Insoluble-bound Phenolic Fractions Research Articles

Ultra-High Hydrostatic Pressure Pretreatment on White Que Zui Tea: Chemical Constituents, Antioxidant, Cytoprotective, and Anti-Inflammatory Activities.

Herbal tea has numerous biological activities and exhibits broad benefits for human health. In China, the flower buds of Lyonia ovalifolia are traditionally processed as herbal tea, namely White Que Zui tea (WQT). This study was aimed to evaluate the effect of ultra-high hydrostatic pressure (UHHP) pretreatment on the chemical constituents and biological activities of free, esterified, and insoluble-bound phenolic fractions from WQT. A total of 327 chemical constituents were identified by a quasi-targeted metabolomics analysis. UHHP pretreatment extremely inhibited reactive oxygen species (ROS) production and cell apoptosis in H2O2-induced HepG2 cells, and it increased the activities of intracellular antioxidant enzymes (SOD and CAT) and GSH content in different phenolic fractions from WQT. In addition, after UHHP pretreatment, the anti-inflammatory effects of different phenolic fractions from WQT were improved by inhibiting the production of nitric oxide (NO) and pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) in LPS-induced RAW264.7 cells. Thus, the UHHP method might be a potential pretreatment strategy for improving the bioavailability of phytochemicals from natural plants.

Effect of High-Pressure Processing (HPP) on Phenolics of North Atlantic Sea Cucumber (Cucumaria frondosa).

Sea cucumber contains a wide range of bioactive compounds, including phenolics. This study investigated the free, esterified, and insoluble-bound phenolics of sea cucumber body wall as affected by high-pressure processing (HPP) pretreatment. Sea cucumber body wall was subjected to HPP (200, 400, and 600 MPa for 5, 10, and 15 min), followed by the extraction of phenolics. The contents of total phenolics and antioxidant activity were monitored. Compared to untreated samples, those treated with HPP exhibited significantly higher total phenolics, flavonoids, and antioxidant activities. Treatment of 600 MPa for 10 min offered the optimal results. The highest amount of phenolics was observed in the free phenolic fraction, followed by esterified and insoluble-bound phenolic fractions. Moreover, phenolic extracts showed inhibitory effects against cupric ion-induced low-density lipoprotein (LDL)-cholesterol oxidation, peroxyl and hydroxyl radical-induced DNA scission, α-glucosidase activity, and formation of advanced glycation end products (AGEs). Ultra-high-performance liquid chromatography equipped with a quadrupole time of fight and mass spectrometer (UHPLC-QTOF-MS/MS) identified 20 phenolic compounds, mainly phenolic acids and flavonoids, from the body wall of this species for the first time. Thus, sea cucumber may lead to the production of a multitude of value-added products.

The effect of ultra-high pretreatment on free, esterified and insoluble-bound phenolics from mango leaves and their antioxidant and cytoprotective activities

Ultra-high pressure (UHP) is a novel non-thermal pretreatment method in food processing for improving the extraction yield of polyphenols and functional properties. The present work investigated the phenolic profiles, antioxidant activities, and cytoprotective effects of the free, esterified, and insoluble-bound phenolic fractions from mango leaves before and after ultra-high pressure (UHP) treatment. UHPLC-Q-Orbitrap-MS/MS analysis resulted in the identification of 42 phenolic compounds in the different phenolic forms. UHP pretreatment could significantly influence the contents of total phenols, total flavonoids and individual compounds in the different phenolic fractions (p < 0.05). After UHP pretreatment, these phenolic fractions exhibited greater antioxidant activity, and inhibited reactive oxygen species production and cell apoptosis (p < 0.05). Meanwhile, IBP were the most potential antioxidative and cytoprotective ingredients. Therefore, UHP pretreated mango leaves with enhanced bioactivity could be used as biological agents in the health food industry to improve its application and economic values.

Identification and quantification of free, esterified, and insoluble-bound phenolics in grains of hulless barley varieties and their antioxidant activities

To study the phenolics in grains of hulless barley varieties harvested in the Qinghai-Tibet plateau region, free, esterified, and insoluble-bound phenolic fractions were extracted from grain of fourteen varieties. The phenolic components and antioxidant activity of the fractions were studied. Identification of phenolics profile in QB35 variety was studied using ultra-high-performance liquid chromatography-diode array with quadrupole time-of-flight and tandem mass spectrometry (UPLC-QTOF-MS/MS), which revealed fourteen phenolics in the free form, four in the esterified form, and seventeen in the insoluble-bound form. Total phenolic contents (TPC) of the fractions were tested finding significantly (p < 0.05) higher phenolics content and greater antioxidant capacity (via DPPH and ABTS free radical scavenging assays) in insoluble-bound fraction than that of free and esterified fractions for the same hulless barley variety. In terms of phenolic components, ferulic acid was the dominant phenolic in all varieties. Chrysoeriol-7-O-glucuronide and chrysoeriol were identified and quantified in hulless barley varieties for the first time. This study also showed TPC, ferulic acid and luteolin significantly contributed to the antioxidant activities (p < 0.01). The fourteen hulless barley varieties could be classified depending on the geographical locations and the color of their grains via hierarchical cluster analysis (HCA). This study provides valuable new insights into the phenolics in grains of hulless barley varieties and their antioxidant potentials.

Determination of soluble and insoluble-bound phenolic compounds in dehulled, whole, and hulls of green and black lentils using electrospray ionization (ESI)-MS/MS and their inhibition in DNA strand scission

The soluble and insoluble-bound phenolic fractions of hull, whole, and dehulled black and green lentil extracts were identified and quantified using electrospray ionization (ESI)-MS/MS. Several in vitro antioxidant tests and inhibition of DNA strand scission were conducted to assess different pathways of activity. The most abundant phenolics in the soluble fractions were caffeic acid (412.2 μg/g), quercetin, (486.5 μg/g) quercetin glucoside (633.6 μg/g) luteolin glucoside (239.1 μg/g) and formononetin (920 μg/g), while myricetin (534.1 μg/g) and catechin (653.4 μg/g) were the predominant phenolics in the insoluble bound fraction. Hulls of both lentil cultivars had the highest phenolic content and the strongest antioxidant activity followed by whole and dehulled samples. Thus, lentil hulls would serve as an excellent source for the production of functional foods. Moreover, ESI-MS/MS (direct infusion) analysis was the rapid and high-throughput approach for the determination of bioactives in lentils by reducing the analysis time.

Digestive Enzyme Inhibition of Different Phenolic Fractions and Main Phenolic Compounds of Ultra-High-Pressure-Treated Palm Fruits: Interaction and Molecular Docking Analyses

The purpose of the present work was to evaluate the inhibitory effects of different phenolic extracts from non- and ultra-high-pressure- (UHP-) treated palm fruits and their main phenolic compounds against pancreatic lipase and α-glucosidase and to further analyze the interaction and inhibitory mechanisms of two main phenolics (caffeic acid and catechin). Results showed that the free, esterified, and insoluble-bound phenolic fractions from the non- and UHP-treated fruits demonstrated good inhibitory effects towards two enzymes. The insoluble-bound phenolic fraction, regardless of UHP treatment, presented the strongest inhibitory capacities, and UHP treatment significantly upgraded the inhibitory effects of these phenolic fractions (lipase IC50 : 78.01 vs. 72.50 μg/mL; α-glucosidase IC50 : 76.42 vs. 64.51 μg/mL). Catechin and caffeic acid, main phenolic compounds detected in all phenolic fractions of the fruits, showed similar efficiencies on inhibiting the two enzymes, which were consistent with the findings observed by molecular docking analysis. Moreover, these two phenolic compounds exhibited a synergy effect on inhibiting pancreatic lipase and α-glucosidase at a relatively high combination concentration with the ratio of 1 : 1. Therefore, the present work may be helpful for further application of palm fruits as food supplements or nutraceuticals to control energy intake to improving some chronic metabolic diseases.

The Effect of Bioactive Polyphenols from &lt;i&gt;Anacardium occidentale&lt;/i&gt; Linn. Leaves on α-Amylase and Dipeptidyl Peptidase IV Activities

Anacardium occidentale Linn. (A. occidentale L.) leaves possess bioactive polyphenols which are associated with antidiabetic potency for the management of type 2 diabetes mellitus (T2DM). In this study, free, soluble ester, and insoluble-bound phenolic fractions from young and mature leaves of A. occidentale L. were extracted. Subsequently, all fractions were investigated for their inhibitory effect on α-amylase and dipeptidyl peptidase IV (DPPIV) activities. Both free (72.45 ± 3.6%) and soluble ester (83.40 ± 4.7%) phenolic fractions in the mature leaves extracts had significantly demonstrated greater α-amylase inhibitors than the young leaves. Likewise, soluble ester (4.09 ± 0.34 µg/mL) and insoluble-bound (4.87 ± 0.32 µg/mL) phenolic fractions in the mature leaves extracts were significantly more effective in inhibiting DPPIV than the young leaves. As for fractions comparison, insoluble-bound derived from the young leaves extract was a more potent α-amylase inhibitor than free and soluble ester phenolic fractions (p &lt; 0.0001). Besides, soluble ester and insoluble-bound phenolic fractions showed a stronger inhibitor of DPPIV than the free phenolic (p &lt; 0.001), irrespective of the maturity of the leaves. In conclusion, this study showed that A. occidentale L. extracts possessed antidiabetic properties, which may potentially be used as an alternative treatment for T2DM management.

Quantitative Assessment of Phenolic Acids, Flavonoids and Antioxidant Activities of Sixteen Jujube Cultivars from China.

Increasing attention has been paid to the nutritional values and pharmacological effects of Ziziphus jujuba. Therefore, in this study, four phenolic and flavonoid fractions of 16 jujube cultivars from different geographic regions of China were separated and quantified. In addition, the antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH·) scavenging method and the ferric reducing antioxidant power (FRAP) assay. The total phenols and flavonoids contents ranged from 253.4 to 494.9mg GAE/100g and 125.3 to 425.4mg rutin/100g, respectively. Subsquently, a total of 10 phenolic acids and two flavonoids were identified, and most quantified phenolic acids with antioxidant activity were mainly present in the glycosided and insoluble-bound phenolic fractions. The results of this study indicate that some jujube cultivars, especially Zanghuang Z. jujuba, Leling Z. jujuba, and Jiaxian Z. jujuba could be selected to promote a healthy diet due to their more plentiful nutritional and phytochemical beneficial effects.

Antioxidant activity of free and hydrolyzed phenolic compounds in soluble and insoluble dietary fibres derived from hulless barley

Phenolic compounds associated with dietary fibre are present in free, soluble conjugated and insoluble-bound forms. In this study, total soluble, free, esterified, etherified and insoluble-bound phenolic fractions were extracted from the insoluble dietary fibre (IDF) and soluble dietary fibre (SDF) of hulless barley. Total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities of five phenolic fractions of IDF and SDF were evaluated. Major phenolic acids and flavonoids were analyzed by high performance liquid chromatography. The results revealed that the TPC and TFC of five phenolic fractions of IDF were 2.42–7.33 and 3.08–10.00 times, respectively, which were higher than those in SDF. Insoluble-bound phenolic fractions had the highest TPC and TFC among the five phenolic fractions. A significant positive linear correlation between TPC and antioxidant activity was observed in each of the five phenolic fractions from IDF and SDF (P < 0.05). Furthermore, ferulic acid was an abundant phenolic compound in total soluble and insoluble-bound phenolic fractions among IDF and SDF. This study indicates that IDF and SDF are rich in phenolic compounds which can be considered as functional food ingredients or nutraceuticals.

Comparison of Free, Esterified, and Insoluble-Bound Phenolics and Their Bioactivities in Three Organs of Lonicera japonica and L. macranthoides.

Dried flower buds of Lonicera japonica and L. macranthoides have long been used as herbs in numerous Chinese traditional medicines. Comparisons of three phenolic fractions (i.e., free, esterified, and insoluble-bound phenolics) in three different organs (i.e., flower, leaf, and stem) of the two species revealed that the free phenolics were the highest in terms of total phenol and total flavonoid content, composed of the most numerous phenolics and flavonoids; thus, they exhibited the most excellent antioxidant activities (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS), and oxygen radical absorbance capacity (ORAC)), as well as protective effects on DNA damage induced by free radicals. In identical free and esterified phenolics of a same organ, higher contents and bioactivities were observed in L. macranthoides than in L. japonica. Phenolics identified by ultra-performance liquid chromatography with a diode array detector, alongside tandem mass spectrometry coupled with a quadrupole time-of-flight mass spectrometer (UPLC-DAD–QTOF-MS/MS) mainly included chlorogenic acid and its five derivatives, three flavonoids that were only found in the free phenolic fraction and closely correlated with its bioactivity, and caffeic acid that was the major contributor to antioxidant activity of the esterified and insoluble-bound phenolic fractions. It was, thus, concluded that, like L. japonica, L. macranthoides, which was underestimated since being separately listed by the 2010 edition of the Chinese Pharmacopoeia, is also a good (and better) herbal medicine.

Phenolic profiles, antioxidant activities and cytoprotective effects of different phenolic fractions from oil palm (Elaeis guineensis Jacq.) fruits treated by ultra-high pressure

The present work investigated the phenolic profiles, antioxidant activities, and cytoprotective effects of the free, esterified, and insoluble-bound phenolic fractions from oil palm fruits treated under ultra-high pressure (UHP). Results showed that UHP treatment significantly increased the total phenolic and flavonoid contents of all three phenolic fractions (p < 0.05). A total of 11 and 12 phenolic compounds were detected and quantified in non-treated and UHP-treated fruits, with caffeic acid having the highest concentration in insoluble-bound phenolic fractions with 8.68 and 11.27 mg/g of dry extract, respectively. The antioxidant activities, intracellular reactive oxygen species inhibition, and cytoprotective effects of all three phenolic fractions were dramatically enhanced after UHP pretreatment (p < 0.05). Therefore, UHP-treated oil palm fruits with increased bioactivities could be used in functional food or the nutraceutical industry to enhance their applications and economic value.

Gamma-irradiation induced changes in microbiological status, phenolic profile and antioxidant activity of peanut skin

The effects of gamma-irradiation on the microbial growth, phenolic composition, and antioxidant properties of peanut skin were evaluated. Gamma-irradiation at 5.0 kGy decreased the microbiological count of the product. Total phenolic and proanthocyanidin contents, ABTS radical cation, DPPH radical, H2O2, and hydroxyl radical scavenging capacities as well as the reducing power of the sample were increased upon gamma-irradiation in both the free and insoluble-bound phenolic fractions. However, a decrease in the esterified phenolics was noticed. The bioactivity of the free phenolics against in vitro human LDL-cholesterol oxidation and copper induced DNA strand breakage was improved upon gamma-irradiation. Phenolic acids, flavonoids, and proanthocyanidins were positively or tentatively identified by HPLC-DAD-ESI-MSn and their distribution was in the decreasing order of free > esterified > insoluble-bound forms. Procyanidin dimer A was increased in all phenolic fractions, whereas procyanidin dimer B decreased. Gamma-irradiation induced changes may be explained by molecular conversion, depolymerization, and cross-linking.