The effects of food components on the digestion of DNA by pepsin

Abstract

Recently, our study found that naked nucleic acids (NAs) can be digested by pepsin. To better understand the fate of dietary DNA in the digestive tract, in this study we investigated the effects of several food compositions on its digestion. The results showed that protein inhibited the digestion of DNA when the protein:DNA ratio was higher than 80:1 (m/m). DNA found in nucleoprotein (NA), which more closely resembles the state of DNA in food, was as efficiently digested as naked DNA. When the carbohydrate:DNA ratio was 50:1–140:1 (m/m), mono-, di- and polysaccharides did not inhibit DNA digestion. NaCl exhibited an inhibitory effect at 300 mM, whereas divalent cations (Ca²⁺and Mg²⁺) exerted a much stronger inhibitory effect even at 50 mM. The polycation compounds (e.g. chitosan and spermine) showed a significant inhibitory effect at N/P (NH₃⁺/PO₄⁻) = 10:1. The close relationship between food composition and DNA digestion suggests that dietary habits and food complexes are important for understanding the in vivo fate of the ingested DNA in the digestive tract.

Keywords:

• Dietary habits
• digestion
• food components
• nucleic acids
• pepsin

Acknowledgement

We thank Quanjiang Dong (Department of Gastroenterology, Qingdao Municipal Hospital) for the comprehensive information of food digestion in the stomach.

Disclosure statement

The authors declare no competing financial interests.

Funding information

This work was financially supported by the National Natural Science Foundation of China (Grant No. 31201327), the Project sponsored by SRF for ROCS, SEM (Grant No. 31301420), the National Natural Science Foundation of China (NSFC)-Shandong Joint Fund for Marine Science Research Centers/NSFC Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406402), Shandong Province Funds for Distinguished Young Scientists (Grant No. JQ201204).