Profiling for Bioactive Molecules from Targeted Plant Species with Potential for the Prevention and Treatment of Diabetes through Diet or Supplementation

Abstract

Type 2 Diabetes (T2D) is a growing problem throughout the globe leading to many health complications, including cardiovascular disease, kidney and liver disease, stroke and is a major cause of premature death. Natural products offer a key source of potentially useful antidiabetic agents that could help tackle this global problem, both through diet and supplementation. Many studies have looked at plants used in traditional medicine for the treatment of T2D, but largely focus on polyphenolics and medium-polarity compounds, using organic solvents as an extracting medium, with far less attention paid to very polar and difficult to analyse compounds. These include iminosugars, structurally analogous to sugars, which are known to be potent inhibitors of glycolytic enzymes with consequent effect on carbohydrate metabolism.

This project investigated foodplants and herbal preparations, reported to have application for the treatment and prevention of diabetes for the presence of bioactive iminosugars and related compounds.

In total ten different plants and one multiherbal preparation were initially profiled and a selection narrowed down to potato (seven varieties), sweet potato, Baphia pubescens, Gymnema sylvestre and okra. The prevalence of calystegines in different potato varieties was observed and compared to the sweet potato. Hydroxycinnamates and flavonoid compounds were also detected. An iminosugar acid, BR1, was isolated from G. sylvestre and B. pubescens amongst other Baphia
compounds, including novel Baphione. Compounds and extracts were tested for bioactivity on digestive enzymes, with results supporting their potential antidiabetic effects.

A randomised cross-over intervention trial was also carried out to investigate the effect of okra on blood sugar levels. Sixteen healthy volunteers were given capsules with a fixed dose of whole okra pod powder or placebo (cellulose) 30 minutes before an oral glucose challenge. Blood glucose levels were then monitored over a 2-hour period. A significant difference (p<0.05) was detected between okra and placebo at the zero time point but not at any of the subsequent time points. Three participants showed a general positive trend to the okra supplement though this was not statistically significant (at p<0.05).

Date of Award	2024
Original language	English
Awarding Institution	Aberystwyth University
Supervisor	Ana Winters (Supervisor) & Luis Mur (Supervisor)