Abstract
Hedyotis diffusa is a Chinese herbal medicine widely used in combination with other herbal medicines such as Scutellaria barbata to treat various types of cancer. Late-stage and recurrent cancer patients usually use H. diffusa during chemotherapy in expecting to achieve additive or synergistic therapeutic effects. Several classes of active ingredients, including anthraquinones, iridoid glucosides and stigmasterols, have been isolated and characterized from H. diffusa. In the current study, we isolated alkaloid/flavonoid from H. diffusa and showed that the crude alkaloid/flavonoid extract rather than its three major components possessed antitumor activity against human breast cancer cell line MCF7. Co-administration of H. diffusa water extract diminished the cytotoxicities of chemotherapy drugs doxorubicin, cyclophosphamide and docetaxel towards the MCF7 cells, implicating that H. diffusa should not be used during breast cancer chemotherapy.