Effect of lime water processing of Pinelliae Rhizoma Praeparatum on toxic component lectin protein

Abstract

The present study investigated the effect of immersion in the excipient lime water on the toxic component lectin protein and explained the scientific connotation of lime water detoxication during the processing of Pinelliae Rhizoma Praeparatum. Western blot was used to investigate the effects of immersion in lime water with different pH(pH 10, 11, and 12.4), saturated sodium hydroxide, and sodium bicarbonate solution on the content of lectin protein. The protein compositions of the supernatant and the precipitate after immersing lectin protein in lime water of different pH were determined by the SDS-PAGE method combined with the silver staining technique. The MALDI-TOF-MS/MS technique was used to detect the molecular weight distribution of peptide fragments in the supernatant and precipitate after immersing lectin protein in lime water of different pH, and circular dichroism spectroscopy was used to detect the ratio changes in the secondary structure of lectin protein during the immersion. The results showed that immersion in lime water at pH>12 and saturated sodium hydroxide solution could significantly reduce the content of lectin protein, while immersion in lime water at pH<12 and sodium bicarbonate solution had no significant effect on lectin protein content. The corresponding lectin protein bands and molecular ion peaks were not detected at the 12 kDa position in the supernatant and precipitate after immersing the lectin protein in lime water at pH>12, which was attributed to the fact that lime water immersion at pH>12 could significantly change the ratio of the secondary structure of lectin protein, resulting in irreversible denaturation, while lime water immersion at pH<12 did not change the ratio of the secondary structure of lectin protein. Therefore, pH>12 was the key condition for the detoxication of lime water during the processing of Pinelliae Rhizoma Praeparatum. Lime water immersion at pH>12 could cause irreversible denaturation of lectin protein, resulting in a significant decrease in the inflammatory toxicity of Pinelliae Rhizoma Praeparatum, which played a key role in detoxification.