Thermal Degradation Kinetics Modeling of Benzophenones and Xanthones during High-Temperature Oxidation of Cyclopia genistoides (L.) Vent. Plant Material

Abstract

Degradation of the major benzophenones, iriflophenone-3-C-glucoside-4-O-glucoside and iriflophenone-3-C-glucoside, and the major xanthones, mangiferin and isomangiferin, of Cyclopia genistoides followed first-order reaction kinetics during high-temperature oxidation of the plant material at 80 and 90 °C. Iriflophenone-3-C-glucoside-4-O-glucoside was shown to be the most thermally stable compound. Isomangiferin was the second most stable compound at 80 °C, while its degradation rate constant was influenced the most by increased temperature. Mangiferin and iriflophenone-3-C-glucoside had comparable degradation rate constants at 80 °C. The thermal degradation kinetic model was subsequently evaluated by subjecting different batches of plant material to oxidative conditions (90 °C/16 h). The model accurately predicted the individual contents of three of the compounds in aqueous extracts prepared from oxidized plant material. The impact of benzophenone and xanthone degradation was reflected in the decreased total antioxidant capacity of the aqueous extracts, as determined using the oxygen radical absorbance capacity and DPPH(•) scavenging assays.

Phenolic and physicochemical stability of a functional beverage powder mixture during storage: effect of the microencapsulant inulin and food ingredients

“…The position of the sugar on the xanthone backbone therefore affects the stability of these xanthones. Beelders et al . reported a similar trend for their relative stability when honeybush plant material and the pure compounds were subjected to high temperatures.…”

“…Compounds that did not show substantial degradation included the benzophenone 3‐β‐ d ‐glucopyranosyl‐4‐β‐ d ‐glucopyranosyloxyiriflophenone (IDG), the flavone scolymoside and the flavanones eriocitrin and hesperidin (data not shown). IDG was previously shown to be very stable when Cyclopia genistoides plant material was heated at 80 and 90 °C for 16 h . Hesperidin remained stable during heating of orange juice at 90 °C for up to 4 h …”

“…For phenolic compounds where the percentage remaining was less than 80% for at least one of the treatment combinations, regression analysis with time as independent variable was also performed for each experimental unit to describe change in compound content over time. The exponential function associated with a first‐order reaction was implemented as this was shown to describe the thermal degradation of the major honeybush xanthones and benzophenones adequately . The data fitted the function well in cases where significant decline over time was observed ( r 2 > 0.80, P < 0.05).…”

Thermal Degradation Kinetics and pH-Rate Profiles of Iriflophenone 3,5-C-β-d-diglucoside, Iriflophenone 3-C-β-d-Glucoside and Mangiferin in Aquilaria crassna Leaf Extract

“…Regression analysis was applied in the evaluation of the effect of temperature on the stability of the dried AE and AE solution, with time (day) as the independent variable, for each temperature condition, and regression analysis was also used to describe the decrease in the amount of compounds 1-3 in dried AE and AE solution over time. The order of the thermal degradation reactions of compounds 1-3 were predicted using Equation 1 [1,22].…”

“…This model can help in controlling and predicting the quality over time of the plant extracts and changes affecting shelf-life. This method had also been applied to several stability studies, including studies of the degradation of the polyphenols, benzophenones and xanthonoids in the plant material of honeybush (Cyclopia genistoides L. Vent) [1], the degradation of flavonoids in the elderberry (Sambucus nigra L.) [2] and the extracts of sour cherry (Prunus cerasus) [3]. In these prior studies, it was found that the degradation rate constants were influenced the most by temperature; warmer temperatures resulted in greater degradation.…”