Cuscuta seeds have been used as a Chinese medicine for many years. In this study, the chemical constituent profile and pharmacological bioactivities of extracted Cuscuta campestris seeds after a plain stir-baking process were investigated. Using a LC/MS-based metabolomics strategy, the compounds that changed significantly after plain stir-baking of the seeds were identified. Compared with unprocessed seeds, LC-MS/MS and HPLC chromatography analysis demonstrated that the compound that increased most significantly in the processed seeds was quercetin (23 fold). Moreover, the stir-baked seeds exhibited higher anti-inflammatory activity against RAW264.7 cells and higher antiproliferative activity against MDA-MB-231 and MCF-7 cells. Here for the first time it is shown that Cuscuta seeds have anti-inflammatory and antiproliferative activities. In addition, it was found that processed seeds had higher levels of these two activities than unprocessed seeds. Taken together, these results suggest that quercetin in C campestris seeds plays an important role in these two bioactivities. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.