The synthesis of a novel series of potent chiral inhibitors of histone deacetylase (HDAC) is described that contain a heterocyclic capping group and a N-(2-aminophenyl)benzamide unit that binds in the active site. In vitro assays for the inhibition of HDAC1, HDAC2, HDAC3-NCoR1, and HDAC8 by the N-(2-aminophenyl)benzamide 24a gave respective IC50 values of 930, 85, 12, and 4100 nM, exhibiting class I selectivity and potent inhibition of HDAC3-NCoR1. Both imidazolinone and thiazoline rings are shown to be effective replacements for the pyrimidine ring present in many other 2-(aminophenyl)benzamides previously reported, an example of each ring system at 1 μM causing an increase in histone H3K9 acetylation in the human cell lines Jurkat and HeLa and an increase in cell death consistent with induction of apoptosis. Inhibition of the growth of MCF-7, A549, DU145, and HCT116 cell lines by 24a was observed, with respective IC50 values of 5.4, 5.8, 6.4, and 2.2 mM.

A novel series of potent chiral inhibitors of histone deacetylase (HDAC) is described that contains an oxazoline capping group and a N-(2-aminophenyl)-benzamide unit. Among several new inhibitors of this type exhibiting Class I selectivity and potent inhibition of HDAC3-NCoR2, in vitro assays for the inhibition of HDAC1, HDAC2, and HDAC3-NCoR2 by N-(2-aminophenyl)-benzamide 15k gave respective IC50 values of 80, 110, and 6 nM. Weak inhibition of all other HDAC isoforms (HDAC4, 5, 6, 7, and 9: IC50 > 100 000 nM; HDAC8: IC50 = 25 000 nM; HDAC10: IC50 > 4000 nM; HDAC11: IC50 > 2000 nM) confirmed the Class I selectivity of 15k. 2-Aminoimidazolinyl, 2-thioimidazolinyl, and 2-aminooxazolinyl units were shown to be effective replacements for the pyrimidine ring present in many other 2-(aminophenyl)-benzamides previously reported, but the 2-aminooxazolinyl unit was the most potent in inhibiting HDAC3-NCoR2. Many of the new HDAC inhibitors showed higher solubilities and lower binding to human serum albumin than that of Mocetinostat. Increases in histone H3K9 acetylation in the human cell lines U937 and PC-3 was observed for all three oxazolinyl inhibitors evaluated; those HDAC inhibitors also lowered cyclin E expression in U937 cells but not in PC-3 cells, indicating underlying differences in the mechanisms of action of the inhibitors on those two cell lines.

Modification of the ring nucleus of tetramic acids derived from serine gives chiral heterocyclic libraries that exhibit antibacterial activity, and correlation with various physicochemical parameters indicates that chiral tetramic acids may provide a potentially valuable non-aromatic skeleton for fragment-based drug discovery.

The synthesis and biological properties of a structurally novel, potent and non-peptidic inhibitor of peptidylarginine deiminase are described. The novel drug-like PAD inhibitor contains a 3,5dihydroimidazol-4-one ring that replaces the acyclic guanidine-binding unit present in arginine residues.This new drug-like PAD inhibitor was effective at 100 nM or below and could have relevance to diseases in which PAD expression is up-regulated, including rheumatoid arthritis, cancer, multiple sclerosis, and neural injury.

A chemoselective Dieckmann ring closure using an oxazolidine derived from serine may be used to generate a tetramic acid, the further manipulation of which by reduction and ring closure leads to the bicyclic core of isatisine; depending on the nature of the ring closing electrophile, different diastereomers are obtained. None of the compounds from this sequence exhibited activity against S. aureus but several showed activity against E. coli.