ABT-491 is highly potent, selective and orally active platelet-activating factor (PAF) receptor antagonist, developed by Abbott Laboratories for allergic rhinitis treatment. ABT-491 is a potent antagonist of responses linked to the PAF receptor at the cellular level, especially platelets and neutrophils. ABT-491 was also effective in blocking platelet activation in blood, indicating that the presence of high concentrations of protein and other serum factors slightly alters the ability of ABT-491 to interact with PAF receptor. ABT-491 effectively antagonizes PAF-induced platelet and neutrophil responses at submicromolar concentrations in vitro and exhibits in vivo efficacy in alleviating PAF-mediated inflammatory and pathological processes in various animals, including guinea pigs, mice, and rats, via either i.v., i.p. or p.o. routes.

Stachydrine, a pyrrolidine betaine, was first isolated from seed husk and the pulp of the fruit of C. Leonurus, and many other Asian plants and fruits. Stachydrine is an anti-metastatic agent. Stachydrine hydrochloride induces apoptosis in MCF-7 and T47D cells and exerts inhibitory effects on proliferation by concurrently suppressing Akt and ERK survival signals, suggesting its potential efficiency in treatment of breast cancer. Stachydrine (Sta) has also been reported to possess numerous cardioprotective effects. It ameliorated pressure overload-induced diastolic heart failure by suppressing myocardial fibrosis.