Albumin-Oxanorbornadiene Conjugates Formed ex Vivo for the Extended Circulation of Hydrophilic Cargo.

Oxanorbornadiene dicarboxylate (OND) reagents were explored for the purpose of binding and releasing chemical cargos from endogenous circulating serum albumins. ONDs bearing gadolinium chelates as model cargos exhibited variable conjugation efficiencies with albumin in rat subjects that are consistent with the observed reactivity of each linker and their observed stability toward serum hydrolases in vitro. The terminal elimination rate from circulation was dependent on the identity of the OND used, and increased circulation time of gadolinium cargo was achieved for linkers bearing electrophilic fragments designed to react with cysteine-34 of circulating serum albumin.

P450 3A-Catalyzed O-Dealkylation of Lapatinib Induces Mitochondrial Stress and Activates Nrf2.

Lapatinib (LAP), an oral tyrosine kinase inhibitor for the treatment of metastatic breast cancer, has been associated with idiosyncractic hepatotoxicity. Recent investigations have implicated the importance of P450 3A4/5 enzymes in the formation of an electrophilic quinone imine (LAPQI) metabolite generated through further oxidation of O-dealkylated lapatinib (OD-LAP). In the current study, hepatic stress was observed via mitochondrial impairment.

13-Methylarachidonic acid is a positive allosteric modulator of endocannabinoid oxygenation by cyclooxygenase.

Cyclooxygenase-2 (COX-2) oxygenates arachidonic acid (AA) and the endocannabinoids 2-arachidonoylglycerol (2-AG) and arachidonylethanolamide to prostaglandins, prostaglandin glyceryl esters, and prostaglandin ethanolamides, respectively. A structural homodimer, COX-2 acts as a conformational heterodimer with a catalytic and an allosteric monomer. Prior studies have demonstrated substrate-selective negative allosteric regulation of 2-AG oxygenation.

Gauging reactive metabolites in drug-induced toxicity.

Over the past decades, it has become abundantly clear that enzymes evolved to detoxify and eliminate foreign chemicals from the body, occasionally generate highly reactive metabolites which have toxicological implications. To decrease the probability of late clinical failure or market withdrawal, there has been an increased prioritization on understanding key metabolic processes that might cause drug interactions or toxicities. Significant advances have been made in the detection of reactive metabolites and in understanding the structure activity relationship.