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Phytosterol supplements do not inhibit dipeptidyl peptidase-4

Gupta, A, Narkowicz, CK, Al-Aubaidy, HA ORCID: 0000-0001-9564-0120, Jelinek, HF, Nichols, DS ORCID: 0000-0002-8066-3132, Burgess, JR ORCID: 0000-0003-4748-9571 and Jacobson, GA ORCID: 0000-0002-3409-8769 2020 , 'Phytosterol supplements do not inhibit dipeptidyl peptidase-4' , Diabetes & Metabolic Syndrome: clinical research & reviews, vol. 14 , pp. 1475-1478 , doi: 10.1016/j.dsx.2020.07.019.

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Background and aims: Several commercially available phytosterol supplements are promoted for theircholesterol-lowering effects. However, limited information is available about their potential antihyperglycaemic effects. This study aimed to evaluate the dipeptidyl peptidase-4 (DPP-4) inhibitory effects of phytosterol supplements in silico and in vitro to determine their potential for anti-diabeticactivity.Methods: Docking studies were carried out in silico to evaluate the potential for interactions betweenthree major phytosterol compounds (stigmasterol, b-sitosterol, campesterol) and the DPP-4 enzyme, theenzyme that is inhibited by the anti-diabetic gliptins. Gas chromatographyetandem mass spectrometry(GC-MS/MS) was used to analyse three different supplements for phytosterol content. DPP-4 inhibitoryactivity was tested in vitro for these phytosterol supplements and two major phytosterol standards.Results: In silico calculations predicted free binding energies for DPP-4 with the phytosterols to be:stigmasterol - 8.78 kcal/mol; b-sitosterol - 8.70 kcal/mol; campesterol - 8.40 kcal/mol. These bindingenergies indicated a potential for significant DPP-4 inhibition. However, these results were not supportedby the in vitro studies. Stigmasterol and b-sitosterol had an IC50 > 50 mg/ml (maximum tested concentration) and the Thompson’s Cholesterol Manager® and Mega Strength Beta Sitosterol® supplementsgave an IC50 > 100 mg/ml (maximum tested concentration). Blackmores Cholesterol Health® gave an IC50value of 40 mg/ml which was attributed to b-carotene content.Conclusions: Phytosterol supplements do not appear to offer any anti-diabetic activity potential viapathways that involve the inhibition of DPP-4.

Item Type: Article
Authors/Creators:Gupta, A and Narkowicz, CK and Al-Aubaidy, HA and Jelinek, HF and Nichols, DS and Burgess, JR and Jacobson, GA
Keywords: phytosterols, dipeptidyl peptidase-4, gas chromatography, in silico, in vitro, molecular docking, dipeptidyl peptidase-4 inhibitory assay, stigmasterol, b-Sitosterol, campesterol
Journal or Publication Title: Diabetes & Metabolic Syndrome: clinical research & reviews
Publisher: Elsevier Inc.
ISSN: 1871-4021
DOI / ID Number: 10.1016/j.dsx.2020.07.019
Copyright Information:

Copyright 2020 Elsevier Ltd.

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