Abstract: Objective To explore the therapeutic effect of transdermal patches containing Cassia seed extract applied at the navel on slow transit constipation (STC) in rats and explore the spectrum- effect relationship of the patches. Method In a STC rat model established by gavage of compound diphenoxylate suspension for 14 days, the transdermal patches containing low, medium and high doses of Cassia seed extract (41.75, 125.25, and 375.75 mg/kg, respectively) were applied at the Shenque acupoint on the abdomen for 14 days after modeling, with constipation patches (13.33 mg/kg) as the positive control. After the treatment, fecal water content and intestinal propulsion rate of the rats were calculated, the pathological changes in the colon were observed with HE staining. Serum NO and NOS levels and the total protein content and NO, NOS and AChE expressions in the colon tissue were determined. HPLC fingerprints of the transdermal patches were established, and the spectrum-effect relationship between the common peaks of the patches and its therapeutic effect were analyzed. Results Treatment with the transdermal patches containing Cassia seed extract significantly increased fecal water content and intestinal propulsion rate of the rat models, where no pathological changes in the colon tissue were detected. The treatment also suppressed the elevations of serum and colonic NO and NOS levels and reduction of AChE in STC rats. Twenty-eight common peaks were confirmed in the HPLC fingerprints of 6 batches of Cassia seed extract- containing patches. Analysis of the spectrum- effect relationship showed that autrantio- obtusin had the greatest contribution to the therapeutic effect of the patches in STC rats. Conclusion The Cassia seed extract- containing patches alleviates STC in rats via synergistic actions of multiple active ingredients in the extract, where autrantio-obtusin, rhein, chrysoobtusin, obtusin, obtusifolin, emodin, chrysophanol, and physcion are identified as the main active ingredients.

Key words: slow transit constipation; transdermal patches containing Cassia seed extract; intestinal propulsion rate; grey relation analysis method; spectrum-effect relationship