Quinones from Rubia manjith and their antitumor activity

Rubia plants, well-recognized as medicinal resources, are characterized by diverse phytoconstituents and a broad spectrum of biological activities, and have traditionally been employed in managing various diseases. R. manjith, a representative species of the genus Rubia enriched with quinone derivatives, has long been used in traditional Chinese medicine for the treatment of hematemesis, hematuria, inflammation, ulcers, and dermatological disorders. However, up to now, no research on the chemical components of this plant has been carried out. The present study focuses on the quinone constituents of R. manjith with the aim of identifying potential anti-tumor agents. From the roots and rhizomes of R. manjith, four previously undescribed anthraquinones (1-4), together with thirty-one known quinones (5-35), were successfully isolated and identified. Their cytotoxic activities were assessed against several colorectal cancer cell lines, among which 6 exhibited pronounced antiproliferative effects. Furthermore, network pharmacology analysis in combined with molecular docking was employed to elucidate the potential mechanisms underlying the anti-tumor activity of 6.