Showing papers by "Ka-Wing Cheng published in 2021"

Bioactive compounds, health benefits, and industrial applications of Tartary buckwheat ( Fagopyrum tataricum)

Abstract: Tartary buckwheat belongs to the family Polygonaceae, which is a traditionally edible and medicinal plant. Due to its various bioactive compounds, the consumption of Tartary buckwheat is correlated to a wide range of health benefits, and increasing attention has been paid to its potential as a functional food. This review summarizes the main bioactive compounds and important bioactivities and health benefits of Tartary buckwheat, emphasizing its protective effects on metabolic diseases and relevant molecular mechanisms. Tartary buckwheat contains a wide range of bioactive compounds, such as flavonoids, phenolic acids, triterpenoids, phenylpropanoid glycosides, bioactive polysaccharides, and bioactive proteins and peptides, as well as D-chiro-inositol and its derivatives. Consumption of Tartary buckwheat and Tartary buckwheat-enriched products is linked to multiple health benefits, e.g., antioxidant, anti-inflammatory, antihyperlipidemic, anticancer, antidiabetic, antiobesity, antihypertensive, and hepatoprotective activities. Especially, clinical studies indicate that Tartary buckwheat exhibits remarkable antidiabetic activities. Various tartary buckwheat -based foods presenting major health benefits as fat and blood glucose-lowering agents have been commercialized. Additionally, to address the safety concerns, i.e., allergic reactions, heavy metal and mycotoxin contaminations, the quality control standards for Tartary buckwheat and its products should be drafted and completed in the future.

Novel roles of hydrocolloids in foods: Inhibition of toxic maillard reaction products formation and attenuation of their harmful effects

Abstract: Background Maillard reaction in foods gives rise to toxic byproducts such as heterocyclic amines (HCAs), acrylamide (AA) and advanced glycation end products (AGEs) Inhibition of their formation during thermal processing is the most practical way to minimize their dietary exposure and thus the associated health risks Various effective strategies have been proposed, especially with the use of exogenous additives such as polyphenols and emerging hydrocolloids Hydrocolloids have attracted increasing attention due to their unique structural diversities that enable them to actively participate in Maillard reaction to mitigate the formation of toxic byproducts They also have the potential to attenuate the harmful effects of these toxic byproducts Hence, hydrocolloids represent an important class of food ingredients with dual beneficial potential, whereas a systematic review is currently lacking Scope and approach This review summarizes influencing factors (precursors, processing methods and parameters, and exogenous additives) of thermally induced toxicants (HCAs, AA and AGEs) formation, as well as inhibitory strategies emphasizing on the effects and potential inhibitory mechanism of hydrocolloids The ability of hydrocolloids to attenuate their harmful effects is also highlighted Key findings and conclusions Hydrocolloids, alone or in combination with other purported inhibitors of harmful Maillard reaction products (MRPs), may be used in form of powders or aqueous solution for pretreatment of food Moreover, their water-holding and gelling properties render them suitable for application in form of coatings that may offer additional benefits (eg reduction of oil uptake during frying) besides inhibiting the formation of hazardous MRPs Although a reasonable number of studies have demonstrated the effectiveness of hydrocolloids against both the formation and the harmful effects of Maillard byproducts, more detailed and systematic analyses are needed to clearly characterize their structure-activity relationships and their mechanisms of action

Investigation of carbon and energy metabolic mechanism of mixotrophy in Chromochloris zofingiensis

Abstract: Mixotrophy can confer a higher growth rate than the sum of photoautotrophy and heterotrophy in many microalgal species Thus, it has been applied to biodiesel production and wastewater utilization However, its carbon and energy metabolic mechanism is currently poorly understood To elucidate underlying carbon and energy metabolic mechanism of mixotrophy, Chromochloris zofingiensis was employed in the present study Photosynthesis and glucose metabolism were found to operate in a dynamic balance during mixotrophic cultivation, the enhancement of one led to the lowering of the other Furthermore, compared with photoautotrophy, non-photochemical quenching and photorespiration, considered by many as energy dissipation processes, were significantly reduced under mixotrophy Comparative transcriptome analysis suggested that the intermediates of glycolysis could directly enter the chloroplast and replace RuBisCO-fixed CO2 to provide carbon sources for chloroplast organic carbon metabolism under mixotrophy Therefore, the photosynthesis rate-limiting enzyme, RuBisCO, was skipped, allowing for more efficient utilization of photoreaction-derived energy Besides, compared with heterotrophy, photoreaction-derived ATP reduced the need for TCA-derived ATP, so the glucose decomposition was reduced, which led to higher biomass yield on glucose Based on these results, a mixotrophic metabolic mechanism was identified Our results demonstrate that the intermediates of glycolysis could directly enter the chloroplast and replace RuBisCO-fixed CO2 to provide carbon for photosynthesis in mixotrophy Therefore, the photosynthesis rate-limiting enzyme, RuBisCO, was skipped in mixotrophy, which could reduce energy waste of photosynthesis while promote cell growth This finding provides a foundation for future studies on mixotrophic biomass production and photosynthetic metabolism

The apple dihydrochalcone phloretin suppresses growth and improves chemosensitivity of breast cancer cells via inhibition of cytoprotective autophagy

Abstract: The inhibitory effect and mechanism of the apple dihydrochalcone, phloretin, on breast cancer cell growth were evaluated in in vitro conditions simulating complete nutrition and glucose-restriction, respectively. In two breast cancer cell lines with different histological backgrounds, phloretin consistently exhibited much stronger activity against cell growth in glucose-limiting than in full media. RNA-seq analysis showed that key autophagy-related genes were downregulated upon phloretin treatment in both estrogen-receptor-positive MCF7 and triple-negative MDA-MB-231 cells. Immunoblotting verified significantly decreased expression of LC3B-II by phloretin in low-glucose and glucose-free media, but not in full medium. Together with the use of two pharmacological autophagy inhibitors, chloroquine and 3-methyladenine, and confocal microscopy of breast cancer cell lines transfected with GFP-LC3B, phloretin demonstrated a strong capability to suppress autophagic flux, which was likely mediated through downregulation of mTOR/ULK1 signaling, whereas the expression of canonical autophagy regulators ATG5 and ATG7 was not significantly affected. Phloretin also reversed tamoxifen- and doxorubicin-induced cytoprotective autophagy in the breast cancer cell lines, and this was manifested in its synergistic growth inhibitory effect with these chemotherapeutic agents. Furthermore, it was able to restore or enhance the chemosensitivity of a tamoxifen-resistant cell line. Taken together, our study has, for the first time, revealed that phloretin could effectively suppress glucose-starvation- and chemotherapeutic-induced cytoprotective autophagy in breast cancer cell lines likely through downregulation of mTOR/ULK1 signaling.

Neuroprotective Potential of Mung Bean (Vigna radiata L.) Polyphenols in Alzheimer's Disease: A Review.

Abstract: Mung bean contains various neuroprotective polyphenols, so it might be a healthy food for Alzheimer's disease (AD) prevention. Totally, 19 major phenolic compounds were quantified in mung bean, including 10 phenolic acids and 9 flavonoids. After summarizing their contents and effective doses in rodent AD models, it was speculated that vitexin, isovitexin, sinapic acid, and ferulic acid might be the major bioactive compounds for mung bean-mediated neuroprotection. The mechanisms involved inhibition of β-amyloidogenesis, tau hyperphosphorylation, oxidative stress, and neuroinflammation, and promotion of autophagy and acetylcholinesterase enzyme activity. Notably, the neuroprotective phenolic profile in mung bean changed after germination, with decreased vitexin and isovitexin, and increased rutin, isoquercitrin, isorhamnetin, and caffeic acid detected. However, only studies of individual phenolic compounds in mung bean are published at present. Hence, further studies are needed to elucidate the neuroprotective activities and mechanisms of extractions of mung bean seeds and sprouts, and the synergism between different phenolic compounds.

Advance toward isolation, extraction, metabolism and health benefits of kaempferol, a major dietary flavonoid with future perspectives.

Abstract: As a major ubiquitous secondary metabolite, flavonoids are widely distributed in planta. Among flavonoids, kaempferol is a typical natural flavonol in diets and medicinal plants with myriad bioactivities, such as anti-inflammatory activity, anti-cancer activity, antioxidant activity, and anti-diabetic activity. However, the natural sources, absorption and metabolism as well as the bioactivities of kaempferol have not been reviewed comprehensively and systematically. This review highlights the latest research progress and the effect of kaempferol in the prevention and treatment of various chronic diseases, as well as its protective health effects, and provides a theoretical basis for future research to be used in nutraceuticals. Further, comparison of the different extraction and analytical methods are presented to highlight the most optimum for PG recovery and its detection in plasma and body fluids. Such review aims at improving the value-added applications of this unique dietary bioactive flavonoids at commercial scale and to provide a reference for its needed further development.

Advances in smart delivery of food bioactive compounds using stimuli-responsive carriers: Responsive mechanism, contemporary challenges, and prospects

Abstract: Many important food bioactive compounds are plant secondary metabolites that have traditional applications for health promotion and disease prevention. However, the chemical instability and poor bioavailability of these compounds represent major challenges to researchers. In the last decade, therefore, major impetus has been given for the research and development of advanced carrier systems for the delivery of natural bioactive molecules. Among them, stimuli-responsive carriers hold great promise for simultaneously improving stability, bioavailability, and more importantly delivery and on-demand release of intact bioactive phytochemicals to target sites in response to certain stimuli or combination of them (e.g., pH, temperature, oxidant, enzyme, and irradiation) that would eventually enhance therapeutic outcomes and reduce side effects. Hybrid formulations (e.g., inorganic-organic complexes) and multi-stimuli-responsive formulations have demonstrated great potential for future studies. Therefore, this review systematically compiles and assesses the recent advances on the smart delivery of food bioactive compounds, particularly quercetin, curcumin, and resveratrol through stimuli-responsive carriers, and critically reviews their functionality, underlying triggered-release mechanism, and therapeutic potential. Finally, major limitations, contemporary challenges, and possible solutions/future research directions are highlighted. Much more research is needed to optimize the processing parameters of existing formulations and to develop novel ones for lead food bioactive compounds to facilitate their food and nutraceutical applications.

Development of an Isotope Dilution UHPLC-QqQ-MS/MS-Based Method for Simultaneous Determination of Typical Advanced Glycation End Products and Acrylamide in Baked and Fried Foods.

Abstract: In this work, a stable isotope dilution ultrahigh-performance liquid chromatography triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS) method was developed and validated for simultaneous determination of Ne-(carboxymethyl)lysine (CML), Ne-(carboxyethyl)lysine (CEL), and acrylamide (AA) in baked and fried foods Ground food samples were extracted with acetone followed by two parallel assays In assay A, a cleanup procedure based on dispersive solid-phase extraction was conducted for AA, free CML, and CEL analysis using the supernatant In assay B, a multistep process including reduction, protein precipitation, acid hydrolysis, and solid-phase extraction was conducted for bound CML and CEL analysis using precipitation The developed method was validated in terms of linearity, sensitivity (limit of detection, LOD; limit of quantitation, LOQ), accuracy, and precision The results showed that the method had a wide linear range (025-500 ng/mL for CML and CEL, 05-500 ng/mL for AA), low LOD and LOQ (047-094 and 152-191 μg/kg, respectively), and good linearity (R2 > 0999) The recovery test on baby biscuit and French fries samples showed the recovery rates of 902-1083% for CML, 890-1061% for CEL, and 945-1123% for AA with satisfactory precision (relative standard deviation (RSD) < 10%) Finally, the developed method was successfully applied to 11 baked and fried food samples, and total CML, CEL, and AA contents varied in the ranges of 407-3588 mg/kg, 199-1449 mg/kg, and 556-50664 μg/kg, respectively Therefore, the isotope dilution UHPLC-QqQ-MS/MS method developed herein is promising for routine analysis of CML, CEL, and AA in baked and fried foods

Oral administration of EGCG solution equivalent to daily achievable dosages of regular tea drinkers effectively suppresses miR483-3p induced metastasis of hepatocellular carcinoma cells in mice.

Abstract: The effect of non-cytotoxic doses of epigallocatechin-3-gallate (EGCG) on the metastatic capability of human hepatocellular carcinoma (HCC) cells was investigated in vitro and in vivo. miR483-3p, a microRNA whose expression correlates inversely with survival and positively with disease progression in HCC patients, was found to promote HCC cell migration and invasion in vitro as well as lung metastasis in nude mice established by the tail-vein injection of HCC cells. The induction of reactive oxygen species (ROS) and downregulation of antioxidant defense factors Nrf2 and SOD2 appeared to be an important underlying mechanism and treatment with a non-cytotoxic dose of EGCG effectively reversed the miR483-3p-induced enhancement of HCC cell migration and invasion in vitro. Moreover, administration through drinking water at doses (0.1% and 0.5% EGCG solution, respectively) equivalent to the intake of regular to heavy tea drinkers could also significantly inhibit lung metastasis of HCC cells based on the estimation from the USDA Database for the Flavonoid Content of Selected Foods and FDA guidelines for the conversion of animal dose to human equivalent dose. EGCG also significantly counteracted the miR483-3p-induced alteration in the expression of epithelial–mesenchymal transition (EMT) markers, E-cadherin and vimentin, and downregulated the endogenous expression of miR483-3p in HCC cells through an epigenetic mechanism that led to the hypermethylation of the miR483-3p promoter region. The data from our study illustrate that miR483-3p promotes HCC metastasis likely through the induction of oxidative stress and uncover a novel role of EGCG for protection against miR483-3p-mediated HCC metastasis via the epigenetic modulation of miR483-3p expression. These findings therefore provide further evidence supporting that regular tea consumption may contribute to protection against miR-483-3p-induced ROS and the associated HCC progression.

Red Wine High-Molecular-Weight Polyphenolic Complex: An Emerging Modulator of Human Metabolic Disease Risk and Gut Microbiota.

Abstract: Moderate red wine consumption has been linked to reduced chronic disease risk. Thus far, little has been known about the physicochemical properties and potential biological effects of high-molecular-weight polyphenolic complexes (HPPCs), a major fraction of red wine polyphenols. In this work, the stability and biochemical properties of HPPCs under simulated gastrointestinal conditions in vitro were studied. The results showed that HPPCs were resistant to simulated gastric digestion (SGD) and simulated intestinal digestion (SID). They exhibited significant inhibitory activity against key metabolic syndrome-associated digestive enzymes, achieving 17.1-90.9% inhibition of pancreatic α-amylase, lipase, and cholesterol esterase at 0.02-0.45 mg/mL. HPPCs were metabolized by gut microbiota (GM), leading to significantly enhanced antioxidant capacity when compared with the original, SGD, and SID samples. Furthermore, they favorably modulated GM profiles, which was accompanied by significantly increased short-chain fatty acid generation during the early colonic fermentation phase. These findings suggest that HPPCs are a promising modulator of human metabolic disease risk.

Tricoumaroylspermidine from rose exhibits inhibitory activity against ethanol-induced apoptosis in HepG2 cells

Abstract: Hepatocyte apoptosis is involved in the pathogenesis of alcohol-associated liver disease (ALD) and anti-apoptotic agents/extracts are thereby of great importance in the prevention/treatment of ALD. In this study, the protective effects of 10 edible flowers against ethanol-induced cell death were investigated in HepG2 cells, with rose (Rosa rugosa) showing the strongest activity. Therefore, rose was chosen for further separation and purification of bioactive fractions. A special fraction, SLs, was found to significantly increase the viability of EtOH-treated cells and attenuated EtOH-induced apoptosis partially via the activation of the AMPK/SIRT1 signaling pathway. Chromatographic analysis identified a series of hydroxycinnamic acid amides, kaempferol glycosides, and quercetin glycosides in this fraction, while the following intracellular uptake and cytotoxicity studies revealed that N1,N5,N10-(E)-tri-p-coumaroylspermidine (a hydroxycinnamic acid amide) in this fraction exhibited remarkable hepatoprotective activity with similar effective dosage to sulforaphane. Hence, our results highlighted the anti-alcohol and hepatoprotective benefits of consuming rose.

Multi-Mechanistic Antidiabetic Potential of Astaxanthin: An Update on Preclinical and Clinical Evidence.

Abstract: Diabetes mellitus (DM) is a cluster of physiological dysfunctions typified by persistent hyperglycemia. Diet plays a paramount role in human health, and regular consumption of a fruit- and vegetable-rich diet can delay or prevent DM and its associated complications. The promising effect of fruits and vegetables could be partly attributed to their antioxidant constituents, including carotenoids. Carotenoids are natural antioxidants that occur in many vegetables, fruits, microalgae, and other natural sources. Astaxanthin is a xanthophyll carotenoid predominantly present in microalgae and some red-colored marine organisms. It is currently marketed as a health supplement and is well-known for its antioxidant capacity. Accumulating evidence indicates that astaxanthin exerts its beneficial effects against DM by acting on various molecular targets and signaling pathways in multiple organs/tissues. Astaxanthin can lower blood glucose levels by preserving β-cell function, improving insulin resistance (IR), and increasing insulin secretion. This manuscript summarizes the connection between glucose homeostasis, oxidative stress, and DM. This is followed by a review of recent studies on astaxanthin's pharmacological effects against IR, microvascular (diabetic retinopathy, diabetic nephropathy, and neurological damage), and macrovascular DM complications emphasizing the cellular and molecular mechanisms involved. A few lines of clinical evidence supporting its antidiabetic potential are also highlighted. This article is protected by copyright. All rights reserved.

Lipid-Lowering Bioactivity of Microalga Nitzschia laevis Extract Containing Fucoxanthin in Murine Model and Carcinomic Hepatocytes.

Abstract: Non-alcoholic fatty liver disease (NAFLD), characterized by hepatic steatosis, is one of the most common liver diseases worldwide. So far, no definitive medical treatment has been established to treat NAFLD except for lifestyle medication. Nitzschia laevis extract (NLE), a microalgal extract rich in fucoxanthin, has been previously demonstrated to reduce bodyweight in high-fat-diet (HFD) C57BL/6J mice, indicating potential for prevention of NAFLD. In the present study, we investigated the lipid-lowering effects of NLE in HFD-induced steatosis murine model and palmitate-treated HepG2 cells. The results showed that NLE significantly lowered inguinal fat and attenuated hepatic steatosis in C57BL/6J mice. Especially, NLE significantly prevented lipid accumulation in HepG2 cells. This was probably due to its capability to enhance hepatic mitochondrial function as evidenced by the increased oxygen consumption rate (OCR) and mitochondrial membrane potential (MMP), and repress fatty acid synthesis through phosphorylation of acetyl-CoA carboxylase (ACC). Moreover, fucoxanthin was identified to be responsible for the lipid-lowering effect of NLE. Taken together, NLE or other microalgal fucoxanthin-rich products are promising natural products that may help prevent against NAFLD.