α-Glucosidase Inhibitory Depsidones from the Lichen Parmotrema tsavoense.

Chemical investigation of the lichen led to the isolation of 5 new depsidones, parmosidones F - J (1:  - 5: ). These compounds were structurally elucidated using spectroscopic methods including HRESIMS and 2D NMR data. Compounds 1, 3: , and 4: were evaluated for their inhibition of glucosidase. All exhibited potent glucosidase inhibitory activity with IC values ranging from 10.7 to 17.6 µM, which was much lower than that of the positive control acarbose (IC 449 µM).