Preparation of Clinically Useful Sennoside-reduced Rhubarb.

OBJECTIVE

The aim of this study was to develop a method of removing sennoside to reduce the cathartic effect of rhubarb while conserving its other pharmacological activities.

METHODS

Rhubarb powder was steam autoclaved at 121°C and 0.14 MPa for 20, 60, or 120 minutes, and HPLC analysis was conducted to determine levels of rhubarb components. Mice were fed non-autoclaved or 20-minute-autoclaved rhubarb extracts. Feces were collected and weighed over a 24-hour period. India ink was orally administered to determine the distance of fecal migration through the intestinal tract.

RESULTS

Autoclaving 20, 60, and 120 minutes decreased sennoside A and B to trace levels but only autoclaving 20 minutes conserved most of the (+)-catechin, (-)-epicatechin, and (-)-epicatechin gallate contents (i.e., 69%, 90%, 88%, respectively). Therefore only rhubarb autoclaved for 20 minutes was used in subsequent experiments. Fecal output (in g) in mice treated with water (control), autoclaved rhubarb, and non-autoclaved rhubarb was 2.78 ± 0.07, 3.30 ± 0.13 (p = 0.348), and 3.81 ± 0.07 (p = 0.005). India ink migration was far less in mice treated with autoclaved rhubarb vs non-autoclaved rhubarb.

CONCLUSIONS

Steam autoclaving the rhubarb for 20 minutes reduces sennoside levels and its cathartic activity while conserving its other pharmacological activities.