Cucumis sativus extract elicits chloride secretion by stimulation of the intestinal TMEM16A ion channel

Abstract

Context

Cucumber (Cucumis sativus Linn. [Cucurbitaceae]) is widely known for its purgative, antidiabetic, antioxidant, and anticancer therapeutic potential. However, its effect on gastrointestinal (GI) disease is unrecognised.

Objective

This study investigated the effect of C. sativus fruit extract (CCE) on intestinal chloride secretion, motility, and motor function, and the role of TMEM16A chloride channels.

Materials and methods

CCE extracts were obtained from commercially available cucumber. Active fractions were then purified by HPLC and analysed by high resolution mass spectrometry. The effect of CCE on intestinal chloride secretion was investigated in human colonic T84 cells, ex vivo mouse intestinal tissue using an Ussing chamber, and the two-electrode voltage-clamp technique to record calcium sensitive TMEM16A chloride currents in Xenopus laevis oocytes. In vivo, intestinal motility was investigated using the loperamide-induced C57BL/6 constipation mouse model. Ex vivo contractility of mouse colonic smooth muscles was assessed by isometric force measurements.

Results

CCE increased the short-circuit current (ΔIsc 34.47 ± µA/cm²) and apical membrane chloride conductance (ΔI_Cl 95 ± 8.1 µA/cm²) in intestinal epithelial cells. The effect was dose-dependent, with an EC₅₀ value of 0.06 µg/mL. CCE stimulated the endogenous TMEM16A-induced Cl^- current in Xenopus laevis oocytes. Moreover, CCE increased the contractility of smooth muscle in mouse colonic tissue and enhanced small bowel transit in CCE treated mice compared to loperamide controls. Mass spectrometry suggested a cucurbitacin-like analogue with a mass of 512.07 g/mol underlying the bioactivity of CCE.

Conclusion

A cucurbitacin-like analog present in CCE activates TMEM16A channels, which may have therapeutic potential in cystic fibrosis and intestinal hypodynamic disorders.

Keywords:

• Loperamide-induced C57BL/6 constipation mouse model
• T84 cells

Disclosure statement

The authors declare they have no financial interest or competing interest.

Additional information

Funding

This research was funded by the Department of Biotechnology, BT/HD/35/02/07/2009 and Indian Council of Medical Research, 3/1/3/ICMR/VFS/HRD-2016 (to K.M.H) and NIH to NL [P20GM130459 and 1RO1HL146054].