The potential of click reactions for the synthesis of bioactive triterpenes

Click reactions between alkynes and azides using the privileged scaffold of triterpenes have been of interest for biological chemistry. Many publications deal with the synthesis of novel bioactive molecules; these conjugates have also been used for bioanalytical and diagnostic purposes. As a result, conjugates of better physicochemical properties were obtained; even compounds of improved solubility in water and physiological fluids were made through the introduction of a triazol residue. "Hybrid-structures", i.e. molecules consisting of two independently bioactive subunits linked by a triazole residue were higher bioactive than their parent compounds but not as active as expected, and with a few exceptions the ultimate breakthrough has not yet been achieved. Only in the synthesis of compounds with anti-leishmanial activity some new and promising lead structures were found. As a consequence, triazole modified triterpenes seem to hold their greatest future prospect rather as diagnostic reagents and molecular probes than as drugs.

Monitoring Reactions on Solid Phases with Raman Spectroscopy

The benefits of Raman spectroscopy were shown for the on-bead monitoring of diverse reactions. Raman spectroscopy was used for the development of new procedures on established linker systems, the real-time observation of several reactions on solid phases and the estimation of the reaction time for a new cleavage strategy. Selected conversions on solid phases, such as the on-bead conversion of functional groups and the attachment of novel building blocks, were demonstrated. Raman spectra were obtained after isolation and purification of the solid supports, but they were also measured directly in the reaction vessels. Even the detection of Raman-active functional groups in swollen polymer resins and in reaction mixtures was demonstrated, and allows real-time observation of the progress of diverse reactions on solid supports.

Efficient Syntheses of 1,2,3-Triazoloamide Derivatives Using Solid- and Solution-Phase Synthetic Approaches

Efficient synthetic routes for the preparation of secondary and tertiary 1,2,3-triazoloamide derivatives were developed. A secondary α-1,2,3-triazoloamide library was constructed and expanded by a previously developed solid-phase synthetic route and a tertiary 1,2,3-triazoloamide library was constructed by a parallel solution-phase synthetic route. The synthetic routes rely on amide formation with secondary amines and chloro-acid chlorides; S_N2 reaction with sodium azide; and the selective [3 + 2] Hüisgen cycloaddition with appropriate terminal alkynes. The target secondary and tertiary 1,2,3-triazoloamide derivatives were obtained with three-diversity points in excellent overall yields and purities using the reported solid- and solution-phase synthetic routes, respectively.

The 1,2,3-triazole derivative KP-A021 suppresses osteoclast differentiation and function by inhibiting RANKL-mediated MEK-ERK signaling pathway

The triazole family of compounds has been implicated in modulating various biological processes such as inflammation, tumorigenesis, and infection. To our knowledge, this is the first study to demonstrate the effects of 1,2,3-triazole substituted biarylacrylonitrile compounds, including KP-A021, on the differentiation and function of osteoclasts. KP-A021 and its triazole derivatives, at a concentration that does not cause a cytotoxic response in bone marrow macrophages (BMMs), significantly inhibited osteoclast differentiation induced by receptor activator of nuclear factor-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) as assessed by tartrate-resistant acid phosphatase (TRAP) staining. KP-A021 also dramatically inhibited the expression of marker genes associated with osteoclast differentiation, such as TRAP, cathepsin K (Cat K), dendritic cell-specific transmembrane protein (DC-STAMP), and nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1). Furthermore, KP-A021 inhibited actin ring formation in osteoclasts as well as resorption pit formation induced by osteoclasts. Analysis of the signaling pathway for KP-A021 indicated that this triazole compound inhibited the RANKL-induced activation of extracellular signal-regulated kinase (ERK) and its upstream signaling molecule, mitogen-activated protein kinase kinase1/2 (MEK1/2). Taken together, these results demonstrate that KP-A021 has an inhibitory effect on the differentiation and function of osteoclasts via modulation of the RANKL-induced activation of the MEK-ERK pathway.