Zeitschrift für Phytotherapie 2013; 34 - P26
DOI: 10.1055/s-0033-1338228

Mechanism of prosecretory action of individual extracts of the herbal medicine STW 5 in human intestine

S Allam 1, D Kreuger 1, O Kelber 2, IE Demir 3, G Ceyhan 3, F Zeller 4, M Schemann 1
  • 1Humanbiologie TUM, Freising
  • 2Steigerwald Arzneimittelwerk GmbH, Darmstadt
  • 3Surgery, Klinikum Rechts der Isar TUM, Munich
  • 4Surgery, Hospital Freising, Freising

Background & Aims: STW5 (Iberogast®) is a herbal combination from bitter candy tuft, chamomile, peppermint (P), caraway, liquorice, lemon balm (L), angelica (A), greater celandine and milk thistle, used for treatment of functional dyspepsia and irritable bowel syndrome (IBS). We reported that STW5 increased ion secretion in the human intestine and proposed that this prosecretory action may be involved in its clinical efficacy. Our aim was to investigate the secretory potential of the nine extracts on human gut epithelium in order to reveal target oriented herbal combinations.

Methods: We used the Ussing chamber voltage clamp method to measure the short circuit current (Isc) which reflects mucosal ion secretion. Studies were performed in vitro on 291 mucosa/submucosa preparations of human small or large intestinal specimens from 81 patients undergoing abdominal surgeries.

Results: We first confirmed that a combination of the individual extracts at concentrations present in 512 µg/ml of the mother compound STW5 evoked comparable prosecretory actions (medians [25/75 percentiles]: 17.7 [11.1/36] µA/cm2; versus 25.8 [6.6/38.6] µA/cm2). At concentrations that corresponded to their concentrations in 512 µg/ml STW5, only angelica evoked a secretion (18.6 [9.6/28.8] µA/cm2). However, at ten times higher concentrations, which are still sub-therapeutic, additionally peppermint (7.7 [3.4/18] µA/cm2) and lemon balm (7 [6/23.5] µA/cm2) exhibited prosecretory potentials. A, P and L were equally potent in small and large intestine. Combined application of A+P+L as in 512 or 5120 µg/ml STW5 evoked an Isc increase of (14.2 [8.4/22] and 23.5 [18.34/32.6] µA/cm2), respectively. This prosecretory action was significantly reduced by adenylate cyclase inhibitor MDL12,330A, cAMP-activated Cl– channel blocker CFTRinh-172 or Ca2+-activated Cl– channel blocker SITS by 76%, 71% and 88% respectively.

Conclusion: We showed that the prosecretory action of STW5 is mainly due to angelica, peppermint and lemon balm. Their effects involve activation of cAMP- and Ca2+-activated Cl– channels. Our results suggest that STW5 or its prosecretory components may be used to normalize impaired intestinal secretion which may occur in C-IBS or chronic constipation.