Identification of DPP-IV inhibitory peptides derived from buffalo colostrum: Mining through bioinformatics, in silico and in vitro approaches.

Bioactive peptides derived from foods provide physiological health benefits beyond nutrition. This study focused on profiling small peptide inhibitors against two key serine proteases, dipeptidyl peptidase-IV (DPP-IV) and prolyl oligopeptidase (POP). DPP-IV is a well-known protein involved in diverse pathways regulating inflammation, renal, cardiovascular physiology, and glucose homeostasis. POP is yet another key target protein for neurodegenerative disorders. The study evaluated peptide libraries of buffalo colostrum whey and fat globule membrane proteins derived from pepsin and pepsin-pancreatin digestion through in silico web tools and structure-based analysis by molecular docking and binding free-energy estimation, followed by in vitro assay for DPP-IV inhibition for the lead peptides. The bioinformatic study indicated 49 peptides presented motifs with DPP-IV inhibition while 5 peptides with sequences for POP inhibition. In the molecular docking interactions study, 22 peptides interacted with active site residues of DPP-IV and 3 peptides with that of POP. The synthesized peptides, SFVSEVPEL and LTFQHNF inhibited DPP-IV in vitro with an IC50 of 193.5 µM and 1.782 mM, respectively. The study revealed the key residues for inhibition of DPP-IV and POP thus affirming the DPP-IV inhibitory potential of milk-derived peptides.

Inhibitory potential of Buffalo (Bubalus bubalis) colostrum immunoglobulin G on Klebsiella pneumoniae.

The unique components of colostrum like free oligosaccharides and glycoconjugates are known to offer resistance to enzymatic digestion in the gastrointestinal tract and have the ability to inhibit the localized adherence of enteropathogens to the digestive tract of the neonates. In this context, we have evaluated the in vitro effect of buffalo colostrum immunoglobulin G on human pathogen Klebsiella pneumoniae, a predominant multidrug resistant pathogen associated with nasocomial infections. The investigation revealed growth inhibitory potential of immunoglobulin G in a dose dependent manner supported by scanning electron microscopic studies. The N-glycan enriched fraction of immunoglobulin G after PNGase treatment was found more effective, comparable to ampicillin than native immunoglobulin G supporting the fact that colostrum derived oligosaccharides is crucial and act as ideal substrates for undesirable and pathogenic bacteria. The MALDI TOF/TOF analysis confirmed the glycostructures of abundant N-glycans of immunoglobulin G exerting antibacterial activity. The proteomic analysis revealed variations between control and treated cells and expression of chemotaxis-CheY protein (14kDa) was evidenced in response to immunoglobulin G treatment. Hence, it would be interesting to investigate the mode of inhibition of multidrug-resistant K. pneumoniae by buffalo colostrum immunoglobulin G with the identification of a newly expressed signalling protein.