Hot News About Chili Peppers

Two studies open windows on the function and biochemical impact of capsaicinoids, the family of compounds that give some chili peppers their kick. Joshua J. Tewksbury at the University of Washington and colleagues found evidence that peppers produce the chemicals as a defense against a fungus that destroys chili seeds (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.0802691105). Peppers that contain various capsaicinoids have better resistance to the fungus, which is transmitted by insects that feed on the fruit. Meanwhile, Yasser A. Mahmmoud of the University of Aarhus, in Denmark, has discovered how capsaicin, the parent compound for this chemical class, raises body temperature and increases metabolism (J. Biol. Chem. 2008, 283, 21418). Mahmmoud reports that capsaicin alters the way muscle cells utilize energy produced through ATP hydrolysis. When a cell hydrolyzes ATP normally, the SERCA protein uses some of the resulting energy to pump calcium ions into a cellular compartment known as the sarcoplasmic reticulum. But capsaicin alters SERCA’s conformation and uncouples these two processes. As a result, the ATP energy isn’t used to pump calcium; instead, it’s released as heat.