Protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase inhibitory activities of Schisandra chinensis (Turcz.) Baill

• The stems of SCTZ's anti-diabetes effect and the fractions and constituents against the PTP1B and α-glucosidase mechanism is reported for the first time.
• Four fractions and 10 known compounds were evaluated for protein tyrosine phosphatase 1B and α-glucosidase inhibitory activities from Schisandra chinensis (Turcz.) Baill.
• All fractions and constituents exhibited significant inhibitory activities.
• IC50 values of compound 1 and PE fraction for PTP1B was lower than 5 μM or μg/mL.
• IC50 values of EtOAc extract for α-glucosidase was lower than 2 μg/mL.

Schisandra chinensis (Turcz.) Baill. (SCTB) is a functional, economical and medicinal herb that has numerous medicinal and nutritional properties. The present study was carried out to investigate its inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase. The extracts and compounds isolated from petroleum ether (PE) extract were further tested for their PTP1B and α-glucosidase inhibitory activities. The data showed that the anti-diabetic activity of SCTB is attributable to the PE (IC50 = 1.77 ± 0.20 μg/mL) and EtOAc (IC50 = 1.04 ± 0.20 μg/mL) extracts as well as compounds 1 (IC50 = 2.36 ± 0.20 μM) and 4 (IC50 = 9.78 ± 0.10 μM) that were compared with the positive controls NaVO4 (IC50 = 22 ± 0.20 μM) and acarbose (IC50 = 2.10 ± 0.10 μg/mL), respectively. These results demonstrate that the stems of SCTB are useful as potential functional food ingredients for the prevention and treatment of type-2 diabetes.