Mechanisms involved in the muscle relaxing effects of STW 5 in guinea pig stomach.

INTRODUCTION: The herbal preparation STW 5 ameliorates functional dyspepsia partly by relaxing smooth muscle of the proximal stomach, thus improving gastric accommodation. We explored the unknown pathways responsible for this effect by testing targets known to modulate gastric smooth muscle relaxation. METHODS: STW 5-induced relaxation of smooth muscle strips from guinea pig gastric corpus before and after pharmacological interventions were recorded with force transducers in an organ bath. ORAI1 mRNA expression was tested in the proximal stomach. KEY RESULTS: Blockade of Ca2+ -activated K+ and Cl- channels, voltage-gated L- or T-type Ca2+ channels, TRPA1-, TRPV1-, adenosine or 5-HT4 receptors, antagonizing ryanodine receptors, inhibiting cyclooxygenase or sarcoplasmic reticulum calcium ATPase did not affect STW 5-evoked relaxation. Likewise, protein-kinase A or G were not involved. However, the relaxation evoked by STW 5 was significantly reduced by phorbol-12-myristat-13-acetat, an activator of protein-kinase C, by 2- aminoethyldiphenylborinate, an inhibitor of the IP3 receptor-mediated Ca2+ release from the sarcoplasmic reticulum or by SKF-96365, a nonselective store-operated calcium entry (SOCE) blocker. Furthermore, the mixed TRPC3/SOCE inhibitor Pyr3, but not the selective TRPC3 blocker Pyr10, reduced the effect of STW 5. Finally, BTP2, a potent blocker of ORAI-coupled SOCE, almost abolished STW 5-evoked relaxation. Expression of ORAI1 could be demonstrated in the corpus/fundus. CONCLUSIONS & INFERENCES: STW 5 inhibited SOCE, most likely ORAI channels, which are modulated by IP3- and PKC-dependent mechanisms. Our findings impact on the design of drugs to induce muscle relaxation and help identify phytochemicals with similar modes of actions to treat gastrointestinal disturbances.

Androgen receptor blockade by flutamide down-regulates renal fibrosis, inflammation, and apoptosis pathways in male rats.

AIM: this study aims to explore the effect of androgen receptor (AR) blockade by flutamide on some renal pathologic changes such as inflammation, apoptosis, and fibrosis in male rats. MAIN METHODS: Firstly, we investigated the potential effect of AR blockade on renal inflammatory intermediates including IL-1ß, IL-6, TNF-α, NF-Òšß proteins, and the renal gene expression of NF-Қß. Besides inflammation, we also assessed the apoptosis pathways including the caspases 3 & 9, mTOR, pAKT proteins, and BAX gene expression. Besides inflammation and apoptosis pathways, we also investigated the effect of androgen blockade on renal fibrosis intermediates including vimentin, TGFß-1, α-SMA, MMP-9, collagen type-III, collagen type-IV, and the renal expression of the col1A1 gene. Besides previous pathological pathways, we assessed the expression of chloride channel protein-5 (ClC-5), as an important regulator of many renal pathological changes. Finally, we assessed the impact of previous pathological changes on renal function at biochemical and pathological levels. KEY FINDINGS: We found that AR blockade by flutamide was associated with the down-regulation of renal inflammation, apoptosis, and fibrosis markers. It was associated with expression down-regulation of IL-1ß & IL-6, TNF-α, NF-Қß, caspases 3 & 9, mTOR, MMP-9, collagens, TGFß-1, and α-SMA. Away from down-regulation, we also found that AR blockade has upregulated ClC-5 and pAKT proteins. SIGNIFICANCE: AR is a major player in androgens-induced nephrotoxicity. AR blockade downregulates renal fibrosis, inflammation, and apoptosis pathways. It may be helpful as a strategy for alleviation of renal side effects associated with some drugs. However; this needs further investigations.

Siah2 inhibitor and the metabolic antagonist Oxamate retard colon cancer progression and downregulate PD1 expression.

BACKGROUND: Solid tumors such as colon cancer are characterized by rapid and sustained cell proliferation, which ultimately results in hypoxia, induction of hypoxia-inducible factor-1α (HIF-1α), and activation of glycolysis to promote tumor survival and immune evasion. We hypothesized that a combinatorial approach of menadione (MEN) as an indirect HIF-1α inhibitor and sodium oxamate (OX) as a glycolysis inhibitor may be a promising treatment strategy for colon cancer. OBJECTIVES: We investigated the potential efficacy of this combination for promoting an antitumor immune response and suppressing tumor growth in a rat model of colon cancer. METHODS: Colon cancer was induced by once-weekly subcutaneous injection of 20 mg/kg dimethylhydrazine (DMH) for 16 weeks. Control rats received the vehicle and then no further treatment (negative control) or MEN plus OX for 4 weeks (drug control). Dimethylhydrazine-treated rats were then randomly allocated to four groups: DMH alone group and other groups treated with MEN, OX, and a combination of (MEN and OX) for 4 weeks. Serum samples were assayed for the tumor marker carbohydrate antigen (CA19.9), while expression levels of HIF-1α, caspase-3, PHD3, LDH, and PD1 were evaluated in colon tissue samples by immunoassay and qRT-PCR. Additionally, Ki-67 and Siah2 expression levels were examined by immunohistochemistry. RESULTS: The combination of MEN plus OX demonstrated a greater inhibitory effect on the expression levels of HIF-1α, Siah2, LDH, Ki-67, and PD1, and greater enhancement of caspase-3 and PHD3 expression in colon cancer tissues than either drug alone. CONCLUSION: Simultaneous targeting of hypoxia and glycolysis pathways by a combination of MEN and OX could be a promising therapy for inhibiting colon cancer cell growth and promoting antitumor immunity [1].

Perindopril sensitizes hepatocellular carcinoma to chemotherapy: A possible role of leptin / Wnt/ ß-catenin axis with subsequent inhibition of liver cancer stem cells.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death. The major challenge in managing HCC is the resistance to chemotherapy. Leptin hormone is associated with different oncogenic pathways implicated in drug resistance. Angiotensin II was found to decrease the production and secretion of leptin. Objective: This study investigated the potential role of an ACEI perindopril as a chemosensitizer agent to sorafenib. Method: HCC was induced in mice using a single dose of diethylnitrosamine DENA (200 mg/kg) followed by phenobarbital 0.05% in drinking water for 16 weeks. Mice were then treated with perindopril (1 mg/kg/day), Sorafenib (30 mg/kg/day), or both of them for another four weeks. Leptin, VEGF, MMP-9, Cyclin D1, EpCAM, and ß-catenin were measured using immunoassay while Wnt and ALDH1 were assayed using western blotting assay. Results: Perindopril whether alone or in combination with sorafenib decrease liver enzymes and preserve the liver architecture. Our study revealed that perindopril significantly increased the antineoplastic, antiangiogenic as well as anti-metastatic effects of sorafenib. This effect was correlated with the downregulation of the leptin / Wnt / ß-catenin pathway and overexpression of ALDH1 while downregulation of EpCAM. Conclusion: This study presents perindopril as a potential chemosensitizer agent that works through decreased expression of the leptin / Wnt / ß-catenin pathway.

Modulating the Siah2-PHD3-HIF1α axis and/or autophagy potentially retard colon cancer proliferation possibly, due to the damping of colon cancer stem cells.

BACKGROUND: Hypoxic microenvironment of colon cancer is associated with HIF-1α upregulation. HIF-1α response elements are responsible for autophagy induction that promotes tumor proliferation. Moreover, HIF-1α induces tumor cell proliferation via maintaining cancer stem cells (CSCs) survival. Siah2 is E3 ubiquitin ligase that indirectly stabilizes HIF-1α. We hypothesized that dual inhibition of Siah2 as well as autophagy could be a promising approach that may inhibit CSCs growth. AIM OF THE WORK: This study investigated the possible effect of vitamin K3 as a Siah2 inhibitor and hydroxychloroquine as an autophagy inhibitor in colon cancer management. The effect (if any) of these agents on CSCs growth will be also manipulated. METHODS: Colon cancer was induced by dimethylhydrazine. MDA and GSH were selected as oxidative stress markers, Expression of HIF-1α, Caspase-3, VEGF, MMP-9, EpCAM, SCF, and CA19.9 were assayed using immunoassay. The Western blot technique was used to assess LC3Ⅰ, CD44, and CD133 whereas RT-PCR was used to investigate PHD3 and CD44 in colon tissues. Additionally, Ki-67 and Siah2 were detected immunohistochemically. RESULTS: vitamin K3 and hydroxychloroquine either alone or in combination downregulated the expression of Siah2 and HIF-1α through upregulating PHD3 in colon tissues. This combination significantly downregulated MDA, Ki-67, VEGF, and MMP-9 expression and upregulated the expression of GSH and caspase-3. LC3Ⅰ was also upregulated. Interestingly, these therapeutic options were correlated with down-regulation of the cancer stem cell marker such as CD44 and EpCAM. CONCLUSION: Our results suggested that suppression of both Siah2-PHD3-HIF-1α axis and autophagy retard colon cancer proliferation and dampened CSCs.

Ambroxol, a mucolytic agent, boosts HO-1, suppresses NF-κB, and decreases the susceptibility of the inflamed rat colon to apoptosis: A new treatment option for treating ulcerative colitis.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology that increases the risk of developing colorectal cancer and imposes a lifelong healthcare burden on millions of patients worldwide. Current treatment strategies are associated with significant risks and have been shown to be fairly effective. Hence, discovering new therapies that have better efficacy and safety profiles than currently exploited therapeutic strategies is challenging. It has been well delineated that NF-κB/Nrf2 crosstalk is a chief player in the interplay between oxidative stress and inflammation. Ambroxol hydrochloride, a mucolytic agent, has shown antioxidant and anti-inflammatory activity in humans and animals and has not yet been examined for the management of UC. Therefore, our approach was to investigate whether ambroxol could be effective to combat UC using the common acetic acid rat model. Interestingly, a high dose of oral ambroxol (200 mg/kg/day) reasonably improved the microscopic and macroscopic features of the injured colon. This was linked to low disease activity and a reduction in the colonic weight/length ratio. In the context of that, ambroxol boosted Nrf2 activity and upregulated HO-1 and catalase to augment the antioxidant defense against oxidative damage. Besides, ambroxol inactivated NF-κB signaling and its consequent target pro-inflammatory mediators, IL-6 and TNF-α. In contrast, IL-10 is upregulated. Consistent with these results, myeloperoxidase activity is suppressed. Moreover, ambroxol decreased the susceptibility of the injured colon to apoptosis. To conclude, our findings highlight the potential application of ambroxol to modify the progression of UC by its anti-inflammatory, antioxidant, and antiapoptotic properties.

Carbocisteine as a Modulator of Nrf2/HO-1 and NFκB Interplay in Rats: New Inspiration for the Revival of an Old Drug for Treating Ulcerative Colitis.

Ulcerative colitis (UC), an inflammatory bowel disease, is a chronic condition of a multifaceted pathophysiology. The incidence of UC is increasing internationally. The current therapies for UC lack relative effectiveness and are associated with adverse effects. Therefore, novel therapeutic options should be developed. It has been well documented that modulating the Nrf2/NFκB is a promising therapeutic target in inflammation. Carbocisteine is a mucoregulatory medication and its efficacy in COPD was found to be more closely related to its antioxidant and anti-inflammatory properties. Carbocisteine has not yet been examined for the management of UC. Hence, our approach was to investigate the potential coloprotective role of carbocisteine in acetic acid-induced colitis in rats. Our results revealed that carbocisteine improved colon histology and macroscopic features and subdued the disease activity as well. Additionally, carbocisteine attenuated colon shortening and augmented colon antioxidant defense mechanisms via upregulating catalase and HO-1 enzymes. The myeloperoxidase activity was suppressed indicating inhibition of the neutrophil infiltration and activation. Consistent with these findings, carbocisteine boosted Nrf2 expression along with NFκB inactivation. Consequently, carbocisteine downregulated the proinflammatory cytokines IL-6 and TNF-α and upregulated the anti-inflammatory cytokine IL-10. Concomitant to these protective roles, carbocisteine displayed anti-apoptotic properties as revealed by the reduction in the Bax: BCL-2 ratio. In conclusion, carbocisteine inhibited oxidative stress, inflammatory response, and apoptosis in acetic acid-induced UC by modulating the Nrf2/HO-1 and NFκB interplay in rats. Therefore, the current study provides a potential basis for repurposing a safe and a commonly used mucoregulator for the treatment of UC.

The potential protective effects of estradiol and 2-methoxyestradiol in ischemia reperfusion-induced kidney injury in ovariectomized female rats.

AIMS: Investigating the impact of 17ß estradiol (E2) and its endogenous non-hormonal metabolite 2-methoxyestradiol (2ME) on renal ischemia-reperfusion (RIR) induced kidney injury in ovariectomized (OVX) rats and the role of catechol-O-methyltransferase (COMT) in their effects. MAIN METHODS: Eighty female rats were allocated into eight groups. Control group, Sham group, OVX group, OVX and RIR group, OVX + RIR + E2 group, OVX + RIR + 2ME group, OVX + RIR + E2 + Entacapone group and OVX + RIR + 2ME + Entacapone group, respectively. Twenty-four hours post RIR, creatinine (Cr) and blood urea nitrogen (BUN) were determined in serum, while malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), Glutathione (GSH), myeloperoxidase (MPO), as well as the expressions of COMT, hypoxia inducible factor-1α (HIF-1α) and tyrosine hydroxylase (TH) were assessed in the kidney tissues. KEY FINDINGS: Serum Cr, BUN, MPO, as well as HIF-1α and TH expressions were significantly higher with concomitant decrease in COMT expression, SOD and CAT activities and GSH content observed in OVX and RIR group compared to sham group. E2 and 2ME treatment significantly ameliorated all parameters measured in OVX and RIR rats. On the other hand, Entacapone significantly decreased the effect of E2, with no effect on 2ME treatment. SIGNIFICANCE: E2 ameliorates RIR-induced kidney injury and this effect is mediated, at least in part, via its COMT-mediated conversion to 2ME. Thus, 2ME by the virtue of its pleiotropic pharmacological effects can be used as a safe and effective treatment of RIR injury.

Febuxostat attenuates testosterone-induced benign prostatic hyperplasia in rats via inhibiting JAK/STAT axis.

AIM: To investigate the possible modulatory effect of febuxostat in testosterone-induced benign prostatic hyperplasia (BPH) in rats with emphasis on xanthine oxidase (XO)/Janus Kinases (JAK)/signal transducer and activator of transcription (STAT) axis. MAIN METHODS: Male Wistar rats were treated with testosterone with/out febuxostat. Effect of febuxostat on BPH was assessed at the structural level by histopathology and determination of prostate weight/index. Cyclin D1 protein expression was assessed immunohistochemically and the ratio of Bax/Bcl-2 mRNA expression was determined by real time polymerase chain reaction analysis (RT-PCR). Besides, uric acid serum level was determined colorimetrically. Prostatic XO activity, as well as oxidative stress and inflammatory markers were evaluated. Additionally, western blot analysis was performed for determination of JAK-1 and phosphorylated form of STAT-3 expression in tissues. KEY FINDINGS: Results revealed that febuxostat inhibited the increase in prostatic weight and index compared to testosterone-treated group. Additionally, febuxostat ameliorated testosterone-induced histopathological changes, prevented the rise in cyclin D1 expression and enhanced Bax/Bcl2 ratio. Febuxostat suppressed testosterone induced- increase in XO activity in prostates and serum level of uric acid. Moreover, it regulated oxidative stress markers including; malondialdehyde (MDA), superoxide dismutase (SOD) activity and glutathione (GSH) content. Also, it inhibited the increase in prostate contents of interleukin-6 (IL-6), interleukin-1ß (IL-1 ß), tumor necrosis factor (TNF-α) and nuclear factor (NF-κB). Interestingly, febuxostat markedly reduced JAK-1 and subsequent phosphorylation of STAT-3 protein expression. SIGNIFICANCE: Febuxostat ameliorates testosterone-induced BPH via suppressing XO/JAK/STAT axis. This may help to re-purpose the use of XO inhibitors.

The modulatory effects of cinnamaldehyde on uric acid level and IL-6/JAK1/STAT3 signaling as a promising therapeutic strategy against benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a widespread disorder in elderly men. Cinnamaldehyde, which is a major constituent in the essential oil of cinnamon, has been previously reported to reduce xanthine oxidase activity, in addition to its anti-inflammatory, anti-oxidant, and anti-proliferative activities. Our study was designed to investigate the potential modulatory effects of cinnamaldehyde on testosterone model of BPH in rats through reduction of uric acid level, and suppression of IL-6/JAK1/STAT3 signaling pathway. Cinnamaldehyde (40 and 75 mg/kg) was orally administered to male Wistar rats for 3 weeks, and concurrently with testosterone (3 mg/kg, s.c.) from the second week. Cinnamaldehyde ameliorated the elevation in prostatic weight and index compared to rats treated with testosterone only, that was also confirmed by alleviation of histopathological changes in prostate architecture. The protective mechanisms of cinnamaldehyde were elucidated through inhibition of xanthine oxidase activity and reduced uric acid level. That was accompanied by reduction of the pro-inflammatory cytokines; interleukin-6 (IL-6), IL-1ß, tumor necrosis factor-alpha (TNF-α), and the nuclear translocation of the transcription factor NF-κB p65, that could be attributed also to the enhanced anti-oxidant defense by cinnamaldehyde. The protein expression of JAK1, which is IL-6 receptor linked protein, was reduced with subsequently reduced activation of STAT3 protein. That eventually suppressed the formation of the proliferation protein cyclin D1, while elevated Bax/Bcl2 ratio. It can be concluded that reducing uric acid level through xanthine oxidase inhibition and suppression of the inflammatory signaling cascade; IL-6/JAK1/STAT3; by cinnamaldehyde could be a novel and promising therapeutic approach against BPH.

Ameliorative effect of 2-methoxyestradiol on radiation-induced lung injury.

AIMS: Radiation-induced lung injury (RILI) is a serious complication of radiation therapy. Development of an effective drug that selectively protects normal lung tissues and sensitizes tumor cells to radiotherapy is an unmet need. 2-Methoxyestradiol (2ME2) possesses polypharmacological properties, which qualifies it as an effective radioprotector. Our aim is to explore the potential protective effects of 2ME2 against early and late stages of RILI and the underlying mechanisms. MAIN METHODS: BALB/c mice were either treated with 2ME2 (50 mg/kg/day i.p., for 4 weeks); or received a single dose of 10 Gy ionizing radiation (IR) delivered to the lungs; or 10 Gy IR and 2ME2. Animal survival and pulmonary functions were evaluated. Immune-phenotyping of alveolar macrophages (AM) in the broncho-alveolar lavage fluids (BALF) was determined by flow cytometry. ELISA was used to evaluate the expression levels of TNF-α, TGF-ß; and IL-10 in BALF. Lung tissues were used for histopathological examination or immunofluorescence staining for CD68 (pan-macrophage marker), Arginase-1 (Arg1, M2-specific marker), inducible nitric oxide synthase (iNOS, M1-specific marker) and HIF-1α. VEGF and γH2AX expression in lung tissues were detected by western blot. KEY FINDINGS: The results demonstrated that 2ME2 improved the survival, lung functions and histopathological parameters of irradiated mice. Additionally, it attenuated the radiation-induced AM polarization and reduced the pneumonitis and fibrosis markers in lung tissues. Significant reduction of TNF-α and TGF-ß with concomitant increase in IL-10 concentrations were observed. Moreover, the expression of HIF-1α, VEGF and γH2AX declined. SIGNIFICANCE: 2ME2 is a promising radioprotectant with fewer anticipated side effects.

Androgen/androgen receptor affects gentamicin-induced nephrotoxicity through regulation of megalin expression.

AIM: Investigation whether androgen/androgen receptor (AR) might regulate megalin expression and/or functionality and thus affecting Gentamicin-induced nephrotoxicity (GIN). MAIN METHODS: Male Wistar rats were treated with gentamicin with/out AR ligands (testosterone as agonist and flutamide as antagonist). Megalin expression in the kidney tissues was determined by real-time RT-PCR and western blot. Besides, megalin functionality was assessed using immunofluorescence imaging of fluorescein isothiocyanate (FITC) conjugated bovine serum albumin (BSA) (FITC-BSA). The effects of different treatments on the kidney were assessed at the structural level by histopathological evaluation and the biochemical level by colorimetric assay of blood urea nitrogen (BUN), serum creatinine (SCr) and urinary albumin/creatinine (A/C) ratio, besides, kidney expression of neutrophil gelatinase-associated lipocalin (NGAL) by immunoblotting. KEY FINDINGS: Our results revealed that treatment with testosterone either alone or combined with gentamicin increased megalin expression at mRNA and protein levels as well as at the functional level. These effects were paralleled by increased GIN as manifested by increased SCr, BUN, A/C ratio, renal expression of NGAL or histopathological changes. On the other hand, treatment with flutamide ameliorated GIN and megalin expression and functionality. Computational analysis of megalin promotor revealed the presence of multiple response elements that mediate androgen response. SIGNIFICANCE: Androgen/AR regulates megalin expression at the transcriptional level and consequently GIN. This may explain the sexual dimorphism in GIN and might represent a druggable target for treatment or prevention of GIN.

The effect of aryl hydrocarbon receptor ligands on gentamicin-induced nephrotoxicity in rats.

Polycyclic aromatic hydrocarbons (PAHs)/aryl hydrocarbon receptor (AhR) regulate the expression of target genes, including drug transporter genes which harbor xenobiotic response element (XRE) in their promoter regions. Thus, PAHs/AhR could alter the toxicokinetic profile of many nephrotoxic drugs, including aminoglycosides. In the current study, we investigated the expression and localization of AhR and megalin in rat kidney. Furthermore, we investigated whether AhR and its ligands could modulate the expression of megalin and consequently the gentamicin-induced nephrotoxicity (GN) in rats. Both megalin and AhR receptors are expressed in the proximal tubules of the rat kidney. Treatment with AhR agonist benzo(a)pyrene aggravated GN as indicated by a significant increase in serum creatinine, BUN, KIM1, NAGL, CD-86, and urinary albumin/creatinine ratio. On the other hand, treatment with AhR antagonist resveratrol ameliorated GN as manifested by a pronounced decrease in the aforementioned parameters. The effects of AhR ligands on GN were associated with altered expression of megalin receptor.

Design And Characterisation Of Novel Sorafenib-Loaded Carbon Nanotubes With Distinct Tumour-Suppressive Activity In Hepatocellular Carcinoma.

PURPOSE: Over the past 30 years, no consistent survival benefits have been recorded for anticancer agents of advanced hepatocellular carcinoma (HCC), except for the multikinase inhibitor sorafenib (Nexavar®), which clinically achieves only ~3 months overall survival benefit. This modest benefit is attributed to limited aqueous solubility, slow dissolution rate and, consequently, limited absorption from the gastrointestinal tract. Thus, novel formulation modalities are in demand to improve the bioavailability of the drug to attack HCC in a more efficient manner. In the current study, we aimed to design a novel sorafenib-loaded carbon nanotubes (CNTs) formula that is able to improve the therapeutic efficacy of carried cargo against HCC and subsequently investigate the antitumour activity of this formula. MATERIALS AND METHODS: Sorafenib was loaded on functionalized CNTs through physical adsorption, and an alginate-based method was subsequently applied to microcapsulate the drug-loaded CNTs (CNTs-SFN). The therapeutic efficacy of the new formula was estimated and compared to that of conventional sorafenib, both in vitro (against HepG2 cells) and in vivo (in a DENA-induced HCC rat model). RESULTS: The in vitro MTT anti-proliferative assay revealed that the drug-loaded CNTs formula was at least two-fold more cytotoxic towards HepG2 cells than was sorafenib itself. Moreover, the in vivo animal experiments proved that our innovative formula was superior to conventional sorafenib at all assessed end points. Circulating AFP-L3% was significantly decreased in the CNTs-SFN-MCs-treated group (14.0%) in comparison to that of the DENA (40.3%) and sorafenib (38.8%) groups. This superiority was further confirmed by Western blot analysis and immunofluorescence assessment of some HCC-relevant biomarkers. CONCLUSION: Our results firmly suggest the distinctive cancer-suppressive nature of CNTs-SFN-MCs, both against HepG2 cells in vitro and in a DENA-induced HCC rat model in vivo, with a preferential superiority over conventional sorafenib.

Extracts from peppermint leaves, lemon balm leaves and in particular angelica roots mimic the pro-secretory action of the herbal preparation STW 5 in the human intestine.

AIM: The herbal preparation STW 5 contains fresh plant extracts from bitter candytuft whole plant, extracts from greater celandine herb, angelica root, lemon balm leaves, peppermint leaves, caraway fruit, liquorice root, chamomile flower and milk thistle fruit. We recently reported that STW 5 increased intestinal chloride secretion and proposed that this action may be involved in its clinical efficacy in the treatment of irritable bowel syndrome. The aim of this study was to identify the extracts responsible for the secretory action in order to provide the basis to develop novel target oriented herbal combinations. METHODS: We used the Ussing chamber voltage clamp technique to study the effects of individual extracts of STW 5 on short circuit current (Isc, reflecting electrogenic ion transport across epithelial cells) in mucosal/submucosal preparations of human small or large intestinal specimens and the human epithelial cell line T84. RESULTS: STW 5 at concentrations of 512 µg/ml and 5120 µg/ml evoked an increase in Isc. The increase at the lower concentration was due to pro-secretory effects of angelica which were nerve mediated. The increase at the higher concentration was additionally mimicked by peppermint and lemon balm. The remaining extracts did not influence ISC in the large intestine. The results were similar in T84 cells except that angelica had no effect while chamomile induced secretion. These pro-secretory effects were reduced by adenylate cyclase inhibitor MDL-12330A, cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor CFTRinh-172 and calcium activated chloride channels blocker 4-acetamido-4-isothiocyanatostilbene-2,2-disulphonic acid (SITS). Liquorice decreased ISC only in small intestine which was reversed by the epithelial sodium channel blocker amiloride. CONCLUSIONS: Results suggested that the pro-secretory action of STW 5 is mainly due to angelica with lesser contribution of peppermint and lemon balm. Their effects involve activation of cAMP- and Ca(++)-activated Cl(-) channels. We suggest that peppermint, lemon balm and in particular angelica may be the basis to develop novel herbal preparations to specifically treat secretory disorder based on impaired epithelial secretion, such as constipation.