Cytochathiazines A–C: Three Merocytochalasans with a 2H-1,4-Thiazine Functionality from Coculture of Chaetomium globosum and Aspergillus flavipes

Cytochathiazines A–C (1–3), which represent a new type of merocytochalasan, were isolated from coculture of Chaetomium globosum and Aspergillus flavipes. Compounds 1–3 are the first natural products featuring an unprecedented 2H-1,4-thiazine functionality. Plausible biosynthetic pathways for 1–3 with a chaetoglobosin and a dipeptide as the main constitutional units were proposed. Compound 2 induced apoptosis in leukemia cells through the activation of caspase-3 and the degradation of poly ADP-ribose polymerase.