Cardioprotectant Effect Of Bay Leaf Extract (Syzygiumpolyanthum) On Myocardium Thickness Of Rat Heart

High salt diet and prednisone administration will increase blood pressure which chronically causes heart muscle remodeling so that it appears macroscopically as left ventricular hypertrophy. Bay leaf extract contains flavonoids which can lower blood pressure and decrease left ventricular thickening. To determine the effect of bay leaf extract (Syzygiumpolyanthum) on the left ventricle thickening of rat heart (Rattus norvegicus wistar strain) in hypertensive model. True experimental post-test only controls group design with simple random sampling technique. The subjects of this study were 25 male Wistar rats aged 2-3 months weighing 150-200 grams. Rats were induced with prednisone 1.5 mg/ KgBW / day in 2% NaCl for 6 weeks followed by administration of bay leaf extract at a dose of 70 mg/ KgBW, a dose of 140 mg/ KgBW, and a dose of 280 mg/ KgBW. Data analyzed by One Way ANOVA, Post Hoc Bonferroni, followed by Linear: One Way ANOVA test showed significant differences between treatments (p = 0.000). The Bonferroni Post Hoc test concluded that there were significant differences in the treatment of the P2 and P3 groups. Linear regression test obtained R square 0.663 and obtained the equation Y = 1965.838 1.275X. The extract of bay leaf (Syzygiumpolyanthum) has an effect on decreasing the left ventricle thickening of the white male rat heart (Rattus norvegicus wistar strain) hypertension model. Keyword: Bay Leave Extract, Flavonoid, Hypertension, Thickening of Left Ventricular. Copyright © 2021, Lestari D. Y et al This is an open access article under the CC–BY-SA license


INTRODUCTION
The national prevalence of hypertension in 2013 reached 25.8% which is equivalent to 65 million people (Riskesdas, 2013). Untreated hypertension can lead to damage to various organs such as the heart, kidneys, and brain (Singh, Shankar, & Singh, 2017). The highest prevalence of target heart organ damage is heart failure due to left ventricular hypertrophy (Left Ventricular Hypertrophy = The high prevalence of LVH due to hypertension is a reason for discovering safe treatment with minimal side effects. One of the alternative medicinal methods is by consuming medicinal plants such as bay leaves. Bay (Syzygiumpolyanthum) can be impelement as an alternative medicine to treat hypertension because it contains natural antioxidants, called flavonoids (Ismail, et al., 2013).
Flavonoids have vasorelaxant effect that can lower blood pressure and heart rate (Ismail & Wan Ahmad, 2017). In addition, flavonoids also have a cardioprotective effect by suppressing enzymes for the formation of Reactive Oxygen Species (ROS) which play a role in the mechanism of LVH. (Widiasari, 2018) Until now there has been no research that has examined the effect of bay leaves on LVH, so the result of this study are expected to be used as a basic research on the effects of bay leaves as herbal therapy to protect LVH. From these calculations, a large range of samples was obtained per treatment group of 3-5 mice.

This
The controlled variable of this study was the left ventricle thickening of the hypertensive model rats heart and the independent variable was the dose of methanol extract of bay leaves.
The subject of this study was adapted for 1 week and then divided into 5 groups, namely K-, K +, P1, P2, P3. Group K-was given only standard food and drink. Groups K +, P1, P2, and P3 were induced with prednisone 1.5 mg/ KgBW/ day in 2% NaCl solution for 6 weeks. Then the whole group had their blood pressure measured at the end of week 6. Furthermore, the K + group was given distilled water for 2 weeks. Group P1 was given bay leaf extract at a dose of 70mg / KgBW/ day, P2 was given bay leaf extract at a dose of 140mg / KgBW / day, and P3 was given bay leaf extract at a dose of 280mg/ KgBW/ day for 2 weeks.
After that the mice were turned off, and their heart organs were taken. Histopathology preparations were made with HE staining. Furthermore, histopathological observations of the left Dian Yuliarta L., Rizky T. / SM Vol.17 No.1 June 2021 Page 19-26 21 ventricle of rat's heart were carried out using a light microscope. The data obtained were then processed by One Way ANOVA test, Bonferroni Post Hoc, and Linear Regression test with SPSS 24 software.

RESULTS AND DISCUSSION
The results of histopathological observations of the left ventricle of rat heart through a light microscope with a 40x magnification and Optilab software, as well as measuring the thickness of the ventricular wall which was calculated from the lumen to the outer layer with Image Raster software.. The results of histopathological observations of the left ventricle of rat heart showed that induction of prednisone 1.5/ KgBW/ day in 2% NaCl solution caused increased systemic blood pressure which chronically could lead to cardiac muscle remodeling so that it would appear macroscopically as myocardial hypertrophy in the left ventricle. Cardiac hypertrophy is a myocardial compensatory response to an increase in heart burden due to high blood pressure over a long period of time. When the body failed to compensate high blood pressure, the heart will experience oxidative stress due to the excessive release of proinflammatory cytokines (especially TNF-α). Apart from stimulating TNF-α, an increase in Reactive Oxygen Species (ROS) levels can also be caused by an increase in angiotensin II in the heart.
In vitro it has been shown that if hypertrophic stimuli such as angiotensin II and TNF-α increase, it will stimulate the production of ROS. Increased levels of ROS lead to an enlargement in the size of the heart myocyte cells leading to cardiac hypertrophy (Hingtgen, et al., 2010).
The results of this study have proven that there was a significant decrease in the thickening of the left ventricular wall of the rat heart that was induced by predinson and NaCl starting from the P1 treatment group with a dose of 70 mg/ KgBW/ day, the P2 treatment group with a dose of indicated by the lower mean of left ventricular wall thickening in the P1, P2, and P3 groups compared to the positive control group which was induced only by prednisone and NaCl. The results obtained from the P1 group were the mean reduction in the thickening of the left ventricle of the heart by 1825.24 ± 32.71µm. The mean reduction in left ventricular thickening in group P2 was 1767.97 ± 89.47 µm. The result of decreased left ventricular wall thickening of the P3 group was 1631.21 ± 60.42µm, where the value was lower than the average in the K group, namely 1683.26 ± 140.04µm.
The decrease in left ventricular thickening of the heart which was more significant in the P3 group than in the K-group could occur because one of the mice in the K-group had a high average thickness, which is 1918.40 µm. This condition can be caused by various endogenous and exogenous factors from the mice themselves. In addition, because the initial condition of the rats' hearts were not examined, they also had the possibility of having abnormalities before the treatment was given.
The administration of bay leaf methanol extract in this study was able to reduce the thickening of the left ventricle of the heart with a significant result, namely p <0.05 on the One Way ANOVA test results. In the post hoc bonferroni test, the value was <0.05 in the P1, P2, and P3 groups, which means that the dose that showed a therapeutic effect was starting from the P1 dose, which was 70 mg/ KgBW/ day.. (H2O2) (Uzun, et al, 2013). Hormone (CRH) which results in the release of Adenocorticotropic Hormone (ACTH) by the anterior pituitary which stimulates the adrenal cortex to release glucocorticoids which will increase the accumulation of glutamate in the synapse and will poison the hippocampus (Taliaz, et al, 2011) .
The side effect of glutamate activity is an increase in the activity of Ca2 + dependent enzymes in excess, resulting in degenerative changes and an increase in free radicals (Arjadi, et al, 2014).
Researchers used the methanol extract of bay leaves to reduce the left ventricle thickening of the heart because in the methanol extract of bay leaves contains flavonoids which can act as antioxidants that can reduce ROS levels by inhibiting the formation of ROS. When the level of ROS in the myocardium decreases, the heart will return from a state of oxidative stress so that the proliferation of myocyte sarcomere will stop. In addition, antioxidants can enhance the function of damaged endothelium so that they are able to produce eNOS (endothelial Nitric Oxide synthase), which is responsible for the production of endogenous vasodilators, NO, so that vasodilation happen. So then, heart load will decrease and sarcomere proliferation can be stopped, then the left ventricle myocardium thickening will be decreased.
This result is in line with previous research that giving various fruit extracts containing flavonoids such as lemon, grape, and chocolate extracts can reduce the interventricular septal wall thickening of the rat heart with hypertension. (Paredes, et al., 2018).
The limitation in this study is that the researchers only observed the presence or absence of changes in the left ventricle thickening of the rats in the histopathological picture. The researchers did not calculate the mass of the heart muscle, observed other histological changes in the heart myocardium, and did not calculate the diameter of the left ventricular chamber, because these three are also indicators of the left ventricle thickening. The researchers were also unable to control the amount of water intake, the amount of feed consumed, and the urine output of rats because these three are endogenous factors that can be confounding.