Permeation-enhancing effect of aloe-emodin anthrone on water-soluble and poorly permeable compounds in rat colonic mucosa

Targeting TRPV1 and TRPA1: A feasible strategy for natural herbal medicines to combat postoperative ileus

Under physiological or pathological conditions, transient receptor potential (TRP) channel vanilloid type 1 (TRPV1) and TRP ankyrin 1 (TRPA1) possess the ability to detect a vast array of stimuli and execute diverse functions. Interestingly, increasing works have reported that activation of TRPV1 and TRPA1 could also be beneficial for ameliorating postoperative ileus (POI). Increasing research has revealed that the gastrointestinal (GI) tract is rich in TRPV1/TRPA1, which can be stimulated by capsaicin, allicin and other compounds. This activation stimulates a variety of neurotransmitters, leading to increased intestinal motility and providing protective effects against GI injury. POI is the most common emergent complication following abdominal and pelvic surgery, and is characterized by postoperative bowel dysfunction, pain, and inflammatory responses. It is noteworthy that natural herbs are gradually gaining recognition as a potential therapeutic option for POI due to the lack of effective pharmacological interventions. Therefore, the focus of this paper is on the TRPV1/TRPA1 channel, and an analysis and summary of the processes and mechanism by which natural herbs activate TRPV1/TRPA1 to enhance GI motility and relieve pain are provided, which will lay the foundation for the development of natural herb treatments for this disease.

Research progress regarding potential effects of traditional Chinese medicine on postoperative intestinal obstruction

OBJECTIVES

Postoperative intestinal obstruction is a common postoperative complication with typical symptoms of abdominal pain, vomiting, abdominal distension and constipation. The principal aim of this paper is to provide a full-scale review on the categories and characteristics of postoperative intestinal obstruction, pathophysiology, effects and detailed mechanisms of compounds and monomers from traditional Chinese medicine for treating postoperative intestinal obstruction. Moreover, the possible development and perspectives for future research are also analyzed.

METHODS

Literature regarding postoperative intestinal obstruction as well as the anti-pio effect of aqueous extracts and monomers from traditional Chinese medicine in the last 20 years was summarized.

KEY FINDINGS

To date, approximately 30 compounds and 25 monomers isolated from traditional Chinese medicine including terpenes, alkaloids, polysaccharides, flavonoids, phenylpropanoids and quinones, have exerted significant antipio effect. This paper reviews the effective doses, models, detailed mechanisms, and composition of these traditional Chinese medicine compounds, as well as the structure of these monomers. Moreover, challenges existed in the current investigation and further perspectives were discussed as well, hoping to provide a reference for future clinical treatment of postoperative intestinal obstruction and the development of new drugs.

CONCLUSIONS

Above all, the convincing evidence from modern pharmacology studies powerfully supported the great potential of traditional Chinese medicine in the management of postoperative intestinal obstruction. Regrettably, less attention was currently paid on the mechanisms of traditional Chinese medicine compounds and monomers with antipio effect. Consequently, future study should focus on monomer-mechanism and structure-function relationship.

Betahistine dihydrochloride transdermal delivery via optimized thermosensitive gels: percutaneous absorption evaluation using rat growth as a biomarker

The aim of this study was to develop and optimize a betahistine dihydrochloride (BH) thermoreversible bioadhesive gel intended for transdermal delivery. The gels were obtained via cold method. A full factorial design was employed to investigate the joint effect of Poloxamer 407 concentration (18 and 20%), adhesive polymer type (Polyvinyl pyrolidone, Hydroxypropyl methylcellulose, and Carbopol 934), and adhesive polymer concentration (0.5 and 1.5%) on gelling temperature, viscosity at 37 °C, and adhesion strength. Data collected were analyzed using multiple linear regression. A desirability index approach with relative importance weight was used to choose the most desirable formulation. F4 (20% Poloxamer+1.5% Carbopol) was selected for further characterization. F4 released 96.97% drug in 12 h across hairless rat skin. F4 gelation temperature and time were 36 ± 0.35 °C, and 6 ± 0.7 min, respectively. F4 adhesive force was 8835.68 dyne/cm². F4 was tested for its appetite suppressing effect in a rat model and it was evaluated histopathologically. Rats' chow intake and weight gain was significantly decreased with no signs of inflammation or lipolysis when the optimized BH gel formulation, F4, was compared with untreated animals and animals treated with BH free gel. The results suggest that BH is percutaneously absorbed from the gel base and that the BH gel is tolerable. The desirability index approach with relative importance weight of responses was effective in determination of the optimum formulation. BH is systemically effective and well-tolerated when applied topically in hydrogel-based systems. The Carbopol-Poloxamer gel is a promising modality for transdermal delivery of BH.

Characteristics of emodin on modulating the contractility of jejunal smooth muscle

Emodin is traditionally used as a laxative and is found to increase or decrease the contractility of intestinal smooth muscle in low doses and high doses, respectively. In this study, we propose that bidirectional regulation (BR) on the contractility of jejunal smooth muscle (CJSM) is inducible by emodin in the absence of control by the central nervous system. The results indicated that emodin-induced BR had the following characteristics. A stimulatory effect on CJSM was induced by emodin at 7 low contractile states, and an inhibitory effect was induced on CJSM at 7 high contractile states. Emodin-induced BR on myosin phosphorylation was also observed. BR was not observed in the presence of tetrodotoxin, suggesting that enteric nervous system is required for producing BR. The stimulatory effect of emodin on CJSM was abolished by atropine and diphenhydramine, respectively, suggesting that BR was correlated with cholinergic and histamine system while jejunal smooth muscle was at low contractile state. The inhibitory effect of emodin on CJSM was abolished by phentolamine, propranolol, and L-NG-nitroarginine (L-NNA), respectively, suggesting that BR was related to adrenergic hyperactivity and with a nitric oxide relaxing mechanism while jejunal smooth muscle was in a high contractile state. The exact mechanism, however, needs further investigation.

Emodin induces chloride secretion in rat distal colon through activation of mast cells and enteric neurons

BACKGROUND AND PURPOSE

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is an active component of many herb-based laxatives. However, its mechanism of action is unclear. The aim of the present study was to investigate the role of mast cells and enteric neurons in emodin-induced ion secretion in the rat colon.

EXPERIMENTAL APPROACH

Short-circuit current (I(SC)) recording was used to measure epithelial ion transport. A scanning ion-selective electrode technique was used to directly measure Cl(-) flux (J(Cl)-) across the epithelium. RIA was used to measure emodin-induced histamine release.

KEY RESULTS

Basolateral addition of emodin induced a concentration-dependent increase in I(SC) in colonic mucosa/submucosa preparations, EC(50) 75 µM. The effect of emodin was blocked by apically applied glibenclamide, a Cl(-) channel blocker, and by basolateral application of bumetanide, an inhibitor of the Na(+) -K(+) -2Cl(-) cotransporter. Emodin-evoked J(Cl)- in mucosa/submucosa preparations was measured by scanning ion-selective electrode technique, which correlated to the increase in I(SC) and was significantly suppressed by glibenclamide and bumetanide. Pretreatment with tetrodotoxin and the muscarinic receptor antagonist atropine had no effect on emodin-induced ΔI(SC) in mucosa-only preparations, but significantly reduced emodin-induced ΔI(SC) and J(Cl)- in mucosa/submucosa preparations. The COX inhibitor indomethacin, the mast cell stabilizer ketotifen and H(1) receptor antagonist pyrilamine significantly reduced emodin-induced ΔI(SC) in mucosa and mucosa/submucosa preparations. The H(2) receptor antagonist cimetidine inhibited emodin-induced ΔI(SC) and J(Cl)- only in the mucosa/submucosa preparations. Furthermore, emodin increased histamine release from the colonic mucosa/submucosa tissues.

CONCLUSIONS AND IMPLICATIONS

The results suggest that emodin-induced colonic Cl(-) secretion involves mast cell degranulation and activation of cholinergic and non-cholinergic submucosal neurons.

An evaluation of the biological and toxicological properties of Aloe barbadensis (miller), Aloe vera

Aloe barbadensis (Miller), Aloe vera, has a long history of use as a topical and oral therapeutic. The plant is the source of two products, gel and latex, which are obtained from its fleshy leaves. Aloe vera products contain multiple constituents with potential biological and toxicological activities, yet the active components elude definition. Ingestion of Aloe vera is associated with diarrhea, electrolyte imbalance, kidney dysfunction, and conventional drug interactions; episodes of contact dermatitis, erythema, and phototoxicity have been reported from topical applications. This review examines the botany, physical and chemical properties, and biological activities of the Aloe vera plant.

Effect of emodin on small intestinal peristalsis of mice and relevant mechanism

AIM: To investigate the effect of emodin on small intestinal peristalsis of mice and to explore its relevant mechanisms.

METHODS: The effect of emodin on small intestinal peristalsis of mice was observed by charcoal powder propelling test of small intestine. The contents of motilin and somatostatin in small intestine of mice were determinated by radioimmunoassay. The electrical potential difference (PD) related to Na⁺ and glucose transport was measured across the wall of reverted intestinal sacs. Na⁺–K⁺-ATPase activity of small intestinal mucosa was measured by spectroscopic analysis.

RESULTS: Different dosages of emodin can improve small intestinal peristalsis of mice. Emodin increased the content of motilin, while reduced the content of somatostatin in small intestine of mice significantly. Emodin 0.2, 0.4, 0.8, and 1.6 g/L decreased PD when there was glucose. However, emodin had little effect when glucose was free. The Na⁺–K⁺-ATPase activity of small intestinal mucosa of mice in emodin groups was inhibited obviously.

CONCLUSION: Emodin can enhance the function of small intestinal peristalsis of mice by mechanisms of promoting secretion of motilin, lowering the content of somatostatin and inhibiting Na⁺–K⁺-ATPase activity of small intestinal mucosa.

Membrane-related effects underlying the biological activity of the anthraquinones emodin and barbaloin

Commercial plant extracts containing anthraquinones are being increasingly used for cosmetics, food and pharmaceuticals due to their wide therapeutic and pharmacological properties. In this work, the interaction with model membranes of two representative 1,8-dihydroxyanthraquinones, barbaloin (Aloe) and emodin (Rheum, Polygonum), has been studied in order to explain their effects in biological membranes. Emodin showed a higher affinity for phospholipid membranes than barbaloin did, and was more effective in weakening hydrophobic interactions between hydrocarbon chains in phospholipid bilayers. Whereas emodin induced the formation of hexagonal-H(II) phase, barbaloin stabilized lamellar structures. Barbaloin promoted the formation of gel-fluid intermediate structures in phosphatidylglycerol membranes at physiological pH and ionic strength values. It is proposed that emodin's chromophore group is located at the upper half of the membrane, whereas barbaloin's one is in a deeper position but having its glucopyranosyl moiety near the phospholipid/water interface. Moreover, membrane disruption by emodin or barbaloin showed specificity for the two major phospholipids present in bacterial membranes, phosphatidylethanolamine and phosphatidylglycerol. In order to relate their strong effects on membranes to their biological activity, the capacity of these compounds to inhibit the infectivity of the viral haemorrhagic septicaemia rhabdovirus (VHSV), a negative RNA enveloped virus, or the growth of Escherichia coli was tested. Anthraquinone-loaded liposomes showed a strong antimicrobial activity whereas these compounds in their free form did not. Both anthraquinones showed antiviral activity but only emodin was a virucidal agent. In conclusion, a molecular mechanism based on the effect of these compounds on the structure of biological membranes is proposed to account for their multiple biological activities. Anthraquinone-loaded liposomes may suppose an alternative for antimicrobial, pharmaceutical or cosmetic applications.