Paeonol induces vasodilatation in rat mesenteric artery via inhibiting extracellular Ca²⁺ influx and intracellular Ca²⁺ release

Natural L-type calcium channels antagonists from Chinese medicine

L-type calcium channels (LTCCs), the largest subfamily of voltage-gated calcium channels (VGCCs), are the main channels for Ca2+ influx during extracellular excitation. LTCCs are widely present in excitable cells, especially cardiac and cardiovascular smooth muscle cells, and participate in various Ca2+-dependent processes. LTCCs have been considered as worthy drug target for cardiovascular, neurological and psychological diseases for decades. Natural products from Traditional Chinese medicine (TCM) have shown the potential as new drugs for the treatment of LTCCs related diseases. In this review, the basic structure, function of LTCCs, and the related human diseases caused by structural or functional abnormalities of LTCCs, and the natural LTCCs antagonist and their potential usages were summarized.

Traditional uses, phytochemistry, pharmacology, and pharmacokinetics of the root bark of Paeonia x suffruticosa andrews: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Moutan Cortex (MC), commonly known as "Mu dan pi", refers to the dried root bark of Paeonia x suffruticosa Andrews and is broadly used as a traditional herbal medication in China, Japan, and Korea. For thousands of years, it has been utilized to treat female genital, extravasated blood, cardiovascular, and stagnant blood disorders.

AIM OF THE REVIEW

The purpose of this review article was to summarize information on the traditional uses, phytochemistry, pharmacology and pharmacokinetics of MC, as well as to outline the further research directions for the development of new drugs and the associations between traditional uses and pharmacological effects.

MATERIALS AND METHODS

The information involved in the study was gathered from a variety of electronic resources, including PubMed, Web of Science, ScienceDirect, SciFinder, China Knowledge Resource Integrated Database, and Google Scholar. The date was from 1992 to 2022.

RESULTS

Approximately 163 chemical compounds have been extracted and identified from MC, including monoterpenes, monoterpene glycosides, triterpenes, phenolics, flavonoids, volatile oils, alkaloids, and others. In these categories, the monoterpene glycosides and phenols being the most common. A wide variety of pharmacological effects have been described for MC crude extracts and active molecules, such as antioxidant, anti-inflammatory, antibacterial and antiviral, antitumor, antidiabetic, organ protection, and neuroprotective activities, as well as treating cardiovascular diseases. Pharmacokinetics has been also used in the study of MC, including its crude extracts or chemical constituents, in order to explore the therapeutic mechanism, direct clinically appropriate application and provide new ideas for the exploitation of innovative medicines.

CONCLUSION

Modern pharmacological research has demonstrated that MC, as a significant therapeutic resource, has the ability to heal a wide range of diseases, particularly female genital and cardiovascular problems. These researches propose therapeutic ideas for the development of novel MC medicines. Furthermore, preclinical and clinical study have verified several observed pharmacological properties related with the traditional usages of MC.

Biological Activities of Paeonol in Cardiovascular Diseases: A Review

Paeonol is a naturally existing bioactive compound found in the root bark of Paeonia suffruticosa and it is traditionally used in Chinese medicine for the prevention and management of cardiovascular diseases. To date, a great deal of studies has been reported on the pharmacological effects of paeonol and its mechanisms of action in various diseases and conditions. In this review, the underlying mechanism of action of paeonol in cardiovascular disease has been elucidated. Recent studies have revealed that paeonol treatment improved endothelium injury, demoted inflammation, ameliorated oxidative stress, suppressed vascular smooth muscle cell proliferation, and repressed platelet activation. Paeonol has been reported to effectively protect the cardiovascular system either employed alone or in combination with other traditional medicines, thus, signifying it could be a hypothetically alternative or complementary atherosclerosis treatment. This review summarizes the biological and pharmacological activities of paeonol in the treatment of cardiovascular diseases and its associated underlying mechanisms for a better insight for future clinical practices.

Pharmacokinetics, Tissue Distribution and Excretion of Paeonol and Its Major Metabolites in Rats Provide a Further Insight Into Paeonol Effectiveness

Paeonol is a major bioactive ingredient in Moutan Cortex (the root barks of Paeonia suffruticosa Andrews) and exhibited a wide range of bioactivities such as anti-inflammation, anti-oxidation, hypoglycemic effect, analgesic, and others. Even though paeonol has been proven to possess significant pharmacological and therapeutic effects, its pharmacokinetic properties are not satisfactory since it has been found to have a rapid clearance in vivo. In the present study, the pharmacokinetics, tissue distribution and excretion of paeonol and its major metabolites were investigated in rats by an efficient and specific UPLC-MS/MS method. The results indicated that paeonol was rapidly absorbed, extensively metabolized, and widely distributed in various tissues without long-term accumulation after oral administration to rats. The major distribution tissues of paeonol and its metabolites were kidney, liver, and heart. Paeonol was able to cross the blood-brain barrier but rapidly decreased after 10 min. The total excretion of four metabolites in urine, bile, and feces was approximately 35.0% within 24 h, and the metabolites were mainly excreted through the urine. In addition, the hypoglycemic activities of paeonol and its metabolites were investigated by a glucose uptake assay on TNF-α mediated insulin resistance in 3T3-L1 adipocytes. The results showed that paeonol and its major metabolites displayed hypoglycemic activities. This is the first comprehensive and systematic report on the pharmacokinetics of paeonol and its metabolites. This research provides an important basis for the clinical development and application of active metabolites.

Buyang Huanwu Decoction ameliorates ischemic stroke by modulating multiple targets with multiple components: In vitro evidences

Buyang Huanwu Decoction (BYHWD) is a well-known traditional Chinese medicine prescription which is used to treat ischaemic stroke and stroke-induced disabilities. However, the exact mechanism underlying BYHWD's amelioration of ischaemic stroke and its effective constituents remain unclear. The present study aimed to identify the effective constituents of BYHWD and to further explore its action mechanisms in the amelioration of ischaemic stroke by testing the activities of 15 absorbable chemical constituents of BYHWD with the same methods under the same conditions. The following actions of these 15 compounds were revealed: 1) Ferulic acid, calycosin, formononetin, astrapterocarpan-3-O-β-D-glucoside, paeonol, calycosin-7-O-β-D-glucoside, astraisoflavan-7-O-β-D-glucoside, ligustrazine, and propyl gallate significantly suppressed concanavalin A (Con A)-induced T lymphocyte proliferation; 2) Propyl gallate, calycosin-7-O-β-D-glucoside, paeonol, and ferulic acid markedly inhibited LPS-induced apoptosis in RAW264.7 cells; 3) Propyl gallate and formononetin significantly inhibited LPS-induced NO release; 4) Hydroxysafflor yellow A and inosine protected PC12 cells against the injuries caused by glutamate; and 5) Formononetin, astragaloside IV, astraisoflavan-7-O-β-D-glucoside, inosine, paeoniflorin, ononin, paeonol, propyl gallate, ligustrazine, and ferulic acid significantly suppressed the constriction of the thoracic aorta induced by KCl in rats. In conclusion, the results from the present study suggest that BYHWD exerts its ischaemic stroke ameliorating activities by modulating multiple targets with multiple components.

Paeonol Ameliorates Diabetic Renal Fibrosis Through Promoting the Activation of the Nrf2/ARE Pathway via Up-Regulating Sirt1

Diabetic nephropathy (DN) is rapidly becoming the leading cause of end-stage renal disease worldwide and a major cause of morbidity and mortality in patients of diabetes. The main pathological change of DN is renal fibrosis. Paeonol (PA), a single phenolic compound extracted from the root bark of Cortex Moutan, has been demonstrated to have many potential pharmacological activities. However, the effects of PA on DN have not been fully elucidated. In this study, high glucose (HG)-treated glomerular mesangial cells (GMCs) and streptozotocin (STZ)-induced diabetic mice were analyzed in exploring the potential mechanisms of PA on DN. Results in vitro showed that: (1) PA inhibited HG-induced fibronectin (FN) and ICAM-1 overexpressions; (2) PA exerted renoprotective effect through activating the Nrf2/ARE pathway; (3) Sirt1 mediated the effects of PA on the activation of Nrf2/ARE pathway. What is more, in accordance with the in vitro results, significant elevated levels of Sirt1, Nrf2 and downstream proteins related to Nrf2 were observed in the kidneys of PA treatment group compared with model group. Taken together, our study shows that PA delays the progression of diabetic renal fibrosis, and the underlying mechanism is probably associated with regulating the Nrf2 pathway. The effect of PA on Nrf2 is at least partially dependent on Sirt1 activation.

Chronic treatment with paeonol improves endothelial function in mice through inhibition of endoplasmic reticulum stress-mediated oxidative stress

Endoplasmic reticulum (ER) stress leads to endothelial dysfunction which is commonly associated in the pathogenesis of several cardiovascular diseases. We explored the vascular protective effects of chronic treatment with paeonol (2'-hydroxy-4'-methoxyacetophenone), the major compound from the root bark of Paeonia suffruticosa on ER stress-induced endothelial dysfunction in mice. Male C57BL/6J mice were injected intraperitoneally with ER stress inducer, tunicamycin (1 mg/kg/week) for 2 weeks to induce ER stress. The animals were co-administered with or without paeonol (20 mg/kg/oral gavage), reactive oxygen species (ROS) scavenger, tempol (20 mg/kg/day) or ER stress inhibitor, tauroursodeoxycholic acid (TUDCA, 150 mg/kg/day) respectively. Blood pressure and body weight were monitored weekly and at the end of treatment, the aorta was isolated for isometric force measurement. Protein associated with ER stress (GRP78, ATF6 and p-eIF2α) and oxidative stress (NOX2 and nitrotyrosine) were evaluated using Western blotting. Nitric oxide (NO) bioavailability were determined using total nitrate/nitrite assay and western blotting (phosphorylation of eNOS protein). ROS production was assessed by en face dihydroethidium staining and lucigenin-enhanced chemiluminescence assay, respectively. Our results revealed that mice treated with tunicamycin showed an increased blood pressure, reduction in body weight and impairment of endothelium-dependent relaxations (EDRs) of aorta, which were ameliorated by co-treatment with either paeonol, TUDCA and tempol. Furthermore, paeonol reduced the ROS level in the mouse aorta and improved NO bioavailability in tunicamycin treated mice. These beneficial effects of paeonol observed were comparable to those produced by TUDCA and tempol, suggesting that the actions of paeonol may involve inhibition of ER stress-mediated oxidative stress pathway. Taken together, the present results suggest that chronic treatment with paeonol preserved endothelial function and normalized blood pressure in mice induced by tunicamycin in vivo through the inhibition of ER stress-associated ROS.

Paeonol Protects Rat Heart by Improving Regional Blood Perfusion during No-Reflow

No-reflow phenomenon, defined as inadequate perfusion of myocardium without evident artery obstruction, occurs at a high incidence after coronary revascularization. The mechanisms underlying no-reflow is only partially understood. It is commonly caused by the swelling of endothelial cells, neutrophil accumulation, and vasoconstriction, which are all related to acute inflammation. Persistent no-reflow can lead to hospitalization and mortality. However, an effective preventive intervention has not yet been established. We have previously found that paeonol, an active extraction from the root of Paeonia suffruticosa, can benefit the heart function by inhibiting tissue damage after ischemia, reducing inflammation, and inducing vasodilatation. To further investigate the potential cardioprotective action of paeonol on no-reflow, healthy male Wistar rats were randomly divided into four groups: sham, ischemia-reperfusion (I/R) injury (left anterior descending coronary artery was ligated for 4 h followed by reperfusion for 8 h), and I/R injury pretreated with paeonol at two different doses. Real-time myocardial contrast echocardiography was used to monitor regional blood perfusion and cardiac functions. Our data indicated that paeonol treatment significantly reduces myocardial infarct area and no-reflow area (n = 8; p < 0.05). Regional myocardial perfusion (A·β) and cardiac functions such as ejection fraction, stroke volume, and fractional shortening were elevated by paeonol (n = 8; p < 0.05). Paeonol also lowered the serum levels of lactate dehydrogenase, creatine kinase, cardiac troponin T, and C-reactive protein, as indices of myocardial injury. Paeonol exerts beneficial effects on attenuating I/R-associated no-reflow injuries, and may be considered as a potential preventive treatment for cardiac diseases or post-coronary revascularization in which no-reflow often occurs.