Biodistribution and pharmacokinetics of thiolated chitosan nanoparticles for oral delivery of insulin in vivo.

To improve the quality of life of diabetic patients, oral delivery of insulin would be better than subcutaneous injection, and the encapsulation of insulin for its oral delivery is a promising alternative one. In this study, we prepared an oral insulin delivery system using thiolated chitosan nanoparticles (TCNPs) loaded with insulin (Ins) and tested under in vitro and in vivo systems. TCNPs prepared from CS and pentaerythritol tetrakis (3-mercaptopropionate) (PETMP) at 4:1 ratio showed 220 ± 4 nm, 2.3 ± 1 mV, and 119 ± 4 µmol g-1 in their size, charge and sulfhydryl content, respectively. There was a sustained release of insulin from the TCNPs at pH 5.3. TCNPs treatment did not alter cell viability in vitro and oral administration of TCNPs reached over the tip of the microvilli near the intestinal mucosa in vivo. There were increased and decreased the levels of insulin and glucose in the blood, respectively when Ins-TCNPs were orally administered in the diabetes induced rats. Thus, our results suggested that the insulin stays significantly for a prolonged period to make bio-distribution and bioavailability due to its interaction with the mucus of the intestine, thus offering a better oral insulin delivery system for diabetic patients.

In vitro preparation and assessment of radical reducing peptide from Octopus aegina using digestive proteases.

Antioxidant peptides protect biological macromolecules against radical damages. The use of these peptides was evaluated using free radicals scavenging assays [2,2-diphenyl-1 picrylhydrazyl (DPPH) and hydroxyl] with the help of UV-visible and electron spin resonance (ESR) spectroscopy methods. The Octopus aegina mantle protein were tested upon hydrolysis using gastrointestinal enzymes up to 12 h, where pepsin hydrolysate exhibited superior properties (DPPH: 44.39±0.67% and hydroxyl: 38.84±1.07%) compared with trypsin and α-chymotrypsin. Consequently, the antioxidant activity of the purified hydrolysate increased on a successive purification, and the peptide sequence was determined to be 368.9 Da with Gly-Glu-Tyr amino acids. Tripeptide exerted free radical scavenging efficiency in DNA damage, lipid peroxidation and cellular destruction (MCF7 cells) under stress condition. The results obtained with octopus antioxidant peptide suggested its role as an adjunct in food and pharmaceutical industries.

Anti-inflammatory Properties of Bioactive Peptide Derived from Gastropod Influenced by Enzymatic Hydrolysis.

The visceral mass of the gastropod, Harpa ventricosa was hydrolysed using trypsin, alcalase and pepsin for 12 h to produce protein hydrolysates. Subsequently, the active hydrolysate was observed in the 3rd hour of tryptic hydrolysate (29.17 ± 0.62 and 34.85 ± 0.55 %) using human red blood cell (HRBC) membrane stabilization and albumin denaturation (AD) assays. The active hydrolysate was fractionated by membrane filtration unit, where <10-kDa fraction revealed better anti-inflammatory activity with IC50 value 6.27 ± 0.05 and 5.38 ± 0.02 mg/ml for HRBC and AD assays, respectively. Additionally, the active fraction contains essential and non-essential (aspartic acid, arginine, glutamic acid and leucine) amino acids and, sequentially, the active fraction was further purified using consecutive chromatography, in which fraction C-II exhibited strong anti-inflammatory activity (HRBC 56.02 ± 0.52 and AD 50.71 ± 1.10 % assays). The non-toxic, low molecular weight (690.2 Da) hexapeptide (Ala-Lys-Gly-Thr-Trp-Lys) suppressed the nitric oxide (NO) and pro-cytokine production in a dose-dependent manner on THP-1 cell lines.