Exploration of dipeptidyl-peptidase IV (DPP IV) inhibitors in a low-molecular mass extract of the earthworm Eisenia fetida and identification of the inhibitors as amino acids like methionine, leucine, histidine, and isoleucine

Pharmacological effects of bioactive agents in earthworm extract: A comprehensive review

This review compiles information from the literature on the chemical composition, pharmacological effects, and molecular mechanisms of earthworm extract (EE) and suggests possibilities for clinical translation of EE. We also consider future trends and concerns in this domain. We summarize the bioactive components of EE, including G-90, lysenin, lumbrokinase, antimicrobial peptides, earthworm serine protease (ESP), and polyphenols, and detail the antitumor, antithrombotic, antiviral, antibacterial, anti-inflammatory, analgesic, antioxidant, wound-healing, antifibrotic, and hypoglycemic activities and mechanisms of action of EE based on existing in vitro and in vivo studies. We further propose the potential of EE for clinical translation in anticancer and lipid-modifying therapies, and its promise as source of a novel agent for wound healing and resistance to antibiotic tolerance. The earthworm enzyme lumbrokinase embodies highly effective anticoagulant and thrombolytic properties and has the advantage of not causing bleeding phenomena due to hyperfibrinolysis. Its antifibrotic properties can reduce the excessive accumulation of extracellular matrix. The glycolipoprotein extract G-90 can effectively scavenge reactive oxygen groups and protect cellular tissues from oxidative damage. Earthworms have evolved a well-developed defense mechanism to fight against microbial infections, and the bioactive agents in EE have shown good antibacterial, fungal, and viral properties in in vitro and in vivo experiments and can alleviate inflammatory responses caused by infections, effectively reducing pain. Recent studies have also highlighted the role of EE in lowering blood glucose. EE shows high medicinal value and is expected to be a source of many bioactive compounds.

Two novel angiotensin-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) inhibiting peptides from tilapia (Oreochromis mossambicus) skin and their molecular docking mechanism

In the study, papain was used to hydrolyze tilapia (Oreochromis mossambicus) skin to obtain a tilapia skin hydrolysate (TSH) with dual angiotensin-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) inhibitory activities. The resulting TSH was sequentially fractionated by ultrafiltration, size exclusion separation chromatography, and reverse-phase high-performance liquid chromatography. Its inhibitory effects on ACE and DPP-IV were determined by commercial reagent kits. Two peptides purified from TSH were identified as Gly-Pro-Leu-Gly-Ala-Leu (GPLGAL) and Lys-Pro-Ala-Gly-Asn (KPAGN) by the ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Inhibitory concentration (IC50) of GPLGAL on ACE and DPP-IV were 117.20 ± 1.69 and 187.10 ± 2.75 µM, respectively. IC50 of KPAGN on ACE and DPP-IV were 137.40 ± 2.33 and 259.20 ± 2.85 µM, respectively. The molecular simulation demonstrated that the binding affinities of GPLGAL to ACE and DPP-IV proteins were -8.5 and -7.4 kcal/mol, respectively, whereas those of KPAGN to ACE and DPP-IV proteins were -7.9 and -6.7 kcal/mol, respectively. GPLGAL interacted with 21 amino acid residues of the ACE active site, whereas KPAGN engaged with 19 amino acid residues. Additionally, GPLGAL interacted with 10 amino acid residues of the DPP-IV active site, whereas KPAGN engaged with 13 amino acid residues. The two peptides predominantly occupied the active sites of ACE (His513, Tyr523, and Ala354) and DPP-IV (Tyr662 and Arg125) through hydrogen bonding. This leads to the deactivation of ACE and DPP-IV. PRACTICAL APPLICATION: Accelerate tilapia skin development and high-value utilization; provide foundation for preparing the peptides with dual ACE and DPP-IV inhibiting activity.

In Vitro Hypoglycemic Activities of Lactobacilli and Bifidobacterium Strains from Healthy Children's Sources and Their Effect on Stimulating GLP-1 Secretion in STC-1 Cells

A long-term use of chemical drugs cannot cure type II diabetes mellitus (T2DM) and their numerous toxic side effects can be harmful to human health. In recent years, probiotics have emerged as a natural resource to replace chemical drugs in alleviating many human ailments. Healthy children's intestines have a lot of colonized Lactobacilli and Bifidobacterium, and these beneficial bacteria can help promote overall health. The objective of this study was to isolate potential antidiabetic probiotic strains from healthy children and evaluate their application prospects. Firstly, Lactobacillus and Bifidobacterium strains were isolated from healthy children's feces and identified by the pheS or clpC genes with their respective 16S rRNA genes. Then, hydrophobicity, artificial gastrointestinal fluid tolerance, α-Glucosidase and Dipeptidyl peptidase IV (DPP-IV) inhibitory activities of isolated strains were determined, and antioxidant activities and promoting secretion of GLP-1 in STC-1 cells of candidate strains were tested. Results showed that 6 strains of Lactobacillus and Bifidobacterium were obtained from the feces of healthy children aged 3 years, respectively, including Lacticaseibacillus paracasei L-21 and L-25, Levilactobacillus brevis L-16, Lentilactobacillus buchneri L-9, Lactiplantibacillus plantarum L-8 and L-3, Bifidobacterium bifidum 11-1 and B-84, Bifidobacterium longum subsp. longum 6-1, 6-2, B42 and B53. The hydrophobicity and auto-aggregation levels of all these strains were higher than 30% and 50%, respectively, and the decrease in the number of colonies of all strains in the artificial gastrointestinal fluid was less than 2 log CFU/mL. Strains L-3, L-8, L-9, L-21, 6-1, 11-1, B53 and B84 were selected based on their high α-glucosidase inhibitory activity and DPP-IV inhibitory activity, and results of the antioxidant capacity assay showed that the remaining strains all had intense comprehensive antioxidant activity. Additionally, Lacticaseibacillus paracasei L-21 and Bifidobacterium longum subsp. longum B-53 had the most substantial prompting effect on GLP-1 secretion in the STC-1 cell line. These results indicated that Lacticaseibacillus paracasei L-21 and Bifidobacterium longum subsp. longum B-53 could be used as a potential antidiabetic strain; thus, its application as a food supplement and drug ingredient could be recommended after in vivo mitigation of type II diabetes test.

Exploration of Dipeptidyl Peptidase-IV (DPP-IV) Inhibitory Peptides from Silkworm Pupae (Bombyx mori) Proteins Based on In Silico and In Vitro Assessments

This study aimed at exploring dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides from silkworm pupae proteins by in silico analysis and in vitro assessments. In silico analysis of 274 silkworm pupae proteomes indicated that DPP-IV inhibitory peptides can be released from silkworm pupae proteins. In vitro assessments revealed that pepsin and bromelain led to better production of DPP-IV inhibitory peptides from silkworm pupae protein. Notably, peptide fractions (<1 kDa) from pepsin- and bromelain-treated hydrolysates exhibited more potent DPP-IV inhibitory activities. Two novel DPP-IV inhibitory peptides (Leu-Pro-Pro-Glu-His-Asp-Trp-Arg and Leu-Pro-Ala-Val-Thr-Ile-Arg) were identified by LC-MS/MS with IC₅₀ values of 261.17 and 192.47 μM, respectively. Enzyme kinetics data demonstrated that these two peptides displayed a mixed-type DPP-IV inhibition mode, which was further validated by molecular docking data. Overall, in silico analysis combined with in vitro assessments can serve as an effective and rapid approach for discovery of DPP-IV peptides from silkworm pupae proteins.

Automated Recommendation of Research Keywords from PubMed That Suggest the Molecular Mechanism Associated with Biomarker Metabolites

Metabolomics can help identify candidate biomarker metabolites whose levels are altered in response to disease development or drug administration. However, assessment of the underlying molecular mechanism is challenging considering it depends on the researcher’s knowledge. This study reports a novel method for the automated recommendation of keywords known in the literature that may be overlooked by researchers. The proposed method aided in the identification of Medical Subject Headings (MeSH) terms in PubMed using MeSH co-occurrence data. The intended users are biocurators who have identified specific biomarker metabolites from a metabolomics study and would like to identify literature-reported molecular mechanisms that are associated with both the metabolite and their research area of interest. The proposed method finds MeSH terms that co-occur with a MeSH term of the candidate biomarker metabolite as well as a MeSH term of a researcher’s known keyword, such as the name of a disease. The connectivity score S was determined using association analysis. Pilot analyses demonstrated that, while the biological significance of the obtained MeSH terms could not be guaranteed, the developed method can be useful for finding keywords to further investigate molecular mechanisms in association with candidate biomarker molecules.