Effect of sodium caseinate and vitamin A complexation on bioaccessibility and bioavailability of vitamin A in Caco-2 cells.

Native sodium caseinate-vitamin A (VA) complexes (Sodium caseinate-VA complex, NaCaS-VA) and modified sodium caseinate-VA complexes i.e. Succinylated sodium caseinate-VA complex (SNaCaS-VA), reassembled sodium caseinate-VA complex (RNaCaS-VA) and reassembled succinylated sodium caseinate-VA complex (RSNaCaS-VA) were prepared and evaluated for their in-vitro bioaccessibility and in-vitro bioavailability of VA through Caco-2 cell lines.VA degraded under acidic conditions as the physiological pH during digestion in stomach was highly acidic (1.2-1.8). During in-vitro gastric digestion, sodium caseinate provided protection to VA, hence, higher VA content was retained in digesta as compared to free VA (oily form). Vitamin uptake by Caco-2 cells was significantly different for digested sodium caseinate-VA complexes as compared to free VA. The peptide content of casein and various sodium caseinate-VA complexes was monitored throughout digestion process. Variation in the complex composition had an effect on protein digestibility and peptide distribution. The bioavailability of VA through sodium caseinate-VA complexes was evaluated by exposing Caco-2 cells to the digesta of milk fortified with various complexes. The total uptake of VA by Caco-2 cells was highest for milk fortified with RSNaCaS-VA followed by RNaCaS-VA, control milk, SNaCaS-VA, NaCaS-VA and free VA. During the formation of RNaCaS-VA and RSNaCaS-VA complexes more hydrophobic sites are exposed, leading to the attachment of VA on the interior hydrophobic regions of sodium caseinate molecule. This led to higher stability of VA during gastrointestinal digestion and further resulted in higher bioaccessibility and bioavailability of vitamin A in Caco-2 cells.

MP-4 Contributes to Snake Venom Neutralization by Mucuna pruriens Seeds through an Indirect Antibody-mediated Mechanism.

Mortality due to snakebite is a serious public health problem, and available therapeutics are known to induce debilitating side effects. Traditional medicine suggests that seeds of Mucuna pruriens can provide protection against the effects of snakebite. Our aim is to identify the protein(s) that may be important for snake venom neutralization and elucidate its mechanism of action. To this end, we have identified and purified a protein from M. pruriens, which we have named MP-4. The full-length polypeptide sequence of MP-4 was obtained through N-terminal sequencing of peptide fragments. Sequence analysis suggested that the protein may belong to the Kunitz-type protease inhibitor family and therefore may potentially neutralize the proteases present in snake venom. Using various structural and biochemical tools coupled with in vivo assays, we are able to show that MP-4 does not afford direct protection against snake venom because it is actually a poor inhibitor of serine proteases. Further experiments showed that antibodies generated against MP-4 cross-react with the whole venom and provide protection to mice against Echis carinatus snake venom. This study shows that the MP-4 contributes significantly to the snake venom neutralization activity of M. pruriens seeds through an indirect antibody-mediated mechanism.