the identification of the cellular target proteins of rhytidenone
F (2). HeLa cell lysates were incubated with 10 μM negative probe
1
9 or positive probe 18, followed by precipitation with streptavidin
Our next goal is to validate if PA28γ is an on-target or off-target
of rhytidenone F (2). The bioinformatics analysis showed that
PA28γ expression level has a negative correlation to some extent
with the sensitivity of different cancer cell lines to rhytidenone F
(2). K562, SK-MEL-28, MCF-7 with relatively lower PA28γ level
are more resistant to rhytidenone F (Figure S2.). Furthermore, we
have used lentivirus to stably knock down PA28γ gene in HeLa
cells and measured the sensitivity of cells towards rhytidenone F
(2). Comparing with the scrambled control cells, HeLa cells with
PA28γ knockdown also appeared resistance to rhytidenone F (2)
when treated with 0.2 – 0.8 μM rhytidenone F (2) (Figure 1E).
agarose beads. Proteins captured by the beads were observed
on SDS-PAGE with silver staining. A band of about 30~40 kD
appeared only in the cell lysates incubated with positive probe 18
(
Figure 1A). Based on LC-MS/MS analysis, we have identified
PA28γ as a possible candidate binding protein.
To determine if rhytidenone F (2) directly binds to PA28γ, we
treated HeLa cells with 10 μM of this compound and detected its
effect on the thermal stability of PA28γ. The cellular thermal shift
assay[28] demonstrated that rhytidenone F (2) enhanced the
stability of PA28γ at higher temperature (Figure 1C), which
implied a stable interaction between rhytidenone F (2) and PA28γ.
In addition, biotin-labeled rhytidenone F 18 also bound to the in
vitro recombinant PA28γ protein, and this binding was
Therefore, PA28γ is confirmed as
a functional target of
rhytidenone F (2).
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201914257
RESEARCH ARTICLE
PA28γ, also known as REGγ, Ki antigen or PSME3, belongs to a
family of activators of the 20S proteasome that promotes the
degradation of protein substrates in an ubiquitin-ATP-
does not significantly interrupt the interactions of rhytidenone F
and PA28γ (Figure S3). Moreover, we have determined the half-
life of rhytidenone F in pseudo-first order GSH assay is 97
minutes (Figure S4). As a comparison, the half-life of afatinib that
is an FDA-approved covalent drug molecule in this assay is 25
minutes. In addition, we have purified the rhytidenone F –
glutathione adducts and they also showed comparable
cytotoxicity to rhytidenone F in the same assay (Table S1),
suggesting a retro-Michael reaction in cells may happen to
regenerate rhytidenone F and therefore give rise to the anti-tumor
activity.
[
29-30]
independent manner.
Unlike its family members PA28α and
PA28β that preferentially form a heteroheptamer in the cytosol,
PA28γ usually forms a homoheptamer in nucleus.[31] PA28γ is
involved in the regulation of apoptosis and cell cycle progression,
-/-
and PA28γ mice displays smaller body size and increases of G
1
cells.[32] To date, the identified substrates degraded through
PA28γ-dependent proteasome pathway includes steroid receptor
coactivator 3 (SRC3),[33] the cell cycle regulators p21, p16, p19,[34]
and hepatitis C virus core protein.[35] Notably, PA28γ promotes
p53 degradation by acting as an essential cofactor that directly
binds to p53 through its amino acids residues 86-96
(
KRRLDECEEAF) and enhances MDM2-p53 interaction.[36]
Through MDM2-p53 interaction, p53 would be polyubiquitinated
and downregulated through MDM2-mediated proteasomal
degradation.
Because the covalent interaction of rhytidenone F (2) at the Cys92
residue of PA28γ, which is located in the PA28γ-p53 binding
pocket, we hypothesize the interactions of rhytidenone F and
PA28γ would lead to the interference of PA28γ-p53 interactions.
The MDM2-p53 interaction would subsequently be hindered and
less p53 would be degraded. Accumulation of p53 can lead to cell-
cycle arrest or apoptosis of cancer cells.[37-39]
Figure 2. Proposed model of mode of action on rhytidenone F (2) inducing cell
apoptosis.
We then tested this hypothesis by exposing HeLa cells to
increasing concentrations of rhytidenone F (2) for 24 h, and
evaluated the expression level of p53. As shown in Figure 2C, p53
accumulation was observed in the rhytidenone F (2) treated cells
Conclusion
(
HeLa cells, MDA-MB-231 cells). In addition, MDM2 was up-
regulated after the rhytidenone F (2) treatment which is expected
as MDM2 is involved in the feedback loop of the regulation of the
p53 level in cells.[40] Besides, Fas, a death receptor on the surface
of cells, could form the death-inducing signaling complex (DISC)
and lead to programmed cell death. As a downstream substrate
of p53 signaling pathway, Fas gene expression was remarkably
increased accompanied by p53 accumulation. (Figure 1F)
The synthesis of rhytidenone A (6) from rhytidenone F (2) has
been achieved via a biomimetic Michael reaction / aldol /
lactonization cascade, forming 2 rings, 1 C-C bond, 2 C-O bonds,
3
new contiguous stereocenters in one step. We have further
investigated the potent antitumor activity of rhytidenone F (2)
against various cancer cell lines with IC50 values of 0.01 ~ 0.82
μM. The synthesis of biotin-labeled probes and pulldown assay
has enabled the profiling of the cellular proteins that interacts with
rhytidenone F (2). Interestingly, PA28γ, a negative regulator of
p53, is one of the targets of rhytidenone F (2). Knockdown of
PA28γ gene increased rhytidenone F (2)-resistance of HeLa cells,
which demonstrates PA28γ is a functional-target of rhytidenone F
A model of mechanism of action is proposed as described in
Figure 2: To maintain a steady-state level in cells, p53 is
downregulated dynamically by MDM2-mediated proteasomal
degradation. In this process, PA28γ serves as a cofactor that
enhances MDM2-p53 interaction and promotes p53 degradation.
The covalent interaction of rhytidenone F at the Cys92 of PA28γ
(
2). Furthermore, we have discovered that rhytidenone F (2)
covalently attaches to Cys92 of PA28γ, which subsequently
inhibits p53 degradation. The p53 accumulation activates Fas-
dependent signaling pathway and initiates the apoptosis
pathways. To our knowledge, rhytidenone F (2) is the first
reported small molecule inhibitor of PA28γ that inhibits p53
degradation and induces cell apoptosis. This work presents a
promising natural product lead for future anticancer drug
discovery.
(
a residue in PA28γ-p53 binding pocket), inhibits PA28γ-p53
interactions and hinders p53 degradation. Subsequently,
accumulation of p53 activates Fas-dependent signaling pathway
and initiates apoptosis of cancer cells. Moreover, we envisioned
that more experiments are required to further demonstrate
rhytidenone F (2) is relatively stable in the presence of high
concentration of glutathione, which has been shown to be a major
off-target in vivo for active small molecules with good Michael
acceptor.[ To our delight, we have discovered that glutathione
41]
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201914257
RESEARCH ARTICLE
[
19] M. Beigi, S. Waltzer, A. Fries, L. Eggeling, G. A. Sprenger, M.
Muller, Org Lett 2013, 15, 452-455.
Experimental Section
[
[
20] R. Noyori, S. Hashiguchi, Acc. Chem. Res. 1997, 30, 97-102.
21] L. Z. Zhu, A. Talukdar, G. S. Zhang, J. P. Kedenburg, P. G. Wang,
Synlett 2005, 1547-1550.
The data for the X-ray crystallographic structures of 6, 15 and 16 are
available free of charge from the Cambridge Crystallographic Data Center
under accession numbers CCDC: 1958996, 1961315, and 1961828
respectively.
[22] M. P. Georgiadis, S. A. Haroutounian, C. D. Apostolopoulos,
Synthesis-Stuttgart 1991, 379-381.
[
[
23] B. A. Chauder, C. C. Lopes, R. S. C. Lopes, A. J. M. da Silva, V.
Snieckus, Synthesis-Stuttgart 1998, 279-282.
24] B. R. Stockwell, J. P. Friedmann Angeli, H. Bayir, A. I. Bush, M.
Conrad, S. J. Dixon, S. Fulda, S. Gascon, S. K. Hatzios, V. E.
Kagan, K. Noel, X. Jiang, A. Linkermann, M. E. Murphy, M.
Overholtzer, A. Oyagi, G. C. Pagnussat, J. Park, Q. Ran, C. S.
Rosenfeld, K. Salnikow, D. Tang, F. M. Torti, S. V. Torti, S.
Toyokuni, K. A. Woerpel, D. D. Zhang, Cell 2017, 171, 273-285.
Acknowledgements
We thank Prof. Jiang Zhou (Peking University) for helping with the
HRMS analysis. We thank Dr. Jie Su (Peking University) for
assistance with X-ray analyses, crystallographic data collection
and refinement. We thank Mr. Botao Wu for assistance with
computational studies. Financial support from the National Key
[25] D. R. Green, F. Llambi, Cold Spring Harb Perspect Biol 2015, 7.
[
[
26] S. Elmore, Toxicol. Pathol. 2007, 35, 495-516.
27] M. Gersch, J. Kreuzer, S. A. Sieber, Nat. Prod. Rep. 2012, 29,
659-682.
[
28] D. Martinez Molina, R. Jafari, M. Ignatushchenko, T. Seki, E. A.
Larsson, C. Dan, L. Sreekumar, Y. Cao, P. Nordlund, Science
2
013, 341, 84-87.
Research
2017YFA0505200), the National Natural Science Foundation of
China Grant (21625201, 21661140001, 91853202, and
1521003), the Beijing Outstanding Young Scientist Program
BJJWZYJH01201910001001), and the Beijing Municipal
and
Development
Program
of
China
[
[
29] M. Rechsteiner, C. P. Hill, Trends Cell Biol. 2005, 15, 27-33.
30] T. Nikaido, K. Shimada, M. Shibata, M. Hata, M. Sakamoto, Y.
Takasaki, C. Sato, T. Takahashi, Y. Nishida, Clin. Exp. Immunol.
1990, 79, 209-214.
(
2
(
[
[
31] I. Mao, J. Liu, X. Li, H. Luo, Cell. Mol. Life Sci. 2008, 65, 3971-
3980.
Science and Technology Project grant (Z171100000417001) is
gratefully acknowledged.
32] S. Murata, H. Kawahara, S. Tohma, K. Yamamoto, M. Kasahara,
Y. Nabeshima, K. Tanaka, T. Chiba, J. Biol. Chem. 1999, 274,
38211-38215.
[
[
33] X. Li, D. M. Lonard, S. Y. Jung, A. Malovannaya, Q. Feng, J. Qin,
S. Y. Tsai, M. J. Tsai, B. W. O'Malley, Cell 2006, 124, 381-392.
34] X. Chen, L. F. Barton, Y. Chi, B. E. Clurman, J. M. Roberts, Mol.
Cell 2007, 26, 843-852.
Keywords: Natural product, rhytidenone family, cell apoptosis,
PA28γ, p53
[
[
[
[
[
1] K. H. Vousden, D. P. Lane, Nat. Rev. Mol. Cell Biol. 2007, 8, 275-
83.
2] F. Kruiswijk, C. F. Labuschagne, K. H. Vousden, Nat. Rev. Mol.
Cell Biol. 2015, 16, 393-405.
3] C. J. Brown, S. Lain, C. S. Verma, A. R. Fersht, D. P. Lane, Nat.
Rev. Cancer 2009, 9, 862-873.
4] L. Zhou, J. Zhao, T. Shan, X. Cai, Y. Peng, Mini-Rev. Med. Chem.
[35] K. Moriishi, T. Okabayashi, K. Nakai, K. Moriya, K. Koike, S.
Murata, T. Chiba, K. Tanaka, R. Suzuki, T. Suzuki, T. Miyamura,
Y. Matsuura, J. Virol. 2003, 77, 10237-10249.
[36] Z. Zhang, R. W. Zhang, Embo. J. 2008, 27, 852-864.
[37] B. Vogelstein, D. Lane, A. J. Levine, Nature 2000, 408, 307-310.
[38] X. Chen, L. J. Ko, L. Jayaraman, C. Prives, Genes Dev. 1996, 10,
2438-2451.
[39] L. T. Vassilev, B. T. Vu, B. Graves, D. Carvajal, F. Podlaski, Z.
Filipovic, N. Kong, U. Kammlott, C. Lukacs, C. Klein, N. Fotouhi,
E. A. Liu, Science 2004, 303, 844-848.
2
2
010, 10, 977-989.
5] Y. S. Cai, Y. W. Guo, K. Krohn, Nat. Prod. Rep. 2010, 27, 1840-
870.
1
[
[
6] D. J. Newman, G. M. Cragg, J. Nat. Prod. 2016, 79, 629-661.
7] H. A. Weber, N. C. Baenziger, J. B. Gloer, J. Am. Chem. Soc.
[40] C. L. Brooks, W. Gu, Mol. Cell 2006, 21, 307-315.
[41]R. J. Krause, R. A. Kemper, A. A. Elfarra, Chem Res Toxicol 2001,
14, 1590-1595.
1990, 112, 6718-6719.
[
[
8] K. Krohn, A. Michel, U. Florke, H. J. Aust, S. Draeger, B. Schulz,
Liebigs. Ann. Chem. 1994, 1099-1108.
9] P. Seephonkai, M. Isaka, P. Kittakoop, P. Palittapongarnpim, S.
Kamchonwongpaisan, M. Tanticharoen, Y. Thebtaranonth,
Planta. Med. 2002, 68, 45-48.
[
[
10] S. Martinez-Luis, G. Della-Togna, P. D. Coley, T. A. Kursar, W.
H. Gerwick, L. Cubilla-Rios, J. Nat. Prod. 2008, 71, 2011-2014.
11] J. Y. Dong, H. C. Song, J. H. Li, Y. S. Tang, R. Sun, L. Wang, Y.
P. Zhou, L. M. Wang, K. Z. Shen, C. R. Wang, K. Q. Zhang, J.
Nat. Prod. 2008, 71, 952-956.
[
[
[
[
[
12] C. E. Mcdonald, H. Holcomb, T. Leathers, F. Ampadunyarko, J.
Frommer, Tetrahedron Lett. 1990, 31, 6283-6286.
13] K. Pudhom, T. Teerawatananond, J. Nat. Prod. 2014, 77, 1962-
1966.
14] I. Siridechakorn, Z. W. Yue, Y. Mittraphab, X. G. Lei, K. Pudhom,
Bioorg. Med. Chem. 2017, 25, 2878-2882.
15] H. C. Ohishi, N.; Mikawa, T.; Sakaki, T.; Miyaji, S.; Sezaki, M.,
Jpn. Pat. 01294686 1989.
16] K. Pudhom, T. Teerawatananond, S. Chookpaiboon, Mar. Drugs
2014, 12, 1271-1280.
[
[
17] R. J. Bloom, W. W. Westerfeld, Biochemistry 1966, 5, 3204.
18] A. D. Webb, C. J. Muller, in Advances in Applied Microbiology,
Vol. 15 (Ed.: D. Perlman), Academic Press, 1972, pp. 75-146.
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201914257
RESEARCH ARTICLE
RESEARCH ARTICLE
+
+
Zongwei Yue, Hiu C. Lam, Kaiqi Chen,
Ittipon Siridechakorn, Yaxi Liu, Khanitha
Pudhom, Xiaoguang Lei*
Page No. – Page No.
Biomimetic synthesis of rhytidenone
A and elucidation of mode of action
of the cytotoxic rhytidenone F
Text for Table of Contents
This article is protected by copyright. All rights reserved.