Xanthene

About: Xanthene is a research topic. Over the lifetime, 2132 publications have been published within this topic receiving 34803 citations. The topic is also known as: Xanthene & dibenzo[a,e]pyran.

Organic polymer material containing xanthene-2,7-diol compound

Abstract: PROBLEM TO BE SOLVED: To prevent an organic polymer material from the deterioration of its quality such as the change of a physical property even when it experiences thermal history over time during being processed or used by compounding one or more organic compounds having a specific structure with an organic polymer. SOLUTION: A compound combined with an organic polymer is represented by the formula, wherein each of R1, R2 and R3 is hydrogen atom, a 1-4C straight- or branched-chain alkyl group and these may be the same or different to each other. R4 is hydrogen atom, a 1-18C linear, branched or cyclic alkyl group or a (un)substituted aryl group. Preferably, an organic polymer material further comprises a phenolic antioxidant and/or phosphorous antioxidant together with a compound of the formula. The amount of the compound of the formula is preferably 1-20 wt.% relative to the total amount of the polymer material and said antioxidant.

Modelling of antiproliferative activity measured in HeLa cervical cancer cells in a series of xanthene derivatives.

Abstract: Cancer remains one of the leading causes of death in humans, and new drug substances are therefore being developed. Thus, the anti-cancer activity of xanthene derivatives has become an important to...

Migration of the electronic excitation energy in langmuir – blodgett films of xanthene dyes

Abstract: The concentration and temperature dependencies of the photophysical properties of three new amphiphilic xanthene dyes in the Langmuir-Blodgett (LB) films have been studied. The mechanisms of excitation-energy relaxation were discussed in terms of the excitons migration among energetically disordered monomers and the energy trapping by molecular aggregates. The experimental results were analyzed in view of carried out molecular mechanics and MO calcuations. Triplet states of eosin in the LB films were investigated. The observed nonexponential decay kinetics of delayed fluorescence (DF) and phosphorescence were analyzed in the framework of an annihilation model for both exchange and multipolar interactions.

(Oxo-)xanthene derivatives, their preparation and their use as immunomodulators

Abstract: Xanthene derivatives represented by the general formula: wherein R1 is a carboxyl group which may be esterified or amidated; R2 is a hydrogen atom, a hydroxyl group, or a hydrocarbon group which may be substituted; R3 and R4 are the same or different and are a hydroxyl group which may be substituted; R5 and R6 are a hydrogen atom or a halogen atom; R7 is a hydrogen atom, a nitro group, a halogen atom, a hydrocarbon group which may be substituted, a heterocyclic group which may be substituted, or an acyl group which may be substituted; n is an integer of 0 to 2; and Y is an oxygen atom or two hydrogen atoms; and when n is 0, R2 may be a group represented by the formula: wherein the symbols have the same meanings as defined above, or a salt thereof inhibit a binding of B7-1 to CD28, prevent the B7-1-dependent activation of T cells and inhibit IL-2 production from T cells, thus being used as an immunomodulator such as a graft rejection inhibitor or a pharmaceutical composition for therapeutic treatment of allergy, rheumatoid arthritis, autoimmune disease, nephritis, diabetes mellitus and so on; and a microorgansim, Aspergillus terreus FL- 67283 strain, capable of producing some of the compounds according to formula (I); and a method for screening for a compound having an activity for inhibiting or enhancing a binding of CD28 to B7-1, or a salt thereof, which comprises comparing (1) an amount of binding between CD28 and B7-1-Ig obtained when CHO-cell containing CD28 or its cell membrane fraction is contacted with soluble B7-1-Ig, with (2) an amount of binding between CD28 and B7-1-Ig obtained when CHO-cell containing CD28 or its cell membrane fraction is contacted with soluble B7-1-Ig and a test compound; and a CHO cell designated by CD28-CHO-11 (FERM BP-5431), a CHO cell represented by B7-1-CHO-22 (FERM BP-5430) or a CHO cell represented by sB7-1-Ig-CHO-20 (FERM BP-5432)