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Research article
Freeze-Dried Powder of Rubus coreanus Miquel Ameliorates Isoproterenol-Induced Oxidative Stress and Tissue Damage in Rats
Department of Food Science and Biotechnology, Chung-Ang University, Anseong 17546, Republic of Korea
Correspondence to:J. Microbiol. Biotechnol. 2021; 31(9): 1256-1261
Published September 28, 2021 https://doi.org/10.4014/jmb.2106.06047
Copyright © The Korean Society for Microbiology and Biotechnology.
Abstract
Keywords
Graphical Abstract

Introduction
To determine the antioxidative effect of the whole fructus of
In this study, we evaluated the effect of RCP on prevention of heart and liver damage induced by IPN treatment in SD rats, and confirmed the regulatory activities on the anti-oxidative system and/or lipid metabolism.
Materials and Methods
RCP and Diet Preparation
Animal Experiment
Adult male Sprague-Dawley (SD) rats (150–200 g) were purchased from DooYeol Biotech, and randomly divided into five groups; Con (
Induction of Oxidative Stress and Tissue Damage
Isoproterenol (IPN) purchased from Sigma-Aldrich (USA) was prepared by dissolving in phosphate-buffered saline (PBS). Two days before sacrifice, the rats were subcutaneously injected twice with IPN (65 mg/kg BW) at an interval of 24 h for the induction of oxidative stress and myocardial infarction. All animals were then sacrificed and blood samples were taken for serum analysis and the hearts and livers were collected for histological analysis. Each organ was weighed and stored in 10% formalin (Sigma-Aldrich).
Hematoxylin & Eosin (H&E) Staining
The heart and liver tissues in 10% formalin were embedded in paraffin block after the dehydration process and cut into 5-μm-thick tissue sections using a microtome (Leica, Leica Biosystems, Germany). The tissue sections were rehydrated and stained with hematoxylin for nuclear staining and eosin for the cytoplasm for counter staining. The tissues were then examined under a light microscope (Olympus, Japan) for histological changes and pictures were taken.
Serum Analysis
After blood collection, serum was taken by centrifugation at 2,000 ×
Enzyme-Linked Immunosorbent Assay (ELISA)
To evaluate the oxidative stress markers in serum, ELISA was performed. Following the manufacturer’s guidance, the serum was incubated in wells pre-coated with antibody and treated with primary and horseradish peroxidase (HRP)-conjugated secondary antibody. Then, substrate solution was added and the developed color was measured at 450 nm (Molecular Devices, USA). ELISA micro-plate assay kits for detecting GSH (Abbexa Ltd., UK) and MDA (MyBioSource, USA) were used.
Statistical Analysis
The statistical differences were analyzed by IBM SPSS Statistics v.20 software (USA), and mean differences were analyzed using one-way analysis of variance (ANOVA) with Duncan’s post hoc test. Significant difference was at
Results and Discussion
RCP Reduced the Heart Weight Increased by IPN Injection without Affecting the Body Weight in SD Rats
Subcutaneous injection of IPN in rats was reported to increase heart rate and increase the heart weight, where IPN produced greater hypotension, followed by induction of reflex compensatory responses such as cardiac failure [16]. An increase in heart weight is attributed to increase of water content, edematous intramuscular space, and protein content in the heart tissue [17], where 1% increase of myocardial water content resulted in a possible 10% reduction in myocardial function [18]. Also observed were extensive edematous intramuscular space, accumulation of mucopolysaccharides, and cellular infiltration after the induction of myocardial infarction [19].
Here, we confirmed that IPN significantly increased the heart weight as well as the relative heart weight (Table 1). However, the body weight and liver weight were not affected by IPN injection and RCP administration (Fig. 1B and Table 1). The food intakes between groups were not significantly different (Fig. 1B), as indicated by the average consumption of RCP at 70 ± 3, 220 ± 14, and 69 ± 31 mg/day in RCP-L (0.3%), RCP-M (1.0%), and RCP-H (3.0%) groups, respectively. As shown in Table 1, RCP administration significantly suppressed the heart enlargement in a dose-dependent manner from 1.56 ± 0.15 g in IPN group to 1.40 ± 0.06 g in RCPH group, as well as the relative heart weight from 0.43 ± 0.06 g/100 g BW to 0.38 ± 0.02 g/100 g BW, respectively. These results suggest that RCP activates a defense system in vivo, leading to counteract the heart damage by IPN.
-
Table 1 . The effect of RCP on body and organ weights of rats in IPN-induced myocardial injury model.
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H Body weight (g) 385.06±3.55 369.55±26.88 366.44±42.11 366.67±23.49 373.98±29.53 Heart weight (g) 1.16±0.06c 1.56±0.15a 1.44±0.12ab 1.43±0.08ab 1.40±0.06b Liver weight (g) 12.86±0.36 12.76±1.28 13.86±1.60 13.07±1.80 13.97±1.40 Relative heart weight (g/100 g) 0.30±0.01c 0.43±0.06a 0.40±0.03ab 0.39±0.02ab 0.38±0.02b Relative Liver weight (g/100 g) 3.34±0.10 3.48±0.49 3.85±0.74 3.56±0.41 3.73±0.18 The results are expressed as mean ± SD in each group.
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p < 0.05.
-
Fig. 1. Scheme of animal experiment and the changes of body weight and daily food intake. (A) Scheme of the animal experiment. (B) Changes of average body weight and food intake during the experiment. Values represent mean ± SD. Different lowercase letters (a-c) indicate statistically significant differences at
p < 0.05 evaluated by one-way ANOVA followed by Duncan test.
RCP Ameliorated the Liver Toxicity Derived from IPN-Induced Myocardial Injury in SD Rats
IPN is proposed to act as a cardiotoxic agent due to its destruction of myocardial cells, where the severity of necrotic damage in the myocardial membrane was observed [20]. As shown in Table 2, IPN treatment significantly increased the levels of well-known toxicity markers, ALT, from 42.25 ± 6.67 U/L to 108.21 ± 37.10 U/L, AST, from 127.28 ± 38.86 U/L to 781.93 ± 430.56 U/L, and LDH, from 1,132.75 ± 325.89 U/L to 2140 ± 551.59 U/L in serum, which is in line with the previous study [20]. Oral administration of RCPs significantly reduced levels of AST, ALT, and LDH in a dose-dependent manner (Table 2). Especially in RCP-H group, the level of AST, ALT, and LDH was decreased to 42.22%, 30.23%, and 41.97%, respectively, compared to IPN group (Table 2). Interestingly, the level of ALT in RCP-H group was reduced to the level of control group (Table 2). There are many studies demonstrating the effects of berry extracts and their constituents on ameliorating the toxicity in different in vitro and in vivo models, mainly by reducing the oxidative stress [21-23]. The current study also suggests the protective effect of RCP in IPN-induced cardiac injury may derive from the antioxidative activity.
-
Table 2 . The effect of RCP on serum markers of liver toxicity in IPN-induced myocardial injury model.
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H ALT (U/L) 42.25±6.67c 108.21±37.10a 74.87±38.39ab 72.14±41.50ab 45.69±12.39bc AST (U/L) 127.28±38.86b 781.93±430.56a 389.58±139.34ab 372.33±253.85ab 236.84±68.88ab LDH (U/L) 1132.75±325.89b 2140.00±551.59a 1627.67±350.80b 1572.29±551.62b 897.86±358.37b ALT: alanine transaminase, AST: aspartate transaminase, LDH: lactate dehydrogenase.
The results are expressed as mean ± SD in each group.
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p < 0.05.
RCP Reduced the Oxidative Stress Derived from IPN-Induced Myocardial Injury in SD Rats
In IPN-induced cardiac injury model, IPN was reported to trigger the production of reactive oxygen species (ROS) by depleting the endogenous antioxidant system [24]. GSH is one of the phase II detoxifying enzymes, and MDA is produced from lipid peroxidation of polyunsaturated fatty acids, indicating that GSH and MDA are well-known indicators of oxidative stress [25]. Here, we found that IPN significantly increased the level of MDA and decreased the level of GSH in the serum of rats which is consistent with previous studies [26, 27]. As shown in Table 3, oral administration of RCP counteracted the IPN regulation. Especially in RCP-H group, the level of GSH reduced by IPN was recovered from 4.17 ± 0.48 μg/ml to 6.03 ± 0.79 μg/ml, and that of MDA increased by IPN was reduced from 2.46 ± 0.45 nmol/ml to 1.80 ± 0.15 nmol/ml in the serum (Table 3).
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Table 3 . The effect of RCP on serum markers of oxidative stress and lipid metabolism in IPN-induced myocardial injury model.
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H Glutathione (ug/mL) 5.68±0.20a 4.17±0.48b 5.52±0.83a 5.75±0.66a 6.03±0.79a Malondialdehyde (nmol/mL) 1.60±0.13b 2.46±0.45a 2.08±0.48ab 2.08±0.37ab 1.80±0.15b T-Chol (mg/dL) 57.45±3.03 50.18±9.09 56.97±6.58 55.94±9.29 60.86±7.36 TG (mg/dL) 38.51±12.20b 139.14±36.33a 154.63±18.72a 107.40±55.30a 129.86±40.91a LDL (mg/dL) 13.46±1.89b 21.53±7.86a 20.56±4.76a 17.96±2.68ab 19.74±2.14ab HDL (mg/dL) 39.42±0.71a 22.71±5.88c 27.80±2.05bc 30.50±6.10bc 33.87±5.63ab TG: triglyceride, T-Chol: total-cholesterol, LDL: low-density lipoprotein and HDL: high-density lipoprotein.
The results are expressed as mean ± SD in each group.
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p <0.05.
It has been demonstrated that β-adrenoreceptor stimulation by IPN provokes cardiac oxidative stress [28]. The elevated levels of lipid peroxidation by ROS may decrease mitochondrial membrane fluidity, increase the negative surface charge distribution, and alter membrane ionic permeability, including proton permeability, which uncouples oxidative phosphorylation [29], and different polyphenols suppressed the production of IPN-induced lipid peroxides [30, 31]. Therefore, our data suggest that RCP activates the antioxidant system and minimizes the production of ROS caused by IPN in rats.
RCP Improved the Blood Lipid Profiling Derived from IPN-Induced Myocardial Injury in SD Rats
Abnormalities in lipid metabolism induced by isoproterenol were observed to cause a rise in the serum levels of phospholipids, lipid peroxides, LDL, and VLDL as well as a decrease in the serum level of HDL, which was paralleled by abnormal activities of lipid metabolizing enzymes [32]. In the IPN-injected rat model, it was reported that the levels of TG, LDL and VLDL were significantly increased whereas that of HDL was decreased compared to the control [33]. As shown in Table 3, IPN significantly decreased the serum level of HDL known to be involved in the transport of cholesterol from tissues to the liver for its catabolism [34], and RCP exerted significant recovery, almost to the level of the control, in a dose-dependent manner. Especially, HDL level in IPN group and RCP-H group was 22.71 ± 5.88 mg/dL and 33.87 ± 5.63 mg/dL, respectively (Table 3). In case of TG and LDL, IPN significantly increased their serum level. However, the level of TG and LDL in RCP-administered group was not significantly different from those in IPN group although their average values were lower than those in IPN group.
RCP Improved the Liver and Heart Tissue Damage Derived from IPN-Induced Myocardial Injury in SD Rats
Oxidative stress induced by IPN can cause irreversible damage in the heart while promoting necrosis and increasing fibrosis in both heart and liver tissues [35]. The produced oxidated quinones react with oxygen and ROS such as O2- and H2O2 and cause myocardial infarction leading to the development of infarct-like necrosis [36]. Here, we evaluated the tissue quality in the liver and heart by H&E staining. As shown in Fig. 2, the treatment of IPN induced significant myocardial architecture damage including inflammation in the heart and vascular injury in the liver. However, the histologic injuries were ameliorated by the RCP administration in a dose-dependent manner (Fig. 2). Especially, RCP-H exerted significant protection from IPN-induced organ damages to similar levels compared to the control.
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Fig. 2. The protective effect of RCP on tissue damage induced by IPN in rats. The heart (A) and the liver tissue (B) were stained by H&E staining as described in Materials and Methods, and a representative picture was taken under microscope (magnification, 200×).
Various polyphenols such as fisetin and EGCG were reported to restore inotropy and reduce apoptosis and necrosis under IPN-induced oxidative stress, demonstrating the involvement of antioxidant markers GSH and GPx [37, 38]. The condensed juices of
In conclusion, freeze-dried powder of
Acknowledgments
This research was supported by '2020 Discovering Functional Crops Project' of The Food Industry Promotional Agency of Korea and by the Chung-Ang University Research Scholarship Grants in 2020.
Conflict of Interest
The authors have no financial conflicts of interest to declare.
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Related articles in JMB

Article
Research article
J. Microbiol. Biotechnol. 2021; 31(9): 1256-1261
Published online September 28, 2021 https://doi.org/10.4014/jmb.2106.06047
Copyright © The Korean Society for Microbiology and Biotechnology.
Freeze-Dried Powder of Rubus coreanus Miquel Ameliorates Isoproterenol-Induced Oxidative Stress and Tissue Damage in Rats
Jin Tae Kim, Shuai Qiu, Yimeng Zhou, Ji Hyun Moon, Seung Beom Lee, Ho Jin Park, and Hong Jin Lee*
Department of Food Science and Biotechnology, Chung-Ang University, Anseong 17546, Republic of Korea
Correspondence to:Hong Jin Lee, hongjin@cau.ac.kr
Abstract
Rubus coreanus Miquel (bokbunja), Korean black raspberry, is known to possess various phytochemicals that exert antioxidative, anti-inflammatory, and anti-cancer effects. However, most studies on Rubus coreanus Miquel have been performed with the solvent extracts and/or a single component to demonstrate the efficacy, while studies evaluating the effect of the whole fructus of Rubus coreanus Miquel are limited. In this study, therefore, we employed the isoproterenol (IPN)-induced myocardial infarction model and investigated the effect of freeze-dried powder of Rubus coreanus Miquel (RCP) on oxidative stress and prevention of organ damage. Oral administration of RCP reduced the level of toxicity markers, alanine transaminase (ALT), aspartate transaminase (AST), and lactate dehydrogenase (LDH) without affecting body weight and diet intake. The oxidative stress marker glutathione (GSH) increased about 45% and malonaldehyde (MDA) decreased about 27% compared to the IPN group with RCP-H (3%) administration. By histological analysis, IPN induced significant myocardial damage in the heart and vascular injury in the liver, and RCP administration ameliorated the damages in a dose-dependent manner. Taken together, RCP activated the antioxidant system leading to prevention of damage to organs by IPN in rats, making it possible to expect beneficial efficacies by consuming the whole fructus of Rubus coreanus Miquel.
Keywords: Bokbunja, isoproterenol, myocardial infarction, oxidative stress, Rubus coreanus Miquel
Introduction
To determine the antioxidative effect of the whole fructus of
In this study, we evaluated the effect of RCP on prevention of heart and liver damage induced by IPN treatment in SD rats, and confirmed the regulatory activities on the anti-oxidative system and/or lipid metabolism.
Materials and Methods
RCP and Diet Preparation
Animal Experiment
Adult male Sprague-Dawley (SD) rats (150–200 g) were purchased from DooYeol Biotech, and randomly divided into five groups; Con (
Induction of Oxidative Stress and Tissue Damage
Isoproterenol (IPN) purchased from Sigma-Aldrich (USA) was prepared by dissolving in phosphate-buffered saline (PBS). Two days before sacrifice, the rats were subcutaneously injected twice with IPN (65 mg/kg BW) at an interval of 24 h for the induction of oxidative stress and myocardial infarction. All animals were then sacrificed and blood samples were taken for serum analysis and the hearts and livers were collected for histological analysis. Each organ was weighed and stored in 10% formalin (Sigma-Aldrich).
Hematoxylin & Eosin (H&E) Staining
The heart and liver tissues in 10% formalin were embedded in paraffin block after the dehydration process and cut into 5-μm-thick tissue sections using a microtome (Leica, Leica Biosystems, Germany). The tissue sections were rehydrated and stained with hematoxylin for nuclear staining and eosin for the cytoplasm for counter staining. The tissues were then examined under a light microscope (Olympus, Japan) for histological changes and pictures were taken.
Serum Analysis
After blood collection, serum was taken by centrifugation at 2,000 ×
Enzyme-Linked Immunosorbent Assay (ELISA)
To evaluate the oxidative stress markers in serum, ELISA was performed. Following the manufacturer’s guidance, the serum was incubated in wells pre-coated with antibody and treated with primary and horseradish peroxidase (HRP)-conjugated secondary antibody. Then, substrate solution was added and the developed color was measured at 450 nm (Molecular Devices, USA). ELISA micro-plate assay kits for detecting GSH (Abbexa Ltd., UK) and MDA (MyBioSource, USA) were used.
Statistical Analysis
The statistical differences were analyzed by IBM SPSS Statistics v.20 software (USA), and mean differences were analyzed using one-way analysis of variance (ANOVA) with Duncan’s post hoc test. Significant difference was at
Results and Discussion
RCP Reduced the Heart Weight Increased by IPN Injection without Affecting the Body Weight in SD Rats
Subcutaneous injection of IPN in rats was reported to increase heart rate and increase the heart weight, where IPN produced greater hypotension, followed by induction of reflex compensatory responses such as cardiac failure [16]. An increase in heart weight is attributed to increase of water content, edematous intramuscular space, and protein content in the heart tissue [17], where 1% increase of myocardial water content resulted in a possible 10% reduction in myocardial function [18]. Also observed were extensive edematous intramuscular space, accumulation of mucopolysaccharides, and cellular infiltration after the induction of myocardial infarction [19].
Here, we confirmed that IPN significantly increased the heart weight as well as the relative heart weight (Table 1). However, the body weight and liver weight were not affected by IPN injection and RCP administration (Fig. 1B and Table 1). The food intakes between groups were not significantly different (Fig. 1B), as indicated by the average consumption of RCP at 70 ± 3, 220 ± 14, and 69 ± 31 mg/day in RCP-L (0.3%), RCP-M (1.0%), and RCP-H (3.0%) groups, respectively. As shown in Table 1, RCP administration significantly suppressed the heart enlargement in a dose-dependent manner from 1.56 ± 0.15 g in IPN group to 1.40 ± 0.06 g in RCPH group, as well as the relative heart weight from 0.43 ± 0.06 g/100 g BW to 0.38 ± 0.02 g/100 g BW, respectively. These results suggest that RCP activates a defense system in vivo, leading to counteract the heart damage by IPN.
-
Table 1 . The effect of RCP on body and organ weights of rats in IPN-induced myocardial injury model..
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H Body weight (g) 385.06±3.55 369.55±26.88 366.44±42.11 366.67±23.49 373.98±29.53 Heart weight (g) 1.16±0.06c 1.56±0.15a 1.44±0.12ab 1.43±0.08ab 1.40±0.06b Liver weight (g) 12.86±0.36 12.76±1.28 13.86±1.60 13.07±1.80 13.97±1.40 Relative heart weight (g/100 g) 0.30±0.01c 0.43±0.06a 0.40±0.03ab 0.39±0.02ab 0.38±0.02b Relative Liver weight (g/100 g) 3.34±0.10 3.48±0.49 3.85±0.74 3.56±0.41 3.73±0.18 The results are expressed as mean ± SD in each group..
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p < 0.05..
-
Figure 1. Scheme of animal experiment and the changes of body weight and daily food intake. (A) Scheme of the animal experiment. (B) Changes of average body weight and food intake during the experiment. Values represent mean ± SD. Different lowercase letters (a-c) indicate statistically significant differences at
p < 0.05 evaluated by one-way ANOVA followed by Duncan test.
RCP Ameliorated the Liver Toxicity Derived from IPN-Induced Myocardial Injury in SD Rats
IPN is proposed to act as a cardiotoxic agent due to its destruction of myocardial cells, where the severity of necrotic damage in the myocardial membrane was observed [20]. As shown in Table 2, IPN treatment significantly increased the levels of well-known toxicity markers, ALT, from 42.25 ± 6.67 U/L to 108.21 ± 37.10 U/L, AST, from 127.28 ± 38.86 U/L to 781.93 ± 430.56 U/L, and LDH, from 1,132.75 ± 325.89 U/L to 2140 ± 551.59 U/L in serum, which is in line with the previous study [20]. Oral administration of RCPs significantly reduced levels of AST, ALT, and LDH in a dose-dependent manner (Table 2). Especially in RCP-H group, the level of AST, ALT, and LDH was decreased to 42.22%, 30.23%, and 41.97%, respectively, compared to IPN group (Table 2). Interestingly, the level of ALT in RCP-H group was reduced to the level of control group (Table 2). There are many studies demonstrating the effects of berry extracts and their constituents on ameliorating the toxicity in different in vitro and in vivo models, mainly by reducing the oxidative stress [21-23]. The current study also suggests the protective effect of RCP in IPN-induced cardiac injury may derive from the antioxidative activity.
-
Table 2 . The effect of RCP on serum markers of liver toxicity in IPN-induced myocardial injury model..
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H ALT (U/L) 42.25±6.67c 108.21±37.10a 74.87±38.39ab 72.14±41.50ab 45.69±12.39bc AST (U/L) 127.28±38.86b 781.93±430.56a 389.58±139.34ab 372.33±253.85ab 236.84±68.88ab LDH (U/L) 1132.75±325.89b 2140.00±551.59a 1627.67±350.80b 1572.29±551.62b 897.86±358.37b ALT: alanine transaminase, AST: aspartate transaminase, LDH: lactate dehydrogenase..
The results are expressed as mean ± SD in each group..
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p < 0.05..
RCP Reduced the Oxidative Stress Derived from IPN-Induced Myocardial Injury in SD Rats
In IPN-induced cardiac injury model, IPN was reported to trigger the production of reactive oxygen species (ROS) by depleting the endogenous antioxidant system [24]. GSH is one of the phase II detoxifying enzymes, and MDA is produced from lipid peroxidation of polyunsaturated fatty acids, indicating that GSH and MDA are well-known indicators of oxidative stress [25]. Here, we found that IPN significantly increased the level of MDA and decreased the level of GSH in the serum of rats which is consistent with previous studies [26, 27]. As shown in Table 3, oral administration of RCP counteracted the IPN regulation. Especially in RCP-H group, the level of GSH reduced by IPN was recovered from 4.17 ± 0.48 μg/ml to 6.03 ± 0.79 μg/ml, and that of MDA increased by IPN was reduced from 2.46 ± 0.45 nmol/ml to 1.80 ± 0.15 nmol/ml in the serum (Table 3).
-
Table 3 . The effect of RCP on serum markers of oxidative stress and lipid metabolism in IPN-induced myocardial injury model..
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H Glutathione (ug/mL) 5.68±0.20a 4.17±0.48b 5.52±0.83a 5.75±0.66a 6.03±0.79a Malondialdehyde (nmol/mL) 1.60±0.13b 2.46±0.45a 2.08±0.48ab 2.08±0.37ab 1.80±0.15b T-Chol (mg/dL) 57.45±3.03 50.18±9.09 56.97±6.58 55.94±9.29 60.86±7.36 TG (mg/dL) 38.51±12.20b 139.14±36.33a 154.63±18.72a 107.40±55.30a 129.86±40.91a LDL (mg/dL) 13.46±1.89b 21.53±7.86a 20.56±4.76a 17.96±2.68ab 19.74±2.14ab HDL (mg/dL) 39.42±0.71a 22.71±5.88c 27.80±2.05bc 30.50±6.10bc 33.87±5.63ab TG: triglyceride, T-Chol: total-cholesterol, LDL: low-density lipoprotein and HDL: high-density lipoprotein..
The results are expressed as mean ± SD in each group..
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p <0.05..
It has been demonstrated that β-adrenoreceptor stimulation by IPN provokes cardiac oxidative stress [28]. The elevated levels of lipid peroxidation by ROS may decrease mitochondrial membrane fluidity, increase the negative surface charge distribution, and alter membrane ionic permeability, including proton permeability, which uncouples oxidative phosphorylation [29], and different polyphenols suppressed the production of IPN-induced lipid peroxides [30, 31]. Therefore, our data suggest that RCP activates the antioxidant system and minimizes the production of ROS caused by IPN in rats.
RCP Improved the Blood Lipid Profiling Derived from IPN-Induced Myocardial Injury in SD Rats
Abnormalities in lipid metabolism induced by isoproterenol were observed to cause a rise in the serum levels of phospholipids, lipid peroxides, LDL, and VLDL as well as a decrease in the serum level of HDL, which was paralleled by abnormal activities of lipid metabolizing enzymes [32]. In the IPN-injected rat model, it was reported that the levels of TG, LDL and VLDL were significantly increased whereas that of HDL was decreased compared to the control [33]. As shown in Table 3, IPN significantly decreased the serum level of HDL known to be involved in the transport of cholesterol from tissues to the liver for its catabolism [34], and RCP exerted significant recovery, almost to the level of the control, in a dose-dependent manner. Especially, HDL level in IPN group and RCP-H group was 22.71 ± 5.88 mg/dL and 33.87 ± 5.63 mg/dL, respectively (Table 3). In case of TG and LDL, IPN significantly increased their serum level. However, the level of TG and LDL in RCP-administered group was not significantly different from those in IPN group although their average values were lower than those in IPN group.
RCP Improved the Liver and Heart Tissue Damage Derived from IPN-Induced Myocardial Injury in SD Rats
Oxidative stress induced by IPN can cause irreversible damage in the heart while promoting necrosis and increasing fibrosis in both heart and liver tissues [35]. The produced oxidated quinones react with oxygen and ROS such as O2- and H2O2 and cause myocardial infarction leading to the development of infarct-like necrosis [36]. Here, we evaluated the tissue quality in the liver and heart by H&E staining. As shown in Fig. 2, the treatment of IPN induced significant myocardial architecture damage including inflammation in the heart and vascular injury in the liver. However, the histologic injuries were ameliorated by the RCP administration in a dose-dependent manner (Fig. 2). Especially, RCP-H exerted significant protection from IPN-induced organ damages to similar levels compared to the control.
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Figure 2. The protective effect of RCP on tissue damage induced by IPN in rats. The heart (A) and the liver tissue (B) were stained by H&E staining as described in Materials and Methods, and a representative picture was taken under microscope (magnification, 200×).
Various polyphenols such as fisetin and EGCG were reported to restore inotropy and reduce apoptosis and necrosis under IPN-induced oxidative stress, demonstrating the involvement of antioxidant markers GSH and GPx [37, 38]. The condensed juices of
In conclusion, freeze-dried powder of
Acknowledgments
This research was supported by '2020 Discovering Functional Crops Project' of The Food Industry Promotional Agency of Korea and by the Chung-Ang University Research Scholarship Grants in 2020.
Conflict of Interest
The authors have no financial conflicts of interest to declare.
Fig 1.

Fig 2.

-
Table 1 . The effect of RCP on body and organ weights of rats in IPN-induced myocardial injury model..
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H Body weight (g) 385.06±3.55 369.55±26.88 366.44±42.11 366.67±23.49 373.98±29.53 Heart weight (g) 1.16±0.06c 1.56±0.15a 1.44±0.12ab 1.43±0.08ab 1.40±0.06b Liver weight (g) 12.86±0.36 12.76±1.28 13.86±1.60 13.07±1.80 13.97±1.40 Relative heart weight (g/100 g) 0.30±0.01c 0.43±0.06a 0.40±0.03ab 0.39±0.02ab 0.38±0.02b Relative Liver weight (g/100 g) 3.34±0.10 3.48±0.49 3.85±0.74 3.56±0.41 3.73±0.18 The results are expressed as mean ± SD in each group..
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p < 0.05..
-
Table 2 . The effect of RCP on serum markers of liver toxicity in IPN-induced myocardial injury model..
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H ALT (U/L) 42.25±6.67c 108.21±37.10a 74.87±38.39ab 72.14±41.50ab 45.69±12.39bc AST (U/L) 127.28±38.86b 781.93±430.56a 389.58±139.34ab 372.33±253.85ab 236.84±68.88ab LDH (U/L) 1132.75±325.89b 2140.00±551.59a 1627.67±350.80b 1572.29±551.62b 897.86±358.37b ALT: alanine transaminase, AST: aspartate transaminase, LDH: lactate dehydrogenase..
The results are expressed as mean ± SD in each group..
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p < 0.05..
-
Table 3 . The effect of RCP on serum markers of oxidative stress and lipid metabolism in IPN-induced myocardial injury model..
Control IPN IPN + RCP-L IPN + RCP-M IPN + RCP-H Glutathione (ug/mL) 5.68±0.20a 4.17±0.48b 5.52±0.83a 5.75±0.66a 6.03±0.79a Malondialdehyde (nmol/mL) 1.60±0.13b 2.46±0.45a 2.08±0.48ab 2.08±0.37ab 1.80±0.15b T-Chol (mg/dL) 57.45±3.03 50.18±9.09 56.97±6.58 55.94±9.29 60.86±7.36 TG (mg/dL) 38.51±12.20b 139.14±36.33a 154.63±18.72a 107.40±55.30a 129.86±40.91a LDL (mg/dL) 13.46±1.89b 21.53±7.86a 20.56±4.76a 17.96±2.68ab 19.74±2.14ab HDL (mg/dL) 39.42±0.71a 22.71±5.88c 27.80±2.05bc 30.50±6.10bc 33.87±5.63ab TG: triglyceride, T-Chol: total-cholesterol, LDL: low-density lipoprotein and HDL: high-density lipoprotein..
The results are expressed as mean ± SD in each group..
Values not sharing a common superscript (a, b, c) differ significantly with each other at
p <0.05..
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