Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787408
Title: Identification of soft-fruit bioactive that regulate postprandial hyperglycaemia
Author: Barik, Sisir Kumar
ISNI:       0000 0004 7972 5273
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2019
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Abstract:
Human intervention stuides have shown that consumption of soft-fruits (berries) reduce postprandial glycaemia. The proposed mechanisms for the reduced postprandial glycaemia are inhibition of carbohydrate digestive enzymes (α-amylase, α-glucosidase), intestinal sugar absorption and transport across small intestine (as assessed via CaCo-2 cell model system). Soft-fruits were selected due to their differences in anthocyanin contents; the compounds which were hypothesised as being the bioactive metabolites. Further, the digestion of the soft-fruits was modeled using in vitro gastrointestinal digestion, where the digested metabolites were identified by LC-MS/MS. The effect of the digested metabolites on α-glucosidase activity and on the activity of cytoplasmic protein; PTP1B was determined using in vitro and in-silico methods. Mirtoselect and black currants, both of which are high in anthocyanins and their digested extracts inhibited yeast α-glucosidase activity at levels lower than Acarbose, whereas wild type bilberry and green currant, which are lower in anthocyanins showed no inhibition. All the soft-fruits showed significant inhibition on salivary α-amylase, glucose uptake, mRNA expressions of sugar transporters (SGLT1, GLUT2, GLUT5) and PTP1B. Selected anthocyanins and 'other phenolics' identified in these soft-fruits by LC-MS/MS analysis were independently evaluated for their inhibitory activity against the same targets. Both the anthocyanins and the 'other phenolics' were shown to inhibit salivary α-amylase, glucose uptake and PTP1B but only the 'other phenolics' were able to inhibit the intestinal sugar transporters (SGLT1, GLUT2, GLUT5). Specific anthocyanins identified in the soft fruits inhibited α-glucosidase, more than Acarbose. Of the selected phenolics, malvidin-3-glucoside and gallic acid demonstrated the highest inhibition of PTP1B, where their mode of inhibition and binding energies were determined using in-silic In summary, anthocyanins, as well as 'other phenolics' identified in the selected soft-fruits were effective in regulating postprandial hyperglycaemia and could lower the associated risk of developing type-2 diabetes.
Supervisor: Hoggard, Nigel ; Russell, Wendy Sponsor: University of Aberdeen ; Rural and Environment Science and Analytical Services (RESAS) ; Nutricia Research Foundation
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.787408  DOI: Not available
Keywords: Hyperglycemia ; Non-insulin-dependent diabetes ; Berries ; Digestion ; Metabolites ; Plant bioactive compounds
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