Macroporous Adsorption Resin Research Articles

Structure and functional properties of sunflower seed protein as affected by enzymatic hydrolysis combined with macroporous resin adsorption decolorization

ABSTRACT In order to improve the color and functional properties of sunflower seed protein, low-temperature defatted sunflower seed meal was used as the raw material to study the effects of limited enzyme hydrolysis combined with macroporous resin adsorption decolorization technology on the color and functional properties of sunflower seed protein. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD), particle size, intrinsic fluorescence intensity, surface hydrophobicity (H0) and scanning electron microscopy (SEM) were used to analyze the influence on its structure. The results showed that the molecular weight of sunflower seed protein was reduced after limited enzyme hydrolysis combined with macroporous resin decolorization; the content of α-helix and β-turn was significantly reduced, and the content of β-sheets and random coils was significantly increased; the average particle size was reduced; the fluorescence intensity was increased and the red shift phenomenon occurred. H0 also increased, SEM results showed that the surface of sunflower seed protein changed from a smooth large sheet-like structure to an irregular fragmented fast-like structure. Solubility, foamability, emulsification and emulsification stability were all significantly improved (p < .05), while foam stability and oil retention were reduced. The above results indicate that limited enzyme hydrolysis combined with macroporous resin adsorption and decolorization changes the structure of sunflower seed protein, and then improve its functional properties.

A green and highly efficient method of extracting polyphenols from Lilium davidii var. unicolor Salisb using deep eutectic solvents

It is important to find pollution-free, eco-friendly solvents to replace traditional organic solvents. As a new class of medium, deep eutectic solvents (DESs) provide a source of breaking through the green engineering barrier and bring new opportunities for extraction using green chemistry. In this research, the methods of polyphenol extraction from Lilium davidii var. unicolor Salisb with different types of DESs such as choline chloride, betaine, and tetrabutyl ammonium chloride-based DESs were investigated. Compared with traditional extraction solvent systems using methanol, DESs, which are composed of choline chloride and citric acid, have a higher extractive yield. The extraction conditions of polyphenol from Lilium davidii var. unicolor Salisb were studied; moreover, macroporous adsorptive resin was shown to be an efficient way in which to recover polyphenolic compounds. Recovery and reuse of DESs were also analyzed. DESs as “green and designed” solvent can be used to extract polyphenolic compounds from natural products.

Deep eutectic solvents as green media for flavonoids extraction from the rhizomes of Polygonatum odoratum

Recent years have witnessed the growing popularity of deep eutectic solvents (DESs) in the extraction of functional components. As a novel green alternative to organic reagents, DESs are environmentally friendly, non-toxic, inexpensive, and biodegradable. In the present study, tailor-made DESs were prepared and applied for the first time to extract flavonoids from rhizomes of Polygonatum odoratum. We also investigated the extraction process, extraction efficiency, and solvent recovery efficiency. The response surface methodology (RSM) was adopted to optimise total flavonoid extraction, and the DES was recovered through macroporous resin adsorption. The results show that the DES synthesised by choline chloride and lactic acid at a molar ratio of 1:2 was the most suitable extraction medium. Extraction conditions were optimised as follows: extraction temperature of 51 °C, DES water content of 27%, liquid–solid ratio of 22 mL/g, and extraction time of 21 min. Under these conditions, the extraction rate of total flavonoids reached 11.47 mg/g, close to that of the heat reflux extraction (HRE) with organic solvents. The adsorption and desorption experiments of flavonoids on three types of macroporous resins (HPD826, D101, and AB8) were carried out, and D101 showed higher adsorption/desorption capacities, successively followed by AB8 and HPD826. The extraction rate of the recycled DES reached 10.78 mg/g, putting the reuse rate at 93.98%. In conclusion, the developed DES combined with macroporous resin enrichment can be an alternative method for green and efficient extraction of bioactive flavonoids from plant materials.

Facile preparation of bifunctional adsorbents for efficiently enriching N-glycopeptides and phosphopeptides

In bottom-up strategy, specific enrichment of glycopeptides and phosphopeptides from complicated biological samples is a prerequisite for efficient identifying glycosylation and phosphorylation by mass spectrometry. Although there were a plethora of materials used as either hydrophilic interaction liquid chromatography (HILIC) or immobilized metal affinity chromatography (IMAC) adsorbents, even several bifunctional materials for simultaneous enrichment of glycopeptides and phosphopeptides, most of them are not easily commercialized as many other well-performing adsorbents due to the complicated preparation process. In our case, a one-step modification strategy was developed to prepare bifunctional adsorbents for HILIC and IMAC, employing O-phospho-l-serine as the modifier and poly(GMA-co-EDMA) microspheres, a kind of macroporous adsorption resin (MAR) with epoxy groups, as the matrix. The MARs were directly modified with O-phospho-l-serine under facile condition for HILIC strategy and further chelated with Ti4+ for IMAC strategy. A total of 522 unique N-glycopeptides and 442 unique N-glycosylation sites mapped to 275 N-glycoproteins was identified from HeLa cell proteins, showing excellent enrichment efficiency in HILIC. Additionally, 3141 unique phosphopeptides were unambiguously identified from 200 μg of digest of HeLa cell proteins, demonstrating great enrichment efficiency in IMAC. Moreover, these materials have been successfully applied in the analysis of multiple biological samples including human serum and milk, demonstrating their feasibility for real sample applications and potential business value.

Tyrosinase inhibition by p-coumaric acid ethyl ester identified from camellia pollen.

A tyrosinase inhibitor was separated from camellia pollen with the aid of solvent fraction, macroporous adsorptive resin chromatography, and high‐speed countercurrent chromatography. The inhibitor was identified to be p‐coumaric acid ethyl ester (p‐CAEE) by nuclear magnetic resonance and mass spectrum. Its inhibitory activity (IC50 = 4.89 μg/ml) was about 10‐fold stronger than arbutin (IC50 = 51.54 μg/ml). The p‐CAEE inhibited tyrosinase in a noncompetitive model with the K I and K m of 1.83 μg/ml and 0.52 mM, respectively. Fluorescence spectroscopy analysis showed the p‐CAEE quenched an intrinsic fluorescence tyrosinase. UV‐Vis spectroscopy analysis showed the p‐CAEE did not interact with copper ions of the enzyme. Docking simulation implied the p‐CAEE induced a conformational change in the catalytic region and thus changed binding forces of L‐tyrosine. Our findings suggest that p‐CAEE plays an important role in inhibiting tyrosinase and provides a reference for developing pharmaceutical, cosmetic, and fruit preservation products using pollen.

Extract from Rostellularia procumbens (L.) Nees Inhibits Thrombosis and Platelet Aggregation by Regulating Integrin β3 and MAPK Pathways.

Aim of study: The main objective of this study was to investigate the antithrombotic and antiplatelet effect of the extract from Rostellularia procumbenss (L.) Nees and understand the mechanisms by which it exerts its antithrombotic and antiplatelet mechanisms. Materials and methods: The antithrombotic effective parts (RPE) were isolated using D101 macroporous adsorption resin and potential active ingredients (JAC) were isolated using the preparative liquid-phase method. The lactate dehydrogenase kit was used to determine the toxicity of RPE and JAC to platelets. The antiadhesion effect of RPE and JAC on platelets was observed by fluorescence microscopy with rhodamine phalloidin. Antithrombotic efficacy of RPE and JAC in vivo was evaluated by establishing a rat tail thrombosis model. Contents of p-selectin, TXB2, and 6-keto-PGF1α in rat serum were measured using an enzyme-linked immunosorbent (ELISA) assay, and the rat black tail rate was measured to prove the protective effect of RPE and JAC on the tail thrombus rat model. Western blot was used for detection of serum-related proteins in the tail thrombus rat model. Results: The results showed that RPE had antithrombotic and antiplatelet effects. RPE and JAC have no toxicity to platelets. In vitro experiments showed that RPE and JAC had antiadhesion effects on platelets. In vivo experiments showed that RPE significantly inhibited the increase of p-selectin and TXB2 and significantly increased the content of 6-keto-PGF1α in the serum of rats. Western blot results demonstrated that RPE and JDB significantly inhibited the phosphorylation of the MAPK protein family in the platelets of rats, and RPE also significantly inhibited the phosphorylation of β3 protein. Conclusions: RPE has antithrombotic and antiplatelet activity in vivo and vitro. Its mechanism may be via preventing integrin αIIbβ3 activation, which in turn leads to the inhibition of the phosphorylation of the MAPK family and further suppresses TXA2, which leads to the antithrombotic and antiplatelet effects.

Separation and purification of resveratrol by liquid extraction assistance macroporous adsorption resin mixed-bed technology

ABSTRACT Resveratrol in the aqueous extraction of Polygonum cuspidatum was separated and purified by liquid extraction assistance macroporous adsorption resin mixed bed. Firstly, petroleum ether and ethyl acetate were used to replace diethyl ether that was an effective solvent for separate Resveratrol from aqueous extract. Then, Resveratrol was further separated by macroporous adsorption resin-mixed bed. Finally, the experimental conditions were optimized. When the volume ratio of water and organic mixture was 2/3, extraction time interval was 60 min and extraction times was 5 times, the recovery rate of Resveratrol was 81.10% and the purity was 87.12%.

A simple and efficient method for separation and purification of troxerutin on the SZ-3 resin

PurposeIn view of the current difficulty of separation of troxerutin, the purpose of the paper is to separate and purify semi-synthetic flavonoid compound troxerutin by macroporous adsorption resin (SZ-3).Design/methodology/approachComparing the adsorption performance and resolution of three different polar resins and choosing a resin to optimize the process parameters such as sample volume, eluent concentration and elution temperature to obtain high-purity troxerutin. After separating and enriching by resin column chromatography, detected the sample by LC-MS analysis.FindingsThis research found that the optimal conditions of the adsorption and desorption were sample volume S = 90 mg/g resin, methanol concentration C = 25%, T = 20 °C. the content of troxerutin increased significantly from 88% to more than 96%. Then confirmed the sample was troxerutin by LC-MS. In addition, the resin could be used for at least 10 cycles in the separation and purification experiments of troxerutin.Originality/valuePurification of troxerutin with new SZ-3 resin for the first time. Under the optimal conditions, the purity and recovery of troxerutin was 96.4% and 39%. In this study, the authors established a purification process of troxerutin successfully that was simple, economical, environment friendly, with high purity and high recovery rate to provide a reference program for changing the status of troxerutin separation difficulties.

Efficient direct preparation of antifungal Alteramide B from Lysobacter enzymogenes fermentation broth by macroporous resin adsorption

Alteramide B (ATB) is an antifungal metabolite produced by Lysobacter enzymogenes. However, its separation method has not been explored. This study attempted to directly adsorb ATB from fermentation broth using macroporous adsorption resins (MARs)NKA resin exhibited better adsorption as well as desorption capacities. The static and dynamic adsorption characteristics were assessed to determine the following optimal separation conditions: initial fermentation broth with a pH of 12.0, 2 BV/h flow rate, 8 BV loading volume, and 6 BV 80% aqueous ethanol for elution. After a single treatment, ATB content in the final product was higher by 4.51-fold (i.e, from 12.72 ± 1.21% to 57.35 ± 3.46%), resulting in a recovery yield of 86.20 ± 4.47%. In addition, NKA resin showed superior reusability within eight cycles of adsorption/desorption. The developed method is thus a simple, efficient, and economical process for ATB separation.

Purification and Antioxidant Activity of Flavonoids from Chromolaena Odorata

To purify the flavonoids from Chromolaena odorata (COF) and evaluate its antioxidant activities in vitro. Methods: The COF were purified by macroporous adsorption resin with optimal purification process, and its antioxidant activities were evaluated by scavenging rate of DPPH free radical, ABTS free radical and superoxide anion radical. Results: The COF were obtained using with AB-8 macroporous adsorption resin washed by 60 % ethanol at the flow rate of 2.0 mL/min, and the purity was 74.22 %. After purification, the scavenging activities of COF on DPPH free radical, ABTS free radical and superoxide anion radical, were 91.36 %, 90.13 % and 93.17%, repectively. The purified COF also showed a certain reducing power. Conclusions: The COF showed strong antioxidant activity in vitro.

Preparative Separation of Flavonoids from Goji Berries by Mixed-Mode Macroporous Adsorption Resins and Effect on Aβ-Expressing and Anti-Aging Genes.

Flavonoids are the main constituents of Goji berries and have good biological and pharmacological activities. The mixed-mode macroporous adsorption resins (MARs) for purification of flavonoids from Goji berries through computer-assisted calculation of the molecular size of flavonoids and the precise matching of MAR physical and chemical properties was firstly developed in the present study. Ten varieties of MARs with suitable molecular dimensions and polarities were used for investigating the adsorption/desorption behaviors of the flavonoids. Both AUKJ-1 and BWKX-1 showed higher separation efficiency than other MARs and then were mixed in different ratios to constitute a mixed-mode macroporous adsorption resin to obtain the optimal adsorption phase. Under optimal conditions, total flavonoid content of purified flavonoid (p-FLA) extract increased from 0.97% to 36.88% after one purification. The p-FLA extract from Goji berries significantly improved the expression of six genes with anti-aging effects and played an important role in aging-related Alzheimer’s disease by down-regulating Aβ expression.

Preparation and characterization of a low-phenylalanine whey hydrolysate using two-step enzymatic hydrolysis and macroporous resin adsorption

A low-phenylalanine (Phe) diet is indispensable for phenylketonuria patients. The objectives of this study were to develop a two-step enzymatic method to effectively release Phe from whey protein, and then to prepare a low-Phe hydrolysate (LPH) by using adsorbent. Thermolysin (T) or Pancreatin (P) combined with Protease A2SD (A2) showed the degree of hydrolysis ranging from 42.62% to 45.43% and released more than 90% Phe from whey protein. The D101 macroporous resin column removed 98.38% Phe from TA2 hydrolysate (TA2H), compared to 64.50% of Phe removal by activated carbon. The protein content of LPH prepared by a magnified D101 resin column was 60.41 g/100 g hydrolysate and its Phe content was 1.38 ± 0.11 mg/g protein equivalent. After adsorption, the percentage of peptides below 600 Da significantly increased from 50.79% to 93.60%, while the intensity of bitterness and astringency measured by electronic-tongue also increased. However, aroma-active compounds such as Millard reaction and lipid oxidation products were reduced after absorption. The LPH prepared in our study could be a suitable protein substitute to make phenylketonuria food.

Enrichment in Antioxidant Flavonoids of Stamen Extracts from Nymphaea lotus L. Using Ultrasonic-Assisted Extraction and Macroporous Resin Adsorption.

Nymphaea lotus L. is the medicinal plant that has long been used for food, cosmetics and traditional medicines in Africa and Asia since ancient times. Its flavonoids and other interesting phytochemical compounds from rhizome, leaf and the whole flowers have been reported in the previous published research. However, stamens, which are essential for reproductive functions, may also represent new alternative sources of potential antioxidant flavonoids, as investigated in this study. The innovative green chemistry methods, i.e., ultrasound-assisted extraction (UAE) as well as a macroporous resin (MPR) purification procedure, were employed in this current research. Using a full factorial design coupled to three-dimensional (3D) surface plot methodology, the influence of three variables, namely aqEtOH concentration (ranging from 50 to 100% (v/v), US frequency (ranging from 0 (no US applied) to 45 kHz), and the extraction duration (ranging from 20 to 60 min), were evaluated. Five MPRs with different surface areas, average pore diameters, matrix types and polarities were also investigated for the purification of total flavonoids. The optimal UAE condition is 90% (v/v) aqEtOH with 34.65 khz ultrasonic frequency and 46 min of extraction duration. Compared with the conventional heat reflux extraction (HRE) method, a significant 1.35-fold increase in total flavonoids content was obtained using optimized UAE conditions (169.64 for HRE vs. 235.45 mg/g dry weight for UAE), causing a 2.80-fold increase when this UAE associated with MPR purification (475.42 mg/g dry weight). In vitro cell free antioxidant activity of N. lotus stamen extracts and in cellulo antioxidant investigation using yeast model showed the same trend, indicating that the best antioxidant flavonoid can be found in UAE coupled with MPR purification. Moreover, in the yeast model, the expression of key antioxidant genes such as SIR2 and SOD2 were expressed at the highest level in yeast cells treated with the extract from UAE together with MPR purification. Consequently, it can be seen that the UAE combined with MPR purification can help enhance the flavonoid antioxidant potential of the stamens extract from this medicinal species.

Optimization of the fermentation conditions of Bacillus nematodes and screening of macroporous adsorption resin

Bacillus sp. SMrs28, metabolites from which had significant nematicidal activity, was isolated from the rhizosphere soil of Stellera chamaejasme. To determine the optimal fermentation conditions of the strain and the resin type of preliminary purified active ingredient, fermentation conditions were optimized by single factor experiment, while the macroporous resin types were screened in a static adsorption experiment. The results showed that the optimal fermentation conditions of SMrs28 strain were as follows: glucose and yeast powder were the best carbon source and nitrogen source, fermentation for 48 h, inoculum volume of 10%, temperature at 28 ℃,a rotation speed of 180 r·min-1, liquid volume of 30 mL in 150 mL triangular flask, and with an initial pH of 7.2. The static adsorption experiments showed that the adsorption and desorption of active ingre-dients in the fermentation broth by the macroporous adsorption resin D101 was significantly better than that of XAD-4, HP20 and AB-8, with the nematicidal activity of the desorption liquid being significantly improved. The nematicidal activity of fermentation broth was significantly improved by the optimization of fermentation conditions and the screening of optimal macroporous adsorption resins. These results laid a foundation for the further isolation and purification of active ingredients from SMrs28 strain, and provided theoretical basis for the development and utilization of microbial nematicides.

Simultaneous adsorption of acid and flavonoids from hawthorn juice onto resins

To explore the mechanism of adsorbates onto selected resin and provide a theoretical basis for the reduction of acidity in hawthorn fruit juice. In this study, the adsorption processes of titratable acidity (TA) and total flavonoids (TF) from hawthorn fruit juice onto macro-porous adsorption resins were studied. The experimental data were fitted by two widely used isotherm models namely, Langmuir and Freundlich. Kinetics of the adsorption processes were fitted by Pseudo-first-order, Pseudo-second-order kinetics, Elovich kinetics and Web and Morris intra-particle diffusion model. The experiment data showed D315 resin exhibited the highest adsorption capacity, Qe = 176.28 mg/mL, and selectivity coefficient, α = 3.588. The results also showed that the adsorption of adsorbates on D315 resin correlated better with the Langmuir isotherm model. The adsorption processes of adsorbates were better fitted by pseudo-second-order kinetics. In addition, the adsorption process of TA and TF on D315 resin is chemical adsorption, spontaneous and endothermic. The results indicated that D315 resin had a good adsorption effect on TA in hawthorn fruit juice and provided the theoretical basis for further exploration.

Glutathione Surface Molecularly Imprinted Polymer from CLX1180 via Three Modes of Polymerization for Selective Adsorption of Glutathione.

A novel glutathione (GSH) surface molecularly imprinted polymer (SMIP) was prepared using modified macroporous adsorption resin (MAR) CLX1180 as a solid substrate, glutathione as a template, acrylamide (AM) and N-vinyl pyrrolidone (NVP) as functional monomers, and N,N′-methylenebisacrylamide (NMBA) as a cross-linker. The reaction could be initiated by three different ways, using CLX1180, GSH, and both, which was proved by the experimentation. The morphology and structure of this polymer were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and time-of-flight mass spectrometry (TOF-MS). The maximum adsorption capacity of GSH approached 39.03 mg·g–1, and the separation degree related to l-cysteine was as high as 4.18. Pseudo-first-order and Langmuir models were well fitting the adsorption properties. GSH-SMIP could be used for three adsorption/desorption cycles with only a slight decrease of adsorption capacity.

Pre-formulation physicochemical properties of component-based Chinese medicine of Qinqi Fengshi Fang

Pre-formulation physicochemical properties of the component-based Chinese medicine of Qinqi Fengshi Fang were investigated to provide a research basis for the design of the dosage form for component-based Chinese medicine of Qinqi Fengshi Fang. The macroporous resin adsorption and refining technology was used to prepare the total glycosides extract of Gentianae Macrophyllae Radix, Panacis Majoris Rhizome and Corni Fructus respectively in the prescription of Qinqi Fengshi Fang. Their physicochemical properties were investigated, including solubility, wettability, hygroscopicity, equilibrium solubility, oil-water partition coefficient, and stability. The results showed that the total glycosides of Gentianae Macrophyllae Radix, Panacis Majoris Rhizome and Corni Fructus all had good solubility and wettability. The solubility index of each total glycoside component was greater than 85%, and the water absorption index was greater than 50%. In the range of pH 2.0-7.4, the equilibrium solubility of three kinds of total glycosides all increased with the increase of pH, showing a consistent change trend of solubility. The hydrophilicity was also suitable and similar. Overall, three kinds of total glycosides showed good stability, but strong hygroscopicity. The degree of hygroscopicity was as follows: total glycosides of Gen-tianae Macrophyllae Radix &gt; total glycosides of Corni Fructus &gt; total glycosides of Panacis Majoris Rhizome. Therefore, the hygroscopi-city needed to be considered in the preparation of the component-based Chinese medicine of Qinqi Fengshi Fang. The excipients and packaging materials can be properly selected to reduce the hygroscopicity of the preparation. This study provides a reference for the dosage form design of the component-based Chinese medicine of Qinqi Fengshi Fang.

Antibacterial activity of tea saponin from Camellia oleifera shell by novel extraction method

Natural preservatives are substances that are secreted by organisms or present in the body and have bacteriostatic effects, so they are not toxic to humans. Natural preservatives have become a research focus because of their high safety and strong antibacterial effects. Some commodities in the market are added with tea saponins, such as a brand of foaming cleanser, shampoo, and toothpaste rich in tea saponins. In this study, A high concentration of tea saponin was obtained through extraction and purification from Camellia oleifera shells, and its antibacterial activity for the two tested bacteria was determined in vitro. The results revealed that AB-8 macroporous adsorption resin was used in combination with Sephadex G-15 to obtain tea saponin with 82.5 % purity. The optimal purification process conditions were: the loading quantity of sample is 1 bed volume (BV), the loading solution is 25 mg/mL, the loading solution PH is 5, the loading flow rate is 3 BV/h, the elution volume is 4 BV, the elution flow rate is 3 BV/h, the eluent ethanol concentration is 95 %, and the eluent pH is 9. Tea saponin had good bacteriostatic effect on Escherichia coli and Staphylococcus aureus with its minimum inhibitory concentration of 1 and 0.5 mg/mL, respectively. In addition, its minimum bactericidal concentration was 4 mg/mL. Tea saponin could change membrane permeability, destroy cell membrane structure, and inhibit bacterial growth. This study provides basic guidance for the application of tea saponin in the development of natural antibacterial agents, is conducive to the high-value utilization of tea saponin, provides a reference for the economical of camellia tea waste, and plays a benefit in increasing agricultural income.

Separation and purification of hydroxytysol and oleuropein from Olea europaea L. (olive) leaves using macroporous resins and a novel solvent system

The separation and purification of hydroxytysol and oleuropein from Olea europaea L. (olive) using a macroporous resin with a novel solvent system was systematically investigated. Static adsorption experiments with BMKX-4 resin revealed that the experimental data of both hydroxytysol and oleuropein fitted best to the pseudo-second-order kinetic and Freundlich isotherm models. The thermodynamic parameters indicated spontaneous and exothermic adsorption processes. The novel solvent system, composed of n-hexane:ethyl acetate:methanol:water in a (v/v/v/v) ratio of 1:9:1:9, had two phases (upper and lower). The separation and purification parameters of hydroxytysol and oleuropein were optimized using dynamic adsorption/desorption on a column packed with BMKX-4 resin. The effects of flow rates and volumes of the upper and lower phases on the separation efficiency were systematically studied. Under optimal conditions, the fraction of hydroxytysol in the final product increased by 6.34-fold from 0.46 to 2.96%, with a yield rate of 88.58% w/w, while that of oleuropein increased 4.17-fold from 11.40 to 47.59%, with a 93.31% w/w yield rate. These results may be help in selecting a suitable eluent for improved separation of macroporous adsorption resins.

Enhancing effect of macroporous adsorption resin on gamma-aminobutyric acid production by Enterococcus faecium in whole-cell biotransformation system.

Gamma-aminobutyric acid (GABA) biosynthesis depended to a great extent on the biotransformation characterization of glutamate decarboxylase (GAD) and process conditions. In this paper, the enhancing effect of D101 macroporous adsorption resin (MAR) on the GABA production was investigated based on the whole-cell biotransformation characterization of Enterococcus faecium and adsorption characteristics of D101 MAR. The results indicated that the optimal pH for reaction activity of whole-cell GAD and pure GAD was 4.4 and 5.0, respectively, and the pH range retained at least 50% of GAD activity was from 4.8 to 5.6 and 4.0-4.8, respectively. No substrate inhibition effect was observed on both pure GAD and whole-cell GAD, and the maximum activity could be obtained when the initial L-glutamic acid (L-Glu) concentration exceeded 57.6mmol/L and 96.0mmol/L, respectively. Besides, GABA could significantly inhibit the activity of whole-cell GAD rather than pure GAD. When the initial GABA concentration of the reaction solution remained 100mmol/L, 33.51 ± 9.11% of the whole-cell GAD activity was inhibited. D101 MAR exhibited excellent properties in stabilizing the pH of the conversion reaction system, supplementing free L-Glu and removing excess GABA. Comparison of the biotransformation only in acetate buffer, the GABA production, with 50g/100mL of D101 MAR, was significantly increased by 138.71 ± 5.73%. D101 MAR with pre-adsorbed L-Glu could significantly enhance the production of GABA by gradual replenishment of free L-Glu, removing GABA and maintaining the pH of the reaction system, which would eventually make the GABA production more economical and eco-friendly.