Intravenous pretreatment with magnolol protects myocardium against stunning

Magnolol reduces myocardial injury induced by renal ischemia and reperfusion

BACKGROUND

Magnolol is a component of the bark of Magnolia officinalis, which is a traditional herbal remedy used in China. In this study, we investigated whether magnolol can reduce myocardial injury induced by renal ischemia and reperfusion (I/R).

METHODS

Renal I/R was elicited by a 60-minute occlusion of the bilateral renal arteries and a 24-hour reperfusion in Sprague-Dawley rats. Magnolol was administered intravenously 10 minutes before renal I/R to evaluate its effects on myocardial injury induced by renal I/R.

RESULTS

Renal I/R significantly increased the serum levels of creatine phosphokinase (CPK), lactate dehydrogenase (LDH), and cardiac troponin I and caused myocardial damage. The terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive nuclei and caspase-3 activation was significantly increased in the myocardium, indicating increase of apoptosis. Echocardiography revealed left ventricular dysfunction, as evidenced by reduction of left ventricular ejection fraction and left ventricular fractional shortening. Furthermore, serum levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 were significantly elevated, while the IL-10 level was suppressed. However, intravenously, pretreatment with magnolol at doses of 0.003 and 0.006 mg/kg 10 minutes before renal I/R significantly prevented the increases of CPK, LDH, and cardiac troponin I levels, as well as the histological damage and the apoptosis in the myocardium. Echocardiography showed significant improvement of left ventricular function. Furthermore, the increases in TNF-α, IL-1β, and IL-6 and the decrease in IL-10 were significantly limited, while Bcl-2 was increased and Bax was decreased in the myocardium. Phosphorylation of Akt and extracellular signal-regulated kinases 1 and 2 was increased, while phosphorylation of p38 and c-Jun N-terminal kinase was reduced.

CONCLUSION

Magnolol reduces myocardial injury induced by renal I/R. The underlying mechanisms for this effect might be related to modulation of the production of pro- and anti-inflammatory cytokines and the limiting of apoptosis.

The rich pharmacological activities of Magnolia officinalis and secondary effects based on significant intestinal contributions

ETHNOPHARMACOLOGICAL RELEVANCE

Magnolia officinalis Cortex (M. officinalis) is a traditional herbal drug widely used in Asian countries. Depending on its multiple biological activities, M. officinalis is used to regulate gastrointestinal (GI) motility, relieve cough and asthma, prevent cardiovascular and cerebrovascular diseases, and treat depression and anxiety.

AIM OF THE REVIEW

We aimed to review the abundant form of pharmacodynamics activity and potential mechanisms of action of M. officinalis and the characteristics of the internal processes of the main components. The potential mechanisms of local and distance actions of M. officinalis based on GI tract was provided, and it was used to reveal the interconnections between traditional use, phytochemistry, and pharmacology.

MATERIALS AND METHODS

Published literatures about M. officinalis and its main components were collected from several scientific databases, including PubMed, Elsevier, ScienceDirect, Google Scholar and Web of Science etc. RESULTS: M. officinalis was shown multiple effects including effects on digestive system, respiratory system, central system, which is consistent with traditional applications, as well as some other activities such as cardiovascular system, anticancer, anti-inflammatory and antioxidant effects and so on. The mechanisms of these activities are abundant. Its chief ingredients such as magnolol and honokiol can be metabolized into active metabolites in vivo, which can increase water solubility and bioavailability and exert pharmacological activity in the whole body. In the GI tract, M. officinalis and its main ingredient can regulate GI hormones and substance metabolism, protect the intestinal barrier and affect the gut microbiota (GM). These actions are effective to improve local discomfort and some distal symptoms such as depression, asthma, or metabolic disorders.

CONCLUSIONS

Although M. officinalis has rich pharmacological effects, the GI tract makes great contributions to it. The GI tract is not only an important place for absorption and metabolism but also a key site to help M. officinalis exert local and distal efficacy. Pharmacodynamical studies on the efficacies of distal tissues based on the contributions of the GI tract hold great potential for understanding the benefits of M. officinalis and providing new ideas for the treatment of important diseases.

A review of the phytochemistry and pharmacological activities of Magnoliae officinalis cortex

ETHNOPHARMACOLOGICAL RELEVANCE

Magnoliae Officinalis Cortex (the dried bark of Magnolia officinalis), a widely used traditional Chinese medicine, is also known as 'Houpo' (Chinese: ). Magnoliae Officinalis Cortex has a wide range of pharmacological effects and has been used to treat conditions such as abdominal distention, vomiting, diarrhea, food accumulation, Qi stagnation, constipation, phlegm and fluid retention and cough resulting from asthma.

AIMS OF THE REVIEW

The present paper reviews advances in research relating to the botany, ethnopharmacology, phytochemistry, pharmacology and toxicology of Magnoliae Officinalis Cortex. Prospects for future investigation and application of this herb are also discussed.

MATERIALS AND METHODS

Information on Magnoliae Officinalis Cortex was obtained from published materials, including ancient and modern books; PhD and MSc dissertations; monographs on medicinal plants; the pharmacopoeia of different countries and electronic databases, such as SCI finder, PubMed, Web of Science, ACS, Science Direct, Wiley, Springer, Taylor, AGRIS, Europe PMC, EBSCO host, CNKI, WanFang DATA, J-STAGE and Google Scholar.

RESULTS

More than 200 chemical compounds have been isolated from Magnoliae Officinalis Cortex, including lignans, phenylethanoid glycosides, phenolic glycosides, alkaloids, steroids and essential oils. The plant has been reported to have pharmacological effects on the digestive system, nervous system and cardiovascular and cerebrovascular systems, as well as antibacterial, anti-tumour, analgesic, anti-inflammatory and anti-oxidative effects.

CONCLUSIONS

Magnoliae Officinalis Cortex is an essential traditional Chinese medicine with pharmacological activities that mainly affect the digestive system, nervous system and cardiovascular and cerebrovascular systems. This review summarises its botany, ethnopharmacology, phytochemistry, pharmacology and toxicology. These information suggest that we should focus on the development of new drugs related to Magnoliae Officinalis Cortex, including specific constituents, so that Magnoliae Officinalis Cortex can exert greater therapeutic potential. Meanwhile, it is important to pay attention to the rational use of Magnolia resources, avoiding over-harvesting which could lead to lack of resources. We should also pursue research on Magnolia substitutes and develop resources such as Magnoliae Officinalis Flos and Magnolia Leaf.

Modulation of Rat Hepatic CYP1A and 2C Activity by Honokiol and Magnolol: Differential Effects on Phenacetin and Diclofenac Pharmacokinetics In Vivo

Honokiol (2-(4-hydroxy-3-prop-2-enyl-phenyl)-4-prop-2-enyl-phenol) and magnolol (4-Allyl-2-(5-allyl-2-hydroxy-phenyl)phenol) are the major active polyphenol constituents of Magnolia officinalis (Magnoliaceae) bark, which has been widely used in traditional Chinese medicine (Houpu Tang) for the treatment of various diseases, including anxiety, stress, gastrointestinal disorders, infection, and asthma. The aim of this study was to investigate the direct effects of honokiol and magnolol on hepatic CYP1A and 2C-mediated metabolism in vitro using rat liver microsomes and in vivo using the Sprague-Dawley rat model. Honokiol and magnolol inhibited in vitro CYP1A activity (probe substrate: phenacetin) more potently than CYP2C activity (probe substrate: diclofenac): The mean IC₅₀ values of honokiol for the metabolism of phenacetin and diclofenac were 8.59 μM and 44.7 μM, while those of magnolol were 19.0 μM and 47.3 μM, respectively. Notably, the systemic exposure (AUC and C_max) of phenacetin, but not of diclofenac, was markedly enhanced by the concurrent administration of intravenous honokiol or magnolol. The differential effects of the two phytochemicals on phenacetin and diclofenac in vivo pharmacokinetics could at least be partly attributed to their lower IC₅₀ values for the inhibition of phenacetin metabolism than for diclofenac metabolism. In addition, the systemic exposure, CL, and V_ss of honokiol and magnolol tended to be similar between the rat groups receiving phenacetin and diclofenac. These findings improve our understanding of CYP-mediated drug interactions with M. officinalis and its active constituents.

Magnolol Reduces Renal Ischemia and Reperfusion Injury via Inhibition of Apoptosis

Magnolol, a constituent of the bark of Magnolia officinalis, has been reported to decrease myocardial stunning and infarct size. In this study, we investigated whether magnolol can reduce renal ischemia and reperfusion (I/R) injury. Renal I/R, induced by a 60-min occlusion of bilateral renal arteries and a 24-h reperfusion, significantly increased blood urea nitrogen (BUN) and creatinine levels, and caused histological damage to the kidneys of rats. Apoptosis, as evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and caspase-3 activation, was significantly increased in the kidneys. Furthermore, serum levels of tumor necrosis factor-[Formula: see text] (TNF-[Formula: see text]), interleukin-1β (IL-1β), and interleukin-6 (IL-6) were significantly elevated, while the interleukin-10 (IL-10) level was suppressed. However, intravenous pretreatment with magnolol at doses of 0.003[Formula: see text]mg/kg and 0.006[Formula: see text]mg/kg 10[Formula: see text]min before renal I/R significantly limited the increases of BUN, creatinine, the histological damage, and apoptosis in the kidneys. The increases in TNF-[Formula: see text], IL-1β, and IL-6, and the decrease in IL-10 were also significantly inhibited. Additionally, magnolol increased Bcl-2 and decreased Bax in the kidneys. Phosphorylation of the prosurvival kinases, including Akt and extracellular signal-regulated kinases 1 and 2 (ERK1/2), was elevated, while phosphorylation of the pro-apoptotic mitogen-activated protein kinases, including p38 and c-Jun N-terminal kinase (JNK), was suppressed. In conclusion, magnolol reduces renal I/R injury. The underlying mechanisms for this effect might be related to the prevention of apoptosis, possibly via the inhibition of both extrinsic and intrinsic apoptotic pathways, including the reduction of TNF-[Formula: see text] production and the modulation of pro- and anti-apoptotic signaling elements.

Cardiovascular protection of magnolol: cell-type specificity and dose-related effects

Magnolia officinalis has been widely used in traditional Chinese medicine. Magnolol, an active component isolated from Magnolia officinalis, is known to be a cardiovascular protector since 1994. The multiplex mechanisms of magnolol on cardiovascular protection depends on cell types and dosages, and will be reviewed and discussed in this article. Magnolol under low and moderate dosage possesses the ability to protect heart from ischemic/reperfusion injury, reduces atherosclerotic change, protects endothelial cell against apoptosis and inhibits neutrophil-endothelial adhesion. The moderate to high concentration of magnolol mainly acts on smooth muscle cells and platelets. Magnolol induces apoptosis in vascular smooth muscle cells at moderate concentration and inhibits proliferation at moderate and high concentration. High concentration of magnolol also abrogates platelet activation, aggregation and thrombus formation. Magnolol also serves as an smooth muscle relaxant only upon the high concentration. Oral intake of magnolol to reach the therapeutic level for cardiovascular protection is applicable, thus makes magnolol an agent of great potential for preventing cardiovascular diseases in high-risk patients.

The protective efficacy of magnolol in hind limb ischemia-reperfusion injury

We investigated the protective effects of magnolol, an active antioxidant and free radical scavenger extracted from Magnolia officinalis, in a hind limb ischemic-reperfusion animal model. Adult male Sprague-Dawley rats were subjected to hind limb ischemic insult for 2 hours and were intravenously treated with magnolol at 0.01 mg/kg (n=8), 0.3 mg/kg (n=8) mg/kg or 1 mg/kg (n=8) mg/kg, or vehicle (n=8). At 24 h post-insult, the levels of nitrite/nitrate (NOX), malondialdehyde (MDA) and myeloperoxidase (MPO), as well as the degree of muscle damage, were assessed. Relative to controls, animals treated with magnolol (0.3 and 1 mg/kg) had attenuated muscular inflammation, edema and damage. Magnolol (0.3-1 mg/kg) also effectively reduced postischemic rises in the MDA, NOx and MPO levels (p<0.05, respectively). Magnolol administrated at 0.01 mg/kg, however, failed to protect against the ischemic-perfusion limb injury. In addition, magnolol (0.01-1 mg/kg) did not affect local muscular blood reperfusion or other physiological parameters, including hematocrit, glucose, arterial blood gases and mean arterial blood pressure. Thus, intravenous administration with magnolol at 0.3-1 mg/kg protects against ischemic limb damage in rats. This cytoprotection may be attributed to its antioxidant, anti-nitrosative and anti-inflammatory actions.

Effect of desflurane-induced preconditioning following ischemia-reperfusion on nitric oxide release in rabbits

Nitric oxide (NO) is the mediator of ischemic preconditioning against myocardial infarction. Desflurane produces anesthetic preconditioning to protect the myocardium against infarction. In the model of myocardial ischemia-reperfusion injury in rabbits, we evaluated desflurane-induced ischemic preconditioning and studied its mechanism of NO synthesis. Thirty-two male adult New Zealand white rabbits were anesthetized with intravenous (IV) 30 mg/kg pentobarbital followed by 5 mg/kg/hr infusion. All rabbits were subjected to 30 minutes (min) long lasting left anterior descending coronary artery (LAD) occlusion and three hours (hr) of subsequent reperfusion. Before LAD occlusion, the rabbits were randomly allocated into four groups for preconditioning treatment (eight for each group). The control group did not receive any preconditioning treatment. The desflurane group received inhaled desflurane 1.0 MAC (minimal end-tidal alveolar concentration) for 30 min that was followed by a 15 min washout period. The L-NAME-desflurane group received L-NAME (NG-nitro-L-arginine methyl ester; non-selective Nitric Oxide Synthetase (NOS) inhibitor) 1 mg/kg IV 15 min before 1.0 MAC inhaled desflurane for 30 min. The L-NAME group received L-NAME 1 mg/kg IV. Infarct volume, ventricular arrhythmia, plasma lactate dehydrogenase (LDH), creatine kinase (CK) activity and myocardial perfusion were recorded simultaneously. We have found that hemodynamic values of the coronary blood flow before, during, and after LAD occlusion were not significantly different among these four groups. For the myocardial ischemia-reperfusion injury animals, the infarction size (mean +/- SEM) in the desflurane group was significantly reduced to 18 +/- 3% in the area at risk as compared with 42 +/- 7% in the control group, 35 +/- 6 in the L-NAME group, and 34 +/- 4% in the L-NAME-desflurane group. The plasma LDH, CK levels, and duration of ventricular arrhythmia were also significantly decreased in the desflurane group during ischemia-reperfusion injury. Our results indicate that desflurane is an anesthetic preconditioning agent, which could protect the myocardium against the ischemia-reperfusion injury. This beneficial effect of desflurane on the ischemic preconditioning is probably through NO release since L-NAME abrogates the desflurane preconditioning effect.

Brief pressure overload of the left ventricle preconditions rabbit myocardium against infarction

BACKGROUND

Several nonischemic stimuli have been shown to precondition myocardium. We investigated cardioprotective effects and underlying mechanisms of brief pressure overload of the left ventricle in this study.

METHODS

Brief pressure overload of the left ventricle was achieved by two 10-minute partial snaring of the ascending aorta so that systolic left ventricular pressure was raised 50% above the baseline value. Ischemic preconditioning was elicited by two 10-minute coronary artery occlusions. Ten minutes after different pretreatments, myocardial infarction was induced by a 60-minute coronary artery occlusion followed by 3-hour reperfusion. Area at risk and myocardial infarct was determined by blue dye injection and triphenyl tetrazolium chloride staining.

RESULTS

The myocardial infarct size, expressed as percentage of area at risk, was significantly reduced in the pressure overload group (15.9% +/- 2.9%, p < 0.001, n = 9) as well as in the ischemic preconditioning group (14.9% +/- 1.9%, p < 0.001, n = 9) versus the control group (30.0% +/- 6.9%, n = 10). Pretreatment with a blocker of stretch-activated ion channels (gadolinium, 40 micromol/kg, intravenous) abolished the protection induced by pressure overload and ischemic preconditioning. Gadolinium itself did not alter the extent of infarct. There was no significant difference in hemodynamics, area at risk, and mortality among all groups of animals.

CONCLUSIONS

Brief pressure overload of the left ventricle by partial snaring of the ascending aorta preconditioned rabbit myocardium against infarction. The underlying mechanism might be related to activation of stretch-activated ion channels.

The ethnomedicinal uses of magnoliaceae from the southeastern United States as leads in drug discovery

In Asia and North America, members of the family Magnoliaceae have been and are presently used extensively in indigenous herbal medicine. Many taxa of the genus Magnolia produce lignans and sesquiterpene lactones, some with considerable in vitro bioactivities. This review focuses on selected natural products of the genus Magnolia from the southeastern United States with demonstrated biological and pharmacological properties. Ethnomedicinal data obtained from the Native Americans of the southeastern United States correlate well with the results of pharmacological investigations.