Structural determination of stevastelins, novel depsipeptides from Penicillium sp

Structural Diversity and Biological Activities of Cyclic Depsipeptides from Fungi

Cyclic depsipeptides (CDPs) are cyclopeptides in which amide groups are replaced by corresponding lactone bonds due to the presence of a hydroxylated carboxylic acid in the peptide structure. These peptides sometimes display additional chemical modifications, including unusual amino acid residues in their structures. This review highlights the occurrence, structures and biological activities of the fungal CDPs reported until October 2017. About 352 fungal CDPs belonging to the groups of cyclic tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-, and tridecadepsipeptides have been isolated from fungi. These metabolites are mainly reported from the genera Acremonium, Alternaria, Aspergillus, Beauveria, Fusarium, Isaria, Metarhizium, Penicillium, and Rosellina. They are known to exhibit various biological activities such as cytotoxic, phytotoxic, antimicrobial, antiviral, anthelmintic, insecticidal, antimalarial, antitumoral and enzyme-inhibitory activities. Some CDPs (i.e., PF1022A, enniatins and destruxins) have been applied as pharmaceuticals and agrochemicals.

Dual-specificity phosphatases as targets for antineoplastic agents

Dual-specificity protein phosphatases are a subclass of protein tyrosine phosphatases that are uniquely able to hydrolyse the phosphate ester bond on both a tyrosine and a threonine or serine residue on the same protein. Dual-specificity phosphatases have a central role in the complex regulation of signalling pathways that are involved in cell stress responses, proliferation and death. Although this enzyme family is increasingly the target of drug discovery efforts in pharmaceutical companies, a summary of the salient developments in the biology and medicinal chemistry of dual-specificity phosphatases has been lacking. We hope that this comprehensive overview will stimulate further progress in the development of small-molecule inhibitors that could form the basis for a new class of target-directed therapeutic agents.

Cdc25 as a potential target of anticancer agents

Ever since its discovery in yeast more than a decade ago [1], Cdc25 has continued to surprise and intrigue researchers. This dual-specificity protein tyrosine phosphatase (dsPTPase) and other members of the protein tyrosine phosphatase family (PTPases) have only recently joined the protease and kinase enzyme families in drug discovery efforts. The role of phosphatases in tumourigenesis was reviewed recently by Parsons [2]. He is arguing that the phosphatase family of enzymes is involved in a variety of cancers and thus poses both a challenge and an opportunity for new therapeutics. The general biology and biochemistry of Cdc25 were recently reviewed [3]. Here I shall first summarize the recent literature on the role of Cdc25 in disease, as well as on new insights into the regulation of this family of proteins. In the second part, I will review current knowledge of the Cdc25 protein structure and the chemical structures and activities of published Cdc25 inhibitors.