Synthesis, biological evaluation and molecular modelling of 2,4-disubstituted-5-(6-alkylpyridin-2-yl)-1-imidazoles as ALK5 inhibitors.

A series of 2,4-disubstituted-5-(6-alkylpyridin-2-yl)-1-imidazoles, , , and has been synthesised and evaluated for their ALK5 inhibitory activity in an enzyme assay and in a cell-based luciferase reporter assay. Incorporation of a quinoxalin-6-yl moiety and a methylene linker at the 4- and 2-position of the imidazole ring, respectively, and a CONH substituent in the phenyl ring generated a highly potent and selective ALK5 inhibitor . Docking model of ALK5 in complex with showed that it fitted well in the ATP-binding pocket with favourable interactions.

Antitumor activity of spinasterol isolated from Pueraria roots.

We purified phytoestrogens from Pueraria root (Pueraria mirifica from Thailand and Pueraria lobata from Korea), which is used as a rejuvenating folk medicine in Thailand and China. Dried, powdered plant material was extracted with 100% ethanol and further separated by concentration, filtration, and thin layer silica gel chromatography. Using the fractions obtained during separation, we first investigated their cytotoxicity in several cancer cell lines from various tissues.

Synthesis and biological activity of novel retinamide and retinoate derivatives.

Retinoic acid and its amide derivative, N-(4-hydroxyphenyl)retinamide (4-HPR), have been proposed as chemopreventative and chemotherapeutic agents. However, their low cytotoxic activity and water solubility limit their clinical use. In this study, we synthesized novel retinoid derivatives with improved cytotoxicity against cancer cells and increased hygroscopicity.

Synthesis of new glycyrrhetinic acid (GA) derivatives and their effects on tyrosinase activity.

To synthesize glycyrrhetinic acid (GA) derivatives (3, 4, 5, 10, 13, 14, 15, and 16), we first removed the ketonic group in the C-11 position, and the carboxylic function at the C-30 position was kept intact, reduced to an alcohol, or transformed to an aldehyde corresponding derivatives 10 and 13. Glycyrrhetinic acid (GA) derivatives (3, 4, 5, 15, and 16) were coupled with 4-amino piperpyridine derivatives (12 and 14) and 4-fluorobenzyl bromide at C-30 carboxylic acid position of glycyrrhetinic acid. In subsequent tyrosinase assays, we found that GA derivatives 4, 5, and 16 were not active at early time points, but strongly inhibited tyrosinase activity at late time points.

Efficacy validation of synthesized retinol derivatives In vitro: stability, toxicity, and activity.

Retinol (vitamin A) is used as an antiwrinkle agent in the cosmetics industry. However, its photo-instability makes it unsuitable for use in general cosmetic formulations. To improve the photo-stability of retinol, three derivatives (3, 4, and 5) were synthesized and their biological activities were analyzed.