Large Molecular Weight Research Articles

Analysis and prospect of correlation between relative molecular weight and efficacy of polysaccharides from medicinal plant resources

Polysaccharides from medicinal plant resources are a kind of polymers extracted from medicinal plants. They are complex long chains formed by different monosaccharides connected via glucosidic bonds. These polysaccharides usually have straight chain and branched chain structures, and their relative molecular weight changes greatly. Modern studies have shown that the biological activi-ty of polysaccharides from medicinal plant resources is closely related to their relative molecular weight. This paper first reviewed the preparation and detection methods of polysaccharides from medicinal plant resources with different relative molecular weights. Then, the paper summarized and analyzed the general experience of the correlation between efficacy and relative molecular weight of polysaccharides from medicinal plant resources with different molecular weights. It was considered that polysaccharides with large relative molecular weights(>100 kDa) play a leading role in immune regulation. Polysaccharides with medium relative molecular weights(10-100 kDa) play a leading role in immune regulation and the protection of the liver. Polysaccharides with small relative molecular weights(<10 kDa) play a leading role in anti-oxidation, regulation of intestinal flora, regulation of blood glucose and lipids, anti-fatigue, and the protection of nerves. Therefore, precise development of polysaccharides from medicinal plant resources based on relative molecular weight is expected to improve their biological activity and application value.

Hemoadsorption Combined with Hemodialysis and the “Inflammation Mitigation Hypothesis”

ABSTRACT Clinical outcomes are still unsatisfactory in patients undergoing chronic maintenance dialysis. Signs and symptoms of uremic intoxication are often present even in presence of an adequate dialysis delivery. These along with cardiovascular and skeletal complications, have been correlated to the accumulation of inflammatory chemical mediators, beta-2 microglobulin (β2M), parathyroid hormone (PTH) and other middle to large molecular weight toxins that are insufficiently cleared by current dialysis techniques. Such condition determines a vicious loop where a subclinical status of inflammation causes a disruption of the immunological response affecting outcomes by accelerated atherosclerosis, anemia, and frequent infections. The overall picture can be described as a systemic inflammatory syndrome with simultaneous activation of the innate and the adaptive immunity. In such condition, new options and techniques are required to achieve a more effective blood purification and to correct the altered immuno-homeostasis. New efficient and biocompatible sorbents are today available (HA 130 Cartridge, Jafron Medical, Zhuhai, China) and they can be advantageously coupled in series with the hemodialyzer to perform hemoadsorption combined with hemodialysis (HA-HD). This technique has been already studied in at least two randomized trials demonstrating an effective improvement of clinical and biochemical outcomes. We have calculated the kinetics of β2M in a single session, in a series of three consecutive sessions of a week and in a period of three months using different frequencies of application (first month: Three sessions per week; second month: Two sessions per week; third month: One session per week). In the single session the reduction ratio was superior to other techniques such as hemodialysis (HD), high-flux hemodialysis (HFD) or hemodiafiltration (HDF). In the thrice weekly regime, the time average concentration (TAC) of β2M resulted inferior to HD and HDF. In the long period, a lower concentration of β2M was maintained even with a once-a-week regime. Considering the parallel reduction of inflammatory parameters, we could hypothesize that the enhanced removal of uremic toxins and chemical mediators led to a mitigation of the systemic inflammation with a progressive reduction in the generation of β2M. This “inflammation mitigation hypothesis (IMH)” supports the prescription of HA-HD once a week, possibly after a month of thrice weekly regime.

Cinnamic acid promotes elongation of hair peg-like sprouting in hair follicle organoids via oxytocin receptor activation

Considerable global demand exists for the development of novel drugs for the treatment of alopecia. A recent report demonstrated that oxytocin promotes hair growth activity in human dermal papilla (DP) cells; however, its application in drugs or cosmetic products is challenging because rapid degradation and relatively large molecular weight prevent long-term topical administration on the scalp. Here, we examined cinnamic acid, a small molecule activator for oxytocin receptor (OXTR) expression. Treatment with cinnamic acid led to upregulation of OXTR and trichogenic gene expression in human DP cells. Furthermore, inhibition of OXTR with an antagonist, L-371,257, suppressed hair growth-related gene expression in DP cells. These findings suggest that cinnamic acid enhances the hair growth ability of DP cells via oxytocin signaling. Additionally, we tested the hair growth-promoting effects of cinnamic acid using hair follicle organoids in vitro and observed that cinnamic acid significantly promoted the growth of hair peg-like sprouting. These promising results may be useful for developing hair growth-promoting products targeting oxytocin.

Physicochemical and emulsification properties of okara-derived soluble dietary fiber modified by steam explosion

The effective utilization of by-products still poses a challenge in the food industry. In this work, soluble dietary fiber (SDF) extracted from okara was modified by steam explosion (SE) via adjusting steam pressure (1.0, 1.5, and 2.0 MPa) and SE duration (60 and 120 s). The structural and emulsification properties of modified SDF were studied. The untreated SDF exhibited a low yield (5.17%) and poor emulsification properties due to its large molecular weight (162.67 kDa), compact structure, and high interfacial tension (14.27 mN/m). SE increased SDF content by a maximum of 30.31%, 4.86 times higher than that of untreated SDF. Under mild SE conditions (1.0 MPa for 60 s), SDF displayed a loose structure with abundant side chains and a higher glyoxylate content (26.77%). Its near-neutral contact angle (82.0°) and lower interfacial tension (12.69 mN/m) endowed it with higher emulsification capacity, smaller emulsion droplet size, and enhanced emulsifying stability. The molecular weight of SDF decreased and the specific surface area enlarged with increasing SE intensity. Notably, SDF exhibited the best interfacial adsorption characteristics under SE of 2.0 MPa for 120 s, attributed to its low molecular weight (46.99 kDa) and higher protein content (7.58%). Overall, the improved emulsification properties of SDF were attributed to the synergistic effects of amphiphilic equilibrium, electrostatic repulsion, spatial resistance, and enhanced droplet-to-droplet interactions.

Adaptive laboratory evolution of Naematelia aurantialba under high temperature for efficient production of exopolysaccharide

Liquid fermentation could revolutionize mushroom polysaccharide production, but the low temperature constraint hampers the process. This study implemented adaptive laboratory evolution (ALE) to enhance the thermotolerance of Naematelia aurantialba strains and increase expolysaccharide production. After 75 ALE cycles at 30 °C, the adaptive strain surpassed the wild-type strain by 5 °C. In a 7.5 L fermentor at 30 °C, the ALE strain yielded 17 % more exopolysaccharide than the wild type strain at 25 °C. Although the exopolysaccharide synthesized by both strains shares a consistent monosaccharide composition, infrared spectrum, and glycosidic bond composition, the ALE strain's exopolysaccharide has a larger molecular weight. Furthermore, the ALE strain's exopolysaccharide exhibits superior cryoprotection performance compared to that produced by the original strain. The adapted strain demonstrated lower ROS levels and increased activity of antioxidant enzymes, indicating improved performance. Fatty acid profiling and transcriptomics revealed reconfiguration of carbohydrate metabolism, amino acid metabolism, and membrane lipid synthesis in thermophilic strains, maintaining cellular homeostasis and productivity. This study provides efficient strains and fermentation methods for high-temperature mushroom polysaccharide production, reducing energy consumption and costs.

Determination of Escherichia coli Ligase Activity by Carbon Nanotube Fluorescence Anisotropy

The characterization of nucleic acid ligase activity is of great significance for the study of physiological processes. In the present work, a new method for the detection of E. coli DNA ligase is designed based on the non-covalent interaction of carbon nanotubes with dyes and ssDNA and DNA ligation reactions. When no E. coli DNA ligase is present, the ssDNA probe and dye SG I adsorb to the surface of carbon nanotubes. After centrifugation, the carbon nanotubes with DNA and dye SG I have larger molecular weights, resulting in higher fluorescence anisotropy. When E. coli DNA ligase is present, a double-stranded structure is formed, with SG I embedded in the groove of the DNA double strand. Due to the weak interaction between the DNA double-strand structure and the carbon nanotubes, after centrifugation, the supernatant does not contain the carbon nanotubes, resulting in lower fluorescence anisotropy. The feasibility of the assay was confirmed by optimizing the conditions. This method improves the accuracy of the detection with a relative error within 1%. The increase of fluorescence anisotropy in samples is small compared with in the buffer solution. Therefore, the system has good selectivity and is suitable for the characterization of enzyme activity in biological samples. Moreover, the method does not require the labeling of fluorescent molecules or a special design of nucleic acid sequences, which avoids complex probe modification.

Chemical Multiverse and Diversity of Food Chemicals.

Food chemicals have a fundamental role in our lives, with an extended impact on nutrition, disease prevention, and marked economic implications in the food industry. The number of food chemical compounds in public databases has substantially increased in the past few years, which can be characterized using chemoinformatics approaches. We and other groups explored public food chemical libraries containing up to 26,500 compounds. This study aimed to analyze the chemical contents, diversity, and coverage in the chemical space of food chemicals and additives and, from here on, food components. The approach to food components addressed in this study is a public database with more than 70,000 compounds, including those predicted via omics techniques. It was concluded that food components have distinctive physicochemical properties and constitutional descriptors despite sharing many chemical structures with natural products. Food components, on average, have large molecular weights and several apolar structures with saturated hydrocarbons. Compared to reference databases, food component structures have low scaffold and fingerprint-based diversity and high structural complexity, as measured by the fraction of sp3 carbons. These structural features are associated with a large fraction of macronutrients as lipids. Lipids in food components were decompiled by an analysis of the maximum common substructures. The chemical multiverse representation of food chemicals showed a larger coverage of chemical space than natural products and FDA-approved drugs by using different sets of representations.

Different behavior of Ferguson plot between agarose and polyacrylamide gels

In this study, we conducted Ferguson plot analyses using both agarose and polyacrylamide gels in native electrophoresis and SDS-PAGE. The results revealed intriguing differences in the behavior of bovine serum albumin (BSA) and other model proteins. Specifically, BSA exhibited Ferguson plot slopes that were dependent on the oligomer size in agarose native gel electrophoresis, while such size-dependent behavior was not observed in native-PAGE or SDS-PAGE. These findings suggest that Ferguson plot analysis is a suitable approach when using agarose gel under the electrophoretic conditions employed in this study. Furthermore, our investigation extended to model proteins with acidic isoelectric points and larger molecular weights, namely Ferritin and caseinolytic peptidase B (ClpB). Notably, these proteins displayed distinct Ferguson plot slopes when subjected to agarose gel electrophoresis. Intriguingly, when polyacrylamide gel was employed, ClpB exhibited multiple bands, each with its unique Ferguson plot slope, deviating from the expected behavior based on molecular size. This divergence in Ferguson plot characteristics between agarose and polyacrylamide gels points to an interesting and complex interplay between protein properties and gel electrophoresis conditions.

Meticulous Molecular Engineering of Crystal Orientation and Morphology in Conjugated Polymer Thin Films for Field-Effect Transistors.

The ability to precisely tailor molecular packing and film morphology in conjugated polymers offers a robust means to control their optoelectronic properties. This, however, remains a grand challenge. Herein, we report the dependency of molecular packing of an important conjugated polymer, poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), on a set of intrinsic parameters and unveil the correlation between their crystalline structures and charge transport characteristics. Specifically, a family of PBTTT with varying side chains (i.e., hexyl, octyl, decyl, dodecyl, tetradecyl, and hexadecyl referred to as C6, C8, C10, C12, C14, and C16, respectively) and molecular weights (MWs) with a focus on C14 are judiciously designed and synthesized. Various crystalline structures are yielded by tuning the alkyl chain and MW of PBTTT together with thermal annealing. It reveals that extending the alkyl chain length of PBTTT to C14, along with a larger MW and heating at 180 °C, promotes the formation of edge-on crystallites with significantly improved orientation and ordering. Furthermore, these distinct crystalline structures greatly impact their charge mobilities. This study sheds light on the tailored design of crystalline structures in PBTTT through a synergetic approach, which paves the way for potential applications of PBTTT and other conjugated polymers in optoelectronic devices with enhanced performance.

Is monochloramine pre-oxidation a viable strategy for enhancing the treatment efficiency of algae-laden water with conventional drinking water treatment process?

Algal blooms worldwide pose many challenges to drinking water production. Pre-oxidation with NaClO, KMnO4, or ozone is commonly used to enhance algal removal in conventional drinking water treatment processes. However, these currently utilized oxidation methods often result in significant algal cell lysis or impede the operation of the subsequent units. Higher algal removal with pre-chlorination in algal solutions prepared with natural water, compared to those prepared with ultrapure water, has been observed. In the present studies, preliminary findings indicate that ammonium in natural water alters chlorine species to NH2Cl, leading to improved treatment efficiency. NH2Cl with 1.5–3.0 mg∙L−1 as Cl2 with an oxidation time of 3–7 h significantly enhancing algal removal by coagulation. The selective oxidation of surface-absorbed organic matter (S-AOM) by NH2Cl, followed by the subsequent peeling off of this material from the algal surface, leading to an increase in zeta potential from −20.2 mV to −3.8 mV, constitutes the primary mechanism of enhanced algal removal through coagulation. These peeled S-AOM retained their large molecular weight and acted as polymer aids. Compared with NaClO and KMnO4, NH2Cl displays the best performance in improving algal removal, avoiding cell lysis, and decreasing the potential for nitrogenous disinfection byproducts formation under the reaction conditions used in this study. Notably, in major Chinese cities, water purification plants commonly rely on suburban lakes or reservoirs as water sources, necessitating the transportation of raw water over long distances for times up to several hours. These conditions favor the implementation of NH2Cl pre-oxidation. The collective results indicate the potential of NH2Cl oxidation as a viable pretreatment strategy for algal contamination during water treatment processes.

Azaphosphinate Dyes: A Low Molecular Weight Near-Infrared Scaffold for Development of Photoacoustic or Fluorescence Imaging Probes.

Near-infrared (NIR) dyes are desirable for biological imaging applications including photoacoustic (PA) and fluorescence imaging. Nonetheless, current NIR dyes are often plagued by relatively large molecular weights, poor water solubility, and limited photostability. Herein, we provide the first examples of azaphosphinate dyes which display desirable properties such as low molecular weight, absorption/emission above 750 nm, and remarkable water solubility. In PA imaging, an azaphosphinate dye exhibited a 4.1-fold enhancement in intensity compared to commonly used standards, the ability to multiplex with existing dyes in whole blood, imaging depths of 2.75 cm in a tissue model, and contrast in mice. An improved derivative for fluorescence imaging displayed a >10-fold reduction in photobleaching in water compared to the FDA-approved indocyanine green dye and could be visualized in mice. This new dye class provides a robust scaffold for the development of photoacoustic or NIR fluorescence imaging agents.

Residue-Free and Recyclable Starch-Based Flocculants for Dye Wastewater Flocculation.

Flocculants are crucial agents in wastewater treatment because they can remove oppositely charged impurities effectively and swiftly. However, flocculation also inevitably causes secondary contamination due to the residual properties, nonreusability, and nondegradability of traditional flocculant molecules. Herein, an ecofriendly starch-based flocculant, i.e., 2,4-bis(dimethylamino)-[1,3,5]-triazine-6-starch, was synthesized via a preactivation-etherification strategy. The large molecular weight property of the flocculant produced by this method enhances the intermolecular hydrophobic association, achieving complete phase separation of all flocculant molecules from water and residue-free flocculation for the first time. Importantly, a large molecular weight tertiary amine starch-based flocculant (LMTS) exhibits a remarkable flocculation capacity of over 1800 mg·g-1 for dye wastewater, which is significantly higher than that of traditional polyacrylamide and polyaluminum chloride flocculants. Furthermore, the LMTS flocculant could be recycled by pH adjustment, and its structural stability ensured sustained reusability. This high-performance residue-free biomass-based flocculant offers a green advance for wastewater treatment.

Comparison of the in-vitro effect of five prebiotics with different structure on gut microbiome and metabolome

This study aimed to compare the effects of sodium alginate (SA), galactooligosaccharides (GOS), lactulose (LC), polydextrose (PDX), and inulin (IN) on gut microbiome and metabolome using stable in vitro human gut fermentation model. The five prebiotics with different structure were effective in promoting beneficial bacteria, such as increased Bifidobacterium, Enterococcus, and Ruminococcaceae_UCG_014 in the GOS group, and Parabacteroides and Phascolarctobacterium in the PDX group. Also, prebiotics promoted total short chain fatty acids (SCFAs) production, especially the butyric acid increased by SA with the largest molecular weight and high content of ManA. Most prebiotics affected carbohydrate metabolism, amino acid metabolism, and lipid metabolism pathways. The changed metabolic pathways were similar between the LC and GOS with the smallest molecular weight, and IN and PDX with analogous molecular weight and monosaccharide composition were strongly associated with energy metabolism pathways. This paper could promote the application and development of prebiotics in food industry.

Gastroprotective Effects of Biological Macromolecule: Polysaccharides

AbstractThe large molecular weight of the macromolecules sets them apart from all other components. This may range from 10 000 to over a million. While the molecular weight of other plant metabolites is seldom beyond 1000. Chemically, macromolecules are made up of long chains and little “building pieces,” which are joined covalently in a variety of ways. Biological macromolecules are large, naturally occurring cellular building blocks that play a range of crucial roles in the development and existence of living organisms. Biomacromolecules are essential in the biomedical field and other related professions. They feature a variety of beneficial properties, including excellent biodegradability, suitable mechanical strength, enhanced bioavailability, etc. They also have significant biocompatibility. They display a variety of biological characteristics, such as antimalignant, antidiabetic, antibacterial, antioxidant, and immunomodulatory. The use of essential carbohydrates including alginate, chitosan, pectin, starches, carrageenan, fucoidan, etc. is common in commercial applications. Natural substance‐based pharmacotherapy is now considered to be a highly promising future alternative to conventional medicine. Along with proteins and polynucleotides, polysaccharide is a vital biomacromolecule that has a crucial function in the growth and expansion of living things. A crucial element of higher plants, cell membranes of animal, and cell walls of microbes is polysaccharide. It is intimately tied to physiological processes as well. The importance of polysaccharides as a significant class of bioactive natural compounds has received more attention recently. Numerous studies have shown that natural polysaccharides contain bioactivities, which have led to the use of polysaccharides in the treatment of illness. The many parts of the research findings on the bioactivities of polysaccharides in gastro‐protection are included in this paper.

Synthesis of Topological Gels by Penetrating Polymerization Using a Molecular Net

AbstractTopological gels possess structures that are cross‐linked only via physical constraints; ideally, no attractive intermolecular interactions act between their components, which yields interesting physical properties. However, most reported previous topological gels were synthesized based on supramolecular interlocked structures such as polyrotaxane, for which attractive intermolecular interactions are essential. Here, we synthesize a water‐soluble “molecular net” (MN) with a large molecular weight and three‐dimensional network structure using poly(ethylene glycol). When a water‐soluble monomer (N‐isopropylacrylamide) is polymerized in the presence of the MNs, the extending polymer chains penetrates the MNs to form an ideal topological MN gel with no specific attractive interactions between its components. The MN gels show unique physical properties as well a significantly high degree of swelling and high extensibility due to slipping of the physical cross‐linking. We postulate this method to yield a new paradigm in gel science with unprecedented physical properties.

Adsorption characteristics and mechanisms of water-soluble polymers (PVP and PEG) on kaolin and montmorillonite minerals

The excessive use and accumulation of water-soluble polymers (WSPs, known as “liquid plastics”) in the environment can pose potential risks to both ecosystems and human health, but the environmental fate of WSPs remains unclear. Here, the adsorption behavior of WSPs with different molecular weight on kaolinite (Kaol) and montmorillonite (Mt) were examined. The results showed that the adsorption of PEG and PVP on minerals were controlled by hydrogen bond and van der Waals force. The Fourier transform infrared (FTIR) spectra and two-dimensional correlation spectroscopy (2D-COS) analysis revealed that there were interactions between the Al-O and Si-O groups of the minerals and the polar O- or N-containing functional groups as well as the alkyl groups of PEG and PVP. The adsorption characteristics of WSPs were closely related to their molecular weight and the pore size of minerals. Due to the relatively large mesopore size of Kaol, both PEG and PVP were absorbed into inner spaces, for which the adsorption capacity increased with molecular weight of the polymers. For Mt, all types of PEG could enter its micropores, while PVP with larger molecular weights appeared to be confined externally, leading to a decrease in the adsorption capacity of PVP with increasing molecular weight. The findings of this study provide a theoretical basis for scientific evaluation of environmental processes of WSPs.

Recommendations on the Use of Multiple Labels in Human Mass Balance Studies.

The administration of radiolabeled drug candidates is considered the gold standard in absorption, distribution, metabolism, and excretion studies for small-molecule drugs since it allows facile and accurate quantification of parent drug, metabolites, and total drug-related material independent of the compound structure. The choice of the position of the radiolabel, typically 14C or 3H, is critical to obtain relevant information. Sometimes, a biotransformation reaction may lead to cleavage of a part of the molecule. As a result, only the radiolabeled portion can be followed, and information on the fate of the nonlabeled metabolite may be lost. Synthesis and administration of two or more radiolabeled versions of the parent drug as a mixture or in separate studies may resolve this issue but comes with additional challenges. In this paper, we address the questions that may be considered to help make the right choice whether to use a single or multiple radiolabel approach and discuss the pros and cons of different multiple-labeling strategies that can be taken as well as alternative methods that allow the nonlabeled part of the molecule to be followed. SIGNIFICANCE STATEMENT: Radiolabeled studies are the gold standard in drug metabolism research, but molecules can undergo cleavage with loss of the label. This often results in discussions around potential use of multiple labels, which seem to be occurring with increased frequency since an increasing proportion of the small-molecule drugs are tending towards larger molecular weights. This review provides insight and decision criteria in considering a multiple-label approach as well as pros and cons of different strategies that can be followed.

Comparison of modification methods for the preparation of coarse organic flocculant with macromolecular products from the hydrothermal liquid phase of sludge

Implementing appropriate measures to recycle and convert the organic matter in sewage into valuable products can effectively contribute to resource recovery. The macromolecular products derived from the hydrothermal liquid phase of sewage sludge (HL-MMP) were utilized as raw materials for preparing coarse organic flocculant (Co-flocculant), which can be re-used to enhance organic matter removal from sewage via flocculent settling. Two distinct chemical modification methods, namely etherification and grafting copolymerization, were compared and analyzed in terms of their suitability for the preparation.Through coagulation experiments, it was found that the Co-flocculant obtained from both methods yield satisfactory turbidity and COD removal. However, to achieve a higher turbidity and COD removal, the required dosage of the Co-flocculant (M-GTA) obtained by etherification is significantly larger than that of the Co-flocculant (M-DMC) obtained by graft copolymerization. Meanwhile the HL-MMP and Co-flocculant were characterized using FTIR, XPS, SEM and Charge Density, Intrinsic Viscosity of the latter were measured. The results of FT-IR and XPS showed that HL-MMP possesses numerous functional groups, which can serve as active sites for both modifying reactions. The charge density of the Co-flocculant obtained through the two methods is similar, however, the intrinsic viscosity of M-GTA is lower than that of M-DMC, indicating that the graft copolymerization seems to form products with larger molecular weight. Additionally, the analysis of the reaction mechanism revealed that the HL-MMP exhibits self-polymerization and bound monomer, DMC, facilitates polymerization in the graft copolymerization. Conversely, in the etherification, polymerization mainly depend on the addition of etherized monomer, GTA. The difference of reaction mechanisms can explain the relative quantitative requirements of modifying monomers and different preparation conditions. Therefore, graft copolymerization is deemed more suitable for modifying HL-MMP to synthetic Co-flocculant and deserves further comprehensive and detailed investigation.

Supported Molecular Matrix Electrophoresis.

Distinct bands of mucins cannot be banded using a gel electrophoresis based on a molecular sieving effect due to their very large molecular weight and remarkable diversity in glycosylation. In contrast, membrane electrophoresis can separate mucins as round bands. Here, we present an analysis of mucin separation via membrane electrophoresis using a porous polyvinylidene difluoride membrane, which is highly stable against chemical modifications and various organic solvents. The separated mucins can not only be stained with dyes but also with antibodies and lectins, and glycans can be released from the excised bands and analyzed.

Color characteristics and pyrolysis volatile properties of main colored fractions from the Maillard reaction models of glucose with three amino acids

The effects of hydrosoluble colored fractions generated in the Maillard reaction models on the volatiles of pyrolytic Maillard reaction products was investigated. The hydrosoluble colored fractions obtained by reaction of glucose with glycine (Gly-Glc), proline (Pro-Glc) and phenylalanine (Phe-Glc) respectively at 125 °C were separated using Sephadex LH-20 Gel column. The colored fraction with large molecular weight had a higher contribution to the overall color and more glucose residue structures in main skeleton than that with small molecular weight in the same model. Gel permeation chromatography analysis indicated that these colored fractions had continuous relative molecular weight distribution (1000–80000 Da). Pyrolysis - gas chromatography - mass spectrometry determination (pyrolysis temperature: 160∼900 °C) suggested that furans and pyrroles were the main volatiles of two Gly-Glc fractions after pyrolysis, and the key pyrolysis volatiles of Pro-Glc fraction were furans, pyrroles, pyran, indole and cyclopentenes, which gave a freshly baked bread, nutty, coffee-like and sweet caramel-like odor. Especially phenyl-containing compounds seemed typical indicators of Phe-Glc fraction pyrolysis products, exhibiting a benzene-like, tallowy, sweet, balsamic and floral odor. The hydrosoluble colored fractions produced by different Maillard reactions had different pyrolytic volatile properties and were suitable for the development of bakery food improver with different color and flavor requirements.