A chemifluorescent immunoassay for the determination of marinobufagenin in body fluids.

We describe here the development of a chemifluorescent competitive enzyme-linked immunosorbent assay (ELISA) that quantifies marinobufagenin (MBG) levels in biological fluids. Based on a polyclonal antibody raised against a novel MBG-bovine serum albumin conjugate, this assay achieved an MBG detection limit of less than 9 pg/mL. MBG levels in various rat urine and serum samples were effectively determined using this methodology.

Resibufogenin corrects hypertension in a rat model of human preeclampsia.

The study of the pathogenesis of preeclampsia has been hampered by a relative dearth of animal models. We developed a rat model of preeclampsia in which the excretion of a circulating inhibitor of Na/K ATPase, marinobufagenin (MBG), is elevated. These animals develop hypertension, proteinuria, and intrauterine growth restriction.

Cephalostatin 1 selectively triggers the release of Smac/DIABLO and subsequent apoptosis that is characterized by an increased density of the mitochondrial matrix.

Cephalostatin 1 is a bis-steroidal marine natural product with a unique cytotoxicity profile in the in vitro screen system of the National Cancer Institute, suggesting that it may affect novel molecular target(s). Here we show that cephalostatin 1 induces a novel pathway of receptor-independent apoptosis that selectively uses Smac/DIABLO (second mitochondria-derived activator of caspases/direct inhibitor of apoptosis-binding protein with a low isoelectric point) as a mitochondrial signaling molecule. At nanomolar concentrations, cephalostatin 1 triggers dose- and time-dependent DNA fragmentation in leukemia Jurkat T cells.

QSAR evaluation of the Ch'an Su and related bufadienolides against the colchicine-resistant primary liver carcinoma cell line PLC/PRF/5(1).

QSAR analysis has been used to identify the essential structural requirements for increasing the inhibitory activities of selected bufadienolides from the Chinese drug Ch'an Su (and other sources) against the primary liver carcinoma cell line PLC/PRF/5 (PLC) and the derived colchicine-resistant line (COL). The variable substituent domain of the proposed pharmacophore of the bufadienolides was investigated using a Comparative Molecular Field Analysis (CoMFA) approach. A model with considerable predictive ability was obtained.

Biological activity of a novel nonpeptide antagonist to the interleukin-6 receptor 20S,21-epoxy-resibufogenin-3-formate.

Interleukin (IL)-6 is a key mediator in the regulation and coordination of the immune response and participates in pathogenesis of cancer cachexia, autoimmune disease, and postmenopausal osteoporosis. In the course of a screening program aimed at IL-6 inhibitor from natural products, we isolated 20S,21-epoxy-resibufogenin-3-formate (ERBF) from bufadienolide and examined the effect of ERBF on activities of various cytokines. ERBF dose dependently suppressed IL-6 activity and caused a parallel rightward shift of dose-response curves to IL-6 at concentrations of 0.

Isolation and structure of a 20,21-epoxybufenolide series from "Ch'an Su".

Steroid bufenolides resulting from epoxidation of the 17beta-2-pyrone ring of bufadienolides are rare. Five 20,21-epoxybufenolides, namely, 20S,21-epoxyresibufogenin (1), 20R,21-epoxyresibufogenin (2), 3-O-formyl-20S,21-epoxyresibufogenin (3), 3-O-formyl-20R,21-epoxyresibufogenin (4), and 3-oxo-20S,21-epoxyresibufogenin (5), were isolated from the Chinese toad skin extract drug Ch'an Su. The structures were elucidated by spectroscopic and chemical methods.