No abstract

Naturally occurring symbioramide, (2S,3R,2'R,3'E)-N-(2'-hydroxy-3'-octadecenoyl)-dihydrosphingosine 1a, was synthesized from d-erythro-dihydrosphingosine (amino part, 2) and (2R,3E)-2-hydroxy-3-octadecenoic acid (acid part, 3a), both of which were prepared from l-serine. Its diastereomer, (2S,3R,2'S,3'E)-1b, having an enantiomer of the unnatural-type acid part that was prepared from d-mannitol, and its corresponding (Z)-isomers, (2S,3R,2'R,3'Z)-1c and (2S,3R,2'S,3'Z)-1d, were also prepared. The antileukemic activities of 1a-d against HL-60 and L-1210 cells were appreciated by a MTT assay. None of the four symbioramide derivatives showed antileukemic activities in HL-60 cells. In L-1210 cells, all the symbioramide derivatives showed moderate antileukemic activities. Compound 1d had the most effective activity against L-1210 cells among the four derivatives. The data suggest that unnatural types of (2'S)-isomers of acid parts are more active than those of (2'R)-isomers.

Two anionic surfactant-ligands, sodium 2-[1-dodecyl-2,5-bis(dihydroxymethyl)-4-imidazolyl]methylthioethanesulfonate (1) and sodium 1-hexadecyl-2-(2-hydroxymethyl-1-imidazolyl)ethyl sulfate (2), each having a functional imidazole and a hydroxyl moiety, have been examined regarding their catalytic activities in the hydrolysis of p-nitrophenyl 2-pyridinecarboxylate (PNPP) in the presence of Zn2+ or Cu2+ and under co-micellar conditions with surfactants. All of the ligands underwent a remarkable activation of the 2-hydroxymethyl group for transacylation from PNPP when complexed with Cu2+. Some interesting differences were observed between the two ligands, 1 and 2, such as in the modes of complexation and the effects of co-micellar surfactants.

No abstract

The first photochromic dendrimers which involve a 1,3-alternate conformer of a calix[4]arene as a core and azobenzene skeletons as branches have been synthesized and characterized. Photochemical properties of the photochromic dendrimers are described.