Novel Antioxidants and -Glycosidase and Protein Tyrosine Phosphatase 1B Inhibitors from an Endophytic Fungus F4a.

Oxidative stress plays a very important role in the progression of diabetes and its complications. A therapeutic agent that is both antidiabetic and antioxidant would be the preferred choice for the treatment of diabetes. The crude extract of the endophytic fungus F4a has significant antioxidant and -glycosidase and protein tyrosine phosphatase 1B (PTP1B) inhibition activities. Chemical investigation of F4a using an activity-guided isolation led to the discovery of three new compounds called peniorcinols A-C (-) along with six known compounds: penialidins A (), penialidin F (), myxotrichin C (), riboflavin (), indole-3-acetic acid (), and 2-(4-hydroxy-2-methoxy-6-methylphenyl) acetic acid (). Their chemical structures were established by their NMR and HRESIMS. The absolute configurations of and were determined by experimental and calculated electronic circular dichroism (ECD). Their antioxidant activities were evaluated by DPPH and ABTS scavenging assays. Compounds - and - showed moderate to strong free radical scavenging activities. Significantly, - exhibited more potent ABTS scavenging activity than that of the positive control. Their -glycosidase and PTP1B inhibition activities were tested. Among them, compound showed α-glucosidase inhibition activity, and compounds and showed PTP1B inhibitory activity for the first time. It is worth noting that and displayed both antioxidant and -glycosidase or PTP1B inhibition activities. These finding suggest that compounds and could be used as lead compounds to generate new potent drugs for the treatment of oxidative stress-related diabetes.