Effect of Betulin-containing Extract from Birch Tree Bark on α-Amylase Activity In vitro and on Weight Gain of Broiler Chickens In vivo

In vitro effect of betulin-containing extract from Betula pendula Roth. bark on alpha-amylase activity was studied, the kinetic mechanism of interaction was proposed and in vivo effect of betulin-containing extract on weight gain and meat quality of broiler chickens was evaluated. The highest level of inhibitory activity (20 %) was detected in extract concentration of 1,000 mg/L. Increased extract concentration did not lead to increased enzyme inhibition. Using Dixon and Cornish-Bowden coordinates, the competitive mechanism of inhibition was demonstrated. Calculated kinetic parameters were: K_m equal to 0.6 mg/mL, V_max equal to 2.6 and 2.1 mM/min from Lineweaver-Burk and Dixon coordinates, respectively and K_i equal to 3,670?±?230 mg/mL. The partial inhibition of enzyme indicates the existence of low concentration of active inhibitory form, which reaches saturation level with increased extract concentration in applied suspension. Therefore, K_i has an apparent constant character. This partial inhibition of amylase activity observed in in vitro assay did not affect weight gain and meat quality of broiler chickens during in vivo assay. Rather, the tendency to increase the weight of edible parts and muscles compared to diet without additive suggests that the extract may be a potential food additive in poultry farming. Additionally, it could be a source for further pharmaceutical and pharmacological research.     

Investigating the impact of α-amylase, α-glucosidase and glucoamylase action on yeast-mediated bread dough fermentation and bread sugar levels

Wheat flour is generally supplemented with α-amylases to increase maltose levels in bread dough and increase loaf volume. While the preference of yeast for glucose and fructose over maltose as substrate for fermentation is well documented, the impact of maltose versus glucose producing enzymes on bread dough fermentation kinetics and bread sugar levels is ill documented. Hence the impact of α-amylase, α-glucosidase and glucoamylase action on both aspects was investigated. Glucoamylase and α-amylase increase the total fermentable sugar content of dough, while α-glucosidase only affects the glucose/maltose ratio. Due to their effect on total fermentable sugar levels, addition of α-amylase or glucoamylase prolongs the total productive fermentation time, while this is not the case for α-glucosidase. In contrast to α-amylase, both glucoamylase and α-glucosidase supplementation leads to higher CO₂ production rates during the initial stages of fermentation. In the final bread product, different sugar levels are observed depending on the dosage and type of starch-degrading enzyme. The results of this study imply that long and short fermentation processes benefit from α-amylase and α-glucosidase addition, respectively, while glucoamylase supplementation is suitable for both long and short fermentation times.     

Studies on bioactivities of tea (Camellia sinensis L.) fruit peel extracts: Antioxidant activity and inhibitory potential against α-glucosidase and α-amylase in vitro

Tea fruit peel is the main byproduct during manufacture of tea seed oil. The great increase in tea seed oil production in recent years brings the challenge of finding application for tea fruit peel. The aims of this study were to obtain tea fruit peel extracts enriched with bioactive compounds by several solvent extraction methods and to evaluate their antioxidant activity and inhibitory potential against α-glucosidase and α-amylase in vitro. Flavonoids and phenolics were accumulated in ethyl acetate, butanol, and chloroform fractions, and these fractions possessed much better antioxidant activities, including scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) cation radicals (ABTS⁺), and reducing activity, compared with those of the 75% ethanol extract and water fraction. Moreover, the ethyl acetate, butanol, and chloroform fractions exhibited excellent inhibitory activity against α-glucosidase, much stronger than that of the positive control (acarbose). These fractions also showed mild inhibition on α-amylase activity.     

The heterogeneous distribution of α-amylase and endoxylanase activity over a population of preharvest sprouted wheat kernels and their localization in individual kernels

To develop targeted approaches to improve the quality of preharvest sprouted (PHS) wheat as a raw material for food manufacturing, knowledge on the nature and distribution of hydrolytic enzymes in PHS wheat is crucial. Results of the present study indicate that α-amylase and endoxylanase activities are heterogeneously distributed among a population of PHS kernel. Within individual severely sprouted kernels, the enzyme activities are heterogeneously distributed throughout the different tissues. α-Amylase activity, almost exclusively of endogenous nature, is mainly detected in the germ region and to a lesser extent in the aleurone layer. Endoxylanase activity is predominantly of microbial origin and located on the kernel surface. In spite of this, light and epifluorescence microscopy show decreased kernel integrity and cell wall breakdown in the crushed cells layer, the endosperm, and the aleurone layer in a selection of kernels upon preharvest sprouting. This knowledge offers opportunities for the development of treatments to reduce the enzyme load in PHS wheat at postharvest level to improve its flour quality.     

Anthocyanins of <Emphasis Type="Italic">Pithecellobium dulce</Emphasis> (Roxb.) Benth. Fruit Associated with High Antioxidant and α-Glucosidase Inhibitory Activities

Red arils of Pithecellobium dulce fruit, commonly known as guamuchil, show high antioxidant (AOx) and α-glucosidase inhibitory (IαG) activities, which have been mainly associated with the content of unknown anthocyanins. In this study, the AOx (i.e., DPPH and ABTS as Trolox equivalents, μmol TE/g) and IαG (as half-maximal inhibitory concentration, IC₅₀, mg/mL) activities of the anthocyanin-rich fraction (ARF) obtained from red arils were contrasted with those of the methanol extract (ME), and the main ARF anthocyanins were characterized by HPLC-DAD-ESI-MS, GC-MS and ¹H-NMR. The AOx and IαG values of the ARF (DPPH?=?597.8; ABTS?=?884.01; IαG?=?0.06) were better than those of the ME (DPPH?=?41.5; ABTS?=?142.3; IαG?=?17.5); remarkably, the ARF IαG value was about 42 times lower than that of acarbose. The main anthocyanins in ARF were pelargonidin 3-O-glucoside and cyanidin 3-O-glucoside. Thus, the consumption of red P. dulce arils could provide health benefits for prevention/treatment of chronic degenerative diseases such as diabetes.