Oxidative stress induced by crude venom from the jellyfish Pelagia noctiluca
in neuronal-like differentiated SH-SY5Y cells
Rossana Morabitoa, Salvatore Condellob, Monica Curròb, Angela Marinoc, Riccardo Ientileb,
Giuseppina La Spadac,⇑
aDepartment of Cognitive Sciences, University of Messina, Via Concezione 6-8, 98122 Messina, Italy
bDepartment of Biochemical, Physiological and Nutritional Sciences, Policlinico Universitario, Via Consolare Valeria, 98125 Messina, Italy
cDepartment of Life Sciences ‘‘M. Malpighi’’, Section of General Physiology and Pharmacology, University of Messina, Viale F. Stagno D’Alcontres 31, 98166 Messina, Italy
a r t i c l ei n f o
Received 22 September 2011
Accepted 7 March 2012
Available online 14 March 2012
Mitochondrial membrane potential
a b s t r a c t
Marine toxins are a suitable research model and their mechanism of action is intriguing and still under
debate. Either a pore formation mechanism or oxidative stress phenomena may explain the damage
induced by toxins. The effect of crude venom from isolated nematocysts of the jellyfish Pelagia noctiluca
on neuronal-like cells derived from human neuroblastoma SH-SY5Y has been here studied. To prove the
possible oxidative stress events, cell viability, assessed by MTT quantitative colorimetric assay, intracel-
lular reactive oxygen species (ROS) quantified by the non-fluorescent probe H2DCF-DA and changes in
mitochondrial transmembrane potential (DWm) measured by the incorporation of a cationic fluorescent
dye rhodamine-123 were verified on venom-treated cells (0.05–0.5 lg/ml doses). A dose- and time-
dependent reduction of all parameters was observed after venom treatment. NAC (N-acetyl-cysteine),
antioxidant applied before crude venom application, significantly counteracted the decrease in cell via-
bility and ROS production, while DWm was only partially restored. The disruption of mitochondrial mem-
brane by P. noctiluca crude venom may thus induce oxidative stress by inhibiting mitochondrial
respiration and uncoupling oxidative phosphorylation, sensitizing mitochondria in SH-SY5H cells and
facilitating membrane permeability. In sum, our findings suggest that P. noctiluca crude venom directly
induces DWm collapse with further generation of ROS and add novel information to the understanding
of such toxins, still not completely clarified.
? 2012 Elsevier Ltd. All rights reserved.
come a good research model for studying protein structure–func-
tion relationship and served as a novel tool for ascertaining
biological mechanisms and new drug development (Lu et al.,
2010). Furthermore, in many cases a therapeutic potential against
cancer, inflammation processes and neurodegeneration has been
even recognized (Iwamaru et al., 2007; Villa and Gerwick, 2010).
Among aquatic animals, Cnidarians, including jellyfish, sea
anemones and hydroids, are the most venomous phylum and are
a source of bioactive substances. This relevant aspect is due to their
peculiar cells, called nematocytes, specialized stinging cells, lo-
cated in umbrella, tentacles and oral arms. They produce an orga-
noid, the nematocyst, consisting of a capsule wall containing an
inverted tubule and a fluid matrix in which various toxins are
stored. Under both a chemical and mechanical stimulus, the tubule
is rapidly ejected adhering to or penetrating the prey or aggressor,
thus injecting the capsular fluid (discharge). This process, that is
highly effective requiring only 3 ms (Holstein and Tardent, 1984),
has been widely studied (Anderson and Bouchard, 2009; Ozbeck
et al., 2009), though not completely clarified so far.
One of the most relevant features of nematocyte function is the
toxicology of the capsular fluid delivered under discharge. In this
regard, different experiments, both in vivo and in vitro, have been
performed to investigate the physiological effects of cnidarians tox-
ins at cellular and tissue level. Some of Anthozoa, Scyphozoa and
Hydrozoa specimens are known to affect human skin leading, in
some cases, to serious or even fatal outcomes. Such alterations de-
pend on toxins that, once released, can disrupt cellular membranes
affecting ion fluxes, alter myocardium, nervous tissue, hepatic tis-
sue and kidney functions and provoke release of inflammatory
mediators (Castañeda and Harvey, 2009). Such effects may be
0887-2333/$ - see front matter ? 2012 Elsevier Ltd. All rights reserved.
3-(4,5-methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide; DCF-DA, 2,7-dichlo-
rofluorescein diacetate; DMSO, dimethylsulfoxide; RA, retinoic acid; PBS, phosphate
buffered saline solution; CTX3, cardiotoxin 3; EqTx-II, equinatoxin-II; PLTX, paly-
toxin; PEG, polyethyleneglycol; TBA, thiobarbituric acid.
⇑Corresponding author. Tel.: +39 090 6765209; fax: +39 090 394030.
(G. La Spada).
reactive oxygen species; NAC, N-acetyl-cysteine; MEM,
Essential Medium;FBS, fetal bovineserum; MTT,
(R. Morabito), firstname.lastname@example.org
Toxicology in Vitro 26 (2012) 694–699
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Toxicology in Vitro
journal homepage: www.elsevier.com/locate/toxinvit
explained by vasoactive amines, kinins, collagenases, proteases,
myotoxins and antigenic proteins that make up Cnidarians toxins
(Castañeda and Harvey, 2009; Grotendorst and Hessinger, 2000;
Mariottini and Pane, 2010).
Among Cnidarians, Pelagia noctiluca, a holoplanktonic epipelagic
Scyphomedusa, is one of the most dangerous jellyfish in the Med-
iterranean Sea, where its blooming has been very abundant since
many years. Both ecological (Malej and Malej, 2004) and toxicolog-
ical aspects (La Spada et al., 2002a; Mariottini et al., 2002) of this
species have progressively attracted the interest of many research-
ers. The accidental contact with specimens of P. noctiluca causes
complex symptomathology with both local reactions, as redness,
pain, itching, burning and vesicles and systemic ones as vomiting,
hypotension, diarrhea and shock (Mariottini and Pane, 2010 and
Bothin vivoand invitro biologicalassays have beenperformedto
verify and, possibly, measure the toxicity of P. noctiluca crude
venom, whose composition is still not completely defined (Carli
et al., 1996; La Spada et al., 2002a; Marino et al., 2007, 2008a,b).
The hemolytic test on fish, chicken, rabbit and human erythrocytes
has been chosen, being a rapid and suitable test for a first assess-
ment of toxic power (Marino et al., 2007). Findings from these
experimental tests provide evidences for a strong and stable hemo-
toxicological features and the possible mechanism of action of such
venom. Actually, only a few studies have been performed on cul-
tured cells. In this respect, cytotoxic properties of P. noctiluca crude
venom have been assessed by short-term and long-term tests by
Carli et al. (1996) and Mariottini et al. (2002), describing cytotoxic-
ity, genotoxicity and ATP depletion induced on V79 fibroblasts.
Moreover, the cytotoxic activity of P. noctiluca crude venom has
been also described by Olson et al. (1985) in cultured chicken em-
bryo cardiomiocytes, showing a cardiotoxic activity.
In order to better clarify the toxicological features ofP. noctiluca,
in the current study we have examined the effect of the crude ve-
nom on human neuronal-like differentiated SH-SY5Y cells, moni-
toring the possible changes in mitochondrial membrane potential
(DWm) and ROS production.
2. Materials and methods
chased from American Type Culture Collections (ATCC) (Rockville,
MD, USA). Eagle’s Minimum Essential Medium (MEM), Ham’s F12
Nutrient Mixture, fetal bovine serum (FBS), penicillin/streptomycin
mixture, all-trans RA (Retinoic Acid), 3-(4,5-methylthiazol-2-yl)-
2,5-diphenyl-tetrazolium bromide (MTT), 2,7-dichlorofluorescein
diacetate (H2DCF-DA), dimethylsulfoxide
chemicals of analytical grade, were from Sigma (Milan, Italy).
2.2. Specimens collection
along the Sicilian coasts during Spring and Summer 2010. Once col-
lected, the animals were immediately used for nematocysts isola-
tion, not being maintained in close-circuit aquaria as Anthozoans.
2.3. Nematocysts isolation
Nematocysts from oral arms of P. noctiluca were isolated accord-
ing to Salleo and co-workers (1983). Briefly, the oral arms, once
excised, were placed in cold distilled water for 2 h to deliver
un-discharged nematocysts after osmotic lysis of nematocytes.
centrifuge, ALC PK 120R, 4000g, 5 min) and filtered through a plank-
ton net of less than 0.1 mm mesh to discard debris. Holotrichous-
isorhiza great-spherical nematocysts, one of three types present in
P. noctiluca, have been considered for the present investigation.
2.4. Crude venom extraction
Before use, nematocysts were thawed and filtered again. A drop
of nematocyst suspension was placed on a glass and checked under
a light microscope (Leica DMLS). Nematocyst population was then
counted by a Burker chamber and 800 nematocysts/ll suspensions
were considered for the experiments. Sonication on ice (Sonoplus,
30 times, 20 s at 20 kHz) of nematocysts in distilled water let the
capsular fluid (crude venom) be extracted. Crude venom was then
separated from crushed capsules by centrifugation (refrigerated
centrifuge 4000g for 10 min). Protein content of thus obtained
crude venom was measured by Bradford method (1976). Crude
venom was finally lyophilized and re-suspended in PBS at different
concentrations for the cytotoxic assay.
2.5. Cell cultures
Human neuroblastoma cell line SH-SY5Y (ATCC, Manassas, VA,
USA) was cultured in growth medium consisting in a 1:1 mixture
of MEM/Ham’s F-12 supplemented with 10% fetal bovine serum,
1% antibiotic–antimycotic mixture, 1 mM sodium pyruvate, 2 mM
L-glutamine in 5% CO2humified incubator at 37 ?C. The medium
was renewed every 2 days.
To induce differentiation, after 24 h incubation in MEM/F-12,
subconfluent cells were cultured for 5 days in a medium with 1%
FBS and 10 lM all-trans-retinoic acid (RA) (Sigma Aldrich, St. Louis,
MO, USA) diluted in DMSO.
RA-differentiated SH-SY5Y cells were exposed at different times
(30 min, 1 h and 2 h) toP. noctiluca crude venom in a range concen-
tration of 0.05–0.5 lg/ml.
Moreover, in order to counteract the possible pro-oxidant
effects of crude venom in RA-differentiated SH-SY5Y cells, parallel
experiments were carried out using N-acetyl-cysteine (NAC), at the
effective concentration of 100 lM. NAC was added 30 min before
crude venom addition.
2.6. Cell viability assay
To assess the potential harmful effects of the crude venom on
cell viability, a MTT (3-(4,5-methylthiazol-2-yl)-2,5-diphenyl-tet-
razolium bromide) reduction assay was performed. After toxin
treatment, cells, grown in 96-well culture plates (50,000 cells/
well), were incubated with MTT (0.5 mg/ml) at 37 ?C for 1 h. Then,
insoluble purple formazan crystals, produced by mitochondrial
dehydrogenases in viable cells, were dissolved for 10 min at
37 ?C in 100 ll of a 10% (w/v) SDS solution in HCl 0.01 M, and
the optical density at 570 nm was evaluated by a microplate reader
(Sunrise, Tecan Italia, Cologno Monzese, Italy). The percentage of
cell viability was obtained by the absorbance ratio of crude
venom-treated vs untreated cells.
2.7. Evaluation of intracellular ROS production
In order to evaluate ROS production, SH-SY5Y cells, cultured in
6-well culture plates (250,000 cells/ml), were incubated for 30 min
with H2DCF-DA (5 lM) and, at the end of each treatment, were
analyzed as previously described (Condello et al., 2011).
R. Morabito et al./Toxicology in Vitro 26 (2012) 694–699
2.8. Evaluation of mitochondrial transmembrane potential
Changes in mitochondrial transmembrane potential (DWm)
were assayed through the incorporation of a mitochondrial specific
cationic fluorescent dye, rhodamine 123 (Rh-123). Following incu-
bation at the indicated times, SH-SY5Y cells, distributed into 6-well
culture plates at a density of 250,000 cells/ml, were stained for
30 min at 37 ?C in the dark with 1 lg/ml of Rh123.
After incubation with the dye, cells were washed with PBS and
detached with non-enzymatic cell dissociation solution and
washed twice with cold PBS. The fluorescence intensity was ana-
lyzed at wavelength of 488 nm excitation and 525 nm emission
by a microplate reader (Tecan Italia, Cologno Monzese, Italy).
2.9. Statistical analysis
Data obtained from three separate experiments were expressed
as mean ± SD. Statistical analysis has been carried out by One Way
Anova Test followed by Dunnett’s or Student Newman Keuls post
hoc test for multiple comparisons, with p-values less than 0.05
3.1. Effect of crude venom on cell viability
Evaluation of the protein content of crude venom obtained by
from 800 nematocysts/ll suspension showed a protein content of
142,134 ± 0.005 lg/ml.
The exposure of RA-differentiated SH-SY5Y cells to different
crude venom concentrations (0.05, 0.1 and 0.5 lg/ml) for, alterna-
tively, 30 min, 1 h or 2 h caused a dose- and time-dependent
reduction of cell viability, as shown by photometrical measure-
ments of MTT assay (Fig. 1A). However, only 2 h exposure caused
a significant reduction of cell viability at all doses tested when
compared to the control. In particular, treatment with 0.5 lg/ml
crude venom for 2 h markedly reduced the cell viability by
29.4% ± 3.6% (p < 0.05) when compared to the control (Fig. 1 A).
3.2. Effect of N-acetyl-cysteine on cell viability
In order to investigate the crude venom-induced cytotoxic ef-
fects through oxidative stress, RA-differentiated SH-SY5Y cells
were pretreated with NAC, known to counteract oxidative stress
and to replenish antioxidant compounds. Under 100 lM NAC treat-
ment, applied 30 min before the incubation with the most effective
concentration of crude venom (0.5 lg/ml) for 2 h, cell viability was
brought up to 84 ± 5.1%, significantly different compared to ve-
nom-treated, thus showing a protective effect of NAC (Fig. 1B).
3.3. Measurement of intracellular ROS production and effect of
Reactive oxygen species produced by mitochondria play an
important role in cell death signaling. In this study, we monitored
the effect of crude venom on the increase in intracellular ROS pro-
Fig. 1. Effect of crude venom on cell viability and effect of N-acetyl-cysteine. (A) Cell viability was determined by MTT assay after treatment of RA-differentiated SH-SY5Y
cells with different concentrations of crude venom to (0.05, 0.1 and 0.5 lg/ml) for the indicated times (30 min, 1 h and 2 h). A dose- and time-dependent reduction of cell
viability was seen.⁄P < 0.05, significantly different respect to control cells. One Way Anova followed by Dunnet’s post hoc test has been performed. (B) SH-SY5Y cells
pretreated with 100 lM NAC, 30 min prior to incubation with 0.5 lg/ml crude venom for 2 h. NAC showed a protective effect against crude venom-induced damage, being cell
viability restored to values comparable to the control.⁄P < 0.05, significantly different respect to control cells.⁄⁄P < 0.05, significantly different respect to venom-treated cells.
One Way Anova followed by Student Newman Keuls post hoc test for multiple comparisons has been performed.
R. Morabito et al./Toxicology in Vitro 26 (2012) 694–699
duction through the evaluation of changes in fluorescence inten-
sity of the dye dichlorofluorescein (DCF).
Cell incubation with crude venom caused both dose- and time-
dependent redox state alterations, leading to an increase in ROS
levels. Treatment with 0.05 lg/ml crude venom did not signifi-
cantly modify ROS production during the whole experiment. By
increasing venom concentration to 0.1 lg/ml ROS production was
significantly higher, as observed after both 1 and 2 h treatment.
At the highest concentration (0.5 lg/ml) crude venom produced a
significant increase in ROS levels, at all time intervals, approxi-
mately twofold respect to untreated cells (Fig. 2A).
In parallel experiments, RA-differentiated SH-SY5Y cells, trea-
ted with 100 lM NAC 30 min prior to crude venom (0.5 lg/ml)
for 2 h, exhibited a significant reduction in intracellular ROS pro-
duction, reaching values comparable to those of control cells
3.4. Effect of N-acetyl-cysteine on mitochondrial membrane potential
Mitochondrial dysfunction characterized by a loss of transmem-
brane potential (DWm) is one of the earliest intracellular events
leading to cell damage. In this study we evaluated mitochondrial
DWm as an indicator of mitochondrial health in cells treated with
crude venom at different concentrations.
RA-differentiated SH-SY5Y cells were determined by fluorometric
assay using the fluorescent dye Rh-123 whose uptake is propor-
tional to the mitochondrial transmembrane potential. Crude
venom exposure significantly decreased Rh-123 fluorescence in a
dose- and time-dependent manner compared to the control. After
1 h exposure, the highest venom concentration (0.5 lg/ml)
reduced Rh-123 fluorescence, while 2 h exposure caused a signifi-
cant reduction of DWm at all doses when compared to the control
In order to ascertain whether ROS were involved in the alter-
ation of DWm, the effects of crude venom on DWm were evaluated
in presence or absence of NAC. As shown in Fig. 3B, NAC treatment
counteracted the effect of crude venom, but control values were
not completely restored,being DWm
(P < 0.05) respect to the untreated cells.
It is rather difficult to perform a unitary dissertation about tox-
icological features of Cnidaria, due to the variety of specimens and
to the different techniques employed to obtain the venom. These
studies mainly concern toxins from Anthozoans, that are more
suitable for maintenance in laboratory (Anderluh and Macek,
2002; García et al., 2009; Grotendorst and Hessinger, 2000). In
spite of many data about Cnidarian toxins (Anderluh and Macek,
2002; Shiomi, 2009; Suput, 2009), toxicological features of
P. noctiluca are still not completely understood, whereas physiolog-
ical responses, as discharge and cell volume regulation capability
of its nematocytes, along with those of other Cnidarians, have been
Fig. 2. Measurement of intracellular ROS production and effect of N-acetyl-cysteine. (A) Cell incubation with crude venom caused both dose- and time-dependent redox state
alterations, leading to an increase in ROS levels quantified by fluorescence plate reader. Treatment with 0.1 lg/ml crude venom increased significantly ROS production after
both 1 or 2 h of exposure. The highest concentration (0.5 lg/ml) produced a significant increase in ROS levels for each exposure time.⁄P < 0.05,⁄⁄P < 0.01, significantly
different respect to control cells. One Way Anova followed by Dunnet’s post hoc test has been performed. (B) Treatment of RA-differentiated SH-SY5Y cells with 100 lM NAC,
30 min prior to the application of 0.5 lg/ml crude venom for 2 h, produced a significant reduction in intracellular ROS production.⁄P < 0.05, significantly different respect to
control cells.§P < 0.05 significantly different respect to crude venom-treated cells. One Way Anova followed by Student Newman Keuls post hoc test for multiple comparisons
has been performed.
R. Morabito et al./Toxicology in Vitro 26 (2012) 694–699
already investigated by La Spada and co-workers (La Spada et al.,
2002a,b; Marino et al., 2006). Interest in P. noctiluca toxicology
has been increasing in the latter years and both cytotoxic and
hemolytic power of its crude venom have been assessed (Marino
et al., 2007, 2008a,b). Interestingly, such toxicological study,
including the present one, has been specifically referred to the
venom extracted from isolated nematocysts and not deriving from
other tissue components, leading to a more fine strategy to study
toxins, not including other tissue-derived compounds (Marino
et al., 2006, 2007, 2008a,b, 2009).
The present investigation has been performed to contribute to
the understanding of the mechanism of action of P. noctiluca crude
venom, trying to verify an oxidative stress-induced damage. From
our experiments it arises that crude venom of P. noctiluca nemat-
ocysts reduces cell viability in in vitro cultured neuroblastoma cells.
This damage, specifically at doses of 0.5 lg/ml, occurs through ROS
production, as shown by the significant reduction in ROS levels ob-
served when treatment with NAC as an antioxidant compound was
combined with crude venom. Furthermore, by treating cells with
0.5 lg/ml crude venom, a significant reduction of DWm values
has been also observed. In this regard, to ascertain whether mito-
chondrial pathway was involved in ROS production associated with
crude venom-induced cell damage, the effect on DWm was evalu-
ated in presence of NAC. The results showed that, as already said,
NAC was effective in counteracting ROS increase, but it was not able
to bring DWm levels back to those of untreated cells. These results
interestingly suggested that P. noctiluca crude venom alters DWm
in differentiated SH-SY5Y cells and this effect does not depend on
ROS production, so ROS would be produced as a result of mitochon-
drial membrane damage. Similar observations have been already
done by Chen et al. (2008) describing that cardiotoxin 3 (CTX3)
from the cobra Naya naya atra induces both apoptotic death on hu-
man neuroblastoma SK-N-SH cells by ROS generation and decrease
in mitochondrial transmembrane potential, with loss of mitochon-
drial integrity. Pre-treatment with NAC attenuated both cell death
and mitochondrial membrane potential alterations.
Mitochondria are vital for providing cellular energy, but are also
an important endogenous source of ROS. Mitochondrial activity is
particularly important for neurons because of the morphological
complexity of these cells, and because neural processing is
metabolically expensive. Therefore, defects in mitochondrial activ-
ity result in synaptic dysfunction leading to disturbed neurotrans-
mission. In fact, mitochondrial impairment has been described to
play a major role in the pathogenesis of several neurodegenerative
diseases of the central nervous system, such as Parkinson’s disease,
Alzheimer’s disease, and Huntington’s disease (Lauritzen et al.,
2011). Neuroblastoma mitochondria are a good tool for studying
membrane targeting, as reported by Chen et al. (2008).
As concerns lower Metazoa, there is evidence that they are able
to produce ROS, as confirmed by Bartosz et al. (2008), studying the
invertebrate territorial aggression. These authors reported that
venom from the sea anemone Actinia equina, containing heat-
denaturable hemolytic polypeptides, induces intracellular ROS
formation on cultured cells and pointing to a very interesting phar-
macological solution to the conspecific self-intoxication. According
to Butzke and Luch (2010), the high-molecular toxins from box jel-
lyfish, sea anemones and corals, evolving from enzymes needed for
digestive functions, induce ROS or lysophospholipids formation
thus damaging, from one hand, target cells as small preys, and,
on the other hand, contributing to human envenomation. Never-
theless, mechanisms different to that of ROS production, as the
pore forming mechanism, have been even suggested to explain
Fig. 3. Effect of N-acetyl-cysteine on mitochondrial membrane potential. (A) Exposure of RA-differentiated SH-SY5Y cells to crude venom decreased Rh-123 fluorescence in a
dose- and time-dependent manner. After 1 h exposure, the highest concentration (0.5 lg/ml) reduced the Rh-123 fluorescence, while after 2 h exposure a significant
reduction of DWm at all doses tested was observed compared to the control.⁄P < 0.05,⁄⁄P < 0.01, significantly different respect to control cells. One Way Anova followed by
Dunnet’s post hoc test has been performed. (B) Crude venom treatment for 2 h reduced significantly decline in fluorescence and NAC treatment, for 30 min prior to the
application of 0.5 lg/ml crude venom, counteracted the venom-induced alteration, but DWm was not restored, being significantly lower respect to the control.⁄P < 0.05,
⁄⁄P < 0.01, significantly different respect to control cells.§P < 0.05 significantly different respect to crude venom-treated cells. One Way Anova followed by Student Newman
Keuls post hoc test for multiple comparisons has been performed.
R. Morabito et al./Toxicology in Vitro 26 (2012) 694–699
the toxin/induced damage in cell targets. In this regard, it is has Download full-text
been described that EqTx-II, extracted from A. equina (Meunier
et al., 2000), as well as palytoxin (PLTX) (Pelin et al., 2011), may al-
ter membrane permeability and intracellular osmolality, thus
inducing a marked influx of water into the cell target. Accordingly,
Marino et al. (2008a) have demonstrated that the hemolytic power
of crude venom from nematocysts of P. noctiluca is inhibited by
PEG treatment (polyethyleneglycol, 6000 Da), thus suggesting a
pore-forming mechanism for this venom on erythrocytes mem-
brane, rather than an oxidative damage. In the present work, a low-
er P. noctiluca crude venom concentration than the hemolytic one
has been used to verify a possible damage on neuroblastoma cells.
The results suggest a possible pore-forming action mechanism on
mitochondrial membrane, with oxidative damage as an indirect
consequence of venom action, demonstrated by ROS production
and by the DWm decline in these cells. Nevertheless, an oxidative
P. noctiluca crude venom cannot be completely
excluded, since Marino et al. (2009) demonstrated that 115 lg
P. noctiluca venom induced a significant edema in the rat paw
assay, with high TBA (Thio Barbituric Acid) levels, an index of lipo-
peroxidation, ameliorated by melatonin treatment, known as an
antioxidant and anti-inflammatory substance.
In conclusion such results may suggest that the alteration of
mitochondrial membrane by P. noctiluca crude venom induces oxi-
dative stress by inhibiting mitochondrial respiration and reducing
oxidative phosphorylation, thus sensitizing mitochondria in SH-
SY5H cells and facilitating membrane permeability. These findings
point out that P. noctiluca crude venom directly induces DWm col-
lapse with further generation of ROS and add novel information to
the understanding of such toxins, still not completely clarified.
Conflict of interest
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