الفهرس 
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Abstract
Cancer chemotherapy is known to be associated with many complications. Among the anticancer agents, the most potent groups is DOX which is an anthracycline derivative widely used to treat various cancers, including acute leukemias, malignant lymphomas, and a variety of solid tumors. DOX may cause cardiotoxicity which is characterized by ventricular wall thinning and dilation of the Left Ventricular chamber.
DOX initially increases the generation of other ROS (e.g., H2O2) in cardiomyocytes and by redox cycling. Increased DOX-induced ROS generation in cardiomyocytes associated with an impaired antioxidant defense, in turn induces cell damage via lipid peroxidation, mitochondrial dysfunction, inactivation of anti-oxident enzymes and other proteins, which lead to apoptosis of cardiac myocytes, and DOX-induced cardiotoxicity mediating caspase-dependent and -independent cell death pathways, which are also pivotal in DOX-induced cardiotoxicity. However, no single active ingredient has been clinically proved effective and safe for preventing this severe side effect. Therefore, the discovery of natural extracts with cardioprotective effects is important to continue the clinical use of DOX.
Brown algae and consequently their extracts can be the treasure trove of biologically active compounds. Their beneficial properties for humans, animals and plants were recognized in the past and are appreciated nowadays, in the development of new biotechnological products. Brown algae are very rich in several chemical compounds such as alginate, polyunsaturated fatty acids, sterols, proteins and enzymes, vitamins and pigments and, therefore, they may be used in several biological applications related with health benefits.
Alginate was broadly recognized in seaweeds confirming their potent role in preventing radical formation and improving the internal antioxidant system under stress environmental conditions. These activities protect the body from progressive diseases caused by the adverse effects of ROS. Antioxidant measurements confirmed antioxidant activity of alginate increased upon a decrease in molecular weight. Therefore, low molecular weight alginate produced by heating could be considered as a stronger antioxidant than alginate polymer. These products could be useful for industrial and biomedical applications
Alginate treatment could protect against acute DOX cardiotoxicity, and the underlying mechanisms focused on oxidative stress and ER-mediated apoptosis. It was found that alginate pretreatment markedly increased the survival rate of mice insulted with DOX, improved DOX-induced cardiac dysfunction and attenuated DOX-induced myocardial apoptosis.
The present study was designed to investigate the protective efficacy of alginate to improve cardiotoxicity and biochemical abnormalities induced by DOX in the Swiss albino male rats. Study was applied on 7 groups of rats (n=10) for a week as follows:
(I) Control group; rats were fed normally.
(II) DOX group; normal animals were intoxicated with i.p. DOX with dose 15 mg/kg and received no treatment serving as positive controls.
(III) Thermally treated alginate (400 mg/kg b.w); normal animals were received only oral protective TTSA (400 mg/kg b.w).
(IV) Thermally treated alginate (200 mg/kg b.w) + DOX; animals were intoxicated with i.p. DOX administration of (15 mg/kg b.w) after the oral protective dose of TTSA (200 mg/kg b.w).
(V) Thermally treated alginate (400 mg/kg b.w) + DOX; animals were intoxicated with i.p. DOX administration of (15 mg/kg b.w) after the oral protective dose of TTSA (400 mg/kg b.w).
(VI) Alginate (400 mg/kg b.w) + DOX; animals were intoxicated with i.p. DOX with dose (15 mg/kg b.w) after the oral administration of raw non-TTSA (400 mg/kg b.w).
Gene expression: Total mRNA will be extracted from the heart of all the studied groups followed by cDNA synthesis. The resultant cDNA will be used for qRT-PCR for assessment of the expression levels of the following genes in all studied groups for comparing their mRNA in DOX group and in treated groups by thermally treated alginate and alginate extract:
a. Inducible nitric oxide synthase. b. Mitogen activated protein kinase-1.
Apoptotic markers: the current study had selected apoptotic markers such as protein expression of heart p53 and MAPK-1 that will be assayed by western blot technique and Caspase-3 activity will be assayed by Eliza.
Antioxidant contents of heart:
a. Determination of superoxide dismutase. b. Determination of CAT activities.
Heart function tests: Determination of serum level of CK-MB and AST activity.
Histopathological studies: heart specimens in the different groups will be fixed in 10% formalin solution for at least 3 days at 4 ˚C to be stained by hematoxylin and eosin stains.
Our results showed down regulation of MAPK-1 in gene expression and protein level in DOX group. However, MAPK-1 and iNOS could significantly increase in treated groups with thermally treated alginate and alginate extract group in comparison by DOX group. MAPK includes three major signaling cascades: the extracellular signal-related kinases (ERK1/2), the c-Jun N-terminal Kinases (JNK), and the p38 kinase (p38). Alginate induces the activation of MAPK-1 in cardiac pathophysiology which indicated that MAPK-1 has an important role as cardioprotective effect.
Results were observed that activation of p53-initiated intrinsic pathway has been implicated in DOX- induced cardiotoxicity and subsequent chronic cardiomyopathy. Therefore p53 increased significantly in DOX group and significant decrease in treated groups with thermally treated alginate and alginate extract. Caspase-3 was activated by DOX and this induces apoptosis pathways and cardiotoxicity while there is a significant decrease of caspase-3 in treated groups with thermally treated alginate and alginate extract.
Our study showed high significant increase in SOD and CAT in treated groups with thermally treated alginate and alginate extract group in comparison by DOX group. Antioxidants reportedly exert protective effects on DOX-treated cardiomyocytes. However, no single active ingredient has been clinically proved effective and safe for preventing this severe side effect. Therefore, the discovery of alginate extract with cardioprotective effects is important to continue the clinical use of DOX.
Heart function tests shown significant decrease in treated groups with thermally treated alginate and alginate extract group in comparison by DOX group which indicate that the powerful anti-oxidant effect of thermally treated alginate and alginate extract. Although DOX group showed a marked increase in CK-MB and AST. This is due to the proposed principal mechanisms of DOX cardiotoxicity which have reported that DOX induces oxidative stress, lipid peroxidation and overproduction of ROS cascade such as hydroxyl radicals, oxygen and hydrogen peroxide, DNA/RNA damage, inhibition of autophagic flux and ER mediated apoptosis which have all been linked to DOX-induced cardiotoxicity. Histopathological studies showed the significant cardioprotective effect of alginate groups versus DOX group.
from our study results it can be concluded that the thermal treatment of sodium alginate derived from seaweed Sargassum aquifolium enhanced the antixidant properties of this biopolymer. Furthermore, the pharmaceutical efficacy of this biopolymer, as a potential cardioprotective supplement, was also improved in terms of increasing the expression of cardioprotective mediators, down-regulating the pro-apoptotic markers, and normalizing the cellular redox potential. The thermally treated sodium alginate, in particular the 400 mg/kg b.w. concentration, suggested being prophylactic therapy in the treatment DOX-linked cardiotoxicity and apoptotic patterns.
It is recommended that alginate can be used as prophylactic therapy during treatment with DOX therapy. TTSA can be used rather than the raw one to decrease the side effects of various oxidant inducing drugs. It could be recommended with nanoparticles therapy as a non-toxic and potent antioxidant delivery system.