Cardamom extract: An effective weapon in prevention of cardiorenal syndrome induced in rats by cisplatin and high-fat diet

Abstract

BACKGROUND

Overnutrition and unhealthy dietary habits are established risk factors for cardiovascular and renal diseases, which may lead to the development of cardiorenal syndrome (CRS).

AIM

To evaluate the cardiorenal protective potential of crude ethanol extract (CEE) of green cardamom (Elettaria cardamomum L., Family Zingiberaceae).

METHODS

Rats were fed a high-fat diet to induce dyslipidemia and subsequently administered cisplatin (7.5 mg/kg) to induce CRS. CEE was administered orally to CRS rats at low (100 mg/kg) and high (200 mg/kg) doses for one month. Oxidative stress, inflammatory markers, cardiovascular disease markers, cardiac indices, and renal function (in plasma and urine) were assessed. The antioxidant activity and phenolic compound profile of CEE were evaluated. Additionally, the potential interactions of CEE phenolics with components of the Hippo signaling pathway (mammalian sterile 20-like kinase 1, large tumor suppressor kinase 1, Yes-associated protein, and transcriptional coactivator with PDZ-binding motif) were investigated using molecular docking.

RESULTS

Cisplatin administration combined with a high-fat diet effectively induced CRS, as evidenced by elevated oxidative stress, inflammation, and impaired cardiorenal parameters. Treatment with CEE at both doses improved these parameters, with the high dose demonstrating greater efficacy. CEE exhibited significant DPPH radical scavenging activity. Rosmarinic acid and gallic acid were identified as the major phenolic constituents. Molecular docking revealed strong binding affinities of rosmarinic acid and rutin with targets in the Hippo signaling pathway.

CONCLUSION

These findings demonstrate the cardioprotective and renoprotective potential of CEE as a phenolic-rich dietary supplement. CEE mitigated inflammation and oxidative stress, key contributors to CRS pathogenesis. Furthermore, molecular docking suggests that the phenolic compounds in CEE may exert protective effects by modulating the Hippo signaling pathway. Overall, CEE shows promise as a natural therapeutic agent for the prevention and/or management of cardiorenal syndrome.

Key Words: Cardiorenal syndrome; Cardamom extract; Hippo signaling pathway; Oxidative stress; Inflammatory markers; Phenolic compounds

Core Tip: In this study, cardiorenal syndrome (CRS) was experimentally induced in rats using a high-fat diet and cisplatin. The protective effects of crude ethanol extract (CEE) of cardamom were evaluated through comprehensive biochemical analyses. The potential mechanistic role of CEE phenolics was explored via molecular docking with the Hippo signaling pathway. The findings suggest that CEE, as a phenolic-rich dietary supplement, may protect against CRS by reducing inflammation and oxidative stress, and by targeting components of the Hippo pathway.

INTRODUCTION

Diet-related chronic diseases such as heart disease, stroke, hypertension, obesity, diabetes, and cancer are major public health concerns that have significantly increased over the past two decades. The global burden of these metabolic disorders is expected to continue rising, with projections indicating that by 2050 they will contribute to the highest number of deaths worldwide[1,2]. This rise is largely attributed to modern lifestyles characterized by unhealthy dietary habits and physical in activity—two primary contributors to the increasing prevalence of diet-related chronic diseases.

The Western diet, often used as a model of an unbalanced diet, plays a central role in elevating the incidence of these diseases by promoting chronic inflammation and oxidative stress[3]. It is typically characterized by a high intake of processed and calorie-dense foods, foods with a high glycemic index, saturated fats, and sodium, combined with low consumption of fruits, vegetables, and dietary fiber[4,5].

Cardiovascular disease (CVD) remains the leading cause of death globally and often coexists with metabolic disorders such as diabetes and kidney disease[4]. The heart and kidneys are both vital organs essential for maintaining life. The kidneys, responsible for excreting exogenous substances like drugs and nutrients, are especially susceptible to injury from these agents[6]. Unhealthy dietary habits can result in both acute and chronic kidney damage—such as kidney stones, which are linked to high oxalate intake[7]. Moreover, certain drugs, like cisplatin, are known to cause nephrotoxicity[8].

Cisplatin is a widely used chemotherapeutic agent for several cancers, including lung, bladder, and cervical cancers. However, its clinical application is limited by its significant toxicity to normal tissues, particularly the kidneys[9]. Drug-induced nephrotoxicity accounts for up to 60% of acute and chronic kidney injuries[6]. Additionally, dyslipidemia-a key dietary-related factor—plays a pivotal role in the pathogenesis of both CVD and chronic kidney disease (CKD). Nutritional disorders have been shown to exacerbate CKD progression and worsen metabolic abnormalities[10].

The American Heart Association defines the coexistence of cardiovascular and kidney disease as cardiorenal syndrome (CRS), which is classified into stages ranging from 0 to 4, based on severity and progression[11]. Given the critical role of nutrition in overall health, dietary interventions are an effective strategy for managing and preventing diet-related chronic diseases and their complications, including CRS[1]. It has been reported that dietary patterns beneficial for heart health are also associated with reduced progression of kidney disease and lower mortality rates[12].

Incorporating dietary supplements or functional foods into daily nutrition may aid in preventing or managing diet-related chronic diseases and their associated complications, due to the presence of bioactive compounds such as phenolic compounds. These compounds exert various biological effects, including anti-inflammatory, antioxidant, antidiabetic, nephroprotective (including reduction of kidney stone formation and protection against nephrotoxicity), and cardioprotective activities[1,7,8].

Herbs and spices, which are inherently linked to human diets, have been extensively studied for their health benefits. Spices have a long history in traditional medicine due to their rich content of bioactive constituents[13]. Green cardamom (Elettaria cardamomum L., Family Zingiberaceae) is a spice consisting of small pods containing dark seeds. It has been used since ancient Egyptian times for its medicinal properties, including as a preventive agent against breast cancer[14,15].

Cardamom contains a variety of compounds, including essential oils, terpenes (e.g., sabinene and myrcene), phenolic acids (e.g., caffeic and ferulic acids), and flavonoids (e.g., quercetin, kaempferol, and luteolin), which are known for their potent antioxidant, anti-inflammatory, cardioprotective, and anticancer effects[16,17].

Recent studies have identified the Hippo signaling pathway as a promising therapeutic target for treating cardiac and renal diseases[18]. This pathway plays a crucial role in organ development and the maintenance of tissue homeostasis in multicellular organisms[19]. Dysregulation of the Hippo pathway is implicated in the pathogenesis of various diseases, including cardiac and renal disorders[19]. The Hippo pathway comprises four key proteins: Mammalian sterile 20-like kinase 1 (MST1), large tumor suppressor kinase 1 (LATS1), Yes-associated protein (YAP), and transcriptional coactivator with PDZ-binding motif (TAZ)[19]. Thus, therapeutic strategies aimed at correcting Hippo pathway dysregulation may prove effective in treating conditions such as cardiorenal syndrome.

Most animal studies focus on single models of diet-related chronic diseases, such as diabetes, CVD, or kidney injury in isolation. In contrast, the present study aims to establish a rat model that combines two diet-related chronic conditions within the same animal. This was achieved by feeding rats a high-fat diet to induce dyslipidemia and cardiovascular complications, followed by intraperitoneal administration of cisplatin to induce kidney injury, ultimately leading to the development of CRS.

This study investigates the protective potential of crude ethanol extract (CEE) of cardamom in this CRS model. The antioxidant activity and phenolic compound profile of CEE were evaluated. Furthermore, molecular docking was employed to assess the interactions between CEE phenolic compounds and components of the Hippo signaling pathway (MST1, LATS1, YAP, and TAZ).

MATERIALS AND METHODS

Plant materials

Green cardamom pods (Elettaria cardamomum L., Family Zingiberaceae) were purchased from the local market, Cairo, Egypt.

Animals

Male Sprague-Dawley rats weighing between 156 and 180 g were used in this study. The animals were obtained from the animal facility at the National Research Centre (NRC), Cairo, Egypt. Each rat was housed individually in a stainless-steel metabolic cage, with ad libitum access to food and water throughout the experimental period. This research was conducted as part of internal project No. 13050203, funded by the NRC. All experimental procedures were approved by the Medical Research Ethics Committee of the NRC (Approval No. 13050203) and complied with the guidelines of the National Institutes of Health Guide for the Care and Use of Laboratory Animals (Publication No. 85-23, revised 1985).

Preparation of cardamom ethanol extract

Dried cardamom powder was subjected to ultrasound-assisted extraction using ethanol as a green solvent. The resulting extract was concentrated by evaporating the solvent under reduced pressure at a temperature not exceeding 40 °C. The concentrated extract was stored in a deep freezer until use. For oral administration to rats, the ethanol extract was dissolved in water.

Phytochemical screening and antioxidant activity of cardamom extract

Total phenolic content in the CEE was determined using the Folin–Ciocalteu method[20], and results were expressed as milligrams of gallic acid equivalents per gram of dried sample (mg GAE/g). The phenolic compound profile of CEE was analyzed by HPLC (Agilent 1260 series) under conditions described by Mohamed et al[7]. Individual phenolics were identified and quantified by comparing their retention times and peak areas with those of a standard mixture containing gallic acid, methyl gallate, chlorogenic acid, catechin, pyrocatechol, rosmarinic acid, syringic acid, rutin, coumaric acid, caffeic acid, naringenin, ferulic acid, vanillin, cinnamic acid, quercetin, hesperetin, and kaempferol. The antioxidant activity of CEE was assessed using the DPPH radical scavenging method as previously described by Bozin et al[21].

Diets

Two dietary regimens were administered during the study. Rats in the cardiorenal syndrome model group were fed a high-fat diet based on the formulation by Mohamed et al[22], comprising 45% of total calories from fat, 0.25% cholic acid, and 1% cholesterol. In contrast, the normal control group received a balanced diet consisting of 10% protein (from casein), 10% corn oil, 68.5% carbohydrates, 1% vitamin mixture, and 3.5% salt mixture. The vitamin and salt mixtures were prepared according to the AIN-93 guidelines[23].

Induction of cardiorenal syndrome in rats

The study included four groups of six rats each. Groups 1 and 2 served as the normal control (fed a balanced diet) and the cardiorenal syndrome control (fed a high-fat diet), respectively. Groups 3 and 4 were fed a high-fat diet and received daily oral doses of cardamom extract at 100 mg/kg and 200 mg/kg body weight, respectively. On day 25, all groups except the normal control received a single intraperitoneal injection of cisplatin (Mayne Pharmaceuticals, Warwickshire, United Kingdom) at 7.5 mg/kg body weight[24].

Five days after cisplatin administration, 24-hour urine samples were collected for the measurement of creatinine, urea, and total protein. Creatinine clearance was calculated as follows: Creatinine clearance (mL/min) = [Urine creatinine (mg/dL) × 24-hour urine volume (mL)]/[Plasma creatinine (mg/dL) × 1440].

At the end of the experiment, blood samples were collected from all rats after overnight fasting in heparinized tubes for the evaluation of plasma lipid profile parameters, including triglycerides, total cholesterol (T-Ch), and high-density lipoprotein cholesterol (HDL-Ch), using colorimetric kits. Oxidized LDL levels were measured using an ELISA kit (Catalogue #SL0554Ra, Sunlong^®). The coronary risk index (CRI) and cardioprotective index (CPI) were calculated as the ratios T-Ch/HDL-Ch and HDL-C/LDL-C, respectively.

Plasma levels of cardiac markers lactate dehydrogenase (LDH)[25] and creatine kinase (CK)[26] were determined. Oxidative stress markers including malondialdehyde (MDA)[27] and catalase activity[28] were measured in both plasma and tissue homogenates (heart and kidneys). Plasma creatinine[29], urea[30], total protein[31], and albumin[32] levels were assessed as indicators of kidney function. The ratio of blood urea nitrogen (BUN) to creatinine was also calculated. Inflammatory markers, including C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6), were determined using ELISA kits (CRP: #SL0202Ra; TNF-α: #SL0722Ra; IL-6: #SL0411Ra; Sunlong^®).

This study was conducted under internal project No. 13050203 and approved by the Medical Research Ethics Committee of the NRC (Approval No. 13050203), in accordance with NIH guidelines.

Molecular docking of cardamom ethanol extract

The structures of MST1, LATS1, YAP, and TAZ were retrieved from the UniProt database. Protein preparation was performed using AutoDock Tools 1.5.7, which included the addition of hydrogen atoms, removal of water molecules, and assignment of partial charges. The major phytochemicals identified in the cardamom ethanol extract were obtained from the PubChem database and subjected to energy minimization using Avogadro (version 1.2.0) with the MMFF94 force field. Molecular docking was conducted using AutoDock Vina, and docking interactions were visualized using BIOVIA Discovery Studio, version 2020[7].

Statistical analysis

Data is expressed as mean ± SE. Statistical comparisons between groups were made using one-way analysis of variance, followed by Duncan’s post hoc test. The value of P < 0.05 was considered statistically significant in all analyses.

RESULTS

Bioactive compounds and antioxidant potential of cardamom extract

The total phenolic content in the cardamom ethanol extract (CEE) was 50.94 ± 0.754 mg GAE/g. Antioxidant activity, measured by the DPPH assay, was 26.55 ± 0.438 mg TE/g. HPLC analysis identified 16 phenolic compounds in the extract (Table 1), with rosmarinic acid being the most abundant (207.79 µg/g), while ellagic acid was the least (12.13 µg/g).

Table 1 HPLC of cardamom crude ethanol extract phenolic compounds profile (µg/g).

Phenolic compounds	Conc. µg/g
Gallic acid	207.79
Chlorogenic acid	120.01
Methyl gallate	59.79
Caffeic acid	191.36
Syringic acid	190.25
Rutin	125.14
Ellagic acid	12.13
Coumaric acid	190.42
Vanillin	58.03
Ferulic acid	65.67
Naringenin	71.84
Rosmarinic acid	655.69
Quercetin	76.86
Cinnamic acid	75.27
Hesperetin	71.57

Effect of cardamom extract on dyslipidemia and cardiac enzymes

Rats in the CRS control group—fed a high-fat diet and injected intraperitoneally with cisplatin (7.5 mg/kg BW)—exhibited significantly elevated levels of total cholesterol (162.29 ± 2.54), triglycerides (109.00 ± 2.02), LDL-C (97.00 ± 2.88), and oxidized-LDL (59.91 ± 2.20), along with a marked reduction in HDL-C (25.43 ± 0.37) (Table 2). Correspondingly, the CRI increased, and the CPI decreased (Figure 1). Significant elevations were also observed in serum CK and LDH activities (Figure 2).

Figure 1 Coronary risk and cardioprotective index of different experimental groups. A: Coronary risk index = T-Ch/HDL-Ch; B: Cardioprotective index = HDL-Ch/LDL-Ch, values are mean ± SE, n = 6, means with different letters show significant difference between values at probability level of 0.05.

Figure 2 Creatine kinase and lactate dehydrogenase as heart function indices in all experimental groups. A: Creatine kinase; B: Lactate dehydrogenase; Values are mean ± SE, n = 6, means with different letters show significant difference between values at probability level of 0.05.

Table 2 Effect of cardamom extract on plasma lipid profile.

Parameters	Normal control	Cardiorenal control	Low-dose cardamom extract	High-dose cardamom extract
T-Ch (mg/dL)	68.70a ± 2.198	162.29b ± 2.543	113.14b,d ± 3.181	83.29a,d,f ± 2.201
TG (mg/dL)	77.43a ± 2.034	109.00b ± 2.024	92.57b,d ± 1.088	82.86d,e ± 1.870
HDL-Ch (mg/dL)	42.86a ± 0.885	25.43b ± 0.369	36.14b,d ± 0.738	41.71b,d,f ± 0.944
LDL-Ch (mg/dL)	20.29a ± 0.474	97.00b ± 2.879	58.00b,d ± 1.215	40.71b,d,f ± 1.063
Oxidized LDL (pg/mL)	24.68a ± 0.681	59.91b ± 2.196	36.28b,c ± 1.457	30.67a,d,e ± 0.786

^aP < 0.01.

^bP < 0.001, statistical significance is expressed vs normal control.

^cP < 0.01.

^dP < 0.001, P values are expressed vs cardiorenal-control.

^eP < 0.01.

^fP < 0.001, P values are expressed as (Low-dose cardamom extract vs High-dose cardamom extract). Values are mean ± SE, n = 6. T-Ch: Total cholesterol; TG: Triglycerides; HDL-Ch: High density lipoprotein-Cholesterol; LDL-Ch: Low density lipoprotein-Cholesterol.

Oral administration of cardamom extract at both low (100 mg/kg BW) and high (200 mg/kg BW) doses resulted in dose-dependent improvements in lipid profiles, CRI, CPI, and cardiac enzyme levels. The high dose showed greater efficacy.

Effect on renal function parameters

CRS control rats demonstrated significant increases in plasma creatinine, urea, BUN, and BUN/creatinine ratio, along with significant reductions in plasma total protein and albumin levels (Table 3). Additionally, urinary creatinine, urea, and total protein were elevated, while creatinine clearance was reduced.

Table 3 Effect of cardamom extract on renal biochemical parameter in plasma and urine of rats.

	Normal control	Cardiorenal control	Low-dose cardamom extract	High-dose cardamom extract
	Plasma
Creatinine (mg/dL)	0.59a ± 0.012	1.44b ± 0.049	0.98b,d ± 0.028	0.77a,d,f ± 0.024
Urea (mg/dL)	32.92a ± 0.709	159.22b ± 3.017	89.79b,d ± 2.365	64.51b,d,f ± 1.252
Albumin (g/dL)	3.91a ± 0.076	2.53b ± 0.046	3.03b,d ± 0.057	3.70d,f ± 0.090
BUN (mg/dL)	15.38a ± 0.331	74.36b ± 1.409	41.93c ± 1.104	30.13d ± 0.585
BUN/creatinine ratio	26.17a ± 0.932	52.13b ± 1.861	43.00b,d ± 1.759	39.15b,d,f ± 1.252
Total protein (g/dL)	7.73a ± 0.062	5.31b ± 0.075	6.30b,d ± 0.098	7.19a,d,f ± 0.114
	Urine
Creatinine (mg/dL)	37.78a ± 0.582	52.71b ± 1.038	46.14b,c ± 1.578	40.71d,e ± 0.746
Urea (mg/dL)	657.77a ± 5.282	984.63b ± 8.335	823.57b,d ± 9.541	697.86a,d,f ± 8.840
Protein (mg/dL)	41.94a ± 0.921	67.29b ± 1.246	62.57b,d ± 1.268	50.00b,d,f ± 0.898
Creatinine clerance (ml/min)	1.24a ± 0.041	0.48b ± 0.033	0.75b,d ± 0.049	0.97b,d,f ± 0.035

^aP < 0.01.

^bP < 0.001, statistical significance is expressed vs normal control.

^cP < 0.01.

^dP < 0.001, P values are expressed vs cardiorenal-control.

^eP < 0.01.

^fP < 0.001, P values are expressed (Low-dose cardamom extract vs high-dose cardamom extract). Values are mean ± SE, n = 6.

Treatment with cardamom extract significantly improved these renal function markers in both plasma and urine. These findings suggest that cardamom extract may mitigate cisplatin-induced nephrotoxicity.

Effect on oxidative stress and inflammation

Markers of oxidative stress, including MDA, were significantly elevated in plasma and tissues (heart and kidneys) of the CRS control group, while catalase activity was significantly reduced (Figure 3). Inflammatory cytokines—CRP, TNF-α, and IL-6—were also significantly increased (Figure 4).

Figure 3 Effect of cardamom extract administration on malondialdehyde and catalase in plasma, heart, and kidney tissues. Values are mean ± SE, n = 6, means with different letters show significant difference between values at probability level of 0.05. MDA: Malondialdehyde; CAT: Catalase.

Figure 4 Effect of cardamom extract administration on plasma inflammatory markers in different groups. A: C-reactive protein; B: Tumor necrosis factor-α; C: Interleukin-6. Values are mean ± SE, n = 6, means with different letters show significant difference between values at probability level of 0.05.

Administration of cardamom extract at both doses significantly attenuated oxidative stress and inflammatory responses in a dose-dependent manner.

Effect on nutritional and organ indices

CRS control rats showed significant reductions in all measured nutritional parameters compared with both the normal and treatment groups (Table 4). Heart and kidney indices were significantly elevated in the CRS control group.

Table 4 Effect of cardamom extract on nutritional parameters.

Parameters	Normal control	Cardiorenal control	Low-dose cardamom extract	High-dose cardamom extract
Initial body weight (g)	170.71a ± 2.76	170.71a ± 2.42	170.29a ± 0.99	170.57a ± 2.82
Final body weight (g)	233.71a ± 1.68	220.43b ± 2.99	229.43c ± 1.21	227.57c ± 1.70
Body weight Gain (g)	63.00a ± 2.33	49.71b ± 2.96	59.14c ± 1.03	57.00c ± 1.38
Total Food intake (g)	500.00a ± 4.49	497.14a ± 7.46	495.00c ± 6.44	493.57a ± 3.57
Food Efficiency Ratio	0.13a ± 0.005	0.10a ± 0.007	0.12c ± 0.002	0.12c ± 0.002
Kidney index	0.52a ± 0.011	0.95b ± 0.027	0.71b,d ± 0.024	0.63a,d ± 0.020
Heart index	0.35a ± 0.008	0.38b ± 0.009	0.36c ± 0.006	0.35d ± 0.005

^aP < 0.01.

^bP < 0.001, statistical significance is expressed vs normal control.

^cP < 0.01.

^dP < 0.001, P values are expressed vs cardiorenal-control. Values are mean ± SE, n = 6.

Cardamom extract treatment significantly improved nutritional parameters and reduced heart and kidney indices.

Molecular docking: Hippo signaling pathway

The molecular docking study examined interactions between phenolic compounds in cardamom extract and four proteins of the Hippo signaling pathway: MST1, LATS1, YAP, and TAZ. Binding affinities are summarized in Table 5.

Table 5 ∆G Binding affinity (kcal/mol) for each ligand with Hippo signaling pathway proteins.

Name of the ligand	MST1	LATS1	YAP	TAZ
	Binding free energy (kcal/mol)
Caffeic acid	-6.9	-6.1	-5.5	-4.8
Chlorogenic	-7.6	-7.7	-6.8	-5.8
Cinnamic acid	-6.3	-6	-5.7	-4.6
Coumaric acid	-6.5	-6.1	-5.8	-4.8
Ellagic acid	-8.7	-7.7	-6	-6.3
Ferulic acid	-7	-6.3	-5.5	-4.6
Gallic acid	-5.8	-6.2	-5	-4.5
Hesperetin	-8	-7.3	-6.6	-6.3
Methyl gallate	-5.8	-5.4	-4.9	-4.4
Naringenin	-7.8	-8.1	-6.5	-6.1
Quercetin	-7.4	-8.3	-6.5	-6
Rosmarinic	-7.9	-7.2	-6.5	-6.1
Rutin	-8.3	-8.9	-7.5	-7.4
Syringic acid	-5.9	-5.4	-5	-4.2
Vanillin	-5.7	-5.2	-4.6	-3.9

MST1: Mammalian sterile 20-like kinase 1, LATS1: Large tumor suppressor kinase 1, YAP: Yes-associated protein, TAZ: Transcriptional coactivator with PDZ-binding motif.

Rutin exhibited the strongest binding to LATS1, YAP, and TAZ, while both rutin and ellagic acid showed the highest affinities for MST1. Moderate binding was observed for quercetin, naringenin, and rosmarinic acid; syringic acid and vanillin showed the weakest interactions.

3D and 2D interaction maps for rutin (highest binding affinity) and rosmarinic acid (most abundant compound) are presented in Figures 5, 6, 7 and 8. Rutin formed multiple hydrogen bonds and hydrophobic interactions at key active site residues of all four proteins, although some unfavorable interactions were also noted. Similarly, rosmarinic acid formed hydrogen bonds and Pi-Pi interactions with MST1, LATS1, YAP, and TAZ, confirming potential regulatory activity through the Hippo pathway.

Figure 5 3D and 2D interactions between each compound with large tumor suppressor kinase 1. LATS1: Large tumor suppressor kinase 1.

Figure 6 3D and 2D interactions between each compound with mammalian sterile 20-like kinase 1. MST1: Mammalian sterile 20-like kinase 1.

Figure 7 3D and 2D interactions between each compound with PDZ-binding motif. TAZ: Transcriptional coactivator with PDZ-binding motif.

Figure 8 3D and 2D interactions between each compound with Yes-associated protein. YAP: Yes-associated protein.

DISCUSSION

Unhealthy dietary patterns, such as the Western diet, combined with a sedentary lifestyle, are major contributors to the global burden of cardiovascular and kidney diseases[1]. There is a well-established, bidirectional relationship between cardiac and renal dysfunctions. Renal impairment is an independent risk factor for the onset and progression of CVD, and vice versa[33]. The American Heart Association has classified the pathological interactions among the heart, kidneys, and metabolic systems under the term CRS, a condition with increasing global prevalence[11]. Identifying effective dietary supplements for CRS management is therefore a strategic priority for reducing disease-related morbidity and mortality.

CRS encompasses a complex, reciprocal interaction between cardiac and renal dysfunction, manifesting in both acute and chronic forms[34]. In the present study, CRS was experimentally induced in rats using a combination of a high-fat diet and intraperitoneal cisplatin injection (7.5 mg/kg body weight). This model was designed to mimic diet-induced chronic diseases affecting both the heart and kidneys. The CRS model displayed hallmark features of the syndrome: Dyslipidemia, elevated cardiac enzymes (CK and LDH), an increased coronary risk index, and a reduced cardioprotective index. Renal dysfunction was evidenced by elevated plasma urea, creatinine, and BUN, alongside reduced total protein, albumin, and creatinine clearance. These abnormalities were accompanied by significant increases in oxidative stress and inflammatory markers, and increased relative heart and kidney weights.

High caloric intake from the high-fat diet contributed to dysregulated lipid metabolism, as evidenced by altered lipid profiles. Similar findings have been reported by Rodríguez-Correa et al[35] and Siqueira et al[36]. Oxidative stress, reflected by elevated MDA and decreased catalase activity in both heart and kidney tissues, was likely driven by dyslipidemia and lipid peroxidation. This aligns with previous observations in similar CRS models[36,37]. Notably, increased oxidized LDL-cholesterol in the current study could promote monocyte-to-macrophage differentiation, endothelial damage, and microalbuminuria—events implicated in impaired glomerular filtration and kidney injury[38-40].

Inflammatory biomarkers—CRP, TNF-α, and IL-6—were also markedly elevated, underscoring their central role in the pathophysiology of CRS[33,41]. Both inflammation and oxidative stress are recognized as core mechanisms underlying CRS progression[42,43].

Cisplatin-induced nephrotoxicity, a known model for acute kidney injury, was corroborated by the observed increases in plasma urea, creatinine, urinary protein levels, and reductions in total protein, albumin, and creatinine clearance—strong indicators of glomerular damage[37,44]. Cisplatin accumulation in renal tubular cells at concentrations significantly exceeding extracellular levels further exacerbates nephrotoxicity[45]. The high-fat diet likely compounded these effects by promoting lipid accumulation and renal inflammation[10,46].

Oral administration of CEE at both low and high doses significantly improved all CRS-associated biochemical markers. The extract ameliorated dyslipidemia, normalized cardiac enzyme levels, improved both coronary risk and cardioprotective indices, and restored kidney function markers in both plasma and urine. Moreover, CEE effectively reduced oxidative stress and inflammatory mediators, indicating strong antioxidant and anti-inflammatory properties.

The in vitro DPPH assay confirmed the antioxidant potential of CEE, which was supported in vivo by reductions in MDA and increased catalase activity. CEE also demonstrated anti-inflammatory effects, evidenced by reductions in CRP, TNF-α, and IL-6. These protective effects can likely be attributed to the phenolic content of the extract, as identified in the HPLC profile—including rosmarinic acid, gallic acid, coumaric acid, hesperetin, and quercetin. These phenolics are well-documented for their antioxidant, anti-inflammatory, hypolipidemic, cardioprotective, and nephroprotective properties[1,7,8,47].

Phenolic compounds mitigate oxidative stress by scavenging reactive oxygen species, thus preventing LDL oxidation, atherosclerosis, and subsequent vascular damage. Oxidative stress also drives DNA damage, a common factor in chronic kidney and cardiovascular diseases[48]. Dietary polyphenols, such as those found in bergamot, have been shown to attenuate cardiorenal damage[43,49]. Rosmarinic acid, in particular, has demonstrated efficacy in reducing organ injury through its antioxidant and anti-inflammatory effects[49-51]. Other phenolics—such as caffeic acid[52], luteolin[53], apigenin[54], hesperetin[55], and naringenin[56]—have shown protective effects against cisplatin-induced nephrotoxicity and other renal injuries, suggesting a plausible mechanistic role for these compounds in the observed renoprotective effects of CEE. Anthocyanins red cabbage rich extract possessed cardioprotective potential in myocardial infarction rats[57]. Herbals and plants containing polyphenol (ferulic acid, caffeic acid, p-coumaric acid and chlorogenic acid) recorded cardioprotective effect in myocardial infarction-induced rabbits[58].

The molecular docking component of this study further explored potential mechanistic pathways by evaluating the interaction of CEE-derived phenolic compounds with the Hippo signaling pathway—a regulatory cascade involved in organ development, cellular proliferation, apoptosis, and fibrosis[18,19]. The core components of this pathway—MST1, LATS1, YAP, and TAZ—were analyzed for binding affinity with major phenolics identified in CEE. Inhibition of the Hippo pathway, which negatively regulates YAP/TAZ, allows these transcriptional co-activators to drive regeneration, survival, and anti-fibrotic responses[59]. Excessive activation of YAP/TAZ, however, is linked to maladaptive kidney repair and fibrosis[60,61]. Dysregulation of this pathway is also implicated in cardiac hypertrophy and CRS pathogenesis[19,62].

Molecular docking results indicated strong binding affinities between rosmarinic acid and rutin with all four Hippo pathway proteins. These interactions suggest that CEE may exert its therapeutic effects, at least in part, via modulation of the Hippo signaling pathway. This hypothesis is supported by similar findings in studies using hazel leaf extract polyphenols[62].

Limitations of the study

This study has some limitations. First, the molecular docking findings, while informative, are predictive in nature and do not confirm in vivo activity. Second, other relevant signaling pathways were not investigated, limiting a broader understanding of CEE’s mechanisms. Future research should include gene expression analyses of the Hippo pathway in heart and kidney tissues and explore additional pathways implicated in CRS. Functional studies in alternative animal models or human samples would also strengthen the translational potential of these findings which would pave the way for novel therapeutic interventions.

CONCLUSION

The results of this study provide compelling evidence for the cardioprotective and reno-protective effects of CEE as a natural dietary supplement rich in phenolic compounds. CEE effectively mitigated inflammation and oxidative stress—key drivers of cardiorenal syndrome—and improved lipid and kidney function profiles in a rat CRS model. Furthermore, molecular docking analysis suggests that the extract’s bioactive compounds may exert protective effects through modulation of the Hippo signaling pathway. These findings highlight the potential of CEE as a promising natural therapeutic candidate for the prevention or management of cardiorenal syndrome.