Thermal stability of the functional ingredients, glucosylated benzophenones and xanthones of honeybush (Cyclopia genistoides), in an aqueous model solution. (15th October 2017)

• Record Type: Journal Article
• Authors: Beelders, Theresa; de Beer, Dalene; Ferreira, Daneel; Kidd, Martin; Joubert, Elizabeth
• Is Part Of: Food chemistry. Volume 233(2017)
• Page Start: 412
• Page End: 421
• Publication Date: 2017-10-15
• Subjects: 3-β-d-glucopyranosyliriflophenone (PubChem CID: 53396784) -- 3-β-d-glucopyranosylmaclurin (PubChem CID: 101876647) -- isomangiferin (PubChem CID: 5318597) -- mangiferin (PubChem CID: 5281647).; Thermal degradation kinetics modelling -- Mangiferin -- Isomangiferin -- 3-β-d-Glucopyranosylmaclurin -- Structure-stability relationships -- Degradation pathways; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2017.04.083
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Addition of 3′-OH to 3- β -d -glucopyranosyliriflophenone decreased stability. Glucosylation of 3- β -d -glucopyranosyliriflophenone at 4-OH enhanced stability. 3- β -d -Glucopyranosylmaclurin cyclised to form mangiferin and isomangiferin. Position of sugar moiety affects xanthone stability. Xanthones were more stable than their benzophenone precursor. Abstract: Thermal stability of the benzophenones, 3- β -d -glucopyranosyl-4- β -d -glucopyranosyloxyiriflophenone (1 ), 3- β -d -glucopyranosylmaclurin (2 ) and 3- β -d -glucopyranosyliriflophenone (3 ), and the xanthones, mangiferin (4 ) and isomangiferin (5 ), was assessed separately in an aqueous model solution (pH 5) to delineate their major degradation products and mechanism(s). Degradation followed first-order reaction kinetics and the temperature-dependence of the respective reaction rate constants complied with the Arrhenius equation. The stability of the compounds increased in the order2 > 4 > 3 > 5 > 1 . 4- O -Glucosylation significantly stabilised1 against degradation compared to3, enediol B-ring functionality of2 decreased stability compared to3 and position of glucosylation affected the stability of the xanthones with5 being more stable than4 . The xanthone nucleus (C-ring) conferred higher stability to4 and5 compared to their benzophenone analogue2 . Cyclisation of2 to4 and5 would underestimate their degradation in mixtures. Other reactions were isomerisation, dimerisation, acetylation and hydrolysis.