Production and characterization of bioactive peptides from rice beans using Bacillus subtilis

Production and characterization of anti-hypertensive and anti-diabetic peptides from fermented sheep milk with anti-inflammatory activity: in vitro and molecular docking studies

BACKGROUND

The present study aimed to evaluate the anti-hypertensive and anti-diabetic activities from biologically active peptides produced by fermented sheep milk with Lacticaseibacillus paracasei M11 (MG027695), as well as to purify and characterize the angiotensin-converting enzyme (ACE) inhibitory and anti-diabetic peptides produced from fermented sheep milk.

RESULTS

After 48 h of fermentation at 37 °C, sheep milk demonstrated significant changes in anti-diabetic effects and ACE-I effects, with inhibition percentages observed for ACE inhibition (76.32%), α-amylase (70.13%), α-glucosidase (70.11%) and lipase inhibition (68.22%). The highest level of peptides (9.77 mg mL-1) was produced by optimizing the growth conditions, which included an inoculation rate of 2.5% and a 48 h of incubation period. The comparison of molecular weight distributions among protein fractions was conducted through sodium dodecyl-sulfate polyacrylamide gel electrophoresis analysis, whereas spots were separated using 2D gel electrophoresis according to both the molecular weight and pH. Peptide characterization with ultra-filtration membranes at 3 and 10 kDa allowed the study to assess molecular weight-based separation. Nitric oxide generated by lipopolysaccharide and the secretion of pro-inflammatory cytokines in RAW 264.7 immune cells were both inhibited by sheep milk fermented with M11. Fourier-transform infrared spectroscopy was employed to assess changes in functional groups after fermentation, providing insights into the structural changes occurring during fermentation.

CONCLUSION

The present study demonstrates that fermentation with L. paracasei (M11) led to significant changes in fermented sheep milk, enhancing its bioactive properties, notably in terms of ACE inhibition and anti-diabetic activities, and the generation of peptides with bioactive properties has potential health benefits. © 2024 Society of Chemical Industry.

Solid-State Fermented Plant Foods as New Protein Sources

The current animal-based production of protein-rich foods is unsustainable, especially in light of continued population growth. New alternative proteinaceous foods are therefore required. Solid-state fermented plant foods from Africa and Asia include several mold- and Bacillus-fermented foods such as tempeh, sufu, and natto. These fermentations improve the protein digestibility of the plant food materials while also creating unique textures, flavors, and taste sensations. Understanding the nature of these transformations is of crucial interest to inspire the development of new plant-protein foods. In this review, we describe the conversions taking place in the plant food matrix as a result of these solid-state fermentations. We also summarize how these (nonlactic) plant food fermentations can lead to desirable flavor properties, such as kokumi and umami sensations, and improve the protein quality by removing antinutritional factors and producing additional essential amino acids in these foods.

Peptidomics-based identification of antihypertensive and antidiabetic peptides from sheep milk fermented using Limosilactobacillus fermentum KGL4 MTCC 25515 with anti-inflammatory activity: in silico, in vitro, and molecular docking studies

This study investigated the synthesis of bioactive peptides from sheep milk through fermentation with Limosilactobacillus fermentum KGL4 MTCC 25515 strain and assessed lipase inhibition, ACE inhibition, α-glucosidase inhibition, and α-amylase inhibition activities during the fermentation process. The study observed the highest activities, reaching 74.82%, 70.02%, 72.19%, and 67.08% (lipase inhibition, ACE inhibition, α-glucosidase inhibition, and α-amylase inhibition) after 48 h at 37°C, respectively. Growth optimization experiments revealed that a 2.5% inoculation rate after 48 h of fermentation time resulted in the highest proteolytic activity at 9.88 mg/mL. Additionally, fractions with less than 3 kDa of molecular weight exhibited superior ACE-inhibition and anti-diabetic activities compared to other fractions. Fermentation of sheep milk with KGL4 led to a significant reduction in the excessive production of NO, TNF-α, IL-6, and IL-1β produced in RAW 267.4 cells upon treatment with LPS. Peptides were purified utilizing SDS-PAGE and electrophoresis on 2D gels, identifying a maximum number of proteins bands ranging 10-70 kDa. Peptide sequences were cross-referenced with AHTPDB and BIOPEP databases, confirming potential antihypertensive and antidiabetic properties. Notably, the peptide (GPFPILV) exhibited the highest HPEPDOCK score against both α-amylase and ACE.

Identification, structural characterization, and molecular dynamic simulation of ACE inhibitory peptides in whey hydrolysates from Chinese Rushan cheese by-product

To realize the high-value utilization of Rushan cheese by-product, Rushan cheese whey was used as a raw material to prepare angiotensin-Ⅰ-converting enzyme inhibitory peptides (ACEIPs). After enzymatic hydrolysisn and ultrafiltration, the sequences of peptides were identified by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Two novel ACE inhibitory peptides Phe-Asp-Arg-Pro-Phe-Leu (FDRPFL) and Lys-Trp-Glu-Lys-Pro-Phe (KWEKPF) were identified. Additionally, both of the peptides exhibited good water-solubility and no toxicity according to in-silico prediction. Fourier transform infrared spectroscopy results show that both FDRPFL and KWEKPF were enriched in β-turn and β-sheet structures. Lineweaver-Burk plots revealed that FDRPFL and KWEKPF exhibited non-competitive and mixed inhibition patterns, respectively. Molecular docking and MD simulation showed that hydrogen bonds and ionic bonds forces allowed FDRPFL and KWEKPF to form stable and compact complexes with ACE. In conclusion, enzymatic hydrolysis of Rushan cheese by-products yields bioactive peptides, increases the added value of whey and reduces environmental pollution.

Probiotic-fermented edible herbs as functional foods: A review of current status, challenges, and strategies

Recently, consumers have become increasingly interested in natural, health-promoting, and chronic disease-preventing medicine and food homology (MFH). There has been accumulating evidence that many herbal medicines, including MFH, are biologically active due to their biotransformation through the intestinal microbiota. The emphasis of scientific investigation has moved from the functionally active role of MFH to the more subtle role of biotransformation of the active ingredients in probiotic-fermented MFH and their health benefits. This review provides an overview of the current status of research on probiotic-fermented MFH. Probiotics degrade toxins and anti-nutritional factors in MFH, improve the flavor of MFH, and increase its bioactive components through their transformative effects. Moreover, MFH can provide a material base for the growth of probiotics and promote the production of their metabolites. In addition, the health benefits of probiotic-fermented MFH in recent years, including antimicrobial, antioxidant, anti-inflammatory, anti-neurodegenerative, skin-protective, and gut microbiome-modulating effects, are summarized, and the health risks associated with them are also described. Finally, the future development of probiotic-fermented MFH is prospected in combination with modern development technologies, such as high-throughput screening technology, synthetic biology technology, and database construction technology. Overall, probiotic-fermented MFH has the potential to be used in functional food for preventing and improving people's health. In the future, personalized functional foods can be expected based on synthetic biology technology and a database on the functional role of probiotic-fermented MFH.

Lentils protein isolate as a fermenting substrate for the production of bioactive peptides by lactic acid bacteria and neglected yeast species

In the current trend where plant-based foods are preferred over animal-based foods, pulses represent an alternative source of protein but also of bioactive peptides (BPs). We investigated the pattern of protein hydrolysis during fermentation of red lentils protein isolate (RLPI) with various lactic acid bacteria and yeast strains. Hanseniaspora uvarum SY1 and Fructilactobacillus sanfranciscensis E10 were the most proteolytic microorganisms. H. uvarum SY1 led to the highest antiradical, angiotensin-converting enzyme-inhibitory and antifungal activities, as found in low molecular weight water soluble extracts (LMW-WSE). The 2039 peptide sequences identified by LMW-WSE were screened using BIOPEP UWM database, and 36 sequences matched with known BPs. Fermentation of RLPI by lactic acid bacteria and yeasts generated 12 peptides undetected in raw RLPI. Besides, H. uvarum SY1 led to the highest abundance (peak areas) of BPs, in particular with antioxidant and ACE-inhibitory activities. The amino acid sequences LVR and LVL, identified in the fermented RLPI, represent novel findings, as they were detected for the first time in substrates subjected to microbial fermentation. KVI, another BP highly characteristic of RLPI-SY1, was previously observed only in dried bonito. 44 novel potential BPs, worthy of further characterization, were correlated with antifungal activity.

Integrating a Multi-label Deep Learning Approach with Protein Information to Compare Bioactive Peptides in Brain and Plasma

Peptide therapeutics is gaining momentum. Advances in the field of peptidomics have enabled researchers to harvest vital information from various organisms and tissue types concerning peptide existence, expression and function. The development of mass spectrometry techniques for high-throughput peptide quantitation has paved the way for the identification and discovery of numerous known and novel peptides. Though much has been achieved, scientists are still facing difficulties when it comes to reducing the search space of the large mass spectrometry-generated peptidomics datasets and focusing on the subset of functionally relevant peptides. Moreover, there is currently no straightforward way to analytically compare the distributions of bioactive peptides in distinct biological samples, which may reveal much useful information when seeking to characterize tissue- or fluid-specific peptidomes. In this chapter, we demonstrate how to identify, rank, and compare predicted bioactive peptides and bioactivity distributions from extensive peptidomics datasets. To aid this task, we utilize MultiPep, a multi-label deep learning approach designed for classifying peptide bioactivities, to identify bioactive peptides. The predicted bioactivities are synergistically combined with protein information from the UniProt database, which assist in navigating through the jungle of putative therapeutic peptides and relevant peptide leads.

Plant Protein-Derived Active Peptides: A Comprehensive Review

Active peptides are a class of physiologically active protein fragments, which can be prepared from different sources. In the past few decades, the production of peptides with various effects from different plant proteins continues to receive academic attention. With advances in extraction, purification, and characterization techniques, plant protein-derived active peptides continue to be discovered. They have been proven to have various functional activities such as antioxidant, antihypertensive, immunomodulatory, antimicrobial, anti-inflammatory, antidiabetic, antithrombotic, and so on. In this review, we searched Web of Science and China National Knowledge Infrastructure for relevant articles published in recent years. There are 184 articles included in this manuscript. The current status of plant protein-derived active peptides is systematically introduced, including their sources, preparation, purification and identification methods, physiological activities, and applications in the food industry. Special emphasis has been placed on the problems of active peptide exploration and the future trend. Based on these, it is expected to provide theoretical reference for the further exploitation of plant protein-derived active peptides, and promote the healthy and rapid development of active peptide industry.

Molecular binding mechanism and novel antidiabetic and anti-hypertensive bioactive peptides from fermented camel milk with anti-inflammatory activity in raw macrophages cell lines

The investigation was to determine the effect of camel milk fermented with Limosilactobacillus fermentum KGL4 (MTCC 25515) on ACE-inhibiting, anti-inflammatory, and diabetes-preventing properties and also to release the novel peptides with antidiabetic and anti-hypertensive attributes with molecular interaction studies. Growth conditions were optimised on the basis of total peptide production by inoculating the culture in camel milk at different rates (1.5, 2.0, and 2.5%) along with different incubation periods (12, 24, 36, and 48 h). However, after 48 h of fermentation with a 2.5% rate of inoculum, the highest proteolytic activity was obtained. Reverse phase high-pressure liquid chromatography (RP-HPLC) was used to calculate the % Rpa from permeates of 3 kDa and 10 kDa fractions. Molecular weight distributions of fermented and unfermented camel milk protein fractions were compared using SDS-PAGE. Spots obtained from 2D gel electrophoresis were separated on the basis of pH and molecular weight. Spots obtained from 2D gel were digested with trypsin, and the digested samples were subjected to RP-LC/MS for the generation of peptide sequences. The inhibition of tumour necrosis factor alpha, interleukin-6, and interleukin-1 during fermentation was studied using RAW 264.7 macrophages. In the study, fermented camel milk with KGL4 (CMKGL4) inhibited LPS-induced nitric oxide (NO) production and pro-inflammatory cytokine production (TNF-α, IL-6, and IL-1β) by the murine macrophages. The results showed that the peptide structures (YLEELHRLNK and YLQELYPHSSLKVRPILK) exhibited considerable binding affinity against hPAM and hMGA during molecular interaction studies.

Distribution, Typical Structure and Self-Assembly Properties of Collagen from Fish Skin and Bone

The source and type of collagen are crucial to its application, and both play a decisive role. Collagen was prepared from both tilapia skin and bone and skate skin and cartilage, named as CI-TI-s, CI-TI-b, CI-SK-s, and CII-SK-c, respectively. Types, distributions, structures, and self-assembly of collagen were studied. It showed that yellow collagen fibers from skin arranged longitudinally, while collagen fibers from skate cartilages displayed varying colors. CI-TI-s, CI-TI-b, CI-SK-s, and CII-SK-c showed the typical amide A (3316-3336 cm-1) and amide B (2929-2948 cm-1) in FTIR spectra. CI-TI-b and CII-SK-c showed 218-229 nm of UV absorption, 11.56-12.20 Å of d values in XRD, and 0.12-0.14 of Rpn values in CD. The thermal denaturation temperatures of CI-TI-s and CI-SK-s were 30.7 and 20.6 °C, respectively. The self-assembly of CI-TI-s and CII-SK-c were maximum at pH 7.2 and 7.4-7.6, respectively. The unique collagen peptides of tilapia and skate were GPSGPQGAVGATGPK, PAMPVPGPMGPMGPR, SPAMPVPGPMGPMGPR, GESGPSGPAGPAGPAGVR, SSGPPVPGPIGPMGPR, GLTGPIGVPGPPGAQGEK, GLAGPQGPR, and GLSGDPGVQGIK, respectively. The unique peptides of type I and type II collagen were GPTGEIGATGLAGAR, GVLGLTGMR, LGLTGMR, GEPGAAGPAGPSGPMGPR, SSGPPVPGPIGPMGPR, and GLSGDPGVQGIK, respectively.

Production and characterization of bioactive peptides in fermented soybean meal produced using proteolytic Bacillus species isolated from kinema

The study aims to enhance the functional properties of soybean meal (SBM) using potent proteolytic Bacillus strains isolated from kinema, a traditional fermented soybean product of Sikkim Himalaya. Selected Bacillus species; Bacillus licheniformis KN1G, B. amyloliquifaciens KN2G, B. subtilis KN36D, B. subtilis KN2B, and B. subtilis KN36D were employed for solid state fermentation (SSF) of SBM samples. The water and methanol extracts of SBM hydrolysates presented a significant increase in antioxidant activity. The water-soluble extracts of B. subtilis KN2B fermented SBM exhibited the best DPPH radical scavenging activity of 2.30 mg/mL. In contrast, the methanol-soluble extract of B. licheniformis KN1G fermented SBM showed scavenging activity of 0.51 mg/mL. Proteomic analysis of fermented soybean meal revealed several common and unique peptides produced by applying different starter cultures. Unique antioxidant peptides (HFDSEVVFF and VVDMNEGALFLPH) were identified from FSBM via LC/MS. B. subtilis KN36D showed the highest diversity of peptides produced during fermentation. The results indicate the importance of specific strains for fermentation to upgrade the nutritional value of raw fermented biomass.

Identification and virtual screening of novel anti-inflammatory peptides from broccoli fermented by Lactobacillus strains

Lactobacillus strains fermentation of broccoli as a good source of bioactive peptides has not been fully elucidated. In this work, the peptide composition of broccoli fermented by L. plantarum A3 and L. rhamnosus ATCC7469 was analyzed by peptidomics to study the protein digestion patterns after fermentation by different strains. Results showed that water-soluble proteins such as rubisco were abundant sources of peptides, which triggered the sustained release of peptides as the main target of hydrolysis. In addition, 17 novel anti-inflammatory peptides were identified by virtual screening. Among them, SIWYGPDRP had the strongest ability to inhibit the release of NO from inflammatory cells at a concentration of 25 μM with an inhibition rate of 52.32 ± 1.48%. RFR and KASFAFAGL had the strongest inhibitory effects on the secretion of TNF-α and IL-6, respectively. At a concentration of 25 μM, the corresponding inhibition rates were 74.61 ± 1.68% and 29.84 ± 0.63%, respectively. Molecular docking results showed that 17 peptides formed hydrogen bonds and hydrophobic interactions with inducible nitric oxide synthase (iNOS). This study is conducive to the high-value utilization of broccoli and reduction of the antibiotic use.

Effect of fermentation on structural properties and antioxidant activity of wheat gluten by Bacillus subtilis

Bacillus subtilis has been extensively studied for its ability to inhibit the growth of harmful microorganisms and its high protease activity. In this study, Bacillus subtilis was used to ferment gluten and assess the effects of the fermentation process on the physicochemical, microstructure and antioxidant properties of gluten. The results of Fourier infrared spectroscopy (FT-IR) and circular chromatography (CD) showed a significant decrease in the content of α-helix structures and a significant increase in the content of β-sheet structures in gluten after fermentation (p < 0.05). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that glutenin was degraded into small molecular peptides with a molecular weight of less than 26 kDa after 24 h of fermentation; meanwhile, the fermentation process significantly increased the free amino acid content of the samples (p < 0.05), reaching 1923.38 μg/mL at 120 h of fermentation, which was 39.46 times higher than that at 24 h of fermentation (p < 0.05). In addition, the fermented back gluten has higher free radical scavenging activity and iron reduction capacity. Therefore, fermented gluten may be used as a functional food to alleviate oxidative stress. This study provides a reference for the high-value application of gluten.

Evaluating the effect of lactic acid bacteria fermentation on quality, aroma, and metabolites of chickpea milk

Legumes are an attractive choice for developing new products since their health benefits. Fermentation can effectively improve the quality of soymilk. This study evaluated the impact of Lactobacillus plantarum fermentation on the physicochemical parameters, vitamins, organic acids, aroma substances, and metabolites of chickpea milk. The lactic acid bacteria (LAB) fermentation improved the color, antioxidant properties, total phenolic content, total flavonoid content, lactic acid content, and vitamin B6 content of raw juice. In total, 77 aroma substances were identified in chickpea milk by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME-GC-MS); 43 of the 77 aroma substances increased after the LAB fermentation with a significant decrease in beany flavor content (p < 0.05), improving the flavor of the soymilk product. Also, a total of 218 metabolites were determined in chickpea milk using non-targeted metabolomics techniques, including 51 differentially metabolites (28 up-regulated and 23 down-regulated; p < 0.05). These metabolites participated in multiple metabolic pathways during the LAB fermentation, ultimately improving the functional and antioxidant properties of fermented soymilk. Overall, LAB fermentation can improve the flavor, nutritional, and functional value of chickpea milk accelerating its consumer acceptance and development as an animal milk alternative.

Peptide candidates for the development of therapeutics and vaccines against β-coronavirus infection

Betacoronaviruses (β-CoVs) have caused major viral outbreaks in the last two decades in the world. The mutation and recombination abilities in β-CoVs resulted in zoonotic diseases in humans. Proteins responsible for viral attachment and replication are highly conserved in β-CoVs. These conserved proteins have been extensively studied as targets for preventing infection and the spread of β-CoVs. Peptides are among the most promising candidates for developing vaccines and therapeutics against viral pathogens. The immunostimulatory and viral inhibitory potential of natural and synthetic peptides has been extensively studied since the SARS-CoV outbreak. Food-derived peptides demonstrating high antiviral activity can be used to develop effective therapeutics against β-CoVs. Specificity, tolerability, and customizability of peptides can be explored to develop potent drugs against β-CoVs. However, the proteolytic susceptibility and low bioavailability of peptides pose challenges for the development of therapeutics. This review illustrates the potential role of peptides in eliciting an adaptive immune response and inhibiting different stages of the β-CoV life cycle. Further, the challenges and future directions associated with developing peptide-based therapeutics and vaccines against existing and future β-CoV pathogens have been discussed.