Mucoadhesive chitosan microcapsules for controlled gastrointestinal delivery and oral bioavailability enhancement of low molecular weight peptides.

A bioactive compound, collagen peptide (CP), is widely used for biological activities such as anti-photoaging and antioxidant effects, with increased oral bioavailability because of its low molecular weight and high hydrophilicity. However, controlling release time and increasing retention time in the digestive tract for a more convenient oral administration is still a challenge. We developed CP-loaded chitosan (CS) microcapsules via strong and rapid ionic gelation using a highly negative phytic acid (PA) crosslinker. The platform enhanced the oral bioavailability of CP with controlled gastrointestinal delivery by utilizing the mucoadhesiveness and tight junction-opening properties of CS. CS and CP concentrations varied from 1.5 to 3.5% and 0-30%, respectively, for optimal and stable microcapsule synthesis. The physicochemical properties, in vitro release profile with intestinal permeability, in vivo oral bioavailability, in vivo biodistribution, anti-photoaging effect, and antioxidant effect of optimized CS microcapsules were analyzed to investigate the impact of controlling parameters. The structure of CS microcapsules was tuned by PA diffused gradient ionic cross-linking degree, resulting in a controlled CP release region in the gastrointestinal tract. The optimized microcapsules increased Cmax, AUC, and tmax by 1.5-, 3.4-, and 8.0-fold, respectively. Furthermore, CP in microcapsules showed anti-photoaging effects by downregulating matrix metalloproteinases-1 via antioxidant effects. According to our knowledge, this is the first study to microencapsulate CP for oral bioavailability enhancement. The peptide delivery method employed is simple, economical, and can be applied to customize bioactive compound administration.

Identification and screening for antimicrobial activity against Clostridium difficile of Bifidobacterium and Lactobacillus species isolated from healthy infant faeces.

The antimicrobial activity against Clostridium difficile of 109 lactic acid bacteria (LAB) isolated from 32 healthy Korean infants was measured. The ability to show similar activity against Escherichia coli O157:H7 and Staphylococcus aureus was also looked for. Twelve of the 109 LAB showed activity against C. difficile and 19 strains were active against E. coli O157:H7, but none against S. aureus. Four strains had antimicrobial activity against both C. difficile and E. coli O157:H7. Of the 12 strains that had activity against C. difficile, four strains were excluded as Streptococcus species, while the other eight were identified using polymerase chain reaction (PCR) assays using group-specific primers designed from the nucleotide sequences of the 16S rDNA and internal transcribed spacer (ITS) regions of the Bifidobacterium and Lactobacillus species. Based on the sequencing results, the eight strains screened were identified as Bifidobacterium infantis and Lactobacillus salivarius.