Search

The purpose of this study was to compare the polyphenol, antioxidant and antidiabetic potential of powdered Matcha and bagged Sencha tea during in vitro digestion. Total phenols (TP), flavonoids (TF), flavanols (TFLA), antioxidant and antidiabetic (α-glucosidase inhibition) activity were higher in Matcha tea before and in most in vitro digestion phases. Upon gastric digestion, in Matcha tea TP, TF, TFLA were 2.6, 1.4 and 1.2 times significantly higher (p ≤ 0.05), respectively; gallic acid, gallocatechin, epigallocatechin, quercetin and kaempferol 1.5, 1.6, 1.8, 1.7, 1.2 times, respectively; whereas antioxidant activity was significantly (p ≤ 0.05) higher 3.2 and 1.1 times with ABTS and FRAP and α-glucosidase inhibition 1.8 times. After the intestinal phase, TP and TFLA were 3.4 and 1.7 times significantly (p ≤ 0.05) higher, respectively, antioxidant activity was significantly (p ≤ 0.05) higher 2.4 and 2.0 times with ABTS and FRAP, respectively, while inhibition of α-glucosidase was 1.7 time significantly (p ≤ 0.05) higher in Matcha tea, but the differences in TF, TP and identified phenolics (with the exception of gallic acid) between Matcha and Sencha tea were neutralized. Our results are the first to demonstrate that, during digestion of Matcha powder together with its water extract, Matcha polyphenols are more bioavailable and possess higher antioxidant and antidiabetic activity compared to Sencha. [ABSTRACT FROM AUTHOR]

Due to extreme climate changes, plants are exposed to severe soil water content, i.e. flooding and drought. The aim of this study was to assess the effect of different soil water content on the nutritional potential of young Chinese cabbage (Brassica rapa ssp. pekinensis) on the level of phenolics, sugars, photosynthetic pigments and antioxidant capacity. Total phenolic acids were induced in plants grown under drought conditions. Both types of stress increased soluble sugars in Chinese cabbage but reduced total tannins. Plants grown under drought had more L-ascorbic acid than the control group; however, the concentration of ferulic acid and quercetin was reduced. On the other hand, excess of water increased the amount of sinapic and ferulic acid, main hydroxycinnamic acids in Chinese cabbage. Photosynthetic pigments were more susceptible to flooding (reduced amount) than drought, the only exception was chlorophyll b whose concentration was significantly higher in plants grown under drought. In addition, among all the measured parameters, chlorophyll b reacted most specifically against flooding (decreased) and drought (increased). Chinese cabbage grown under flooding had reduced amount of porphyrins compared to the one grown under normal and drought conditions, but showed higher antioxidant capacity (ABTS). Based on the results, the use of excess water could be considered as a possibility when growing young Chinese cabbage since it increased the concentration of antioxidants sinapic and ferulic acid and resulted in higher antioxidant capacity, recorded by ABTS assay, compared to control plants. [ABSTRACT FROM AUTHOR]

The phytochemical and antioxidant properties of mature (head stage) Chinese cabbage (Brassica rapa ssp. pekinensis) are known; however, data on the phenolic profile, vitamin C (L-ascorbic acid) content and antioxidant capacity of its fresh sprouts are lacking. Since the human consumption of fresh cruciferous sprouts has significantly increased in recent years, their nutritional characterization has become a somewhat urgent matter. Therefore, in this study the contents of total phenolics, flavonols and hydroxycinnamic acids were measured spectrophotometrically, whereas individual flavonoids, phenolic acids and vitamin C were identified and quantified using a newly-developed high performance liquid chromatography method. Also, the antioxidant capacity of five Chinese cabbage sprout growth stages was determined. These stages contained either cotyledons only (seedlings), cotyledons and two leaves, four leaves, six leaves, or ten leaves. Principal component analysis (PCA) and hierarchical clustering (HC) were implemented in order to visualize the classification trend between the stages. Seedlings contained more sinapic acid and vitamin C than older plants. Plants containing six or ten leaves had more ferulic acid and isorhamnetin than younger ones. Total phenolics, flavonols, hydroxycinnamic acids, quercetin and antioxidant capacity did not statistically differ between seedlings and stages with six or ten leaves and their concentrations were significantly higher than in stages with two or four leaves. PCA and HC confirmed the higher phytochemical similarity between seedlings and plants with six or ten leaves than plants with two or four leaves. Therefore, Chinese cabbage seedlings and plants with six or ten leaves should be preferred over plants with two or four leaves, which were ultimately shown to be of lesser nutritional quality. [ABSTRACT FROM AUTHOR]

Spectrophotometric and chromatographic analysis of phenolics in water and ethanolic extracts of wild asparagus, butcher's broom and black bryony from Croatia was conducted. Their antioxidant capacity (ABTS, DPPH and FRAP assay) and energy content were determined. The gastrointestinal stability of detected phenolics was determined using a two-phase in vitro digestion method with human enzymes. The highest phenolics yield, radical scavenging activity and ferric reducing antioxidant potential were recorded in 40 % ethanolic extract of black bryony, with glycosylated forms of kaempferol as dominant components. Quercetin-3- O-rutinoside and isorhamnetin-3- O-rutinoside were dominant phenolics in all wild asparagus extracts, and salicylic acid was predominant in butcher's broom 40 % ethanolic extract. Phenolic acids of the three species were not stable during gastric and duodenal phases of simulated digestion. Two main black bryony kaempferol glycosides were best preserved after digestion (50 % of each). Black bryony contains more energy than wild asparagus and butcher's broom. Accordingly, we propose black bryony as a valuable source of antioxidant kaempferol glycosides with relevant gastrointestinal stability and higher energy content than so far more conventional vegetable wild asparagus. [ABSTRACT FROM AUTHOR]