Isolation of iqalisetins A and B from a Tolypocladium sp. isolated from marine sediment from Frobisher Bay in Canada’s arctic

Two new decalin-tetramic acid compounds, iqalisetin A (1) and iqalisetin B (2), were identified from a Tolypocladium sp. isolated from a marine sediment sample collected from Frobisher Bay, Nunavut, in Canada’s arctic. The structures of the new compounds were elucidated by NMR experiments. The relative stereochemistry of the decalin skeleton was determined by NOESY experiments and confirmed that 1 and 2 contained a trans-decalin ring system. The absolute stereochemistry of the tetramic acid was determined using Marfey’s method. Compounds 1 and 2 did not exhibit any significant antimicrobial or cytotoxic activity.