LAUSR

Five new heterodimers, chalasoergodimers A–E (1–5), and three known heterodimers (6–8), along with four chaetoglobosin monomers (9–12), were isolated from a marine-derived Chaetomium sp. fungus. The structures of new compounds 1–5 were elucidated by HRESIMS, NMR, chemical calculated 13C NMR and ECD methods. Among them, compound 1 was derived from C-2′ substitution of chaetoglobosin Fex (9) with ergosta-4,6,8(14),22-tetraen-3β-ol, representing a new dimerization mode among chaetoglobosin-ergosterol derivative hybrids. Compound 2 featured substitution at NH-1′ and constituted the first example of this dimeric type bearing an R-configuration at C-3′′. Compounds 3–5 were formed via a Diels–Alder cycloaddition between chaetoglobosins and 14-dehydroergosterol. Furthermore, it was revealed that compound 9–12 exhibited the significant cytotoxic activity against the human non-small cell lung cancer cell (A549), with compound 12 showing the most potent effect at an IC50 of 5.14 μM.