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Phytosterols do not possess DPP-4 inhibitory activity.pdf (262.85 kB)

Phytosterol supplements do not inhibit dipeptidyl peptidase-4

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journal contribution
posted on 21.01.2021, 05:45 by A Gupta, CK Narkowicz, Hayder Al-Aubaidy, HF Jelinek, DS Nichols, JR Burgess, GA Jacobson
© 2020 Diabetes India

Background and aims: Several commercially available phytosterol supplements are promoted for their cholesterol-lowering effects. However, limited information is available about their potential anti-hyperglycaemic 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-diabetic activity. Methods: Docking studies were carried out in silico to evaluate the potential for interactions between three major phytosterol compounds (stigmasterol, β-sitosterol, campesterol) and the DPP-4 enzyme, the enzyme that is inhibited by the anti-diabetic gliptins. Gas chromatography–tandem mass spectrometry (GC-MS/MS) was used to analyse three different supplements for phytosterol content. DPP-4 inhibitory activity 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; β-sitosterol −8.70 kcal/mol; campesterol −8.40 kcal/mol. These binding energies indicated a potential for significant DPP-4 inhibition. However, these results were not supported by the in vitro studies. Stigmasterol and β-sitosterol had an IC50 > 50 mg/ml (maximum tested concentration) and the Thompson's Cholesterol Manager® and Mega Strength Beta Sitosterol® supplements gave an IC50 > 100 mg/ml (maximum tested concentration). Blackmores Cholesterol Health® gave an IC50 value of 40 mg/ml which was attributed to β-carotene content. Conclusions: Phytosterol supplements do not appear to offer any anti-diabetic activity potential via pathways that involve the inhibition of DPP-4.

Funding

The project was funded by School of Health Sciences, University of Tasmania.

History

Publication Date

01/09/2020

Journal

Diabetes and Metabolic Syndrome: Clinical Research and Reviews

Volume

14

Issue

5

Pagination

4p. (p. 1475-1478)

Publisher

Elsevier

ISSN

1871-4021

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