Phytosterol supplements do not inhibit dipeptidyl peptidase-4

Area of Science:

• Biochemistry
• Pharmacology
• Nutraceuticals

Background:

• Phytosterol supplements are widely marketed for cholesterol-lowering benefits.
• Limited research exists on their potential anti-diabetic properties.
• Diabetic treatments often target the dipeptidyl peptidase-4 (DPP-4) enzyme.

Purpose of the Study:

• To investigate the potential anti-diabetic activity of phytosterol supplements.
• To evaluate the dipeptidyl peptidase-4 (DPP-4) inhibitory effects of phytosterols.
• To compare in silico and in vitro findings regarding DPP-4 inhibition.

Main Methods:

• In silico molecular docking simulations were performed for stigmasterol, β-sitosterol, and campesterol against the DPP-4 enzyme.
• Phytosterol content in commercial supplements was analyzed using gas chromatography-tandem mass spectrometry (GC-MS/MS).
• In vitro DPP-4 inhibitory activity assays were conducted for phytosterol standards and supplements.

Main Results:

• In silico analysis predicted favorable binding energies for phytosterols with DPP-4, suggesting potential inhibition.
• In vitro studies revealed weak or no DPP-4 inhibitory activity for stigmasterol and β-sitosterol (IC50 > 50 mg/mL).
• Tested phytosterol supplements exhibited minimal DPP-4 inhibition, with one exception attributed to β-carotene content.

Conclusions:

• Phytosterol supplements do not demonstrate significant anti-diabetic potential through DPP-4 inhibition.
• The in silico findings of DPP-4 interaction were not replicated in in vitro experiments.
• Further research is needed to explore other potential mechanisms for phytosterols in glucose metabolism.