Protective Effects of Aqueous O. gratissimum Extract on
Peroxide-induced Cell Death of H9c2 Myocardiac Cells
Mu-Jang Lee,1Han-Min Chen,2Bor-show Tzang,3Chu-Wen Lin,3Chau-Jong Wang,3Jer-Yuh Liu,4#and Shao-Hsuan Kao3,5*
1
Department of Internal Medicine, Division of Cardiology, Tian-Sheng Memorial Hospital, Pingtung 92843
2
Department of Life Science, Fu-Jen Catholic University, Taipei 24205
3
Institute of Biochemistry and Biotechnology, Chung Shan Medical University, Taichung 40201
4
Graduate Institute of Cancer Biology, China Medical University, Taichung 40402
5
Clinical Laboratory, Chung Shan Medical University Hospital, Taichung 40201, Taiwan, Republic of China.
#Jer-Yuh Liu and Shao-Hsuan Kao contributed equally in this work.
Running head: Protection of cardiomyocyte by OGE
*Corresponding auther: Shao-Hsuan Kao, PhD, Institutes of Biochemistry and Biotechnology, Chung Shan Medical University, No. 110, Sec. 1, Jianguo N. Road, Taichung 40201, Taiwan.
Tel: +886-4-24730022 ext. 11681; Fax: +886-4-23248195 Email: kaosh@csmu.edu.tw
Abstract
Increased cell death of cardiomyocyte by oxidative stress is known to cause
dysfunction of heart. Previous studies have demonstrated that extracts of Ocimum
species are able to protect different cells from oxidative stress-induced damage and
the following cell death. Among the Ocimum species, O. gratissimum is a well-known
medicinal plant and widely used in treatment of inflammatory diseases. Therefore, we
hypothesized that aqueous extract of O. gratissimum leaf (OGE) may have protective
effects on cardiomyocyte. Our findings revealed that hydrogen peroxide (H2O2)
treatment significantly decreased cell viability of H9c2 myocardiac cell, and the
viability was dose-dependently restored by OGE. Condensed staining of nucleus by
DAPI implied that H2O2 treatment led to apoptosis and the apoptosis was attenuated
by OGE. Further investigation showed that OGE inhibited H2O2–induced activation
of caspas-3 and caspase-9, but little affected the activation of caspase-8. The
H2O2–induced Apaf-1 and cytochrome c, upstream of caspase-9 in mitochondrial
pathway, were also decreased by OGE. Additionally, Bcl-2 was significantly induced
by OGE. Analysis of mitogen-activated protein kinase (MAPK) signaling revealed
that OGE mainly induced the activation of AKT and little affected the activation of
effectively inhibited the mitochondrial pathway and increased the Bcl-2 expression
level, which may play important roles in protecting H9c2 cell from H2O2-induced cell
death.
Key words: Ocimum gratissimum, Apoptosis, Bcl-2, Mitochondrial pathway, Akt,
ERK
Introduction
Cardiac cell apoptosis plays an important role in heart development and
pathogenesis of heart dysfunctions related with ischemia-reperfusion, pressure
overload, and chronic heart failure (14). Loss of contractile tissue, compensatory
hypertrophy, and reparative fibrosis caused by cardiac apoptosis is also being reported
to contribute to the development of cardiovascular diseases (24). Therefore, signaling
pathways leading to modification of cardiomyocyte apoptosis have become a major
area of both clinical interest and basic research.
Oxidative stress has been known as an imbalance of oxidant/antioxidant which
could result in cell damage. It is believed that oxidative stress plays a crucial role in
Reactive oxygen species (ROS), including superoxide anion (O2-), hydroxyl ion (OH-)
and hydrogen peroxide (H2O2), has been demonstrated as an important oxidative
stress (15). Increase of intracellular ROS leads to irreversible damage of various
cellular components, such as lipids, proteins and DNA, and accumulation of the
cellular damages is able to further result in cell apoptosis, a programmed cell death
being characterized by cell shrinkage, chromatin condensation, internucleosomal
DNA fragmentation and formation of apoptotic bodies (18,22).
The genus Ocimum, belonging to the family Labiatae, is widely found in tropical
and subtropical regions. The widespread plant is commonly used as not only a fresh
and dried food spice, but also a traditional herb in European and Asian countries for
the treatment of various ailments since ancient times. The ethanolic extract of
Ocimum leaf has shown significant modulatory influence on carcinogen metabolizing
enzymes including cytochrome P450, cytochrome b5 and aryl hydrocarbon
hydroxylase, glutathione-s-transferase. Additionally, the aqueous extract of Ocimum
sanctum is reported to have a more profound effect than both the fresh paste and the
ethanolic extract on reducing the chemical-induced papillomagenesis (17,25).
However, the functions and mechanisms for therapeutic or protective effects of
In this study, we aimed to examine the protective effects of aqueous extract of OG
leaf (OGE) on H9c2 myocardiac cells against H2O2-induced cell death, and to
investigate the mechanisms induced by OGE. Cell viability was determined by MTT
assay. Nucleus was monitored by DAPI staining. Activation of caspase and
mitogen-activated protein kinase (MAPK) signaling was determined by immunoblots
probed with specific antibodies.
Materials and Methods
ChemicalsH2O2, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT),
4,6-diamidino-2-phenylindole dihydrochloride (DAPI), penicillin and
streptomycin were purchased from Sigma (St. Louis, MO, USA). Dulbecco’s
modified Eagle’s medium (DMEM), fetal bovine serum and trypsin-EDTA were
purchase from Gibco BRL (Gaithersburg, MD, USA). Antibodies against
caspase-3, caspase-9, apaf-1, cytochrome c, Bcl-2, ERK1/2, JNK, p38 and AKT
were purchased from Cell Signaling Technologies (Beverly, MA, USA).
Antibodies against -actin, mouse IgG and rabbit IgG were purchased from
American Type Culture Collection (ATCC; Rockville, MD).
Preparation of OGE
Leaves of Ocimum gratissimum Linn were harvested, washed with distilled
water and then homogenized with distilled water by using polytron. The
homogenate was incubated at 95oC for 1 hour (h) and then filtered through two
layers of gauze. The filtrate was centrifuged to remove insoluble pellets (20,000 g
for 15 min at 4ºC) and the supernatant (OGE) was collected, lyophilized and
stored at -70oC until use.
Cell culture and experimental treatments
H9c2 cells were maintained in DMEM supplemented with 10% FBS and
100 g/ml penicillin/streptomycin at 37oC in a humidified atmosphere containing
10% CO2. In all conditions, H9c2 cells were seeded in 6-well culture plates at an
initial density of 1x105 cells/ml and grown to approximately 80% confluence.
Oxidative stress was induced by treating with freshly prepared H2O2. Cells were
pretreated with OGE at indicated concentration for 3 hrs, and then the medium
containing H2O2was added (final concentration at 200M) and incubated for 24
h. After the incubation, the cells were washed with phosphate-buffered saline
the subsequent analysis.
DAPI staining
H9c2 cells (5 x104 cells/ml) were pretreated with 0, 50 and 100g/ml OGE
for 3 hrs and then incubated with 200M H2O2for 24 h. After the treatment, the
cells were stained with DAPI and photographed using a fluorescence microscope
as previously described (7,13).
MTT assay for cell viability
Cell viability was determined by MTT assay (11) in the absence or presence
of 50 or 100g/ml OGE. After the 24 h treatments, medium was removed and the
H9c2 cells were incubated with MTT (0.5 mg/ml) at 37oC for 4 h. The viable cell
number was directly proportional to the production of formazan, which was
dissolved in isopropanol and determined by measuring the absorbance at 570 nm
using a microplate reader (SpectraMAX 360 pc, Molecular Devices, Sunnyvale,
CA).
Immunoblotting
The treated H9c2 cells were washed with PBS and lysed in a lysis buffer (50
mM Tris-HCl, pH 7.5, 150 mM NaCl, 1% Nonidet P-40, 1 mM phenylmethylsulfonyl
were incubated on ice for 30 min and centrifuged at 20,000g for 15 min. The
supernatants were collected and followed by protein quantitation using Bradford
method. Crude proteins (30 g per lane) were electrophoresed on 12.5%
SDS-polyacrylamide gel, and transferred onto a nitrocellulose membrane (Millipore,
Bedford ,MA) as previously described.(19) The blotted membrane was blocked with
5% w/v skimmed milk in PBS, and then incubated for 2 h with 1/1000 dilution of the
specific antibodies against human caspase-3, caspase-9, apaf-1, cytochrome c, Bcl-2,
ERK1/2, JNK, p38, PI3K/Akt and -actin. Bound antibodies were detected using
1/2000 dilution of peroxidase-conjugated secondary antibodies and ECL
chemiluminescence reagent (Millipore) as the substrate system (8).
Statistical analysis
Statistical analysis was performed using the SigmaStat version 3.5 for Windows
(Systat Software Inc. San Jose, CA). The results are presented as mean ± SD. The statisticalsignificancebetween groupswasdetermined using Student’sttest.A p
Results
OGE alleviates H9c2 cells H2O2-induced cell deathPrior to investigate the protective effects OGE on peroxide-induced cell death,
the cytotoxicity of OGE alone was examined. H9c2 cells were treated with a series
concentration of OGE (10-300 g/ml) for 24 h, and the following MTT assay for cell
viability was performed. As shown in Fig. 1A, although the cell viability was slightly
increased by 10 and diminished by 50, 100, 200, and 300 g/ml OGE, the changes
were not statistically significant as comparing to control. Therefore, the protective
effects of OGE on H2O2-induced cell death were then examined. The cell viability of
H9c2 cells treated with 200M H2O2containing 0, 50, 100 and 150g/ml OGE was
determined. As shown in Fig. 1B, the findings showed that H2O2 effectively
diminished the cell viability to 19.5 ± 0.7 % of control, and H2O2combining OGE (50,
100 and 150 ) co-treatment reduced the cell viability to 41.3 ± 2.6, 39.7 ± 8.1, 68.6 ±
0.8 and 88.4 ± 3.1 % of control respectively. Together, OGE alone treatment showed
no significant cytotoxicity to H9c2 myocardiac cells and the OGE co-treatment
dose-dependently recovered the cell viability diminished by H2O2.
OGE attenuates the DNA fragmentation of H9c2 cells induced by H2O2
fragmentation was monitored by DAPI staining. As shown in Fig. 2, H9c2 cells
treated with H2O2 revealed the condensed DAPI staining which probably resulting
from H2O2-induced DNA fragmentation. Pretreated with 50 and 100 g/ml OGE
significantly attenuated the ratio of condensed DAPI-stained cells as comparing to the
treated with H2O2alone, and the attenuation of condensed DAPI-stained cells by OGE
pretreatment was dose-dependent. Therefore, these findings indicated that apoptosis
may involve in the H2O2-induced cell death and OGE pretreatment may attenuate the
apoptosis of H9c2 cells induced by H2O2.
OGE inhibits the mitochondrial pathway induced by H2O2
To further investigate the apoptotic pathways induced by H2O2and the effects of
OGE on these pathways, activation of intrinsic (mitochondrial) pathway and extrinsic
pathway was examined. As shown in Fig. 3, H2O2 treatment reduced the level of
caspase-3 (precursor form, 32 kDa) and increased the level of cleaved caspase-3
(active form, 17 kDa). OGE pretreatment restored the level of caspase-3 and
decreased the level of cleaved caspase-3 induced by H2O2. The activation of the
upstream effectors of caspase-3, caspase-9 and caspase-8, was also determined.
Interestingly, the levels of cleaved form/active form of caspase-9 and caspase-8 were
form of caspase-9 was decreased by OGE pretreatment (Fig. 3). Therefore, the levels
of the upstream effectors of caspase-9, including Bcl-2, Apaf-1 and cytpchrome c,
were further determined. As shown in Fig. 4, H2O2treatment alone decreased the level
of anti-apoptotic Bcl-2 and increased the levels of Apaf-1 and cytochrome c, the
activators for caspase-3. OGE pretreatment significantly increased the level of
anti-apoptotic Bcl-2 and diminished the levels of Apaf-1 and cytochrome c. Taken
together, these findings suggested that OGE attenuated the H2O2-induced apoptosis of
H9c2 cells through inhibiting mitochondrial pathway.
OGE induces the activation of Akt but not affects the other MAPKs
To investigate the anti-apoptotic mechanisms induced by OGE, kinase-mediated
survival signaling and apoptotic signaling was investigated. As shown in Fig. 5,
phosphorylation of Akt (pAkt) and ERK 1/2 (p-ERK 1/2) was increased by H2O2
treatment alone as comparing to control. OGE pretreatment significantly increased the
phosphorylation of Akt as comparing to both H2O2 treatment alone and control.
Interestingly, OGE pretreatment slightly decreased the phosphorylation of ERK 1/2 as
comparing to H2O2 treatment alone. Additionally, the phosphorylation of p38 MAPK
(p-p38) and JNK (p-JNK) was not affected by neither H2O2 treatment alone nor OGE
expression of anti-apoptotic Bcl-2 through activating Akt-mediated signaling and may
suppress the mitochondrial pathway through inhibiting ERK-mediated apoptosis.
Discussion
Direct treatment of cells with oxidants such as H2O2 was thought to cause
necrosis, but recent studies have shown that ROS can induce cellular senescence and
apoptosis under certain circumstances (22,28). In this study, it is found that the H2O2
treatment significantly diminishes the viability of H9c2 cells to 18.7 ± 0.6% and leads
to DNA fragmentation, the characteristics of apoptosis, but the 150 g/ml OGE
pretreatment only recovered the cell viability to 67.8 ± 2.6%. It is suggested that the
H2O2 treatment causes both apoptosis and necrosis of H9c2 cells, but OGE
pretreatment may attenuate the apoptosis and may have little effect on the necrosis.
Mitochondria are important targets of ROS and the interaction leads to
dysfunction of mitochondria and the subsequent cell apoptosis. In situ generated ROS
can open the permeability transition (PT) pore with subsequent mitochondrial
membrane potential and can cause cytochrome c release into the cytosol, which is
required for the formation of the apoptosome and the resultant activation of
which leads to apoptosis. On the contrary, Bcl-2 inhibits apoptosis, PT pore opening
and cytochrome c release (Schlottmann and Schölmerich, 1999), which leads to
anti-apoptosis. Our findings reveal that OGE pretreatment effectively inhibits the
mitochondrial pathway and increases Bcl-2 level, suggesting that OGE pretreatment
should be beneficial to ROS-induced apoptosis,
Polyphenols have been demonstrated to be the important and the major
components in plant extracts for their therapeutic effects. Although the cellular
mechanisms underlying the actions of flavonoids and their metabolites remain unclear,
it is believed that antioxidant activity, free radical scavenging, and MAPK signaling
pathways should be involved (2,9,26). MAPK family, comprising ERKs, JNK and
p38, is activated in response to various stress stimuli. Recently, ERKs, associating
with a variety of biological responses such as proliferation, migration and
differentiation, have also been reported to mediate apoptosis in cultured cells
(3,12,29).
It has been demonstrated that inhibition of ERK1/2 blocks caspase-3 activation
showing both cytochrome c release dependent and independent (23,29). Therefore,
ERK1/2 may act on mitochondria to cause cytochrome c release and/or may affect
also induce apoptosis through regulating the level of caspase-8, an initial caspase in
extrinsic apoptotic pathway (5). Our findings reveal that OGE pretreatment
diminishes the phosphorylation of ERK1/2 induced by H2O2 and the level of
caspase-8 is not affected by OGE pretreatment, suggesting that OGE may
predominantly inhibit ERK1/2 activation and the subsequent mitochondrial pathway.
The phosphatidylinositol 3-kinase (PI3K)/Akt pathway plays an important role
in the regulation of cell survival, and most growth and survival factors activate the
pathway (1). Moreover, activated PI3K/Akt promotes survival via the direct
regulation of anti-apoptotic Bcl-2 and apoptotic proteins including BAD, BCL-XLand
caspase-9 (6,10,16). It is also reported that withdrawal of soluble growth factors from
primary cultured cells leads to activation of ERK1/2, which is accompanied by a great
decrease in Akt activity (27). In this study, both the H2O2 treatment and the OGE
pretreatment are performed without serum deprivation, and the findings indicate that
OGE pretreatment significantly induces the activation of Akt and increases the level
of Bcl-2, suggesting that OGE may also protect H9c2 cells from H2O2 damage
through enhancing survival signal pathway.
In conclusion, the present study provides evidences that OGE attenuated the
inhibition of apoptotic ERK1/2 activity and mitochondrial signaling as well as from
the enhancement of PI3K/Akt survival signaling and the increase of anti-apoptotic
Bcl-2. These findings indicate that OGE should be beneficial to protect
cardiomyocyte from oxidative stress induced by H2O2.
Acknowledgements
This study was partly supported by the grant NSC97-2314-B-040-008-MY2 from the
National Science Council, Taiwan and by the Intercollege Research Grant from
Chung Shan Medical University, Taichung and Tian-Sheng Memorial Hospital,
References
1. Amaravadi, R. and Thompson, C.B. The survival kinases Akt and Pim as
potential pharmacological targets. J Clin Invest 115:2618-2624, 2005.
2. Angeloni, C., Spencer, J.P., Leoncini, E., Biagi, P.L. and Hrelia, S. Role of
quercetin and its in vivo metabolites in protecting H9c2 cells against oxidative
stress. Biochimie 89: 73-82, 2007.
3. Bhat, N.R. and Zhang, P. Hydrogen peroxide activation of multiple
mitogen-activated protein kinases in an oligodendrocyte cell line: role of
extracellular signal-regulated kinase in hydrogen peroxide-induced cell death.
J Neurochem 72: 112-119, 1999.
4. Bishopric, N.H., Andreka, P., Slepak, T. and Webster, K.A. Molecular
mechanisms of apoptosis in the cardiac myocyte. Curr Opin Pharmacol 1:
141-150, 2001.
5. Cagnol, S., Van Obberghen-Schilling, E. and Chambard, J.C. Prolonged
activation of ERK1,2 induces FADD-independent caspase 8 activation and cell
death. Apoptosis 11: 337-346, 2006.
6. Cardone, M.H., Roy, N., Stennicke, H.R., Salvesen, G.S., Franke, T.F.,
caspase-9 by phosphorylation. Science 282: 1318-1321, 1998.
7. Chen, Y.C., Lu P.H., Pan, S.L., Teng, C.M., Kuo, S.C., Lin, T.P., Ho, Y.F.,
Huang, Y.C. and Guh, J.H. Quinolone analogue inhibits tubulin
polymerization and induces apoptosis via Cdk1-involved signaling pathways.
Biochem Pharmacol 74: 10-19, 2007.
8. Chow, L.P., Su, N.Y., Yu, C.J., Chiang, B.L. and Shen, H.D. Identification and
expression of Pen c 2, a novel allergen from Penicillium citrinum. Biochem J
341: 51-59, 1999.
9. Cui, J., Tosaki, A., Cordis, G.A., Bertelli, A.A., Bertelli, A., Maulik, N. and
Das, D.K. Cardioprotective abilities of white wine. Ann N Y Acad Sci 957:
308-316, 2002.
10. Datta, S.R., Dudek, H., Tao, X., Masters, S., Fu H., Gotoh, Y. and Greenberg,
M.E. Akt phosphorylation of BAD couples survival signals to the cell-intrinsic
death machinery. Cell 91: 231-241, 1997.
11. Denizot, F. and Lang, R. Rapid colorimetric assay for cell growth and survival.
Modifications to the tetrazolium dye procedure giving improved sensitivity
and reliability. J Immunol Methods 89: 271-277, 1986.
EGFR-independent activation of p38 MAPK and EGFR-dependent activation
of ERK1/2 are required for ROS-induced renal cell death. Am J Physiol Renal
Physiol 287: F1049-1058, 2004.
13. Ferlin, M.G., Chiarelotto, G., Gasparotto, V., Dalla Via, L., Pezzi, V., Barzon L.,
Palu, G. and Castagliuolo, I. Synthesis and in vitro and in vivo antitumor
activity of 2-phenylpyrroloquinolin-4-ones. J Med Chem 48: 3417-3427, 2005.
14. Gill C., Mestril R. and Samali A. Losing heart: the role of apoptosis in heart
disease-a novel therapeutic target? FASEB J 16:135-146, 2002.
15. Haddad, J.J. Antioxidant and prooxidant mechanisms in the regulation of
redox(y)-sensitive transcription factors. Cell Signal 14: 879-897, 2002.
16. Jones, R.G., Parsons, M., Bonnard, M., Chan, V.S., Yeh, W.C., Woodgett, J.R.
and Ohashi, P.S. Protein kinase B regulates T lymphocyte survival, nuclear
factor kappaB activation, and Bcl-X(L) levels in vivo. J Exp Med 191:
1721-1734, 2000.
17. Karthikeyan, K., Ravichandran, P. and Govindasamy, S. Chemopreventive
effect of Ocimum sanctum on DMBA-induced hamster buccal pouch
carcinogenesis. Oral Oncol 35: 112-119, 1999.
Med 142: 288-297, 2003.
19. Laemmli, U.K. Cleavage of structural proteins during the assembly of the head
of bacteriophage T4. Nature 227: 680-685, 1970.
20. Lee, Y. and Gustafsson A.B. Role of apoptosis in cardiovascular disease.
Apoptosis 14:536-548, 2009.
21. Li, P., Nijhawan, D., Budihardjo, I., Srinivasula, S.M., Ahmad, M., Alnemri
E.S. and Wang, X. Cytochrome c and dATP-dependent formation of
Apaf-1/caspase-9 complex initiates an apoptotic protease cascade. Cell 91:
479-489, 1997.
22. Marczin, N., El-Habashi, N., Hoare, G.S., Bundy, R.E. and Yacoub, M.
Antioxidants in myocardial ischemia-reperfusion injury: therapeutic potential
and basic mechanisms. Arch Biochem Biophys 420: 222-236, 2003.
23. Nowak, G. Protein kinase C-alpha and ERK1/2 mediate mitochondrial
dysfunction, decreases in active Na+ transport, and cisplatin-induced
apoptosis in renal cells. J Biol Chem 277: 43377-43388, 2002.
24. Prakash J. and Gupta S.K. Chemopreventive activity of Ocimum sanctum seed
oil. J Ethnopharmacol 72: 29-34, 2000.
an extract from Ocimum sanctum on mouse skin papillomagenesis and its
enhancement of skin glutathione S-transferase activity and acid soluble
sulfydryl level. Anticancer Drugs 5: 567-572, 1994.
26. Rajadurai, M. and Stanely, Mainzen, Prince, P. Preventive effect of naringin on
lipid peroxides and antioxidants in isoproterenol-induced cardiotoxicity in
Wistar rats: biochemical and histopathological evidences. Toxicology 228:
259-268, 2006.
27. Sinha, D., Bannergee, S., Schwartz, J.H., Lieberthal, W. and Levine, J.S.
Inhibition of ligand-independent ERK1/2 activity in kidney proximal tubular
cells deprived of soluble survival factors up-regulates Akt and prevents
apoptosis. J Biol Chem 279: 10962-10972, 2004.
28. Valko, M., Leibfritz, D., Moncol, J., Cronin, M.T., Mazur, M. and Telser, J.
Free radicals and antioxidants in normal physiological functions and human
disease. Int J Biochem Cell Biol 39: 44-84, 2007.
29. Wang, X., Martindale, J.L. and Holbrook, N.J. Requirement for ERK
activation in cisplatin-induced apoptosis. J Biol Chem 275(50): 39435-39443,
Figure legends
Fig. 1. Effects of OGE on cell viability of H9c2 treated with H2O2. (A) The cell
viability of H9c2 cells treated with a series concentration of OGE (10, 50, 100, 200
and 300g/ml) for 24 h. (B) The cell viability of H9c2 cells pretreated with a series
concentration of OGE (50, 100, and 150g/ml) for 3 h and then treated with 200 M
H2O2. Three independent experiments were performed for statistic analysis. NS, not
significant; ##, p <0.01 as comparing to control (C); *, p <0.05 and **, p <0.01 as
comparing to 0g/ml of OGE.
Fig. 2. Effects of OGE on H2O2-induced DNA fragmentation. H9c2 cells were
pretreated with 0, 50 and 100g/ml OGE for 3 h and then treated with H2O2for 24 h.
After the treatments, the H9c2 cells were stained with DAPI and photographed by
fluorescence microscopy (200X). The cells presented DNA fragmentation were
indicated by arrow.
Fig. 3. Effects of OGE on mitochondrial and extrinsic pathway. The protein levels of
caspase-3, cleaved caspase-3, caspase-9, cleaved caspase-9, caspase-8, and cleaved
caspase-8 were determined by immunoblotting. -actin was used as control. The
Fig. 4. Effects of OGE on protein expression of Bcl-2, Apaf-1 and cytochrome c. The
protein expression of Bcl-2, Apaf-1 and cytochrome c was determined by
immunoblotting. -actin was used as control. The apparent molecular weights for
detected proteins were indicated.
Fig. 5. Effects of OGE on kinase-mediated pathways. The levels of
phosphorylated-Akt (p-Akt), Akt, phosphorylated-ERK (p-ERK), ERK,
phosphorylated-p38 (p-p38) and phosphorylated-JNK (p-JNK) were determined by
