A New Asterosaponin from the Starfish Culcita novaeguineae

A new asterosaponin named novaeguinoside A, along with a known saponin, asteronyl pentaglycoside sulfate, was isolated from the starfish Culcita novaeguineae. The new compound was identitied to be sodium 6α-O-{β-D-fucopyranosyl-(1→2)-β-D-fucopyranosyl-(1→4)-[β-D-quinovopyranosyl-(1→2)]-β-D-xylopyranosyl-(1→3)-[β-D-quinovopyranosyl}-5α-pregn-9(11)-en-20-one-3β-yl-sulfate by extensive spectral analysis and chemical evidence.     

STUDIES OF ELECTRON SPIN RESONANCE ON BILIRUBIN FREE RADICALS

The nature of ESR signals derived from bilirubin-Ⅸα has been studied by focusing onthe samples treated with free radical generating and inhibiting systems, i.e. X-XOD, Fe/EDTA, SOD, mannitol/ascorbate, CO, KCN, etc. In all the cases, the stable signals comprisethose originated from semiquinone radical (g = 2.0012) and superoxide free radical (g_∥=2.041, g_⊥= 2.0040). The superoxide is shown binding with certain metal ions chelated bybilirubin. The free radical scavengers are able to destroy these radicals. The kinetic curveof the regeneration of bilirubin radicals has been determined and the reaction follows azero order mechanism. It is likely that both the physiological and toxic actions of bilirubinare related to the characters of its free radicals. Bilirubin is discussed as "active oxygensink" in mammalians.     

Coupling Reaction of 4-Chloro-7-H-Pyrrolo[2,3-d]Pyrimidine with 2,3,5-Tri-O-Acetyl-β-D-Ribofuranosyl Chloride

Tubercidin (4-amino-7--D-riobofuranosyl-7-H-pyrrolo[2,3-d]pyrimidine) 1, an antibio-tic substance produced in the culture broth of Streptomyces tubericidus1, is an adenosine analog in which N-7 is replaced by a carbon atom. It has attracted much attention due to the biological activities for the growth inhibition of certain tumors, and many derivatives of tubercidin have been synthesized2-5.For the synthesis of tubercidin analogs, 4-chloro-7-H-pyrrolo[2,3-d]pyrimidine-2,3,5-tri-O-acetyl--D-r…     

Two New Constituents from the Soft Coral Nephthea hainansis

Two new compounds, namely 7α, 10α-dimethyl-3β-isopropene-1, 2-ene-octahydro-naphthalene (1) and ethyl 5Z,8Z, 11Z, 14Z-nonadecatetraenoate (2) were isolated from the soft coralNephthea hainansis. Compound 1 was a pseutosesquiterpene and 2 was a polyunsaturated fattyacid ethylate. Their structures were established on the basis of spectroscopic methods.     

Synthesis of New Flavanone Derivatives of Farrerol and Preliminary SAR Studies on Anti-VSMCs Vegetation Activity

A series of new flavanone derivatives of farrerol was designed and synthesized as a potent inhibitor of vascular smooth muscle cells(VSMCs) vegetation according to a convenient method. The structures of all the synthesized compounds were confirmed by 1H NMR, 13C NMR and EIHR-MS. The biological activities of these compounds against VSMCs in vitro were evaluated. The assay results indicate that two compounds, 5,7-dihydroxy-6,8-dimethyl- 2-(2-nitrophenyl)chroman-4-one(7f) and 2,3-dibromo-4,5-dihydroxydiphenylm...     

A New Cyclic Bisdesmoside from Tubers of Bolbostemma paniculatum

The structure of tubeimoside V (1), a new cyclic bisdesmoside, isolated from tubers of Bolbostemma paniculatum (Tu Bei Mu), was established by means of 2D NMR spectral and chemical methods. Compound 1 has inter-saccharide chain bridging by a dicrotalic acid to form aunique macrocyclic structure.     

First total synthesis of eudistalbin A

<正>Eudistalbin A was isolated from marine tunicate eudistoma album and possess cytotoxic activity(ED_(50)3.2μg/mL) in vitro against the growth of KB human buccal carinoma cells.The synthetic eudistalbin A showed potent inhibitory activity against the breast carcinoma cell line MDA-231 with an IC_(50) value of 2.1μmol/L using the metabolic assay MTT.All structures of new compounds were confirmed by ~1H NMR,~(13)C NMR,HRMS and optical rotation.     

Stereoselective Synthesis of N~1-Lyxitol Inosine Derivative

Cyclic ADP-ribose (cADPR) 1 (Figure 1), a intracellular Ca2+-mobilizing messenger, is of great interest because of its significant importance in the signal transduction1. However, the biological as well as chemical instability of cADPR limits the studies of its physiological role, at least in some aspect2. Recently, Shuto et.al.3 constructed a mimic of cADPR, cyclic IDP-carbocyclic-ribose 2, in which the 4'-oxo in furanose is substituted by a methylene group and the stability of 2 is i…