Identification of chickpea seed proteins resistant to simulated in vitro human digestion

Proteins and peptides able to resist gastrointestinal digestion and reach the intestinal mucosa have the potential to influence human health. Chickpea (Cicer arietinum L.) seed proteins are able to resist cooking (86.9% total protein) and/or in vitro simulated human digestion (15.9% total protein resists soaking, cooking and digestion with pepsin and pancreatin). To identify and characterize proteins resisting digestion we made use of different MS methodologies. The efficiency of several proteases (trypsin, AspN, chymotrypsin and LysC) was tested, and two technologies were employed (MALDI-MS/MS and LC-nESI-MS/MS). Digestion with trypsin and AspN were most successful for the identification of seed proteins. When analyzed by MALDI- MS/MS, trypsin allowed the identification of at least one protein in 60% of the polypeptide bands, while AspN allows the identification in 48%. The use of LC-nESI-MS/MS, allowed the identification of much more proteins/polypeptides from digested seeds (232 vs 17 using trypsin). The majority of the proteins found to be able to resist simulated digestion were members of the 7S vicilin and 11S legumin seed storage protein classes, which are reported to contain bio-active functions. In addition, we have found proteins that had not yet been described as potentially able to cause an impact on human health.

SIGNIFICANCE

This is the first proteomic study to analyze the effect of processing and simulated human gastrointestinal digestion on the proteome of chickpea seed. Chickpea is reported to have anti-nutritional effects as well as nutraceutical properties, so the identification and characterization of the proteins able to resist digestion is crucial to understand the targets underlying such properties.

In vitro antioxidant and anti-inflammatory activities of Radix Isatidis extract and bioaccessibility of six bioactive compounds after simulated gastro-intestinal digestion

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Isatidis called "Ban-Lan-Gen" is one of the most commonly-used traditional Chinese medicines for antiviral, anti-inflammatory, antioxidant and antipyretic purposes. Investigate the bioaccessibility of uridine, epigoitrin, adenosine, clemastanin B, indigoticoside A and isolariciresinol as well as the antioxidant and anti-inflammatory activities during an in vitro gastro-intestinal digestion of the Radix Isatidis extract (RIE).

MATERIALS AND METHODS

High performance liquid chromatography (HPLC) technique was adopted to determine the bioaccessibility of six bioactive compounds in RIE. Antioxidant activities of RIE in different digestive stages were determined by 1,1-Diphenyl-2-picrylhydrazyl (DPPH), superoxide anion and hydroxyl radical scavenging abilities. Anti-inflammatory activity was assayed by the inhibitions of inflammatory cytokines such as nitrous oxide (NO), prostaglandin E2 (PGE2) and tumor necrosis factor α(TNF-α) producted by lipopolysaccharide (LPS) stimulated RAW264.7 cells.

RESULTS

The bioaccessibility of uridine, epigoitrin, adenosine, clemastanin B, indigoticoside A and isolariciresinol were 15.38%, 18.28%, 24.01%, 6.50%, 8.65% and 17.78%, respectively. Also, the digestion products still possessed certain antioxidant activities. The antioxidant activity was highly correlated with lignans (clemastanin B, indigoticoside A and isolariciresino). The anti-inflammation activity of the three samples decreased in the order: IN sample (the solution that had diffused into the dialysis tubing)>Nondigested sample (RIE solution)>Gastric sample (post-gastric digestion)>OUT sample (material that remained in the gastro-intestinal tract).

CONCLUSIONS

Results obtained in this research reveal the amount of bioactive compounds from RIE that could be available for absorption in vivo. The antioxidant activity decreased significantly but the anti-inflammatory activity was enhanced in serum-available fraction after gastro-intestinal digestion in vitro. This study could provide a scientific basis for a deeper pharmacological activity study of Radix Isatidis and a simple method for pharmacodynamic material basis research.