Periplaneta americana extract ameliorates recurrent oral ulcers in rats by enhancing the intestinal epithelial barrier and regulating gut microbiota - Kailing Li; Liping Yuan; Jingyu Zhang; Weijun Li; Guanhua Zhao; Zhongze Chen; Yongshou Yang; Zhengchun He; Peiyun Xiao (PLoS ONE, 2026)