Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for the treatment of human ovarian carcinoma?

Article abstract of DOI:10.1016/j.bbrc.2016.04.028

The red pigment caulerpin, a secondary metabolite from the marine invasive green algae Caulerpa cylindracea can be accumulated and transferred along the trophic chain, with detrimental consequences on biodiversity and ecosystem functioning. Despite increasing research efforts to understand how caulerpin modifies fish physiology, little is known on the effects of algal metabolites on mammalian cells. Here we report for the first time the mitochondrial targeting activity of both caulerpin, and its closely related derivative caulerpinic acid, by using as experimental model rat liver mitochondria, a system in which bioenergetics mechanisms are not altered. Mitochondrial function was tested by polarographic and spectrophotometric methods. Both compounds were found to selectively inhibit respiratory complex II activity, while complexes I, III, and IV remained functional. These results led us to hypothesize that both algal metabolites could be used as antitumor agents in cell lines with defects in mitochondrial complex I. Ovarian cancer cisplatin-resistant cells are a good example of cell lines with a defective complex I function on which these molecules seem to have a toxic effect on proliferation. This provided novel insight toward the potential use of metabolites from invasive Caulerpa species for the treatment of human ovarian carcinoma cisplatin-resistant cells.

Full text of DOI:10.1016/j.bbrc.2016.04.028

Biochemical and Biophysical Research Communications xxx (2016) 1e6
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Biochemical and Biophysical Research Communications
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Metabolites from invasive pests inhibit mitochondrial complex II: A
potential strategy for the treatment of human ovarian carcinoma?
,
,
,
Alessandra Ferramosca a *, Annalea Conte a 1, Flora Guerra a 1, Serena Felline a,
Maria Grazia Rimoli b, Ernesto Mollo c, Vincenzo Zara a, Antonio Terlizzi a
Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Universita del Salento, Lecce, Italy
,
d
a
ꢀ
b
ꢀ
Dipartimento di Farmacia, Universita di Napoli Federico II, Napoli, Italy
c Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Pozzuoli, Italy
d Stazione Zoologica Anton Dohrn, Napoli, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
The red pigment caulerpin, a secondary metabolite from the marine invasive green algae Caulerpa
cylindracea can be accumulated and transferred along the trophic chain, with detrimental consequences
on biodiversity and ecosystem functioning. Despite increasing research efforts to understand how cau-
lerpin modifies fish physiology, little is known on the effects of algal metabolites on mammalian cells.
Here we report for the first time the mitochondrial targeting activity of both caulerpin, and its closely
related derivative caulerpinic acid, by using as experimental model rat liver mitochondria, a system in
which bioenergetics mechanisms are not altered. Mitochondrial function was tested by polarographic
and spectrophotometric methods.
Both compounds were found to selectively inhibit respiratory complex II activity, while complexes I, III,
and IV remained functional. These results led us to hypothesize that both algal metabolites could be used
as antitumor agents in cell lines with defects in mitochondrial complex I. Ovarian cancer cisplatin-
resistant cells are a good example of cell lines with a defective complex I function on which these
molecules seem to have a toxic effect on proliferation. This provided novel insight toward the potential
use of metabolites from invasive Caulerpa species for the treatment of human ovarian carcinoma
cisplatin-resistant cells.
Received 5 April 2016
Accepted 7 April 2016
Available online xxx
Keywords:
Marine biological invasions
Caulerpa
Algal metabolites
Mitochondria
Respiration
Ovarian cancer cells
© 2016 Elsevier Inc. All rights reserved.
1. Introduction
(previously known as Caulerpa racemosa var. cylindracea).
C. cylindracea, in particular, has become the favorite food of a native
Recent researches suggest that the study of well-defined
chemical entities contained by invasive species can contribute
both to a better understanding of the biological processes associ-
ated with marine invasions and to propose a possible exploitation
of vast invasive biomasses to obtain valuable chemicals of interest
in pharmacology [1]. Some of those studies concerned about the
compound caulerpin (CAU), a bioactive bisindolic alkaloid (Fig. 1)
introduced in the Mediterranean along with both the invasive alga
Caulerpa taxifolia, a species included in the list of the 100 world's
worst invasive species listed by the International Union for Con-
servation of Nature (IUCN), and its congeneric Caulerpa cylindracea
fish species of considerable commercial importance, the edible
white sea bream Diplodus sargus. It is noteworthy that, as a
consequence of the C. cylindracea-based diet, the fish accumulates
CAU in its tissues [2e5].
Although CAU, which is one of the main lipophilic components
of the above invasive algae, already showed a panel of biological
activities [[1], and references therein], there are still no clear evi-
dence of a direct impact of CAU on the fish health, and/or potential
risks for the human health as a result of fish consumption. More
specifically, it has been observed that, in D. sargus, the exposure to
C. cylindracea modulates the activity of peroxisomal Acyl-CoA oxi-
dase, the first and rate-determining step of the peroxisomal
b-
oxidation of fatty acids, causing an alteration in lipid metabolism
[6]. The increased activity of Acyl-CoA oxidase, observed in fish
with medium and high content of CAU, could also mechanistically
explain changes observed in the fatty acids levels of fish naturally
* Corresponding author.
E-mail address: alessandra.ferramosca@unisalento.it (A. Ferramosca).
1
These authors contributed equally to this work.
http://dx.doi.org/10.1016/j.bbrc.2016.04.028
0006-291X/© 2016 Elsevier Inc. All rights reserved.
Please cite this article in press as: A. Ferramosca, et al., Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for
the treatment of human ovarian carcinoma?, Biochemical and Biophysical Research Communications (2016), http://dx.doi.org/10.1016/
j.bbrc.2016.04.028

2
A. Ferramosca et al. / Biochemical and Biophysical Research Communications xxx (2016) 1e6
Fig. 1. Structures and 1H NMR spectra in DMSO-d6 of (A) CAU and (B) its hydrolysis product CA.
feeding on the alien algae [4]. Interestingly, the increased hepatic
lipid catabolism was reflected by the catalytic induction of cyto-
chrome P450 (CYP450) [5], a condition which is often associated to
elevated oxidative stress and reactive oxygen species (ROS) pro-
duction [7].
Noteworthy, the hypolipidemic activity exerted on rats by
C. cylindracea extracts [8] suggests that algal metabolites might also
produce changes in the lipid metabolism of lower vertebrates. On
the other hand, mammalian mitochondria are considered the
principal target for nutritional and pharmacological control of lipid
metabolism [9,10]. In this regard, mitochondrial and peroxisomal
metabolisms of fatty acids were regarded as closely linked. These
organelles are both able to degrade fatty acids, but only mito-
chondrial metabolism is closely linked to energy production [11].
Moreover, an adverse effect of drugs used to control lipid meta-
bolism is the dysfunction of mitochondria, caused by an over-
production of ROS [12].
A CAU-induced mitochondrial damage was first proposed by Liu
et al. [13], who suggested that this metabolite is able to suppress
mitochondrial respiration in breast cancer by inhibiting mito-
chondrial respiration at electron transport chain complex I.
Although showing that CAU is also able to inhibit the growth of
normal human mammary epithelial cells (HMEC), though to a
lesser extent, the above research especially focuses on the mech-
anism of action in pathologic states of hypoxia, but does not
contribute to a better understanding of the action of CAU under
non-pathological/normoxic conditions. On the other hand, it has
been demonstrated that energetic deficit derived from mitochon-
drial dysfunction correlates with low proliferative index, benign
features and the inability of cancer to adapt to the surrounding
microenvironment [14,15].
The main aim of the present study is to evaluate the effects of
CAU on the mitochondrial respiration in normal mammalian cells.
The study also includes an evaluation of the effects of caulerpinic
acid (CA), which is a closely related derivative of CAU (Fig. 1) also
found in C. cylindracea [16, as C. racemosa]. Mitochondria isolated
from rat liver have been selected as a system in which bioenergetic
mechanisms are not altered, in order to elucidate whether and how
algal CAU and CA affect mitochondrial function, as well as to
confirm if they are complex specific inhibitors.
The obtained results and, in particular, the specificity of CAU and
CA in mitochondrial targeting, led us to investigate the role of algal
metabolites on human ovary cancer cells with specific mitochon-
drial defects [17]. Therefore, by exploring the molecular mechanism
by which CAU and CA eventually affect mitochondria function, the
present study also aims to contribute to propose a novel potential
use of the algal metabolites for human ovarian cancer treatment.
2. Materials and methods
2.1. Purification of CAU
C. cylindracea was collected by scuba divers, brought in the lab
and extracted with acetone. The acetone extract was evaporated
under reduced pressure and the residual water was extracted with
diethyl ether. The ether extract was then concentrated and
analyzed by thin-layer chromatography (TLC) using the mixture
light petroleum ether/diethyl ether in different ratio as eluent. TLC
Please cite this article in press as: A. Ferramosca, et al., Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for
the treatment of human ovarian carcinoma?, Biochemical and Biophysical Research Communications (2016), http://dx.doi.org/10.1016/
j.bbrc.2016.04.028

A. Ferramosca et al. / Biochemical and Biophysical Research Communications xxx (2016) 1e6
3
spots were visualized by spraying with ceric sulphate and heating.
The diethyl ether extract was then fractionated by Sephadex LH-20
chromatography eluted with chloroform/methanol in the ratio 1:1.
The fraction giving a spot with Rf around 0.35 on TLC in petroleum
ether/diethyl ether (1:1), producing a red colour after cerium sul-
phate has reacted, was further purified on preparative TLC eluted
with petroleum ether/diethyl ether (4:6), affording pure CAU (red
orange prisms), identified by comparison with 1H and 13C NMR data
(proton and carbon nuclear magnetic resonance) described in the
literature [16,18e20]. NMR spectra were recorded on Bruker
AM400 MHz in both and DMSO-d6 and CDCl3. TLC chromatography
was carried out using precoated Merck F254 plates.
spectrophotometrically, essentially as described in Ref. [23].
Aconitase and fumarase activity were determined as described
in Ref. [24] and activity ratio of aconitase to fumarase was calcu-
lated as an indicator of mitochondrial ROS production.
2.6. SRB assay
Citotoxic effect of CAU or CA on cellular vitality was evaluated by
the colorimetric sulforhodamine B (SRB) assay [25]. 2008 and
C13 cells were plated in 24-well plates in appropriate medium and,
following overnight incubation, were treated with 10 mM of CAU or
CA (in DMSO) for 72 h. After an incubation period, cell monolayers
were fixed with 50% (wt/vol) trichloroacetic acid and stained with
SRB for 30 min, after which the excess dye was removed by washing
repeatedly with 1% (vol/vol) acetic acid. The protein-bound dye was
dissolved in 10 mM Tris base solution for OD determination at
570 nm using a Victor microplate reader (Wallac Instruments,
Turku, Finland).
2.2. Alkaline hydrolysis of CAU
Pure CAU was dissolved in methanol and NaOH 0.1 N (2:1). The
reaction was stirred on water bath at 50 ꢀC for 4 h, then at room
temperature over night. The solution was then acidified to pH 5
with HCl and evaporated under reduced pressure. Extraction with
diethyl ether and evaporation of the organic phase, followed by a
further purification step on Sephadex LH-20 with chloroform/
methanol in the ratio 1:1, gave pure CA (dark brown flakes), as
confirmed by 1H NMR spectroscopy (Fig. 1).
2.7. Statistical analysis
Data were analyzed through one-way ANOVAs after ensuring
homogeneity of variances by Cochran's C tests. When appropriate,
SNK tests were used for multiple a posteriori comparisons of the
means. ANOVAs were computed by GMAV 5 software (University of
Sydney, Australia).
2.3. Animal studies
Male SpragueeDawley rats were obtained from Harlan (Care-
zzana, Italy) and housed individually in animal cages at a temper-
ature of 22
3. Results
1
ꢀC with a 12:12 h lightedark cycle and 30e40%
humidity. Animal studies were carried out in strict accordance with
the European Committee Council 106 Directive (86/609/EEC) and
with the Italian animal welfare legislation (art 4 and 5 of D.L. 116/
92). The Italian Ministry of Health specifically approved this study.
Rat liver mitochondria were prepared by standard procedures.
The respiratory efficiency of freshly isolated rat liver mito-
chondria in the presence of 10
mM CAU or CA was analysed by
oxygraphic methods (Table 1). When we added respiratory sub-
strates for mitochondrial complexes I, we found that CAU and CA
did not affect particularly mitochondrial respiration efficiency, as
suggested by the RCR values (F2,6 ¼ 1.25, p > 0.05).
2.4. Cell lines
Algal metabolites had a stronger effect on mitochondrial respi-
ration efficiency after the addition of rotenone (an inhibitor of
complex I) and succinate (a substrate for complex II); in this case,
we found a decrease of 40% and 33% respectively in the RCR values
(F2,6 ¼ 24.28, p < 0.01). No effect of CAU and CA was observed after
the inhibition of complex I and III (by the addition of rotenone and
antimycin A) and the addition of respiratory substrates for complex
IV (TMPD and ascorbate).
Human ovarian carcinoma cell lines, 2008 wild type and C13
cisplatin-resistant [17], were gently provided by Prof. Gaetano
Marverti (University of Modena and Reggio Emilia, Italy). Cells were
grown in RPMI-1640 medium, 10% fetal bovine serum (FBS), 2%
glutamine and 1% pen-strep, in humidified conditions at 5% CO2
and 37 ꢀC. Both cell lines have a duplication time about 24 h. Cells
were collected every 2 days with minimum amount of 0.25%
trypsin-0.2% EDTA and seeded at 1 ꢁ 106 density in 100 mm dishes.
We then investigated the enzymatic activity of single respira-
tory complexes by spectrophotometric methods (Fig. 2A). Also in
this case, we found a decrease in the activity of complex II of 50%
and 42% when organelles were incubated with CAU and CA,
respectively (F2,6 ¼ 127.68, p < 0.001). Complexes I, III, and IV
remained functional (Fig. 2A).
As functional indicator of mitochondrial ROS production we
calculated the activity ratio of aconitase to fumarase, because
aconitase is sensitive to inactivation by superoxide, whereas
fumarase is unaffected. We found that this ratio was unchanged
after CAU and CA incubation (Fig. 2B).
These results lead to hypothesize an effect of algal metabolites
in completely blocking mitochondria respiration in cells with de-
fects in mitochondrial complex I, such as cisplatin-resistant C13
ovarian cancer cells. These cell lines are characterized by mtDNA
mutations, reduced oxygen consumption, lower sensitivity to
rotenone and increased dependence of glucose when compared to
their cisplatin-sensitive and wild type counterpart, that is 2008
ovarian cancer cell lines [26,27].
We found that, also in ovarian cancer cells, CAU and CA impair
mitochondrial respiration at level of complex II, both on cisplatin-
sensitive (Fig. 3A; F2,6 ¼ 23.83, p < 0.01) and on cisplatin-
2.5. Mitochondrial functionality assays
Rat liver mitochondria (0.3 mg protein/ml) or digitonin-
permeabilized cells (7.5 ꢁ 106 cells) were incubated for 3 min
without (control) and with 10 mM CAU or CA (dissolved in DMSO).
Oxygen uptake by rat liver mitochondria or by permeabilized
cells was measured by using a Clark-type oxygen probe (Hansatech
oxygraph; Hansatech Pentney, King's Lynn, UK) as described in Refs.
[21,22]. The addition of different substrates permitted to evaluate
mitochondrial respiration when respiratory complexes I (5 mM
pyruvate, 2.5 mM malate), II (5 mM succinate, 5
mM rotenone) or IV
(10 mM ascorbate, 0.2 mM TMPD, 5 M rotenone, 5
m
mM antimycin
A) were stimulated [23]. For each substrate, after 2 min, state 3
respiration was induced by the addition of 0.3 mM ADP. Respiratory
control ratio (RCR) was calculated as the ratio of the rate of oxygen
uptake in the presence of added ADP (state 3) to the rate observed
when added ADP had been completely phosphorylated to ATP
(state 4).
Mitochondrial respiratory complexes activities were evaluated
Please cite this article in press as: A. Ferramosca, et al., Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for
the treatment of human ovarian carcinoma?, Biochemical and Biophysical Research Communications (2016), http://dx.doi.org/10.1016/
j.bbrc.2016.04.028

4
A. Ferramosca et al. / Biochemical and Biophysical Research Communications xxx (2016) 1e6
Table 1
Effect of algal metabolites on oxygen consumption by rat liver isolated mitochondria.
Control
CAU
CA
Pyruvate þ malate (Complex I)
V3 (nmol O2 $ mlꢂ1 $ minꢂ1
4 (nmol O2 $ mlꢂ1 $ minꢂ1
RCR
)
)
17.5 0.7
5.5 0.4
3.2 0.4
59.1 3.8
10.2 0.9
5.8 0.1
49.0 2.7
8.9 0.5
5.5 0.4
13.4 0.8
4.9 0.4
2.7 0.3
17.7 1.1
5.1 0.6
3.5 0.7
47.9 3.9
8.8 0.5
5.5 0.7
12.8 0.9
4.7 0.5
2.8 0.5
19.2 1.0
4.9 0.4
3.9 0.2
45.0 4.2
8.9 0.5
5.2 0.9
V
Succinate þ rotenone (Complex II)
V
3 (nmol O2 $ mlꢂ1 $ minꢂ1
)
)
V4 (nmol O2 $ mlꢂ1 $ minꢂ1
RCR
Ascorbate þ TMPD þ rotenone þ antimycin A (Complex IV)
V
V
3 (nmol O2 $ mlꢂ1 $ minꢂ1
)
)
4 (nmol O2 $ mlꢂ1 $ minꢂ1
RCR
V3 was the rate of oxygen uptake recorded in the presence of added ADP. V4 was the rate of oxygen uptake observed when added ADP had been completely phosphorylated to
ATP. Respiratory control ratio (RCR) was calculated as the ratios of V3 to V4.
landscape over the last twenty years [28]. Among the algal bioac-
tive secondary metabolites Caulerpa, a variety of biological activ-
ities have been ascribed to the bisindolic red pigment CAU. In
particular, it was suggested that the ability of CAU might contribute
to the successful establishment of C. taxifolia in the Mediterranean,
playing a role in defences against herbivores. Although this hy-
pothesis supports the importance of a chemoecological approach to
marine biological invasions [29], studies especially focusing on the
activity of CAU on mammalian cells are limited.
In this paper we have explored the role of mitochondria as po-
tential pharmacological targets of algal metabolites. A previous
research proposed that Caulerpa pigment CAU inhibits mitochon-
drial respiration at electron transport chain complex I in breast
cancer cells (T47D cells) treated with 30 m
M CAU at 37 ꢀC for 2 h,
while complexes II, III, and IV remained functional [13]. Although
showing that CAU is also able to slightly inhibit the growth of
normal human mammary epithelial cells (HMEC), this study does
not contribute to a better understanding of the action of CAU under
physiological conditions. In fact, it is known that energy meta-
bolism and ROS homeostasis in cancer cells are much different from
those in normal cells [30]. Therefore, the data obtained in T47D cells
could be the result of modified mitochondrial metabolism. In this
regard, new evidences [31] revealed that T47D cells have a lower
oxygen consumption rate, reduced ATP levels and higher proton
leak, along with lower levels of cytochrome c oxidase, subunit IV,
isoform 1.
For the first time, in the present study we showed a direct effect
of CAU and its closely related derivative CA mainly on respiratory
complex II under physiological conditions. This finding is consistent
with the recent evidence that complexes I, III and IV are associated
as super-complexes in the mitochondrial inner membrane [32].
Interestingly, in this experimental model, inhibition of complex II
by CAU and CA did not stimulate ROS release. There is increasing
evidence that complex II can be a major regulator of mitochondrial
ROS production under both physiological and pathophysiological
circumstances [33]. In doing so, it can adapt different roles as a
producer or modulator of mitochondrial ROS depending on sub-
strate supply and the activities of the other respiratory complexes
and Krebs cycle enzymes. According to this hypothesis, an increase
in ROS levels was observed in C13 ovarian cancer cells cisplatin-
resistant in comparison to their cisplatin-sensitive and wild type
counterpart, that is 2008 ovarian cancer cell lines.
The choice of these cell lines was based on previous observa-
tions that suggested an involvement of complex I activity in the
metabolic reprogramming in ovarian cancer cells resistant to
cisplatin [27]. Our results confirmed a defective complex I in
C13 cells and demonstrated, for the first time, a toxic effect of CAU
and CA on mitochondrial complex II and an increase of ROS pro-
duction, suggesting that these metabolites could be good candi-
dates for the treatment of cisplatin-resistant cancer. Previous
Fig. 2. Effect of algal metabolites on respiratory complexes activity (A) and on ROS
production (B) in rat liver mitochondria. Rat liver mitochondria (0.3 mg of mito-
chondrial protein/ml) were incubated for 3 min without (control) and with 10 mM CAU
or CA. Enzymatic activities were measured spectrophotometrically. Activity values
recorded in the control group were set to 100%. Different letters where used to indi-
cate, when occurring, significant differences between various exposure conditions for
each mitochondrial respiratory complex (p < 0.001).
resistant cells (Fig. 3B; F2,6 ¼ 24.24, p < 0.01). Interestingly, only
C13 cells showed a defective complex I function (Fig. 3B), con-
firming previous observations [27] and showed a significant in-
crease in mitochondrial ROS production (Fig. 3C; F2,6 ¼ 5.30,
p<0.05). Moreover, CAU and CA stimulate ROS generation (Fig. 3C)
and have a toxic effect especially on proliferation of chemoresistant
cells (C13; F2,6 ¼ 648.04, p < 0.001) (Fig. 4). Interestingly, the effect
exerted by CAU was stronger than that exerted by CA.
4. Discussions
The invasion by C. cylindracea and its congeneric C. taxifolia
profoundly modified the Mediterranean marine sea-bottom
Please cite this article in press as: A. Ferramosca, et al., Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for
the treatment of human ovarian carcinoma?, Biochemical and Biophysical Research Communications (2016), http://dx.doi.org/10.1016/
j.bbrc.2016.04.028

A. Ferramosca et al. / Biochemical and Biophysical Research Communications xxx (2016) 1e6
5
Fig. 3. Effect of algal metabolites on mitochondrial respiratory efficiency of 2008 (A) and C13 lines (B) and on ROS production by ovarian cancer cells (C). The addition of different
substrates permitted to evaluate mitochondrial respiration when respiratory complexes I, II or IV were stimulated. After 2 min, state 3 respiration was induced by the addition of
ADP. RCR was calculated as the ratio of the rate of oxygen uptake in the presence of added ADP (V3) to the rate observed when added ADP had been completely phosphorylated to
ATP (V4). Aconitase and fumarase activity were determined spectrophotometrically. RCR and enzymatic activity values obtained for 2008 cells were set to 100%. Different letters
indicate statistical differences, when occurring, between means of values as indicated by ANOVA and post-hoc comparison (p < 0.01).
increase and a suppression of PPP-derived NADPH production [34].
We are aware that more needs to be done to delineate the
molecular mechanism responsible for the bioactivity of CAU and CA
on ovarian carcinoma and other cancer cell lines. Nevertheless, the
present study provides a preliminary insight into the potential use
of algal metabolites for the prospective treatment of human
cisplatin-resistant ovarian cancer. This should encourage re-
searchers toward a possible pharmacological exploitation of high
added value chemical products from invasive pests huge bio-
masses, paving the way for making the control of invasions
profitable.
Author contributions
A.F., A.C., F.G. and A.T. conceived and designed the study; E.M.
and M.G.R. purified C.A.U and C.A.; A.C. and F.C. performed the
research; A.F., S.F. and V.Z. analyzed the data; A.T. coordinated the
Fig. 4. Effect of algal metabolites on cell vitality of ovarian cancer cells cisplatin-
sensitive (2008) and resistant (C13). Cytotoxic effect of CAU and CA on cellular vital-
ity was evaluated by the SRB assay. Letters above columns illustrate the outcome of
study; A.F., A.C., F.G., S.F., E.M., A.T. wrote the text.
SNK (Student-Newman-Keuls) tests; different letters indicate significant differences at
p < 0.05.
Conflicts of interest
studies demonstrated that C13 cells have an increased glucose-
uptake and consumption, increased expression and activity of the
Pentose Phosphate pathway (PPP) enzyme Glucose-6-Phosphate
Dehydrogenase (G6PDH) and are more sensitive to G6PDH inhibi-
tion [26]. Interestingly, recent studies on antitumor agents sug-
gested a relationship between complex II inhibition, ROS levels
The authors declare no conflict of interest.
Acknowledgments
Financial support provided by MIUR (The Ministry of Education,
Universities and Research) (PRIN 2012, CAULERFISH projects) and
Please cite this article in press as: A. Ferramosca, et al., Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for
the treatment of human ovarian carcinoma?, Biochemical and Biophysical Research Communications (2016), http://dx.doi.org/10.1016/
j.bbrc.2016.04.028

6
A. Ferramosca et al. / Biochemical and Biophysical Research Communications xxx (2016) 1e6
C. Zamagni, P. De Iaco, G. Gasparre, Mitochondrial DNA mutation in serous
ovarian cancer: implications for mitochondria-coded genes in chemo-
resistance, J. Clin. Oncol. 30 (2012) e373e378.
by the EU FP7 PERSEUS Project (Grant Agreement No. 287600).
Flora Guerra was supported by Fondazione Umberto Veronesi
Fellowship.
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Transparency document
[17] P.A. Andrews, M.P. Murphy, S.B. Howell, Differential potentiation of alkylating
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Transparency document related to this article can be found
online at http://dx.doi.org/10.1016/j.bbrc.2016.04.028.
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Please cite this article in press as: A. Ferramosca, et al., Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for
the treatment of human ovarian carcinoma?, Biochemical and Biophysical Research Communications (2016), http://dx.doi.org/10.1016/
j.bbrc.2016.04.028