title: Inhibition of human tumor cell proliferation by novel anthraquinones from daylilies.
abstract: Daylilies (Hemerocallis) are used medicinally in eastern Asia and extracts of the plant had been shown to inhibit cell proliferation and induce cancer cells to undergo differentiation. In our studies of the constituents of Hemerocallis fulva var. 'Kwanzo' roots, we isolated a series of new [kwanzoquinones A (1), B (2), C (4), D (5), E (6), F (7), G (9)] and known [2-hydroxychrysophanol (3) and rhein (8)] anthraquinones. These compounds were tested in order to determine their potential roles as cancer cell growth inhibitors. Kwanzoquinones A-C and E, kwanzoquinone A and B monoacetates (1a and 2a), 2-hydroxychrysophanol, and rhein inhibited the proliferation of human breast, CNS, colon, and lung cancer cells with GI50 values between 1.8 to 21.1 microg/mL. However, upon exposure of the cancer cells to the GI50 concentrations of the bioactive anthraquinones, most of the cancer cell lines exhibited higher than anticipated levels of cell viability. Co-incubation of the anthraquinones with vitamins C and E increased the viability of breast cancer cells. In contrast, vitamins C and E potentiated the cytotoxic effects of the anthraquinones against the colon cancer cells. None of the anthraquinones inhibited the activity of topoisomerase.
authors.affiliation: Bioactive Natural Products and Phytoceuticals, Department of Horticulture and National Food Safety and Toxicology Center, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Cichewicz
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Navindra P
authors.initials: NP
authors.lastname: Seeram
authors.forename: Muraleedharan G
authors.initials: MG
authors.lastname: Nair
mesh_terms: D000880:Anthraquinones / Q000302:isolation & purification / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004338:Drug Combinations; D004354:Drug Screening Assays, Antitumor; D031421:Hemerocallis / Q000737:chemistry*; D006801:Humans; D009369:Neoplasms / Q000473:pathology*; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D000880:Anthraquinones; D000970:Antineoplastic Agents; D004338:Drug Combinations; D010936:Plant Extracts; D014810:Vitamin E; D001205:Ascorbic Acid