Vegetables are not only important dietary components in maintaining our daily life, but also potential resources for healing diseases. Myanmar is endowed with diverse vegetable species and many are also used as traditional medicines. In this study, we investigated 48 vegetable samples from central Myanmar for their inhibitory activities against the type III secretion system (T3SS) of Salmonella enterica serovar Typhimurium, one of the most prevalent pathogenic bacteria that causes infections. Results showed that 15 vegetables exhibited moderate to strong inhibitory activities against the secretion of T3SS effector proteins, providing the scientific evidence for the traditional knowledge of vegetables and their potential pharmacological function. By detailed chemical investigation, we found the vegetables, i.e., Archidendron jiringa (Jack) Nielsen., Neptunia plena (Linn.) Benth. and Ludwigia adscendens (L.) Hara have the potential for discovering the components with anti-T3SS activity. Bioassay-guided isolation of L. adscendens led to identify arjunglucoside II as a new T3SS inhibitor.