ABSTRACT
Macrolines constitute a class of natural products that has more than 100 members and displays diverse biological activities. These compounds feature a cycloocta[b]indole scaffold that represents an interesting target structure for biology-oriented synthesis (BIOS). We have presented a solid-phase synthesis of isomerically pure cycloocta[b]indoles by employing the Pictet-Spengler reaction and the Dieckmann cyclization as key steps. The scope of this reaction sequence was investigated in more detail by using various additional diversification procedures, such as Pd-catalyzed Sonogashira or Suzuki couplings on a solid phase, thus allowing, for example, the generation of 10-substituted cycloocta[b]indole derivatives. Finally, solution-phase decoration of the cycloocta[b]indole skeleton by reduction and saponification was evaluated, thereby further extending the scope of the solid-phase synthesis.
Subject(s)
Indole Alkaloids/chemical synthesis , Indole Alkaloids/chemistry , Indoles/chemistry , Oxindoles , Solutions , Stereoisomerism , Substrate SpecificitySubject(s)
Enzyme Inhibitors/chemistry , Mycobacterium tuberculosis/enzymology , Protein Tyrosine Phosphatases/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Indoles/chemical synthesis , Indoles/chemistry , Indoles/pharmacology , Microbial Sensitivity Tests , Mycobacterium tuberculosis/drug effects , Structure-Activity RelationshipABSTRACT
A collection of approximately 11 000 natural-product derived and inspired compounds was screened for potential apoptosis inducers in the human tumour cell lines HepG2 (liver), HeLa (cervix) and MCF-7 (breast) by means of MTT and ATP-luminescence assays, automated cell counting, caspase 3/7 assay as well as by fluorescence activated cell sorting (FACS) analysis. A group of seven indoloquinolizidine derivatives was identified that exhibited IC(50) values for cell proliferation as low as 2 mumol L(-1), with no major necrosis of cells detectable. At the same time, an increase in the rate of apoptosis of up to 600 % relative to the reference level was observed. FACS analysis indicated that these effects are related to an arrest of cells in the G(2)M phase of the cell cycle.
Subject(s)
Apoptosis/drug effects , Cell Cycle/drug effects , Indoles/chemistry , Quinolizidines/pharmacology , Cell Line , Cell Proliferation/drug effects , Flow Cytometry , Humans , Microscopy, Fluorescence , Quinolizidines/chemistryABSTRACT
Protein phosphatases have recently emerged as important targets for research in chemical biology and medicinal chemistry, and new classes of phosphatase inhibitors are in high demand. BIOS (biology-oriented synthesis) employs the criteria of relevance to nature and biological prevalidation for the design and synthesis of compound collections. In an application of the BIOS principle, an efficient solid-phase synthesis of highly substituted indolo[2,3-a]quinolizidines by using a vinylogous Mannich-Michael reaction in combination with phosgene- or acid-mediated ring closure was developed. Screening of this library for phosphatase inhibitors yielded a new inhibitor class for the Mycobacterium tuberculosis phosphatase MptpB.
Subject(s)
Bacterial Proteins/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Mycobacterium/enzymology , Protein Tyrosine Phosphatases/antagonists & inhibitors , Quinolizines/chemistry , Biological Products/chemistry , Cyclization , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Quinolizines/chemical synthesis , Quinolizines/pharmacologyABSTRACT
Protein phosphatases have very recently emerged as important targets for chemical biology and medicinal chemistry research, and new phosphatase inhibitor classes are in high demand. The underlying frameworks of natural products represent the evolutionarily selected fractions of chemical space explored by nature so far and meet the criteria of relevance to nature and biological prevalidation most crucial to inhibitor development. We refer to synthesis efforts and compound collection development based on these criteria as biology-oriented synthesis. For the discovery of phosphatase inhibitor classes by means of this approach, four natural product-derived or -inspired medium-sized compound collections were synthesized and investigated for inhibition of the tyrosine phosphatases VE-PTP, Shp-2, PTP1B, MptpA, and MptpB and the dual-specificity phosphatases Cdc25A and VHR. The screen yielded four unprecedented and selective phosphatase inhibitor classes for four phosphatases with high hit rates. For VE-PTP and MptpB the first inhibitors were discovered. These results demonstrate that biology-oriented synthesis is an efficient approach to the discovery of new compound classes for medicinal chemistry and chemical biology research that opens up new opportunities for the study of phosphatases, which may lead to the development of new drug candidates.
