Oxidative metabolism of some hydrazine derivatives by rat liver and lung tissue fractions

Targeting the CoREST complex with dual histone deacetylase and demethylase inhibitors

Here we report corin, a synthetic hybrid agent derived from the class I HDAC inhibitor (entinostat) and an LSD1 inhibitor (tranylcypromine analog). Enzymologic analysis reveals that corin potently targets the CoREST complex and shows more sustained inhibition of CoREST complex HDAC activity compared with entinostat. Cell-based experiments demonstrate that corin exhibits a superior anti-proliferative profile against several melanoma lines and cutaneous squamous cell carcinoma lines compared to its parent monofunctional inhibitors but is less toxic to melanocytes and keratinocytes. CoREST knockdown, gene expression, and ChIP studies suggest that corin's favorable pharmacologic effects may rely on an intact CoREST complex. Corin was also effective in slowing tumor growth in a melanoma mouse xenograft model. These studies highlight the promise of a new class of two-pronged hybrid agents that may show preferential targeting of particular epigenetic regulatory complexes and offer unique therapeutic opportunities.

Pharmacogenetics of isoniazid-induced hepatotoxicity

Tuberculosis is still a major problem in some developed and developing countries. The poor compliance to the treatment of tuberculosis patients due to the adverse events was supposed to be an important factor contributing to the high prevalence. This review aims to clarify the role and the pharmacological mechanism of the genes involved in the isoniazid-induced hepatotoxicity. We selected English articles of studies in human from PubMed up to May 2014 with the keywords pharmacogenetic, isoniazid and hepatotoxicity, N-acetyl transferase 2 (NAT2), CYP2E1 and glutathione S transferase (GST). Polymorphisms of NAT2, CYP2E1 and GST1 could increase patients' susceptibility to isoniazid-induced hepatotoxicity. The rapid acetylators of NAT2 and rapid metabolizers of CYP2E1 showed increased concentrations of hepatotoxic metabolites. However, the rapid metabolizers of GST1 could decrease the concentration of hepatotoxic metabolites. Some studies of human leukocyte antigen (HLA), Uridine 5'-dipphospho (UDP) glucuronosyltransferase (UGT), nitric oxide synthase (NOS), Broad complex, Tramtrack, Bric-a-brac (BTB) and cap'n'collar type of basic region leucine zipper factor family (CNC) homolog (BACH) and Maf basic leucine zipper protein (MAFK) polymorphisms showed their roles in isoniazid-induced hepatotoxicity by modifying the expression of antioxidant enzymes. A better insight into the role of polymorphisms of HLA, UGT, NOS, BACH and MAFK in addition to NAT2, CYP2E1 and GST1 in the hepatotoxicity of isoniazid may support physicians in monitoring patients hepatotoxicity symptoms and laboratory data and optimizing pharmacotherapy. Future studies about the role of such polymorphisms in different ethnicities are suggested.

BIOTRANSFORMATION OF HYDRAZINE DERVATIVES IN THE MECHANISM OF TOXICITY

Hydrazine derivatives are environmental and food pollutants but are also important because of their use in medicine for the treatment of tuberculosis and cancer. However, hydrazines also pose significant health risks to humans as they are mutagenic and carcinogenic. This review examines various metabolic pathways (enzymatic and non-enzymatic) of hydrazines for the formation of reactive species that bind to cellular macromolecules and lead to cellular dysfunction. It is believed that this biotransformation is responsible for the pharmacology and pathophysiology of hydrazine derivatives.

Azalysine analogues as probes for protein lysine deacetylation and demethylation

Reversible lysine acetylation and methylation regulate the function of a wide variety of proteins, including histones. Here, we have synthesized azalysine-containing peptides in acetylated and unacetylated forms as chemical probes of the histone deacetylases (HDAC8, Sir2Tm, and SIRT1) and the histone demethylase, LSD1. We have shown that the acetyl-azalysine modification is a fairly efficient substrate for the sirtuins, but a weaker substrate for HDAC8, a classical HDAC. In addition to deacetylation by sirtuins, the acetyl-azalysine analogue generates a novel ADP-ribose adduct that was characterized by mass spectrometry, Western blot analysis, and nuclear magnetic resonance spectroscopy. This peptide-ADP-ribose adduct is proposed to correspond to a derailed reaction intermediate, providing unique evidence for the direct 2'-hydroxyl attack on the O-alkylimidate intermediate that is formed in the course of sirtuin catalyzed deacetylation. An unacetylated azalysine-containing H3 peptide proved to be a potent inhibitor of the LSD1 demethylase, forming an FAD adduct characteristic of previously reported related structures, providing a new chemical probe for mechanistic analysis.

Plasma kinetics of procarbazine and azo-procarbazine in humans

The plasma kinetics of procarbazine (PCB) and its major metabolite azo-procarbazine (azo-PCB) were systematically investigated in humans for the first time. Eight therapy-refractory tumor patients with normal liver and renal function were given a single oral dose of 300 mg PCB hydrochloride as a drinking solution under fasting conditions. With the exception of the single i.v. administration of 10 mg ondansetron hydrochloride immediately before the administration of PCB, the patients were free of any co-medication 4 weeks before and during the study. PCB and azo-PCB were determined by a specially developed HPLC-UV method. PCB was absorbed very rapidly. Mean maximum plasma concentration was 12.5 min. A high elimination rate of PCB from plasma was found. The mean apparent oral systemic clearance and the plasma elimination half-life were estimated at 35.8 l/min and 9.2 min, respectively. Considerable amounts of azo-PCB are found in the plasma of the eight tumor patients. The mean Cmax and AUC ratios of azo-PCB/PCB were estimated at 5.5 and 45.2. Azo-PCB is formed very rapidly from PCB, but eliminated much more slowly from plasma than PCB. Considerable interindividual differences in the conversion rate of azo-PCB to its further metabolites were observed which should have consequences for the individual tumor therapeutic efficiency of PCB. No toxic side-effects or symptoms such as nausea or vomiting were observed during the entire study.