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ORIGINAL ARTICLE
Year : 2023 | Volume
: 9
| Issue : 3 | Page : 338-347
Dalbergia odorifera Essential oil protects against myocardial ischemia through upregulating nrf2 and inhibiting caspase signaling pathways in isoproterenol-induced rats
Can-Hong Wang1, Bao Gong1, Hui Meng1, Yu-Lan Wu1, Xiang-Sheng Zhao2, Jian-He Wei3
1 Hainan Provincial Key Laboratory of Resources Conservation and Development of Southern Medicine; Key Laboratory of State Administration of Traditional Chinese Medicine for Agarwood Sustainable Utilization, Hainan Branch of the Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Haikou, China
2 Hainan Provincial Key Laboratory of Resources Conservation and Development of Southern Medicine, Hainan Branch of the Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Haikou, China
3 Hainan Provincial Key Laboratory of Resources Conservation and Development of Southern Medicine; Key Laboratory of State Administration of Traditional Chinese Medicine for Agarwood Sustainable Utilization, Hainan Branch of the Institute of Medicinal Plant Development; Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine; Ministry of Education and National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
Correspondence Address:
Prof. Jian-He Wei
Hainan Branch of the Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 4, Yaogu 4 Road, Xiuying District, Haikou, Hainan Province 570311
China
Dr. Xiang-Sheng Zhao
Hainan Branch of the Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Haikou
China
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/2311-8571.372727
Objective: Dalbergia odorifera has long been used as a Chinese herbal medicine for the treatment of cardiovascular and cerebrovascular diseases. This study aimed to determine the potential myocardial protective effect and possible mechanism of action of D. odorifera essential oil (DOEO). Materials and Methods: The essential oil of D. odorifera was extracted by hydrodistillation. The cardioprotective effects of DOEO were examined by histopathological observation, myocardial enzyme detection, peroxidation, anti-oxidant level detection, and related protein expression. The compounds in the blood were identified by gas chromatography–mass spectrometry. Results: These results showed that DOEO had significant myocardial cell protection, with IC50 values ranging from 17.64 to 24.78 μg/mL in vitro. Compared to the myocardial ischemia group, the DOEO pretreatment groups had lower levels of myocardial injury, creatinine kinase, lactate dehydrogenase, alanine transaminase, aspartate transaminase, hydrogen peroxide, and nitric oxide, and higher levels of glutathione and superoxide dismutase. In addition, DOEO pretreatment significantly increased Na+-K+-ATPase and Ca2+-ATPase levels. Moreover, immunohistochemical experiments showed that DOEO remarkably increased the protein levels of NF-E2-related nuclear factor 2 (Nrf2) and heme oxygenase-1 (HO-1) and reduced the expression of apoptotic caspases, including caspase 3 and caspase 9. The main components of the blood were transnerolidol and nerolidol oxide. Overall, the study showed that DOEO displayed myocardial protection by upregulating the NF-E2-related nuclear factor- antioxidant response element (Nrf2-ARE) and caspase pathways. DOEO has a therapeutic effect on MI by inhibiting the oxidant and apoptotic effects. Conclusions: D. odorifera may be a potential candidate drug for treating myocardial ischemic injury.
Keywords: Anti-apoptosis, Anti-oxidation, Dalbergia odorifera essential oil, Isoproterenol, Myocardial ischemia
Dalbergia odorifera is a medicinal plant common to the Hainan province in China,[1] and its heartwood named “Jiangxiang” has been medically recorded to activate blood circulation, remove blood stasis, regulate qi, relieve pain, and its modern use, treat cardiocerebrovascular diseases including ischemia.[2],[3]D. odorifera has a wide range of modern pharmacological activities, including anti-inflammation,[4],[5] anti-oxidant,[6] angiogenic,[7] anti-platelet aggregation,[8] anti-tumor,[9],[10] and anti-microbial[8],[11] effects. The major components of D. odorifera are volatile oils and flavonoids.[12] The extracts, such as essential oils and monomeric compounds of D. odorifera display extensive biological activities. We speculate that D. odorifera could be used to treat myocardial ischemia (MI)-related diseases based on its traditional efficacy and modern applications. However, there are a few reports that reveal this effect of D. odorifera,[13] which suggests that in-depth anti-MI effects and mechanisms should be investigated further.
Cardiovascular diseases are one of the most serious diseases endangering human health worldwide, and MI has attracted increasing attention owing to its complex pathophysiological process.[14],[15],[16] The main cause is that the blood supply does not meet the demand of cardiomyocytes, leading to the rapid occurrence and development of MI.[17] Usually, ischemia leads to a disruption of the oxygen supply to cardiomyocytes, which can even lead to tissue injury.[18] The pathogenesis of MI is complex and diverse and includes inflammation,[19] oxidative-free radical damage,[20] and cell apoptosis.[21] There is currently no effective therapy for MI.[22] Traditional Chinese medicine (TCM) is a safe and effective unique treatment method that integrates pathogenesis, diagnosis, and treatment with overall consideration of the body.[23] Clinical trials have shown that TCM can have a potentially effective outcome on cardiac diseases.[24] Furthermore, we previously showed that D. odorifera essential oil (DOEO) provides significant myocardial protection.[25] Therefore, further studies are needed to determine the potential mechanisms of D. odorifera in MI.
This study aimed to evaluate for the first time the potential cardioprotective effect, including the anti-oxidative and anti-apoptotic effects, of DOEO on isoprenaline (ISO)-induced MI in rats, explore its possible mechanisms, and analyze the pharmacodynamic components of DOEO in its anti-MI effects. This study provides the theoretical and data evidence for the in-depth research and clinical application of D. odorifera in the prevention and treatment of myocardial diseases.
Materials and MethodsReagents
ISO was purchased from Harvest Pharma. Co., Ltd. (Shanghai, China). The kits for creatinine kinase (CK), lactate dehydrogenase (LDH), alanine transaminase (ALT), and aspartate transaminase (AST) were obtained from Biosino Bio-Tech. and Sci. Inc. (Beijing, China). hydrogen peroxide (H2O2), nitric oxide (NO), glutathione (GSH), superoxide dismutase (SOD), Na+-K+-ATPase, and Ca2+-ATPase were obtained from Jian Cheng Biotech Co. (Nanjing, China). Antibodies against the Nrf2-ARE and caspase pathways were purchased from Abcam (Cambridge, UK).
Materials
Two batches of heartwood samples of D. odorifera were collected from Dongfang, Hainan province, China and were identified by an expert in the field. Voucher specimens (Batch 1, No. YZS-DODF-01) were deposited at the Resource Center of the Hainan branch of the Institute of Medicinal Plant Development. The volatile oils of D. odorifera (DOEO1 and DOEO2) were prepared by hydrodistillation and dried over MgSO4 before storage in a refrigerator (4°C). The positive control drugs Qishen Yiqi Drops Pills (QSYQ, containing DOEO), Guanxin Danshen Drops Pills (GXDS, containing DOEO), and Suxiao Jiuxin Pills (SXJX) were purchased from Tasili Pharmaceutical Co., Ltd., Tianjin, China Harbin Yerui Pharmaceutical Co., Ltd., Haerbin, China and Tianjin Zhongxin Pharmaceutical Co., Ltd., respectively.
Cell lines and animals
H9C2 cells were purchased from the Shanghai Cell Bank, cultured, passaged, frozen in our laboratory, and stored in liquid nitrogen for later use.
Adult male standard deviation rats (200 ± 20 g) were provided by Changsha Tianqin Biotech. Co. LTD (SCXK 2019-0014, Hunan, China) and kept in an specific-pathogen-free (SPF) animal house. The rats were acclimated for 3 days before the experiments.
Protective effects of Dalbergia odorifera essential oils on myocardial cells in vitro
Isolation and culture of H9C2 cells H9C2 cells (100 μL) were inoculated in 96-well plates with 1 × 104 cells per well. Three replicates per well were set up and incubated in 5% CO2 for 24 h.
Measurement of myocardial protective activity by methyl thiazolyl tetrazolium (MTT) assay H9C2 cells was incubated with DOEOs (12.5, 25, and 50 μg/mL) in 5% CO2 for 22 h. The treated cells were incubated with 400 μM H2O2 for 2 h, in addition to the untreated control group. Next, 20 μL of CCK8 was added to each well. The optical density (OD) was measured at 450 nm after 1 h. The myocardial cell protection/proliferation rate was calculated for the DOEOs. The following formula was used: cell proliferation rate (%) = (treatment group OD value-model group OD value)/model group OD value × 100%.
Animal experiments
Fifty-six rats were divided into seven groups: normal, ISO, QSYQ (300 mg/kg), Guanxin Danshen Drops Pills (300 mg/kg), Suxiao Jiuxin Pills (300 mg/kg), DOEO1 (50 mg/kg), and DOEO2 (50 mg/kg). The normal and ISO groups were administered distilled water (20 mL/kg, once a day). The positive groups were administered oral drugs (20 mL/kg, once a day), and the DOEO treatment groups were intraperitoneally injected (10 mL/kg once a day) continuously for 7 days. Except the normal rats were subcutaneously injected with ISO at 2 and 1 mg/kg, continuously for 2 days to establish the MI model.[25] As there is no SPF animal room in our unit, the animal experiments were performed at the Hainan Institute of Materia Medica (Ethics committee approval number: 2020HL002).
Serum and heart tissue homogenate supernatant preparation
Rats were anesthetized with pentobarbital sodium (concentration: 10 mg/mL, volume: 0.3 mL/100 g, and dose: 30 mg/kg). The rats weighed approximately 250 g at the time of sacrifice. Blood (5 mL) was collected from the abdominal aorta. Serum was prepared by centrifugation and stored at 4°C.
Euthanasia was induced by cervical dislocation and death was verified by the absence of breathing. Heart tissue was removed and weighed, and saline was added at a ratio of 1:9 (M: V). The mixture was thoroughly homogenized and centrifuged at 3000 rpm for 15 min at 4°C and the homogenate supernatant was stored at − 80°C.
Levels of myocardial enzymes in the homogenate supernatant of the heart tissue
Myocardial injury was evaluated by measuring the levels of myocardial enzymes in the homogenate supernatant of the heart tissue. CK, LDH, ALT, and AST levels were measured following the kit instructions.
Detection of the oxidation index level in the homogenate supernatant of the heart tissue
The degree of myocardial oxidative damage was evaluated by measuring the peroxidation index in the heart tissue. The levels of NO, H2O2, GSH, and SOD in the homogenate supernatant of the heart tissue were detected following the kit instructions.
Determination of ATP levels in serum
The myocardial energy metabolism capacity was evaluated by measuring ATPase activity. The Na+/K+-ATPase and Ca2+-ATPase activities were detected following the kit instructions in serum.
Observation on pathological injury of myocardial tissue
The hearts were fixed in 4% paraformaldehyde, dehydrated, paraffin-embedded, and sectioned at 5 μm. The sections were stained with hematoxylin and eosin (H and E) and observed under a light microscope at × 200 magnification. Histological damage was evaluated using the LDI scoring system. The muscle-fiber tissue possessed the following scores: dissolution, 0–3; degeneration, 0–4; necrosis, 0–4; and inflammatory cell infiltration, 0–3.
Immunohistochemical analysis of the levels of proteins involved in anti-oxidation and apoptosis
The heart tissues were fixed in 4% paraformaldehyde solution, dehydrated, embedded, and sectioned. The 5-μm sections were treated with a buffered blocking solution for 15 min. The sections were co-incubated with a primary antibody against Nrf2, HO-1, caspase 3, and caspase 9 at 4°C overnight, and then co-incubated with a secondary antibody at the room temperature for 1 h. Thereafter, sections were washed and co-incubated with buffer in the darkness for 10 min. The sections were stained, observed, and photographed with a light microscope. Protein expression was analyzed using Image-ProPlus 6.0 Software (Media Cybernetics company, Silver Spring Maryland USA).
Analysis of pharmacodynamic components by gas chromatography–mass spectrometry
Sample preparation N-hexane (0.2 mL) was placed in a repeater pipette containing 200 μL serum. Then, the mixture was vigorously mixed for 3 min and centrifugated at 13000 rmp for 10 min at 4°C. The n-hexane layer was then transferred to a sample bottle for gas chromatography–mass spectrometry (GC-MS) analysis.
GC-MS conditions components were analyzed on a GC-MS (Agilent 7890A GC, 5975C quadrupole mass spectrometer, Agilent, California, USA) using a HP-INNOWax column (30 m × 0.25 mm, 0.25 μm). Helium was used as the carrier gas at a flow rate of 1.0 mL/min. The oven temperature was ramped from 100°C (held for 2 min) to 160°C at 3°C/min, then 190°C at 1°C/min, then 220°C at 5°C/min, and then 250 at 10°C/min. The injector temperature was 230°C. Samples (1 μL) were injected into the GC-MS in split mode (10:1). The MS used the electron ionization mode with an electron energy of 70 eV in the full-scan mode for the identification and selected ion monitoring mode to further confirm the compounds in the blood.
Statistical analysis
Data are shown as the mean ± standard error of the mean and were statistically analyzed using the SPSS 17 software (NASDAQ listed company, Chicago, USA). Differences between the groups were compared using the ANOVA and t-test. Statistical significance was set at P < 0.05.
ResultsThe protective effect of DOEOs on oxidative damage in H9C2 cardiomyocytes in vitro MTT screening results showed that the cell inhibition rate of the H2O2 group was 22.79%, while DOEO1 and 2 had better protective effects on myocardial cells. The proliferation rate of cardiomyocytes injured by H2O2 oxidation ranged from 22.85% to 45.67%, with IC50 values of 17.64 and 24.78 μg/mL.
Effect of DOEOs on myocardial enzymes in the homogenate supernatant
As shown in [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d, CK, LDH, ALT, and AST levels were increased in model rats. Comparatively, the CK, LDH, ALT, and AST levels were lower in the DOEO-treated groups. The effect of DOEOs was similar to that of the positive drugs, suggesting that DOEOs remarkably improved ISO-induced MI.
Figure 1: Effects of Dalbergia odorifera essential oil on myocardial enzymes in the homogenate supernatant of the heart tissue. (a) CK, (b) LDH, (c) ALT, and (d) AST. Each value represents the mean ± SD with n = 6, ##P < 0.01 versus the normal group, *P < 0.05, **P < 0.01 and ***P < 0.001 versus the model group. CK: Creatinine kinase, LDH: Lactate dehydrogenase, ALT: Alanine transaminase, AST: Aspartate transaminase, SD: standard deviationEffect of DOEOs on oxidation and antioxidant effects in the homogenate supernatant
As shown in [Figure 2]a, [Figure 2]b, [Figure 2]c, [Figure 2]d, H2O2 and NO levels were higher in the MI group, confirming the occurrence of oxidative damage induced by ISO. However, DOEOs significantly decreased the levels of H2O2 and NO. In contrast, GSH and SOD levels were significantly increased in the DOEO and positive groups, indicating the potential anti-oxidative effect of DOEOs.
Figure 2: Effects of DOEOs on the lipid peroxidation in the homogenate supernatant of the heart tissue. (a) H2O2, (b) NO, (c) GSH, and (d) SOD. Each value represents the mean ± SD with n = 6, #P < 0.05, ##P < 0.01 and ###P < 0.001 versus the normal group, *P < 0.05, **P < 0.01 and ***P < 0.001 versus the model group. DOEOs: Dalbergia odorifera essential oil, NO: Nitric oxide, GSH: Glutathione, SOD: SOD: Superoxide dismutase, SD: Standard deviationEffect of Dalbergia odorifera essential oils on ATPase in the homogenate supernatant
As shown in [Figure 3]a and [Figure 3]b, Na+-K+-ATPase and Ca2+-ATPase activities were markedly decreased in the MI group, confirming a decrease in myocardial metabolic function. However, DOEOs markedly increased the levels of Na+-K+-ATPase and Ca2+-ATPase (P < 0.01) compared to those in the model group, indicating the ability of DOEOs to improve myocardial function.
Figure 3: Effects of DOEOs on ATPase expression in the homogenate supernatant of the heart tissue. (a) Na ± K ± ATPase, (b) Ca2 ± ATPase. Each value represents the mean ± SD with n = 6, ##P < 0.01 versus the normal group, *P < 0.05 and **P < 0.01 versus the model group. DOEO: Dalbergia odorifera essential oil, SD: Standard deviationMyocardial histopathological examination by H and E staining
Myocardial injury was observed [Figure 4] to evaluate the damage to cardiac tissues. A thin and compact arrangement of striated muscle tissue was observed in the normal hearts [Figure 4]a. However, the muscle fibers in the striated muscle of cardiac tissues in the MI group showed dissolution, muscle fiber disorder, edema, degeneration, necrosis, inflammatory cell infiltration, numerous foam cells, hyperemia, and bleeding [Figure 4]b. However, the DOEO-treated groups showed obvious improvement compared to the MI group [Figure 4]c, [Figure 4]d, [Figure 4]e, [Figure 4]f, [Figure 4]g. The histopathological injury index histogram displays the results more intuitively [Figure 4h]. This indicates that the effect of DOEO was similar to that of the positive drugs.
Figure 4: Effects of DOEOs on the myocardial histopathological examination of the heart. (a) Normal group, (b) model group, (c) QSYQ group, (d) GXDS group, (e) SXJX group, (f) JXY1, (g) JXY2, and (h) pathological injury index. Each value represents the mean ± SD with n = 3, ###P < 0.001 versus the normal group, ***P < 0.001 versus the model group. DOEO: Dalbergia odorifera essential oil, SD: Standard deviationEffect of DOEOs on the protein expression of Nrf2 and HO-1 in the heart tissues
We detected the protein expression of the Nrf2-ARE pathway using immunohistochemistry to verify the myocardial protective mechanisms of DOEOs. As shown in [Figure 5]a and [Figure 5]b, the expressions of Nrf2 and HO-1 were higher in the DOEO-treated MI rats, indicating significant anti-oxidant damage through the up-regulation and activation of the Nrf2-ARE pathway.
Figure 5: Effects of DOEOs on the protein expression of Nrf2 and HO-1 in the heart tissue. (a) Nrf2 protein expression, (b) HO-1 protein expression, (A) normal group, (B) model group, (C) QSYQ group, (D) GXDS group, (E) SXJX group, (F) JXY1, (G) JXY2, and (H) relative protein expression. Each value represents the mean ± SD with n = 3, ###P < 0.001 versus the normal group, ***P < 0.001 versus the model group. SD: Standard deviationEffect of DOEOs on the protein expression of caspases 3 and 9 in the heart tissues
Next, we examined the protein expression of the caspase pathway to verify the myocardial protective mechanisms of DOEOs. As shown in [Figure 6]a and [Figure 6]b, the expression of caspases 3 and 9 was lower in the heart tissues of the DOEO-treated groups [Figure 6]c, [Figure 6]d, [Figure 6]e, [Figure 6]f, [Figure 6]g, [Figure 6]h, showing a significant anti-apoptotic effect through the regulation of the caspase pathway.
Figure 6: Effects of DOEOs on the protein expression of caspase 3 and caspase 9 in the heart tissue. (a) Caspase 3 protein expression, (b) caspase 9 protein expression, (A) normal group, (B) model group, (C) QSYQ group, (D) GXDS group, (E) SXJX group, (F) JXY1, (G) JXY2, and (H) relative protein expression. Each value represents the mean ± SD with n = 3, ### P < 0.001 versus the normal group, ***P < 0.001 versus the model group. DOEO: Dalbergia odorifera essential oil, SD: Standard deviationMaterial basis for the efficacy of Dalbergia odorifera essential oil in serum
Qualitative analysis of DOEO was performed using GC-MS. The main volatile compounds were identified based on the standard and mass spectra using the National Institute of Standards and Technology library (NIST 14). [Figure 7]a shows the typical total ion chromatograms for DOEO. Thirty-four volatile compounds were identified. Trans-nerolidol and nerolidol oxide (relative amounts >70%) was the main components of DOEO. The quantification of the main compound was expressed as the percentage of the peak area. The compounds, retention times, and relative amounts of each volatile compound are listed in [Table 1]. The constituents absorbed into the blood were also analyzed using GC-MS. The chromatograms of the blank serum [Figure 7]b and administered serum are shown in [Figure 7]c and [Figure 7]d. The main components of the blood were trans-nerolidol and nerolidol oxide. In addition, lilac alcohol epoxide, caryophyllene oxide, and epoxy-linalool oxide were detected in the blood, but their contents were low.
Table 1: Identification of compounds in Dalbergia odorifera essential oils
Figure 7: Material basis for the efficacy of DOEO in serum. (a) Chromatograms of DOEO, (b) chromatograms of blank serum, (c) chromatograms of medicated serum (scan mode), and (d) chromatograms of medicated serum (SIM mode). 1: Nerolidol oxide I, 2: Trans-nerolidol, 3: Nerolidol oxide II, 4: Nerolidol oxide III, 5: Nerolidol oxide IV. DOEO: Dalbergia odorifera essential oil Discussion D. odorifera has been used for centuries to treat heart disease[26],[27] and has been used in more than 100 proprietary Chinese medicines or compound preparations, such as Qi Shen Yi Qi pills, Guanxin Danshen pills, Xiang Dan injection, Tongxinluo capsules, etc.[28],[29],[30] ISO, a β-adrenergic agonist, can lead to irreversible ischemic myocardial injury if overused.[31],[32] The ISO-induced acute MI injury model is currently recognized as a classical model for MI injury research.[33] The main components of D. odorifera include flavonoids and volatile oils.[12] Some pharmacological studies have demonstrated that the flavonoids of D. odorifera have good bioactivity in coronary heart diseases.[7],[30] Studies have even shown that Chinese patent medicinal compounds containing DOEO have a significant therapeutic effect on coronary heart disease.[23],[26],[27],[28],[29] Furthermore, studies have revealed that DOEO is the main component responsible for the medicinal effects of D. odorifera.[34] However, there are few studies on the anti-myocardial ischemic effects of the volatile oils of D. odorifera. This study aimed to investigate the pharmacological components and mechanisms of action of DOEO against MI. Based on previous reports, the main components of DOEO are nerolidol, β-bisabolene, caryophyllene oxide, and 2, 4-dimethyl-2, 4-heptadienal.[35],[36],[37],[38] In this study, we also verified for the first time that DOEOs could protect against MI. Furthermore, DOEOs markedly inhibited oxidative and apoptotic effects, alleviating myocardial injury, and these effects were similar to those of the positive drugs. The mechanism of the protective effect of DOEO is related to the regulation of the Nrf2-ARE and caspase pathways. In addition, the main components in the blood were trans-nerolidol and nerolidol oxide.
The main characteristics of myocardial-ischemic injury include ultrastructural alterations, remodeling, and systolic and diastolic dysfunction. Higher levels of cardiac enzymes are important indicators that are clinically useful to evaluate MI. These enzyme leakages suggest myocardial cell membrane damage.[39] Myocardial injury and myocardial enzyme elevation were observed in the model rats in this study. DOEOs remarkably reduced the degree of injury and apoptosis. The lower levels of cardiac enzymes in the serum after DOEO treatment suggest that DOEOs have an obvious myocardial protective effect.
Anti-oxidation is an important mechanism in anti-MI.[33] A mass of H2O2 and hydroxyl radicals is produced during ischemic injury.[40],[41] However, a series of antioxidants can control the levels of reactive oxygen species and scavenge free radicals.[42] In addition, activation of Nrf2-ARE signaling is a major mechanism underlying the anti-oxidative and cytoprotective processes.[43] Nrf2 interacts with Keap1 under normal conditions, inhibiting ubiquitination degradation.[44],[45] In the case of exposure to free radicals or other stimulants, Keap1 degrades, activates, and translocates into the nucleus and then binds to AREs to generate an anti-oxidative response.[46],[47] In the present study, DOEOs significantly enhanced the protein expressions of Nrf2 and HO-1 [Figure 5], the levels of GSH, and the activity of SOD [Figure 4]c and [Figure 4]d and decreased the levels of H2O2 and NO [Figure 4]a and [Figure 4]b. Therefore, DOEOs scavenged free radicals and displayed anti-oxidative effects, indicating that DOEOs had myocardial protective effects through the upregulation of the Nrf2-ARE pathway.
Lower Na+/K+-ATPase activity induces myocyte death and dysfunction in cardiac tissues. In several pathological situations, myocardial injury occurs in the heart due to a lower level of Na+/K+-ATPase.[48],[49] Calcium (Ca) plays a major role in the occurrence and development of myocardial apoptosis. Moreover, Ca2+ homeostasis plays a key role in maintaining normal mitochondrial structure and function. Ca2+ overload induces MI injury, apoptosis, and death.[50],[51],[52] In this study, DOEOs significantly decreased ATPase activity, contributing to the restoration of cardiac apoptosis in heart tissues.
Moreover, the mechanisms of MI may be related to the increase in the protein expression of caspase families.[53],[54] Mitochondria-mediated apoptosis is an important mechanism of MI injury. Mitochondrial injury can promote cytochrome c diffusion into the cytoplasm, activating caspase 9, which ultimately activates caspase 3 and induces apoptosis.[55] Previous studies have demonstrated that the expression of caspases is significantly increased during MI. Therefore, the decrease expression of caspases 3 or 9 can relieve MI injury.[56],[57] The expression levels of these caspases were lower in the DOEO-treated groups, indicating the ability of DOEO to inhibit the occurrence of apoptosis.
ConclusionsThis study is the first to confirm the cardioprotective effect of DOEOs, and their effects were similar to those of the positive drugs. Our results indicated that the mechanisms of DOEOs were related to anti-oxidative effects and mitochondrial apoptosis. In addition, we preliminarily analyzed the anti-myocardial ischemic medicinal components of DOEO, trans-nerolidol, and nerolidol oxide. However, the in-depth mechanism of the anti-myocardial ischemic effect of DOEO and its medicinal components require further research and confirmation. In general, D. odorifera could be a good candidate drug to prevent and treat cardiac diseases.
Acknowledgments
This research was supported by the Hainan Province Science and Technology Special Fund (ZDYF2023SHFZ141, ZDYF2018123, ZDYF2021SHFZ077), the CAMS Innovation Fund for Medical Sciences (2021-I2M-1-032), Natural Science Foundation of Hainan Province, China (2019RC344).
Ethics approval and consent to participate
All animal experiments were approved by the Hainan Institute of Materials Medicine (Ethics Committee approval number: 2020HL002).
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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