Preparation, antioxidant and antitumor activities in vitro of different derivatives of levan from endophytic bacterium Paenibacillus polymyxa EJS-3

Structure and characterization of an extracellular polysaccharide from Paenibacillus polymyxa 88A

Levan-type polysaccharides, produced by various organisms, are nontoxic, biocompatible, and biodegradable polymers with a wide range of biological activities. They have high potential for use in medicine, cosmetology, and industry. A large amount of levan (41.1 g L-1) was recovered by ethanol precipitation from a liquid nutrient medium of Paenibacillus polymyxa 88A that contained 15 % w/v sucrose as a carbon source. The levan was fractionated by gel-permeation and anion-exchange chromatography and was analyzed by DRIFT and NMR spectroscopy. It was found that levan was represented by slightly branched chains composed of β-(2→6)-Fruf residues. The average molecular mass of the levan was about 1.9 MDa. When shear stress was applied at different temperatures, aqueous levan solutions showed pseudoplastic behavior. As found by SEM, a freeze-dried powdered levan sample had a microporous structure. The levan had excellent emulsifying activity toward sunflower oil, forming an emulsion with long-term stability. Analysis of the antioxidant activity of the levan showed a higher, dose-dependent activity toward ABTS, as compared with that toward DPPH. Finally, the bioactivity of the levan was examined by MTT assay by using human cervical carcinoma (HeLa) cells.

Nanobiopolymers in cancer therapeutics: advancing targeted drug delivery through sustainable and controlled release mechanisms

Nanobiopolymers have emerged as a transformative frontier in cancer treatment, leveraging nanotechnology to transform drug delivery. This review provides a comprehensive exploration of the multifaceted landscape of nano-based biopolymers, emphasizing their diverse sources, synthesis methods, and classifications. Natural, synthetic, and microbial nanobiopolymers are scrutinized, along with elucidation of their underlying mechanisms and impact on cancer drug delivery; the latest findings on their deployment as targeted drug delivery agents for cancer treatment are discussed. A detailed analysis of nanobiopolymer sources, including polysaccharides, peptides, and nucleic acids, highlights critical attributes like biodegradability, renewability, and sustainability essential for therapeutic applications. The classification of nanobiopolymers based on their origin and differentiation among natural, synthetic, and microbial sources are thoroughly examined for inherent advantages, challenges, and suitability for cancer therapeutics. The importance of targeted drug release at tumour sites, crucial for minimizing adverse effects on normal tissues, is discussed, encompassing various mechanisms. The role of polymer membrane coatings as a pivotal barrier for facilitating controlled drug release through diffusion is elucidated, providing further insight into efficient methods for cancer treatment and thus consolidating the current knowledge base for researchers and practitioners in the field of nanobiopolymers and cancer therapeutics.

Chemical modification of bacterial exopolysaccharides: Antioxidant properties and health potentials

In recent years, there has been a burgeoning interest in the utilization of microbial exopolysaccharides (EPS) because of the added advantage of their renewable, biocompatible, and biodegradable nature in addition to intended applications. The endowed properties of bacterial EPS make them valuable candidates for a wide array of industrial applications. Modification of native EPS is known to enhance various physico-chemical and functional properties. Various modifications such as physical, chemical, biological, and enzymatic modifications were practiced improving the bioactivity of EPS. This paper comprehensively aims to review the most recent chemical modification techniques employed to modify the physico-chemical and functional changes of bacterial EPS in comparison with the unmodified forms. Chemical modification entails strategic alterations to the structure and properties of EPS through various synthetic and semi-synthetic methodologies. Emphasis is given to the antioxidant potential and functional role of these EPS derivatives in human health. Antioxidant properties reveal a significant augmentation in activity compared to their native counterparts. Such enhancement holds a strong promise for potential benefits and therapeutic applications. Chemical derivatives of EPS with overwhelming functional benefits could surely encourage EPS application, particularly as potential hydrocolloids in industrial and biomedical contexts.

Microbial exopolysaccharides: Unveiling the pharmacological aspects for therapeutic advancements

Microbial exopolysaccharides (EPSs) have emerged as a fascinating area of research in the field of pharmacology due to their diverse and potent biological activities. This review paper aims to provide a comprehensive overview of the pharmacological properties exhibited by EPSs, shedding light on their potential applications in various therapeutic areas. The review begins by introducing EPSs, exploring their various sources, significance in microbial growth and survival, and their applications across different industries. Subsequently, a thorough examination of the pharmaceutical properties of microbial EPSs unveils their antioxidant, immunomodulatory, antimicrobial, antidepressant, antidiabetic, antiviral, antihyperlipidemic, hepatoprotective, anti-inflammatory, and anticancer activities. Mechanistic insights into how different EPSs exert these therapeutic effects have also been discussed in this review. The review also provides comprehensive information about the monosaccharide composition, backbone, branches, glycosidic bonds, and molecular weight of pharmacologically active EPSs from various microbial sources. Furthermore, the factors that can affect the pharmacological activities of EPSs and approaches to improve the EPSs' pharmacological activity have also been discussed. In conclusion, this review illuminates the immense pharmaceutical promise of microbial EPS as versatile bioactive compounds with wide-ranging therapeutic applications. By elucidating their structural features, biological activities, and potential applications, this review aims to catalyze further research and development efforts in leveraging the pharmaceutical potential of microbial EPS for the advancement of human health and well-being, while also contributing to sustainable and environmentally friendly practices in the pharmaceutical industry.

Effect of Chitosan and Its Water-Soluble Derivatives on Antioxidant Activity

The antioxidant activity of chitosan (CS) and three water-soluble derivatives was analyzed comparatively by in vitro and in vivo experiments, including hydroxypropyl chitosan (HPCS), quaternary ammonium salt of chitosan (HACC), and carboxymethyl chitosan (CMCS). The results show that chitosan and its water-soluble derivatives have a scavenging ability on DPPH radicals, superoxide radicals, and hydroxyl radicals, and a reducing ability. A remarkable difference (p < 0.05) was found for HACC and HPCS compared with CS on DPPH radicals, hydroxyl radicals, and reducing ability. The antioxidant ability of the four chitosan samples was in the order of HPCS > HACC > CMCS > CS. Furthermore, antioxidant activity of all samples increased gradually in a concentration-dependent manner. The in vivo result indicates that oral CS and its derivatives samples result in a decrease in lipid peroxides (LPO) and free fatty acids (FFA) levels in serum with an increase in superoxide dismutase (SOD) activity. Especially for the HPCS and HACC groups, the LPO, FFA, and SOD activity in serum was different significantly in comparison with the high-fat controlgroup (HF) (p < 0.05). These results indicate that chitosan and its derivatives can be used as good antioxidants, and the antioxidant activity might be related to the molecular structure of chitosan derivatives.

Exopolysaccharides of Paenibacillus polymyxa: A review

Paenibacillus polymyxa (P. polymyxa) is a member of the genus Paenibacillus, which is a rod-shaped, spore-forming gram-positive bacterium. P. polymyxa is a source of many metabolically active substances, including polypeptides, volatile organic compounds, phytohormone, hydrolytic enzymes, exopolysaccharide (EPS), etc. Due to the wide range of compounds that it produces, P. polymyxa has been extensively studied as a plant growth promoting bacterium which provides a direct benefit to plants through the improvement of N fixation from the atmosphere and enhancement of the solubilization of phosphorus and the uptake of iron in the soil, and phytohormones production. Among the metabolites from P. polymyxa, EPS exhibits many activities, for example, antioxidant, immunomodulating, anti-tumor and many others. EPS has various applications in food, agriculture, environmental protection. Particularly, in the field of sustainable agriculture, P. polymyxa EPS can be served as a biofilm to colonize microbes, and also can act as a nutrient sink on the roots of plants in the rhizosphere. Therefore, this paper would provide a comprehensive review of the advancements of diverse aspects of EPS from P. polymyxa, including the production, extraction, structure, biosynthesis, bioactivity and applications, etc. It would provide a direction for future research on P. polymyxa EPS.

Immunomodulatory activity and protective effect of a capsular polysaccharide in Caenorhabditis elegans, isolated from Lactobacillus fermentum GBJ

A capsular polysaccharide, namely CPS-2, was isolated from Lactobacillus fermentum GBJ, purified using DEAE-52 anion exchange chromatography, and structurally characterized. We found that CPS-2 is homogenous, has an average molecular weight of 377 KDa, and is mainly composed of galactose and glucose at a molar ratio of 1.54:1.00. Its backbone comprises α-D-Galp-(1 → 3), α-D-Galp-(1 → 3,6), β-D-Glcp-(1 → 2), β-D-Galp-(1 → 6), and α-D-Galp-(1 → 4) residues with a side chain of β-D-Glcp-(1→). CPS-2 exerts an immunomodulatory effect by improving the proliferation and phagocytosis of macrophage RAW264.7 and promoting the secretion of NO and cytokines. The maximum secretion levels of IL-1β, IL-6, IL-10, and TNF-α were 1.96-, 0.11-, 0.22-, and 0.46-fold higher than those of the control, respectively. Furthermore, CPS-2 could significantly enhance the antioxidant system, extend lifespan, and improve stress tolerance of Caenorhabditis elegans at both exposure doses of 31.25 and 62.5 μg/mL. The average lifespan of nematodes reached a maximum in the 62.5 μg/mL-treated group after 10.39 days, 6.56 h, and 23.56 h in normal, oxidative stress, and heat shock environment, with extension percentages of 16.61 %, 43.23 %, and 15.77 %, respectively; therefore, CPS-2 displays an anti-aging effect. The significant bioactivity of CPS-2 promotes its application as a promising immunomodulatory and anti-aging ingredient in the food or pharmaceutical field.

Evaluation of improved biological properties of chemically modified exopolysaccharides from Lactobacillus plantarum BR2

This work engrosses the production and further chemical modifications of EPS produced by Lactobacillus plantarum BR2 and subsequent evaluation of their biological properties showed greater antioxidant properties for the derivatives compared to its native unmodified form. Of the three derivatives, acetylated EPS (a-EPS), carboxymethylated EPS (Cm-EPS), and sulphated EPS (s-EPS), a-EPS exhibited the highest DPPH radical scavenging and total antioxidant activity in a dose-dependent manner. At all tested concentrations, a-EPS showed higher scavenging activity, and a maximum activity of 73.81% at 2 mg/mL. Meanwhile, s-EPS showed the highest reducing power potential and hydroxyl radical scavenging activities. At 2 mg/mL concentration, the order of reducing power was observed to be s-EPS (41.39%) > a-EPS (37.43%) > Cm-EPS (24.02) > BR2 control EPS (16%) and the hydroxyl radical scavenging activity for the s-EPS was 54.43%. The highest reducing power activity exhibited by s-EPS is 2.6-fold higher and a 1.5-fold increase in the scavenging activity of native BR2 EPS after the sulphonyl group addition was observed. The increase in these activities is due to the addition of various functional groups that contributes largely to the scavenging abilities of different free radicals. The s-EPS and Cm-EPS derivatives also exhibited increased cholesterol-lowering activity of 40 and 34.5%, respectively, than the native EPS. Interestingly, there were hardly any inhibitions on cell growth and viability of normal L929 fibroblast cell lines upon treatment with these EPSes. The improved antioxidant properties resulting from chemical modification opened better avenues for EPS application in the food and pharma sectors. Thus, the potentiality of chemically modified EPS may be explored further in the development of functional foods.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03718-5.

Traversing the diverse avenues of exopolysaccharides-based nanocarriers in the management of cancer

Exopolysaccharides are unique polymers generated by living organisms such as algae, fungi and bacteria to protect them from environmental factors. After a fermentative process, these polymers are extracted from the medium culture. Exopolysaccharides have been explored for their anti-viral, anti-bacterial, anti-tumor, and immunomodulatory effects. Specifically, they have acquired massive attention in novel drug delivery strategies owing to their indispensable properties like biocompatibility, biodegradability, and lack of irritation. Exopolysaccharides such as dextran, alginate, hyaluronic acid, pullulan, xanthan gum, gellan gum, levan, curdlan, cellulose, chitosan, mauran, and schizophyllan exhibited excellent drug carrier properties. Specific exopolysaccharides, such as levan, chitosan, and curdlan, have demonstrated significant antitumor activity. Moreover, chitosan, hyaluronic acid and pullulan can be employed as targeting ligands decorated on nanoplatforms for effective active tumor targeting. This review shields light on the classification, unique characteristics, antitumor activities and nanocarrier properties of exopolysaccharides. In addition, in vitro human cell line experiments and preclinical studies associated with exopolysaccharide-based nanocarriers have also been highlighted.

Recent developments on natural polysaccharides as potential anti-gastric cancer substance: Structural feature and bioactivity

Gastric cancer (GC) is being a serious threat to human health. Seeking safer and more effective ingredients for anti-GC is of significance. Increasing natural polysaccharides (NPs) have been demonstrated to possess anti-GC activity. However, the information on anti-GC NPs is scattered. For well-understanding the potential of NPs as anti-GC substances, the recent developments on structure, bioactivity and mechanism of anti-GC NPs were comprehensively reviewed in this article. Meanwhile, the structure-activity relationship was discussed. Recent studies indicated that anti-GC NPs could be mainly divided into glucan and heteropolysaccharide, whose structures affected by sources and protocols of extraction and purification. NPs exhibited anti-GC activities in cell and animal experiments as well as clinical trials, and the mechanisms might be anti-proliferation, inducing apoptosis, anti-metastasis and anti-invasion, inducing autophagy, boosting immunity, anti-angiogenesis, reducing drug resistance, anti-angiogenesis, improving antioxidant level and changing metabolites. Moreover, structural features included molecular weight, functional groups, uronic acid and monosaccharide composition, glycosidic linkage type, and degree of branching and conformation might influence the activities. Otherwise, modifications could enhance the anti-GC activity of NPs, and anti-GC NPs could be combinedly used with chemotherapeutic drugs. This review supports the applications of NPs in anti-GC and provides theoretical basis for future study.

Biological activity of silver nanoparticles synthesized with Paenibacillus polymyxa exopolysaccharides

Recently, there has been increased interest in the synthesis of nanoparticles by using natural polysaccharides. These polysaccharides are eco-friendly, nontoxic, and cheap to prepare. On the other hand, the attention in hydrocolloids and films has significantly enhanced, and their application is very promising in the food, pharmaceutical, perfumery and cosmetics, oil, paper, and textile industries. In this context, the present study is aimed to prepare silver nanoparticles by using viscous and superviscous exopolysaccharides of the rhizobacterium Paenibacillus polymyxa strains, CCM 1465 and 88A, and examined the properties of the resultant nanoparticles. We examined the synthesis and properties of silver nanoparticles under variable synthetic conditions by using exopolysaccharides of the rhizobacteria Paenibacillus polymyxa CCM 1465 and 88A. To prepare nanoparticles, we used different combinations of exopolysaccharide and silver nitrate concentrations: 1-10 mg/mL and 1-40 mM, respectively. The resulting solutions were alkalinized from pH 7.5-12 and heated for 15, 30, and 60 min to determine the optimal synthetic conditions. We found that the exopolysaccharides of strains CCM 1465 and 88A reduced silver ions and acted as nanoparticle stabilizers. The prepared spherical, oval, and triangular particles were stable and ranged in size from 2 to 40 nm, depending on the strain and on the experimental conditions. The nanoparticles showed antibacterial and antifungal activity against Escherichia coli K-12, Pseudomonas aeruginosa 50.3, Bacillus subtilis 26-D, and Fusarium oxysporum. In addition, the nanoparticles were active against SK-MEL-2 human melanoma cells. This finding shows the promise of further research on the exopolysaccharides of P. polymyxa 1465 and 88А in different fields of science, including medicine.

Microbial polysaccharides: An emerging family of natural biomaterials for cancer therapy and diagnostics

Microbial polysaccharides (MPs) offer immense diversity in structural and functional properties. They are extensively used in advance biomedical science owing to their superior biodegradability, hemocompatibility, and capability to imitate the natural extracellular matrix microenvironment. Ease in tailoring, inherent bio-activity, distinct mucoadhesiveness, ability to absorb hydrophobic drugs, and plentiful availability of MPs make them prolific green biomaterials to overcome the significant constraints of cancer chemotherapeutics. Many studies have demonstrated their application to obstruct tumor development and extend survival through immune activation, apoptosis induction, and cell cycle arrest by MPs. Synoptic investigations of MPs are compulsory to decode applied basics in recent inclinations towards cancer regimens. The current review focuses on the anticancer properties of commercially available and newly explored MPs, and outlines their direct and indirect mode of action. The review also highlights cutting-edge MPs-based drug delivery systems to augment the specificity and efficiency of available chemotherapeutics, as well as their emerging role in theranostics.

Effect of exopolysaccharides of Paenibacillus polymyxa rhizobacteria on physiological and morphological variables of wheat seedlings

Paenibacillus polymyxa is a promising plant-growth-promoting rhizobacterium that associates with a wide range of host plants, including agronomically important ones. Inoculation of wheat seedlings with P. polymyxa strains CCM 1465 and 92 was found to increase the mitotic index of the root cells 1.2- and 1.6-fold, respectively. Treatment of seedlings with the exopolysaccharides (EPSs) of these strains increased the mitotic index 1.9-fold (P. polymyxa CCM 1465) and 2.8-fold (P. polymyxa 92). These increases indicate activation of cell division in the root meristems. Analysis of the morphometric variables of the seedlings showed that P. polymyxa CCM 1465, P. polymyxa 92, and their EPSs promoted wheat growth, increasing root and shoot length up to 22% and root and shoot dry weight up to 28%, as compared with the control. In addition, both strains were found to intensely colonize the seedling root surface. Thus, P. polymyxa EPSs are active metabolites that, along with whole cells, are responsible for the contact interactions of the bacteria with wheat roots and are implicated in the induction of plant responses to these interactions. The strains used in this work are of interest for further study to broaden the existing understanding of the mechanisms of plant-bacterial interactions and to develop effective biofertilizers for agricultural purposes.

Phosphorylation of polysaccharides: A review on the synthesis and bioactivities

Polysaccharides are macromolecules obtained from a wide range of sources and are known to have diverse biological activities. The biological activities of polysaccharides depend on their structure and physicochemical properties, including water solubility, monosaccharide composition, degree of branching, molecular structure, and molecular weight. Phosphorylation is a commonly used chemical modification method that improves the physicochemical properties of native polysaccharides, thus enhancing their biological activity, or even imparting novel biological activity. Therefore, phosphorylated polysaccharides have attracted increasing attention owing to their antioxidant, antitumor, antiviral, immunomodulatory, and hepatoprotective effects. In this review, we have discussed recent advances in the phosphorylation of polysaccharides, and the methods used for phosphorylation, structural characterization, and determination of biological activities, to provide a theoretical basis for the use of polysaccharides. The structure-activity relationship of phosphorylated polysaccharides and their use in the food and pharmaceutical industries needs to be further studied.

Bioactive Levan-Type Exopolysaccharide Produced by Pantoea agglomerans ZMR7: Characterization and Optimization for Enhanced Production

Levan is an industrially important, functional biopolymer with considerable applications in the food and pharmaceutical fields owing to its safety and biocompatibility. Here, levan-type exopolysaccharide produced by Pantoea agglomerans ZMR7 was purified by cold ethanol precipitation and characterized using TLC, FTIR, ¹H, and ¹³C NMR spectroscopy. The maximum production of levan (28.4 g/l) was achieved when sucrose and ammonium chloride were used as carbon and nitrogen sources, respectively, at 35°C and an initial pH of 8.0. Some biomedical applications of levan like antitumor, antiparasitic, and antioxidant activities were investigated in vitro. The results revealed the ability of levan at different concentrations to decrease the viability of rhabdomyosarcoma and breast cancer cells compared with untreated cancer cells. Levan appeared also to have high antiparasitic activity against the promastigote of Leishmania tropica. Furthermore, levan had strong DPPH radical scavenging (antioxidant) activity. These findings suggest that levan produced by P. agglomerans ZMR7 can serve as a natural biopolymer candidate for the pharmaceutical and medical fields.

Box-Wilson Design for Optimization of in vitro Levan Production and Levan Application as Antioxidant and Antibacterial Agents

Background:

Methods:

Results:

Conclusion:

Box-Wilson Design for Optimization of in vitro Levan Production and Levan Application as Antioxidant and Antibacterial Agents

Background

Levan or fructan, a polysaccharide of fructose, is widely used in various commercial industries. Levan could be produced by many organisms, including plants and bacteria. The cloning of the gene from Bacillus licheniformis, which expressed levansucrase in Escherichia coli host, was carried out successfully. In the present study, we performed the in vitro production of levan and analyzed its potential application as antibacterial and antioxidant agents.

Methods

In vitro levan production catalyzed by heterologous-expressed levansucrase Lsbl-bk1 and Lsbl-bk2 was optimized with Box-Wilson design. The antibacterial activity of the produced levan was carried out using agar well diffusion method, while its antioxidant activity was tested by free radical scavenging assays.

Results

The optimum conditions for levan production were observed at 36 °C and pH 7 in 12% (w/v) sucrose for levansucrase Lsbl-bk1, while the optimum catalysis of levansucrase Lsbl-bk2 was obtained at 32 oC and pH 8 in the same sucrose concentration. The in vitro synthesized levan showed an antibacterial activity within a concentration range of 10-20% (w/v) against Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa. The same levan was also able to inhibit the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity with the antioxidant strength of 75% compared to ascorbic acid inhibition.

Conclusion

Our study, therefore, shows that the optimized heterologous expression of levansucrases encoded by Lsbl-bk1 and Lsbl-bk2 could open the way for industrial levan production as an antibacterial and antioxidant agent.

Selenium-Containing Polysaccharides—Structural Diversity, Biosynthesis, Chemical Modifications and Biological Activity

Selenosugars are a group of sugar derivatives of great structural diversity (e.g., molar masses, selenium oxidation state, and selenium binding), obtained as a result of biosynthesis, chemical modification of natural compounds, or chemical synthesis. Seleno-monosaccharides and disaccharides are known to be non-toxic products of the natural metabolism of selenium compounds in mammals. In the case of the selenium-containing polysaccharides of natural origin, their formation is also postulated as a form of detoxification of excess selenium in microorganisms, mushroom, and plants. The valency of selenium in selenium-containing polysaccharides can be: 0 (encapsulated nano-selenium), IV (selenites of polysaccharides), or II (selenoglycosides or selenium built into the sugar ring to replace oxygen). The great interest in Se-polysaccharides results from the expected synergy between selenium and polysaccharides. Several plant- and mushroom-derived polysaccharides are potent macromolecules with antitumor, immunomodulatory, antioxidant, and other biological properties. Selenium, a trace element of fundamental importance to human health, has been shown to possess several analogous functions. The mechanism by which selenium exerts anticancer and immunomodulatory activity differs from that of polysaccharide fractions, but a similar pharmacological effect suggests a possible synergy of these two agents. Various functions of Se-polysaccharides have been explored, including antitumor, immune-enhancement, antioxidant, antidiabetic, anti-inflammatory, hepatoprotective, and neuroprotective activities. Due to being non-toxic or much less toxic than inorganic selenium compounds, Se-polysaccharides are potential dietary supplements that could be used, e.g., in chemoprevention.

Production, Characterization, and Antioxidant Activities of an Exopolysaccharide Extracted from Spent Media Wastewater after Leuconostoc mesenteroides WiKim32 Fermentation

Bacterial exopolysaccharides (EPSs) are important alternatives to plant polysaccharides in fermented products and exhibit antioxidant activity, which is particularly desirable for functional foods. This study evaluated the use of spent media wastewater (SMW) derived from kimchi fermentation for the production of an EPS and analyzed the characterization and antioxidant activity of the resulting EPS. The EPS concentration and conversion yields of sequential purification were 7.7-9.0 g/L and 38.6-45.1%, respectively. Fourier transform infrared spectra and NMR spectra indicated that the EPS was a linear glucan with α-(1 → 6) linkages. The EPS also exhibited thermal tolerance to high temperatures. In vitro antioxidant activity analyses indicated the scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, thiobarbituric acid reactance (TBAR), and ferric ion reducing antioxidant power (FRAP) values of 71.6-79.1, 28.2-33.0%, and 0.04-0.05 mM FeCl3, respectively. These results reveal that the EPS extracted from SMW has potential as a thermally tolerant, nontoxic, and natural antioxidant for industrial applications.

Effects of enzymatic hydrolysis on the structural, rheological, and functional properties of mulberry leaf polysaccharide

Effects of enzymatic hydrolysis on the structural, rheological, and functional properties of mulberry leaf polysaccharide (MLP) were characterized in this study. The enzymatic hydrolysis of MLP raised the carbonyl, carboxyl, and hydroxyl groups from 7.21 ± 0.86 to 10.08 ± 0.28 CO/100 Glu, 9.40 ± 0.13 to 17.55 ± 0.34 COOH/100 Glu, and 5.71 ± 0.33 to 8.14 ± 0.24 OH/100 Glu, respectively. Meanwhile, an increase in thixotropic performance and structure-recovery capacities were observed in hydrolyzed MLP, while the molecular weight, surface tension, apparent viscosity, and thermal stability were decreased. An improved antioxidant activity of MLP was also achieved after the enzymatic degradation. Moreover, the hydrolyzed MLP showed greater ability to promote the growths of Bifidobacterium bifidum, Bifidobacterium adolescentis, Lactobacillus rhamnosus, and Lactobacillus acidophilus and the production of acetic acid, butyric acid, and lactic acid. The results demonstrate that enzymatic modification is a useful approach for polysaccharide processing.

Paenibacillus polymyxa, a Jack of all trades

The bacterium Paenibacillus polymyxa is found naturally in diverse niches. Microbiome analyses have revealed enrichment in the genus Paenibacillus in soils under different adverse conditions, which is often accompanied by improved growth conditions for residing plants. Furthermore, Paenibacillus is a member of the core microbiome of several agriculturally important crops, making its close association with plants an interesting research topic. This review covers the versatile interaction possibilities of P. polymyxa with plants and its applicability in industry and agriculture. Thanks to its array of produced compounds and traits, P. polymyxa is likely an efficient plant growth-promoting bacterium, with the potential of biofertilization, biocontrol and protection against abiotic stresses. By contrast, cases of phytotoxicity of P. polymyxa have been described as well, in which growth conditions seem to play a key role. Because of its adjustable character, we propose this bacterial species as an outstanding model for future studies on host-microbe communications and on the manner how the environment can influence these interactions.

Biomedical Applications of Bacterial Exopolysaccharides: A Review

Bacterial exopolysaccharides (EPSs) are an essential group of compounds secreted by bacteria. These versatile EPSs are utilized individually or in combination with different materials for a broad range of biomedical field functions. The various applications can be explained by the vast number of derivatives with useful properties that can be controlled. This review offers insight on the current research trend of nine commonly used EPSs, their biosynthesis pathways, their characteristics, and the biomedical applications of these relevant bioproducts.

Phosphorylation of levan by microwave-assisted synthesis enhanced anticancer ability

Levan is an exopolysaccharide produced by Bacillus licheniformis (strain FRI MY-55) that shows promising pharmacological activity. Phosphorylation is a chemical modification that can increase the biological and antioxidant properties of levan. In this study, levan was phosphorylated by microwave-assisted synthesis to achieve a degree of substitution of 0.29. The hydroxyl radical scavenging activity of microwave-assisted phosphorylated levan (microwave P) increased significantly (6-fold) over native levan; this activity was only slightly lower than vitamin C. Other free radical scavenging and reducing power tests revealed that Microwave P activity was increased by 30-40%. Microwave P inhibited the proliferation of HCT-116 and A549 cancer cell lines more readily than native levan with an IC₅₀ of 1.03 mg/mL and 1.38 mg/mL for HCT-116 and A549 cells, respectively. Cells treated with native levan and its derivatives remained in the sub-G1 phase according to cell cycle analysis, whereas Microwave P treatment increased the proportion of cells undergoing apoptosis. Furthermore, Microwave P effectively upregulated pro-apoptosis marker Bax and downregulated anti-apoptosis marker Bcl-2, in addition to inducing the expression of caspase-9 and caspase-3. These findings show that levan phosphorylated via microwave-assisted synthesis showed increased antioxidant and antitumor activity over native levan or levan phosphorylated via traditional long-term heating. In particular, Microwave P possesses antiproliferative activity and can induce apoptosis through mitochondrial pathways in cancerous cells.

Enhancement of antioxidant activity of levan through the formation of nanoparticle systems with metal ions

Levan, a natural polymer, is widely used in biomedical applications, such as antioxidants, anti-inflammatory, and anti-tumor. The present study aimed to enhance the antioxidant activity of levan by combining it with various metal ions in the nanoparticle (NP) system. Levansucrase encoding gene from Bacillus licheniformis BK1 has been inserted into an expression vector and the obtained recombinant was labeled as Lsbl-bk1 (accession number MF774877.1). That enzyme was used for in vitro levan synthesis in 12% (w/v) sucrose as a substrate and about 4.28 mg/mL of levan was obtained. Levan-based metal ion NPs were synthesized using the coprecipitation method. In the production of NPs, levan acts as a reducing and stabilizing agent. Four types of levan-based metal ion NPs were synthesized, namely, levan–Fe²⁺ NPs, levan–Cu⁺ NPs, levan–Co²⁺ NPs, and levan–Zn²⁺ NPs. The transmission electron microscopy (TEM) technique was applied to visualize the size and shape of the synthesized levan–metal NPs. All levan-based metal ion NPs have a particle size of less than 100 nm, and even levan–Cu⁺ and levan–Zn²⁺ have particle sizes less than 50 nm. Levan–Fe²⁺ NPs and levan–Cu⁺ NPs exhibited prominent antioxidant activity with an inhibition level of up to 88% and 95%, respectively. And the inhibition level of two metal ion NPs had about 33%–40% higher antioxidant activity compared with the inhibition level of levan only. The two levan–metal ion NPs, therefore, have future prospects to be developed as the new formulation for the antioxidant drugs.

Isolation, characterization and cytoprotective effects against UV radiation of exopolysaccharide produced from Paenibacillus polymyxa PYQ1

A novel exopolysaccharide (EPS) from Paenibacillus polymyxa PYQ1 was extracted, well purified and characterized. This EPS was homogeneous glucomannan-type polysaccharide with the average molecular weight of 4.38 × 10⁶ Da. Structural characterization indicated that the monosaccharides of EPS were pyranoses connected by β-glycosidic linkages. Furthermore, our results showed the protective benefits of EPS against UVC induced cytotoxicity in HaCaT cells through scavenging excessive reactive oxygen species, mitigating the decrease of mitochondrial membrane potential, improving catalase activity and maintaining membrane integrity. Taken together, this study qualified EPS from P. polymyxa PYQ1 was a promising natural polymer which worth further investigation as a skin-care agent.

Chemical modifications of polysaccharides and their anti-tumor activities

With the rising trend of incidence of cancers, effective therapies are urgently needed to control human malignancies. However, the chemotherapy drugs currently on the market cause serious side effects. Polysaccharides belong to a class of biomacromolecules, which have drawn considerable research interest over the years as it possess anti-cancer activities or can increase the efficacy of conventional chemotherapy drugs with fewer side effects. The antitumor activity of many polysaccharides was significantly increased after modification. Based on these encouraging observations, a great deal of effort has been focused on discovering anti-cancer polysaccharides and modified derivatives for the development of effective therapeutics for various human cancers. This review highlights recent advances on the major chemical modification methods of polysaccharides, and discusses the effect of molecular modification on the physicochemical properties and anti-tumor activities of polysaccharides. Meanwhile, the underlying anti-tumor mechanisms of polysaccharide and its modified derivatives were also discussed.

Efficient production of levan using a recombinant yeast Saccharomyces cerevisiae hypersecreting a bacterial levansucrase

Levan is a fructose polymer with diverse applications in the food and medical industries. In this study, levansucrase from Rahnella aquatilis (RaLsrA) was hyper-secreted using a Saccharomyces cerevisiae protein secretion system. An optimal secretion signal, a translation fusion partner (TFP) containing an N-terminal 98 amino acid domain from a mitochondrial inner membrane protein, UTH1, was employed to secrete approximately 50 U/mL of bioactive RaLsrA into culture media with 63% secretion efficiency by fed-batch fermentation. Although the purified RaLsrA was useful for enzymatic conversion of high-molecular-weight levan of approximately 3.75 × 10⁶ Da, recombinant yeast secreting RaLsrA could produce levan more efficiently by microbial fermentation. In a 50-L scale fermenter, 76-g/L levan was directly converted from 191-g/L sucrose by recombinant yeast cells, attaining an 80% conversion yield and 3.17-g/L/h productivity. Thus, we developed a cost-effective and industrially applicable production system for food-grade levan.

Protective effects of five compounds from Livistona chinensis R. Brown leaves against hypoxia/reoxygenation, H2O2, or adriamycin-induced injury in H9c2 cells

Purpose: Discovering new antimyocardial ischemia drug candidates that are highly efficient, have low toxicity, and originate from natural products is a popular trend for new cardiovascular drug development at present. The ethanol extract of Livistona chinensis leaves showed a favorable antioxidant activity in our preliminary screening test. This study aims to screen out antioxidants from the herb leaves further and evaluate their efficacy in acute myocardial ischemia treatment at the cellular level. Materials and methods: Guided with online 1, 1-diphenyl-2-picrylhydrazyl (DPPH)-high-performance liquid chromatography (HPLC) screening, antioxidants were first separated and isolated from the ethanol extract of L. chinensis leaves by preparative-HPLC. Subsequently, offline DPPH approach was used to validate the free radical scavenging activity of the components. Ultimately, the resulting antioxidants were evaluated against the hypoxia/reoxygenation (H/R)-, H2O2-, or adriamycin (ADM)-induced injury in H9c2 cells to verify their cardioprotective effects in vitro. Results: Five antioxidant ingredients, namely, orientin, isoorientin, vitexin, isovitexin, and tricin, were quickly distinguished and isolated from L. chinensis leaves. The IC50 values of these ingredients were further examined by offline DPPH assay, as follows: 15.51±0.22, 6.64±0.38, 11.86±0.24, 8.89±0.66, and 31.86±0.24 μg/mL, respectively. Out of these ingredients, isoorientin showed the strongest antioxidation, which was equivalent to that of the positive control drug (vitamin C, IC50: 6.99±0.62 μg/mL). Using H/R-, H2O2-, and ADM-induced H9c2 cell injury models, the five ingredients had different extents of cardioprotective effects in vitro. In particular, isoorientin showed the strongest protection. All the five ingredients also showed insignificant cytotoxic effect to normal H9c2 cells. Conclusion: The ethanol extract of L. chinensis leaves contained five antioxidants with low cardiac cytotoxicity. Isoorientin possessed the strongest antioxidation, which can predominantly account for the myocardial protection effects within the extract.

Antioxidant and Antiproliferative Activities of Modified Polysaccharides Originally Isolated from Morchella Angusticepes Peck

Polysaccharides extracted from Morchella angusticepes Peck (PMEP) were chemically modified to obtain sulfated, carboxymethylated, and acetyled derivatives. Results showed that the acetyled derivatives with the degree of substitution (0.40 ± 0.07) exerted higher antioxidant ability than native polysaccharides, demonstrating inhibitory effects on growth of human hepatoma cells (EC₅₀  = 0.710 ± 0.002 mg/mL) and human colon cancer cells (EC₅₀  =  1.229 ± 0.008 mg/mL). It indicated that the acetylation was a favorable way to enhance the bioactivities of PMEP. PRACTICAL APPLICATION: Polysaccharides extracted from Morchella angusticepes Peck (PMEP) have many health-promoting properties. Chemical modifications could improve the bioactivities of polysaccharides. We demonstrated that acetylation enhanced the cellular antioxidant and antiproliferative activities of PMEP. The results support further research that explores clinical utility, and may justify ex vivo and in vivo designs toward that end.

Scaling up of levan yield in Bacillus subtilis M and cytotoxicity study on levan and its derivatives

This study focused on kinetics of levan yield by Bacillus subtilis M, in a 150 L stirred tank bioreactor under controlled pH conditions. The optimized production medium was composed of (g/L): commercial sucrose 100.0, yeast extract 2.0, K₂HPO₄ 3.0 and MgSO₄⋅7H₂O 0.2; an increase in both carbohydrates consumption and cell growth depended on increasing the size of the stirred tank bioreactor from 16 L to 150 L. The highest levansucrase production (63.4 U/mL) and levan yield of 47 g/L was obtained after 24 h. Also, the specific levan yield (Y_p/x) which reflects the cell productivity increased with the size increase of the stirred tank bioreactor and reached its maximum value of about 29.4 g/g cells. These results suggested that B. subtilis M could play an important role in levan yield on a large scale in the future. Chemical modifications of B. subtilis M crude levan (CL) into sulfated (SL), phosphorylated (PL), and carboxymethylated levans (CML) were done. The difference in CL structure and its derivatives was detected by FT-IR transmission spectrum. The cytotoxicity of CL and its derivatives were evaluated by HepGII, Mcf-7 and CaCo-2. In general most tested levans forms had no significant cytotoxicity effect. In fact, the carboxymethylated and phosphrylated forms had a lower anti-cancer effect than CL. On the other hand, SL had the highest cytotoxicity showing SL had a significant anti-cancer effect. The results of cytotoxicity and cell viability were statistically analyzed using three-way ANOVA.