From lab to nature: Recent advancements in the journey of gastroprotective agents from medicinal chemistry to phytotherapy

Peptic ulcer, affecting 10 % of the global population, results from imbalances in gastric juice pH and diminished mucosal defences. Key underlying factors are non-steroidal anti-inflammatory drugs (NSAIDs) and Helicobacter pylori infection, undermining mucosal resistance. Traditional treatments like proton pump inhibitors (PPIs) and histamine-2 (H2) receptor antagonists exhibit drawbacks such as adverse effects, relapses, and drug interactions. This review extensively explores the ethnomedicinal, synthetic and pharmacological facets of various potential peptic ulcer treatments. Rigorous methodologies involving electronic databases, and chemical structure verification via 'PubChem' and 'SciFinder' enhance the review's credibility. The provided information, spanning medicinal insights to intricate pharmacological mechanisms, establishes a robust groundwork for future research and the development of plant-derived or synthetic molecules for peptic ulcers, offering a promising alternative to conventional therapies.

Biphasic amplitude oscillator characterized by distinct dynamics of trough and crest

Biphasic amplitude dynamics (BAD) of oscillation have been observed in many biological systems. However, the specific topology structure and regulatory mechanisms underlying these biphasic amplitude dynamics remain elusive. Here, we searched all possible two-node circuit topologies and identified the core oscillator that enables robust oscillation. This core oscillator consists of a negative feedback loop between two nodes and a self-positive feedback loop of the input node, which result in the fast and slow dynamics of the two nodes, thereby achieving relaxation oscillation. Landscape theory was employed to study the stochastic dynamics and global stability of the system, allowing us to quantitatively describe the diverse positions and sizes of the Mexican hat. With increasing input strength, the size of the Mexican hat exhibits a gradual increase followed by a subsequent decrease. The self-activation of input node and the negative feedback on input node, which dominate the fast dynamics of the input node, were observed to regulate BAD in a bell-shaped manner. Both deterministic and statistical analysis results reveal that BAD is characterized by the linear and nonlinear dependence of the oscillation trough and crest on the input strength. In addition, combining with computational and theoretical analysis, we addressed that the linear response of trough to input is predominantly governed by the negative feedback, while the nonlinear response of crest is jointly regulated by the negative feedback loop and the self-positive feedback loop within the oscillator. Overall, this study provides a natural and physical basis for comprehending the occurrence of BAD in oscillatory systems, yielding guidance for the design of BAD in synthetic biology applications.

Natural Products: A Dependable Source of Therapeutic Alternatives for Inflammatory Bowel Disease through Regulation of Tight Junctions

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), can affect the entire gastrointestinal tract and mucosal layer and lead to intestinal damage and intestinal dysfunction. IBD is an inflammatory disease of the gastrointestinal tract that significantly impacts public health development. Monoclonal antibodies and other synthetic medications are currently used to treat IBD, but they are suspected of producing serious side effects and causing a number of other problems with long-term use. Numerous in vitro and in vivo studies have shown that organic macromolecules from plants and animals have an alleviating effect on IBD-related problems, and many of them are also capable of altering enzymatic function, reducing oxidative stress, and inhibiting the production of cytokines and release of proinflammatory transcriptional factors. Thus, in this paper, the natural products with potential anti-IBD activities and their mechanism of action were reviewed, with a focus on the protective effects of natural products on intestinal barrier integrity and the regulation of tight junction protein expression and remodeling. In conclusion, the insights provided in the present review will be useful for further exploration and development of natural products for the treatment of IBD.

Metabolic profile and dynamic characteristic of rhubarb during the vitro biotransformation by human gut microbiota

Rhubarb is a popular food in the world with laxative effects and steamed pieces of rhubarb (SP) have been widely applied to treatment of constipation in China due to its safety and effectiveness. In the study, metabolism in vitro was conducted to study influence of gut microbiota between raw pieces of rhubarb (RP) and SP. The results showed obvious classifications in metabolic profile between RP and SP were revealed by chemometric analysis, and prompted gut microbiota affected metabolism of rhubarb. Furthermore, 16 characteristic components were identified to distinguish the differences in metabolism. Finally, quantitative analysis of 14 components were verified the regulation of gut microbiota on rhubarb and discovered concentration of components affected the rate of metabolism. The study indicated regulation by gut microbiota could be probably responsible for differences of laxative effects between RP and SP, providing new perspective for exploring mechanisms of effectiveness in clinical application for SP.

Emodin - A natural anthraquinone derivative with diverse pharmacological activities

Emodin (1,3,8-trihydroxy-6-methyl-anthraquinone) is a natural anthraquinone derivative that is present in numerous globally renowned herbal medicines. It is recognised as a protein tyrosine kinase inhibitor and as an anticancer drug, active against various tumour cells, including lung, breast, liver, and ovarian cancer cells. Recently, its role in combination chemotherapy with various allopathic medicines, to minimize their toxicity and to enhance their efficacy, has been studied. The use of emodin in these therapies is gaining popularity, due to fewer associated side effects compared with standard anticancer drugs. Emodin has a broad therapeutic window, and in addition to its antineoplastic activity, it displays anti-ulcer, anti-inflammatory, hepatoprotective, neuroprotective, antimicrobial, muscle relaxant, immunosuppressive and antifibrotic activities, in both in vitro and in vivo models. Although reviews on the anticancer activity of emodin have been published, none coherently unite all the pharmacological properties of emodin, particularly the anti-oxidant, antimicrobial, antidiabetic, immunosuppressive and hepatoprotective activities of the compound. Hence, in this review, all of the available data regarding the pharmacological properties of emodin are explored, with particular emphasis on the modes of action of the molecule. In addition, the manuscript details the occurrence, biosynthesis and chemical synthesis of the compound, as well as its toxic effects on biotic systems.

Insights into forsythia honeysuckle (Lianhuaqingwen) capsules: A Chinese herbal medicine repurposed for COVID-19 pandemic

Background

In December 2019, a novel coronavirus, SARS-CoV-2 caused a series of acute atypical respiratory diseases worldwide. However, there is still a lack of drugs with clear curative effects, and the clinical trial research of vaccines has not been completely finished.

Purpose

LH capsules are approved TCM patent medicine that are widely used for the treatment of respiratory tract infectious diseases caused by colds and flu. On April 12, 2020, LH capsules and granules were officially repurposed by the China Food and Drug Administration (CFDA) for patients with mild COVID-19 based on their safety and efficacy demonstrated through multicentre, randomized, controlled clinical trials. We hope to conduct a comprehensive review of it through modern pharmacy methods, and try to explain its possible mechanism.

Methods

Using the full names of LH capsules Lianhuaqingwen, Lianhua Qingwen andSARS-COV-2, COVID-19 as the keywords of the search terms, systemically search for existing related papers in various databases such as Web of Science and PubMed. And completed the collection of clinical data in ClinicalTrials.gov and Chinese Clinical Trial Registry. Last but not least, we have sorted out the anti-inflammatory and antiviral mechanisms of LH capsules through literature and Selleck.

Results

This review systematically sorted out the active ingredients in LH capsules. Furthermore, the related pharmacological and clinical trials of LH capsule on SARS-CoV-2, IAV and IBV were discussed in detail. Moreover, the present review provides the first summary of the potential molecular mechanism of specific substances in LH capsules involved in resistance to SARS-COV-2 infection and the inhibition of cytokine storm syndrome (CSS) caused by IL-6.

Conclusion

This review summarizes the available reports and evidence that support the use of LH capsules as potential drug candidates for the prevention and treatment of COVID-19. However, TCM exerts its effects through multiple targets and multiple pathways, and LH capsules are not an exception. Therefore, the relevant mechanisms need to be further improved and experimentally verified.

Protective effects of curcumin against rat intestinal inflammation‑related motility disorders

Intestinal inflammation frequently occurs alongside dysmotility, which is characterized by altered myosin light chain phosphorylation levels. Curcumin, an active component from the ginger family, is reported to confer anti‑inflammatory effects. However, the effects of curcumin on both diarrhea and constipation associated inflammation remains to be elucidated. The present study was designed to investigate the effects of curcumin on diarrhea and constipation and to determine the related mechanisms. Sprague‑Dawley rats were used to establish diarrhea and constipation models via intracolonic acetic acid (4%) instillation or cold water gavage for 2 weeks, respectively. Blood samples were collected to measure the serum levels of the cytokines TNF‑α and IL‑1β using ELISA kits. Western blotting was performed to measure NF‑κB, RhoA, Rho‑related kinase 2, phosphorylated MLC₂₀, phosphorylated myosin phosphorylated target subunit 1, 130k Da‑MLC kinase (MLCK), c‑kit tyrosine kinase protein expression, and reverse transcription‑quantitative PCR was conducted to measure MLCK expression levels. The results indicated that curcumin reversed the elevations in the pro‑inflammatory cytokines IL‑1β and TNF‑α by inhibiting the NF‑κB pathway in rats with diarrhea and constipation. The results also indicated that myosin light chain (MLC) phosphorylation in intestinal smooth muscle was positively and negatively associated with the motility of inflammation‑related diarrhea and constipation in rats, respectively. Curcumin significantly reversed the increased MLC phosphorylation in the jejunum of the rats with diarrhea, significantly enhanced the reductions in inflammatory mediators, including TNF‑α and IL‑1β, of rats with constipation and significantly ameliorated the related hyper‑motility and hypo‑motility in rats with both diarrhea and constipation. In conclusion, the potential roles of the MLC kinase, c‑kit tyrosine and Rho A/Rho‑associated kinase 2 pathways, which are involved in curcumin‑induced amelioration of inflammation‑related diarrhea and constipation, were explored in the present study. Results from the present study suggested that curcumin has potential therapeutic value for treating intestinal inflammation and inflammation‑related motility disorders.

Engineered liposomes targeting the gut-CNS Axis for comprehensive therapy of spinal cord injury

Effective curative therapies for spinal cord injury (SCI), which is often accompanied by intestinal complications, are lacking. Potential therapeutic targets include astrocytes and their enteric nervous system counterpart, enteric glial cells (EGCs). Based on shared biomarkers and similar functions of both cell types, we designed an orally administered targeted delivery system in which the neuropeptide apamin, stabilized by sulfur replacement with selenium, was adopted as a targeting moiety, and the liposome surface was protected with a non-covalent cross-linked chitosan oligosaccharide lactate layer. The system effectively permeated through oral absorption barriers, targeted local EGCs and astrocytes after systemic circulation, allowing for comprehensive SCI therapy. Given the involvement of the gut-organ axis in a growing number of diseases, our research may shed light on new aspects of the oral administration route as a bypass for multiple interventions and targeted therapy.

Biophysical Characterization and Anticancer Activities of Photosensitive Phytoanthraquinones Represented by Hypericin and Its Model Compounds

Photosensitive compounds found in herbs have been reported in recent years as having a variety of interesting medicinal and biological activities. In this review, we focus on photosensitizers such as hypericin and its model compounds emodin, quinizarin, and danthron, which have antiviral, antifungal, antineoplastic, and antitumor effects. They can be utilized as potential agents in photodynamic therapy, especially in photodynamic therapy (PDT) for cancer. We aimed to give a comprehensive summary of the physical and chemical properties of these interesting molecules, emphasizing their mechanism of action in relation to their different interactions with biomacromolecules, specifically with DNA.

Aloe extract inhibits porcine epidemic diarrhea virus in vitro and in vivo

Porcine epidemic diarrhea virus (PEDV) causes severe diarrhoea and high mortality in neonatal suckling piglets, leading to significant economic losses to the swine industry. Currently there are no adequate control strategies against circulating PEDV variants, making an urgent need to exploit effect antiviral therapies to compensate for vaccines. Here, we report that Aloe extract can hamper completely the proliferation of PEDV at a non-cytotoxic concentration of 16 mg/mL determined by CCK-8 assay in Vero and IPEC-J2 cells in vitro. Furthermore, time course analysis indicated the extract exerted its inhibition at the late stage of the viral life cycle. Moreover, we also confirmed that the extract can inactivated PEDV directly but did not act on the viral genome and S1 protein. Importantly, the extract at a relatively safety concentration of 100 mg/kg of body weight, which was confirmed in mice, could reduce virus load and pathological change in intestinal tract of pigs and protect newborn piglets from lethal challenge with highly pathogenic PEDV variant GDS01 infection, indicating that Aloe extract efficiently inhibited PEDV infection in vivo. Collectively, our findings suggest that the aqueous extract from the Aloe could inhibit PEDV replication in vitro and in vivo and might be a good target for drug development against PEDV.

Gastrointestinal Motility and Improvement Efficacy of Shenhuang Plaster Application on Shenque: Identification, Evaluation, and Mechanism

Constipation, a gastrointestinal function disorder, is one of the side effects of paclitaxel (PTX) chemotherapy. Shenhuang plaster (SHP) application on the Shenque acupoint promotes gut motility in clinical settings. In this study, we elucidated the ingredients in SHP and evaluated its effects on PTX-induced constipation using a tumour-bearing mouse model. SHP was prepared using the traditional Chinese plaster preparation method. The ingredients were analysed using UPLC-MS/MS and identified via screening in a standard drug database. The gastrointestinal transit was evaluated by the movement of a fluorescein-labelled dextran in the gastrointestinal tract. A histological study of the mucosa was carried out after haematoxylin and eosin staining. mRNA expression was assessed using real-time RT-PCR, and the foetal microbiota composition was elucidated through 16 s rDNA sequencing and BLAST analysis. Our results indicate that the application of SHP attenuated weight gain inhibition by PTX; however, no inhibitory effect was observed on tumour growth. PTX-induced sluggish intestine, villus, and mucosal base layer damage were significantly improved following the application of SHP. Further, SHP enhanced the stimulation efficiency of PTX on TLR4 and its downstream cytokines, as well as on IL-1β in intestinal cells. SHP combined with PTX reshaped the microbiota, which showed beneficial effects on health. Hence, these results provide evidence that SHP alleviates PTX-induced constipation and intestinal morphological damage but augments the effects of PTX on the expression of cytokines in the TLR4 pathway and IL-1β. Therefore, we propose that SHP stimulates the host immune response to eradicate cancer cells.

Effect of Emodin on Preventing Postoperative Intra-Abdominal Adhesion Formation

BACKGROUND

Postoperative intra-abdominal adhesions are a major complication after abdominal surgery. Although various methods have been used to prevent and treat adhesions, the effects have not been satisfactory. Emodin, a naturally occurring anthraquinone derivative and an active ingredient in traditional Chinese herbs, exhibits a variety of pharmacological effects. In our study, we demonstrated the effect of emodin treatment on preventing postoperative adhesion formation.

MATERIALS AND METHODS

A total of 48 rats were divided into six groups. Abdominal adhesions were created by abrasion of the cecum and its opposite abdominal wall. In the experimental groups, the rats were administered daily oral doses of emodin. On the seventh day after operation, the rats were euthanized, and blood and pathological specimens were collected. Abdominal adhesion formation was evaluated by necropsy, pathology, immunohistochemistry, Western blot, and enzyme-linked immunosorbent assay analyses.

RESULTS

Abdominal adhesions were markedly reduced by emodin treatment. Compared with the control group, collagen deposition was reduced and the peritoneal mesothelial completeness rate was higher in the emodin-treated groups. Emodin had anti-inflammatory effects, reduced oxidative stress, and promoted the movement of the intestinal tract (P < 0.05).

CONCLUSION

Emodin significantly reduced intra-abdominal adhesion formation in a rat model.

Berberine Depresses Contraction of Smooth Muscle via Inhibiting Myosin Light-chain Kinase

BACKGROUND

Berberine is a natural isoquinoline alkaloid possessing various pharmacological effects, particularly apparent in the treatment of diarrhea, but the underlying mechanism remains unclear. Smooth muscle myosin light-chain kinase (MLCK) plays a crucial role in the smooth muscle relaxation-contraction events, and it is well known that berberine can effectively depress the contraction of smooth muscle. Hence, whether berberine could inhibit MLCK and then depress the smooth muscle contractility might be researched.

OBJECTIVE

The purpose of this study is to investigate the effects of berberine on MLCK. Based on this, the contractility of gastro-intestine, catalysis activity of MLCK, and molecular docking are going to be evaluated.

MATERIALS AND METHODS

The experiment of smooth muscle contraction was directly monitored the contractions of the isolated gastrointestine by frequency and amplitude at different concentration of berberine. The effects of berberine on MLCK were measured in the presence of Ca2+-calmodulin, using the activities of 20 kDa myosin light chain (MLC20) phosphorylation, and myosin Mg2+-ATPase induced by MLCK. The docking study was conducted with expert software in the meantime.

RESULTS

The phosphorylation of myosin and the Mg2+-ATPase activity is reduced in the presence of berberine. Moreover, berberine could inhibit the contractibility of isolated gastric intestine smooth muscle. Berberine could bind to the ATP binding site of MLCK through hydrophobic effect and hydrogen bonding according to the docking study.

CONCLUSION

The present work gives a deep insight into the molecular mechanism for the treatment of diarrhea with berberine, i.e., berberine could suppress the contractility of smooth muscle through binding to MLCK and depressing the catalysis activity of MLCK.

SUMMARY

Berberine significantly reduced the amplitude of contraction in isolated duodenum and gastric strips in ratsBerberine inhibited the phosphorylated extents of MLC20 and Mg2+-ATPase activity of phosphorylated myosin induced by MLCKBerberine binds to the ATP binding site of MLCK by hydrophobic effect and hydrogen bondingBerberine may modulate contraction of smooth muscle by inhibiting MLCK. Abbreviations used: MLCK: Myosin light chain kinase; MLC20: 20 KDa regulating myosin light chain; CaM: Calmodulin.

Ameliorative effects of atractylodin on intestinal inflammation and co-occurring dysmotility in both constipation and diarrhea prominent rats

Intestinal disorders often co-occur with inflammation and dysmotility. However, drugs which simultaneously improve intestinal inflammation and co-occurring dysmotility are rarely reported. Atractylodin, a widely used herbal medicine, is used to treat digestive disorders. The present study was designed to characterize the effects of atractylodin on amelioration of both jejunal inflammation and the co-occurring dysmotility in both constipation-prominent (CP) and diarrhea-prominent (DP) rats. The results indicated that atractylodin reduced proinflammatory cytokines TNF-α, IL-1β, and IL-6 in the plasma and inhibited the expression of inflammatory mediators iNOS and NF-kappa B in jejunal segments in both CP and DP rats. The results indicated that atractylodin exerted stimulatory effects and inhibitory effects on the contractility of jejunal segments isolated from CP and DP rats respectively, showing a contractile-state-dependent regulation. Atractylodin-induced contractile-state-dependent regulation was also observed by using rat jejunal segments in low and high contractile states respectively (5 pairs of low/high contractile states). Atractylodin up-regulated the decreased phosphorylation of 20 kDa myosin light chain, protein contents of myosin light chain kinase (MLCK), and MLCK mRNA expression in jejunal segments of CP rats and down-regulated those increased parameters in DP rats. Taken together, atractylodin alleviated rat jejunal inflammation and exerted contractile-state-dependent regulation on the contractility of jejunal segments isolated from CP and DP rats respectively, suggesting the potential clinical implication for ameliorating intestinal inflammation and co-occurring dysmotility.

Cremophor EL-based nanoemulsion enhances transcellular permeation of emodin through glucuronidation reduction in UGT1A1-overexpressing MDCKII cells

Oral emodin, a natural anthraquinone and active component of many herbal medicines, is poorly bioavailable because of extensive first-pass glucuronidation. Here we aimed to prepare emodin nanoemulsion (EMO-NE) containing cremophor EL, and to assess its potential for enhancing transcellular absorption of emodin using UGT1A1-overexpressing MDCKII cells (or MDCK1A1 cells). EMO-NE was prepared using a modified emulsification technique and subsequently characterized by particle size, morphology, stability, and drug release. MDCKII cells were stably transfected with UGT1A1 using the lentiviral transfection approach. Emodin transport and metabolism were evaluated in Transwell-cultured MDCK1A1 cells after apical dosing of EMO-NE or control solution. The obtained EMO-NE (116 ± 6.5 nm) was spherical and stable for at least 2 months. Emodin release in vitro was a passive diffusion-driven process. EMO-NE administration increased the apparent permeability of emodin by a 2.3-fold (p<0.001) compared to the pure emodin solution (1.2 × 10(-5) cm/s vs 5.3 × 10(-6) cm/s). Further, both apical and basolateral excretion of emodin glucuronide (EMO-G) were significantly decreased (≥56.5%, p<0.001) in EMO-NE group. This was accompanied by a marked reduction (57.4%, p<0.001) in total emodin glucuronidation. It was found that the reduced glucuronidation was due to inhibition of cellular metabolism by cremophor EL. Cremophor EL inhibited UGT1A1-mediated glucuronidation of emodin using the mixed-type inhibition mechanism. In conclusion, cremophor EL-based nanoemulsion greatly enhanced transcellular permeation of emodin through inhibition of UGT metabolism. This cremophor EL-based nanoformulation may be a promising strategy to improve the oral bioavailability of emodin.

Rhubarb to Facilitate Placement of Nasojejunal Feeding Tubes in Patients in the Intensive Care Unit

BACKGROUND

Prokinetic agents are sometimes needed to aid in the placement of nasojejunal feeding tubes in patients at risk of malnutrition. The objective of the present study was to evaluate the feasibility of rhubarb as a new prokinetic agent to replace metoclopramide and erythromycin in the placement of nasojejunal feeding tubes.

MATERIALS AND METHODS

Ninety-four patients who required jejunal feeding tube insertion were included. They were divided into rhubarb (n = 34), metoclopramide (n = 31), and erythromycin groups (n = 29), depending on the use of rhubarb, metoclopramide, and erythromycin as the prokinetic agent. The jejunal feeding tube insertions were performed at the bedside. An abdominal x-ray was taken as the gold standard to determine the position of the tube. Cases in which insertion failed in either group were subjected to a second insertion attempt using rhubarb as the prokinetic agent.

RESULTS

The success rates in the rhubarb, metoclopramide, and erythromycin groups were 91.2%, 87.1%, and 89.7%, respectively. The difference in the success rates was not statistically significant (P = .916). The insertion times in the rhubarb, metoclopramide, and erythromycin groups were 16.0 ± 1.9 minutes, 18.0 ± 1.9 minutes, and 18.8 ± 2.2 minutes, respectively. The insertion time in the rhubarb group was significantly shorter than those in metoclopramide and erythromycin groups (P < .001). No side effects were noted in the rhubarb group.

CONCLUSIONS

Rhubarb could serve as an effective prokinetic agent to promote the insertion of nasojejunal feeding tubes.

Amelioration of hypoxia and LPS-induced intestinal epithelial barrier dysfunction by emodin through the suppression of the NF-κB and HIF-1α signaling pathways

Intestinal barrier dysfunction occurs in critical illnesses and involves the inflammatory and hypoxic injury of intestinal epithelial cells. Researchers are still defining the underlying mechanisms and evaluating therapeutic strategies for restoring intestinal barrier function. The anti-inflammatory drug, emodin, has been shown to exert a protective effect on intestinal barrier function; however, its mechanisms of action remain unknown. In this study, we investigated the protective effects of emodin on intestinal barrier function and the underlying mechanisms in intestinal epithelial cells challenged with lipopolysaccharide (LPS) and hypoxia/reoxygenation (HR). To induce barrier dysfunction, Caco-2 monolayers were subjected to HR with or without LPS treatment. Transepithelial electrical resistance and paracellular permeability were measured to evaluate barrier function. The expression of the tight junction (TJ) proteins, zonula occludens (ZO)-1, occludin, and claudin-1, as well as that of hypoxia-inducible factor (HIF)-1α, phosphor-IκB-α, phosphor-nuclear factor (NF)-κB p65 and cyclooxygenase (COX)-2 was determined by western blot analysis. The results revealed that emodin markedly attenuated the decrease in transepithelial electrical resistance and the increase in paracellular permeability in the Caco-2 monolayers treated with LPS and subjected to HR. Emodin also markedly alleviated the damage caused by LPS and HR (manifested by a decrease in the expression of the TJ protein, ZO-1), and inhibited the expression of HIF-1α, IκB-α, NF-κB and COX-2 in a dose-dependent manner. In conclusion, our data suggest that emodin attenuates LPS- and HR-induced intestinal epithelial barrier dysfunction by inhibiting the HIF-1α and NF-κB signaling pathways and preventing the damage caused to the TJ barrier (shown by the decrease in the expression of ZO-1).

The synergism mechanism of Rhubarb Anthraquinones on constipation elucidated by comparative pharmacokinetics of Rhubarb extract between normal and diseased rats

In the study, it was hypothesized that Rhubarb Anthraquinones synergistically enhanced the purgative effect on constipation rat from the direct and indirect pathway at the same time. A validated HPLC method was successfully applied to elucidate the synergism mechanism from pharmacokinetics aspect after oral administration of Rhubarb extract with a dose of 0.25 g to normal and constipation rats. Comparison of the pharmacokinetic data of normal and constipation rats showed that there were significant differences (p < 0.05) in the main pharmacokinetic parameters. The C max and AUC of emodin in constipation rats were about ten times that of normal rats, while the t 1/2 was remarkably decreased (p < 0.05). However, a significant decrease (p < 0.05) in AUC value for aloe-emodin and rhein was observed in model group compared with normal group. The results may be attributed to the direct action of aloe-emodin and rhein on intestinal cell membranes and the indirect action of emodin on bowel movement through the adjustment by nervous system.

Characteristics of diprophylline-induced bidirectional modulation on rat jejunal contractility

In this study, we propose that diprophylline exerts bidirectional modulation (BM) on the isolated rat jejunal segment depending on its contractile state. The results supported the hypothesis. Diprophylline (20 µM) exerted stimulatory effects on the contractility of jejunal segment in six low contractile states while inhibitory effects in six high contractile states, showing the characteristics of BM. Diprophylline-induced stimulatory effect was significantly blocked by atropine, indicating the correlation with cholinergic activation. Diprophylline-induced inhibitory effect was partially blocked by phentolamine, propranolol, and L-N-Nitro-Arginine respectively, indicating their correlation with sympathetic activation and nitric oxide-mediated relaxing mechanisms. Diprophylline-induced BM was abolished by tetrodotoxin or in a Ca²⁺ free condition or pretreated with tyrosine kinase inhibitor imatinib, suggesting that diprophylline-induced BM is Ca²⁺ dependent, and that it requires the presence of enteric nervous system as well as pacemaker activity of interstitial cells of Cajal. Diprophylline significantly increased the reduced MLCK expression and myosin extent in constipation-prominent rats and significantly decreased the increased MLCK expression and myosin extent in diarrhea-prominent rats, suggesting that the change of MLCK expression may also be involved in diprophylline-induced BM on rat jejunal contractility. In summary, diprophylline-exerted BM depends on the contractile states of the jejunal segments, requires the presence of Ca²⁺, enteric nervous system, pacemaker activity of interstitial cells of Cajal, and MLCK-correlated myosin phosphorylation. The results suggest the potential implication of diprophylline in relieving alternative hypo/hyper intestinal motility.

Life-threatening hypokalemic paralysis in a young bodybuilder

We report a case of life-threatening hypokalemia in a 28-year-old bodybuilder who presented with sudden onset bilateral lower limbs paralysis few days after his bodybuilding competition. His electrocardiogram (ECG) showed typical u-waves due to severe hypokalemia (serum potassium 1.6 mmol/L, reference range (RR) 3.5–5.0 mmol/L). He was admitted to the intensive care unit (ICU) and was treated with potassium replacement. The patient later admitted that he had exposed himself to weight loss agents of unknown nature, purchased online, and large carbohydrate loads in preparation for the competition. He made a full recovery after a few days and discharged himself from the hospital against medical advice. The severe hypokalemia was thought to be caused by several mechanisms to be discussed in this report. With the ever rising number of new fitness centers recently, the ease of online purchasing of almost any drug, and the increasing numbers of youngsters getting into the bodybuilding arena, clinicians should be able to recognize the possible causes of sudden severe hypokalemia in these patients in order to revert the pathophysiology.

Effects of ginsenosides on rat jejunal contractility

CONTEXT

Ginsenosides are primary active ingredients of ginseng, which are believed to have various health benefits. It is found that the biotransformation of ginsenosides mainly takes place in the gastrointestinal tract and the information about ginsenosides-exerted effects on intestinal contractility is not sufficient.

AIMS

The present study proposed that ginsenosides could exert stimulatory or inhibitory effects on intestinal motility depending on the assay condition-related intestinal contractile states and was to characterize the effects of ginsenosides on intestinal motility.

METHODS

Jejunal contractility determination, Western blotting analysis, and real-time polymerase chain reaction were performed to test the effects of total ginsenosides isolated from Panax ginseng C. A. Mey (Araliaceae) root.

RESULTS

The results showed that ginsenosides at the fixed concentration of 20 mg/L exerted bidirectional regulation (BR) on the contractility of isolated jejunal segment (IJS), depending on the contractile states. The contractility of IJS was increased by ginsenosides in low contractile states, which were correlated to the cholinergic activation, and the contractility of IJS was decreased by ginsenosides in high contractile states, which were correlated to the adrenergic activation and nitric oxide related mechanisms. Ginsenosides-induced BR was abolished in the absence of Ca(2+) or by using tetrodotoxin, implicating the requirement of Ca(2+) and the enteric nervous system. Effects of ginsenosides on myosin light chain phosphorylation and the mRNA expression of myosin light chain kinase were also bidirectional.

DISCUSSION AND CONCLUSION

Results suggest that ginsenosides may have the potential clinical implication for reliving the symptoms of alternative hypo- and hyper-intestinal motility.

Characteristics of nobiletin-induced effects on jejunal contractility

Nobiletin, a citrus polymethoxylated flavone, exhibits multiple biological properties including anti-inflammatory, anti-carcinogenic, and anti-insulin resistance effects. The present study found that nobiletin exerted significant stimulatory effects on the contractility of isolated rat jejunal segments in all 6 different low contractile states, and meanwhile significant inhibitory effects in all 6 different high contractile states, showing characteristics of bidirectional regulation (BR). Nobiletin-exerted BR on jejunal contractility was abolished in the presence of c-kit receptor tyrosine kinase inhibitor imatinib or Ca(2+) channel blocker verapamil. In the presence of neuroxin tetrodotoxin, nobiletin only exerted stimulatory effects on jejunal contractility in both low and high contractile states. Hemicholinium-3 and atropine partially blocked nobiletin-exerted stimulatory effects on jejunal contractility in low-Ca(2+)-induced low contractile state. Phentolamine or propranolol or l-NG-nitro-arginine significantly blocked nobiletin-exerted inhibitory effects on jejunal contractility in high-Ca(2+)-induced high contractile state respectively. The effects of nobiletin on myosin light chain kinase (MLCK) mRNA expression, MLCK protein content, and myosin light chain phosphorylation extent were also bidirectional. In summary, nobiletin-exerted BR depends on the contractile states of rat jejunal segments. Nobiletin-exerted BR requires the enteric nervous system, interstitial cell of Cajal, Ca(2+), and myosin phosphorylation-related mechanisms.

Purgative components in rhubarbs: adrenergic receptor inhibitors linked with glucose carriers

Rhubarbs and their extractives have been used as cathartic for many years. There have been numerous breakthroughs in the pharmacological research of the drug. However, as the key point of the mechanism, the targets of the effective components still remain unclear. In this paper, with an in vitro system of isolated intestine, we found that both the rhubarb extractives and the anthraquinone derivatives can antagonize the adrenaline effectively. Furthermore, computer based docking provided the binding model of the anthraquinone derivatives and adrenergic receptor. Then, based on the results of the small intestinal promotion and purgative effect experiments in vivo, we built an "inhibitor-carrier" hypothesis to elucidate the mechanism of rhubarb. This work provided key massages for the pharmacological research of rhubarb, such a common and active medicinal plant, and might be of help for the development of new purgative drugs.

The characteristics of genistin-induced inhibitory effects on intestinal motility

Genistin belongs to isoflavones. Based on the facts that genistin exerts inhibitory effects on the contractility of vascular smooth muscle,the present study was designed to characterize the effects of genistin on intestinal contractility and evaluate its potential clinical implication. Ex vivo [isolated jejunal segment (IJS) of rat], in vitro, and in vivo assays were used in the study. The results indicated that genistin (5-80 μmol/L) inhibited the contraction of IJS in a dose-dependent manner and inhibited the increased-contractility of IJS induced by acetylcholine (ACh), histamine, high Ca(2+), and erythromycin, respectively. The inhibitory effects of genistin were correlated with the stimulation of alpha adrenergic and beta adrenergic receptors since these inhibitory effects were significantly blocked in the presence of phentolamine and propranolol respectively. No further inhibitory effects of genistin were observed in the presence of verapamil or in Ca(2+)-free condition, indicating genistin-induced inhibitory effects are Ca(2+)-dependent. Genistin decreased myosin light chain kinase (MLCK) protein contents and MLCK mRNA expression in IJS, and inhibited both phosphorylation and Mg(2+)-ATPase activity of purified myosin, implicating that the decrease of MLCK contents and inhibition of MLCK activity are involved in the genistin-induced inhibitory effects. The study suggests the potential clinical implications of genistin in relieving intestinal hypercontractility.

Characteristics of deslanoside-induced modulation on jejunal contractility

AIM: To characterize the dual effects of deslanoside on the contractility of jejunal smooth muscle.

METHODS: Eight pairs of different low and high contractile states of isolated jejunal smooth muscle fragment (JSMF) were established. Contractile amplitude of JSMF in different low and high contractile states was selected to determine the effects of deslanoside, and Western blotting analysis was performed to measure the effects of deslanoside on myosin phosphorylation of jejunal smooth muscle.

RESULTS: Stimulatory effects on the contractility of JSMF were induced (45.3% ± 4.0% vs 87.0% ± 7.8%, P < 0.01) by deslanoside in 8 low contractile states, and inhibitory effects were induced (180.6% ± 17.8% vs 109.9% ± 10.8%, P < 0.01) on the contractility of JSMF in 8 high contractile states. The effect of deslanoside on the phosphorylation of myosin light chain of JSMF in low (78.1% ± 4.1% vs 96.0% ± 8.1%, P < 0.01) and high contractile state (139.2% ± 8.5% vs 105.5 ± 7.34, P < 0.01) was also bidirectional. Bidirectional regulation (BR) was abolished in the presence of tetrodotoxin. Deslanoside did not affect jejunal contractility pretreated with the Ca²⁺ channel blocker verapamil or in a Ca²⁺-free assay condition. The stimulatory effect of deslanoside on JSMF in a low contractile state (low Ca²⁺ induced) was abolished by atropine. The inhibitory effect of deslanoside on jejunal contractility in a high contractile state (high Ca²⁺ induced) was blocked by phentolamine, propranolol and L-NG-nitro-arginine, respectively.

CONCLUSION: Deslanoside-induced BR is Ca²⁺ dependent and is related to cholinergic and adrenergic systems when JSMF is in low or high contractile states.