Abstract: Objective To observe and compare the pharmacodynamics of extracts from Pith-decayed and Pith-nodecayed products of Scutellariae Radix on rats with damp-heat ulcerative colitis (UC). Methods Fifty healthy SD rats were randomly divided into 5 groups: normal group, model group, Pith-decayed products of Scutellariae Radix group, Pith-nodecayed products of Scutellariae Radix group and mesalazine group, with 10 rats in each group. The damp-heat UC rat model was established by the combination of high-fat and high-sugar diet+high-liquor administration+5% dextran sodium sulfate (DSS). Each group was given intragastric administration on the first day of modeling, respectively. The dosage of Pith-decayed products group and Pith-nodecayed products group was 5.25 g·kg^-1·d^-1, and that of mesalazine group was 0.266 g·kg^-1·d^-1. Normal group and model group were given equal volume of normal saline. The drug was administered continuously for 28 days. The general condition of rats was observed. The change of body mass and the score of disease activity index (DAI) were evaluated. The colonic mass of rats was measured, the colonic length was measured, and the colonic mass per unit length was calculated. HE staining and PAS staining were performed to observe the histopathological changes of rat colon. Serum levels of interleukin-6 (IL-6), tumor necrosis factor-α(TNF-α), interleukin- 1β (IL-1β) and transforming growth factor-β₁(TGF-β₁) were detected by Elisa. Results Compared with normal group, body mass and colon length of rats in model group were significantly decreased, DAI score, colon mass, colon mass per unit length and serum levels of IL-6, TNF-α and IL-1β were significantly increased, and TGF-β₁ level was significantly decreased(P<0.01). The upper layer of colon tissue was exfoliated, the margins were scattered, the crypts were unclear, the mucosal layer was edema, inflammatory cells infiltrated and invaded the submucosa, and the intestinal glands were disturbed. Compared with model group, the above indexes and related symptoms were significantly improved in Pith-decayed products of Scutellariae Radix group, Pith-nodecayed products of Scutellariae Radix group and mesalazine group(P<0.05, P<0.01). Compared with Pith-decayed products of Scutellariae Radix group, Pith-nodecayed products of Scutellariae Radix group and mesalazine group were superior to Pith-decayed products of Scutellariae Radix group in increasing colon mass per unit length, decreasing DAI score and improving inflammatory factor levels (P<0.05 or P<0.01). Conclusion The extract of Pith-decayed products of Scutellariae Radix and Pith-nodecayed products of Scutellariae Radix have better therapeutic effect on damp-heat UC rats, and Pith-nodecayed products of Scutellariae Radix is superior to Pith-decayed products of Scutellariae Radix.

Key words: Scutellariae Radix, Pith-decayed, Pith-nodecayed, mesalazine, extracts, damp-heat ulcerative colitis, rats