Eumitrins F-H: three new xanthone dimers from the lichen and their biological activities.

The lichen is a fruticose lichen belonging to the . It is well known as a rich source of natural xanthone dimers and possesses various bioactivities. Nevertheless, the chemical investigation on this type of lichen is still rare as most of researches reported its components without structural elucidation.

α-Glucosidase Inhibition by Usnic Acid Derivatives.

This study investigated a set of new potential antidiabetes agents. Derivatives of usnic acid were designed and synthesized. These analogs and nineteen benzylidene analogs from a previous study were evaluated for enzyme inhibition of α-glucosidase.

Salazinic Acid-Derived Depsidones and Diphenylethers with α-Glucosidase Inhibitory Activity from the Lichen Parmotrema dilatatum.

Three new depsidones, parmosidones F - G (1 - 2), and 8'-O-methylsalazinic acid (3), and 3 new diphenylethers, parmetherines A - C (4 - 6), together with 2 known congeners were isolated from the whole thalli of , a foliose chlorolichen. Their structures were unambiguously determined by extensive spectroscopic analyses and comparison with literature data. The isolated polyphenolics were assayed for their α-glucosidase inhibitory activities.

Synthesis, α-glucosidase inhibition, and molecular docking studies of novel N-substituted hydrazide derivatives of atranorin as antidiabetic agents.

A series of novel N-substituted hydrazide derivatives were synthesized by reacting atranorin, a compound with a natural depside structure (1), with a range of hydrazines. The natural product and 12 new analogues (2-13) were investigated for inhibition of α-glucosidase. The N-substituted hydrazide derivatives showed more potent inhibition than the original.

Maydisone, a novel oxime polyketide from the cultures of .

A novel oxime polyketide, maydisone (), along with two known compounds, 7-hydroxy-2,5-dimethylchromone () and 2,5-dimethylbenzoic acid () were isolated from the cultures of . Their structures were identified by the application of NMR and MS data analyses and comparison with previous reports. Compound showed the most powerful inhibition of -glucosidase, with an IC value of 68.

Dilatatone, a new chlorinated compound from .

Chemical investigation of the lichen led to the isolation of a new chlorinated compound, named dilatatone (), along with a known compound, sernanderin (). Their chemical structures were determined by analysis of their 1 D and 2 D NMR spectra, HRESIMS, and ECD data. Both compounds showed weak glucosidase inhibitor activity.