Camellia sinensis powder rich in epicatechin and polyphenols attenuates isoprenaline induced cardiac injury by activating the Nrf2 HO1 antioxidant pathway in rats

Abstract

Myocardial infarction is a leading cause of death and morbidity in individuals with cardiovascular diseases. Natural antioxidants, such as those found in green tea leaves, are beneficial in preventing these diseases. This study evaluated the protective effects of green tea leaves powder against isoprenaline (ISO)-induced myocardial infarction in rats. Four groups of male Long Evans rats were used: Control, Control + green tea leaves powder, ISO, and ISO + green tea leaves powder. Organ and blood plasma samples were collected to measure oxidative stress biomarkers, biochemical parameters, and gene expressions. Furthermore, tissue sections were prepared and stained histologically. ISO-induced rats showed decreased cellular antioxidants (catalase activity and glutathione concentration) and elevated oxidative stress markers. Notable inflammatory cell infiltration and fibrosis were observed in the heart and kidneys of ISO-induced rats. Supplementation with green tea leaves powder significantly restored catalase activity and glutathione concentration (p < 0.05) in plasma and tissues. It also considerably reduced lipid peroxidation, nitric oxide, and advanced oxidation protein products (p < 0.05) in ISO-administered rats. Furthermore, green tea leaves powder supplementation halted inflammatory gene expression (p < 0.05), restored antioxidant genes (p < 0.05) such as Nrf-2-HO-1, and prevented cardiac fibrosis in ISO-administered rats. Green tea leaves powder supplementation may reduce oxidative stress, inflammation, and fibrosis in ISO-administered rats, potentially through the Nrf-2-HO-1-mediated restoration of antioxidant enzymes and prevention of heart inflammation.

Keywords: Camellia sinensis; Fibrosis; Inflammation; Isoprenaline; Myocardial infarction.

Fig. 1

HPLC chromatogram of 16 phenolic compounds (A). HPLC chromatogram of tea leaf extract (B). The peaks detected are: 1, (+)-catechin hydrate (CH); 2, (–)-epicatechin (ECA); 3, syringic acid (SA); 4, rutin hydrate (RH); 5, rosemarinic acid; 6, quercetin; 7, kaempferol.

Fig. 2

Effect of green tea leaf powder supplementation on oxidative stress parameters MDA and NO in the plasma, heart, and kidney tissue homogenates of ISO-administered rats. Data are expressed as mean ± SEM, n = 6. Statistical analysis was done using one-way ANOVA, followed by a Tukey post hoc test. Statistical significance was considered as p < 0.05 and marked as an asterisk mark.

Fig. 3

Effect of green tea powder supplementation on oxidative stress parameters APOP in plasma, heart, and kidney tissue homogenates of ISO-administered rats. Data are expressed as mean ± SEM, n = 6. Statistical analysis was done using one-way ANOVA, followed by a Tukey post hoc test. Statistical significance was considered as p < 0.05 and marked as an asterisk mark.

Fig. 4

Effect of green tea powder supplementation on catalase activity in the plasma, heart, and kidneys of ISO-administered rats. Data are expressed as mean ± SEM, n = 6. Statistical analysis was done by One-way ANOVA, followed by a Tukey post hoc test. Statistical significance was considered as p < 0.05 and marked with an asterisk.

Fig. 5

Effect of green tea powder supplementation on reduced glutathione level in the plasma, heart, and kidneys of ISO-administered rats. Data are expressed as mean ± SEM, n = 6. Statistical analysis was done using one-way ANOVA, followed by a Tukey post hoc test. Statistical significance was considered as p < 0.05 and marked with an asterisk.

Fig. 6

The effect of green tea powder supplementation on CK-MB levels in ISO-administered rats is shown. The values are expressed as mean ± SEM, n = 6. GraphPad Prism Software, version 9, was used for analysis, applying a one-way ANOVA and a Tukey multiple comparisons test. A significance level of p < 0.05 is applied to the results.

Fig. 7

Score plot (A) and biplot (B) for the Principal Component Analysis (PCA) of biochemical parameters in the plasma across different groups. The PAST software, version 4.03, was used to perform the PCA analysis.

Fig. 8

Score plot (A) and biplot (B) graph for the Principal Component Analysis (PCA) of biochemical parameters for the heart in various groups. The PAST software, version 4.03, was used to analyze the PCA.

Fig. 9

Effect of green tea powder supplementation on antioxidant gene expression in the heart of ISO-administered rats. All data were presented as mean ± SEM. For statistical analysis, One-Way ANOVA followed by the Tukey multiple comparisons test was done, where significance was indicated as ns means p < 0.05; * means p ≤ 0.05; ** means p ≤ 0.01.

Fig. 10

Effect of green tea powder supplementation on anti-inflammatory gene expression in the heart of ISO-administered rats. All data were presented as mean ± SEM. For statistical analysis, One-Way ANOVA followed by the Tukey multiple comparisons test was done, where significance was indicated as ns means p < 0.05; * means p ≤ 0.05; ** means p ≤ 0.01.

Fig. 11

The effect of green tea powder supplementation on uric acid and creatinine levels in the plasma and urine of ISO-administered rats. Data are expressed as mean ± SEM, n = 6. Statistical analysis was performed using one-way ANOVA followed by Tukey’s post hoc test. Statistical significance was considered as p < 0.05 and marked with an asterisk.

Fig. 12

Effect of green tea leaves powder supplementation on inflammation and fibrosis in left ventricular myocardium of ISO-treated rats. The upper panel shows H and E staining, (A) Control; (B) Control + tea leaves; (C) ISO; and (D) ISO + tea leaves. The lower panel shows Sirius red staining, (E) Control; (F) Control + tea leaves; (G) ISO; and (H) ISO + tea leaves. (Magnification 40X).

Fig. 13

Effect of green tea leaves powder supplementation on the inflammatory scar and fibrosis in the kidneys of ISO-treated rats. The upper panel shows H and E staining, (A) Control; (B) Control + tea leaves; (C) ISO; and (D) ISO + tea leaves. The lower panel shows Sirius red staining, (E) Control; (F) Control + tea leaves; (G) ISO; and (H) ISO + tea leaves. (Magnification 40X).

Fig. 14

Effect of green tea leaf powder supplementation on iron pigment deposition in the heart and kidneys of ISO-treated rats. The upper panel shows the heart section, (A) Control; (B) ISO; and (C) ISO + tea leaves. The lower panel shows the kidney section, (D) Control; (E) ISO; and (F) ISO + tea leaves—magnification 40X.

Fig. 15

Hypothetical role of green tea polyphenol in cardiac remodeling and fibrosis.

Fig. 16

Flow chart of the experimental design.