Construction Of Nano-transport System For Polyphenols Of Bauhinia Variegata And Its In Vivo Absorption And Metabolism Mechanism

Polyphenols are plant secondary metabolites that are widely found in nature and can be used as dietary supplements to maintain human health due to their various biological activities.However,the poor solubility,instability and low absorption rate of polyphenols during gastrointestinal digestion have led to low bioavailability and limited their application.Currently,the construction of polyphenol nano-transport systems that can resist degradation of polyphenols during gastrointestinal digestion,promote absorption of polyphenols in the intestinal tract and target delivery of polyphenols to target organs and tissues,thus making it a potential solution to improve the bioavailability of polyphenols in vivo.In this study,MBP was selected as the target,and MBP nano-transport systems(MBP-NPs)were constructed based on biomolecules,and their structural properties and physicochemical properties were identified and analysed.The specific results of the study are as follows:(1)Firstly,in this study,CS-SA-MBP NPs and GE-SA-MBP NPs were constructed based on chitosan(CS)and sodium alginate(SA)and gelatin(GE)and sodium alginate(SA),respectively,and their structural properties,physicochemical properties and morphological characteristics were identified and analysed.The results showed that the encapsulation rate of CS-SA-MBP NPs was up to 84.97% and that of GE-SA-MBP NPs was up to 83.19%;the average particle sizes were 516 nm and 710 nm,respectively;the surface morphology was three-dimensional reticular structure;and they had good photothermal stability.(2)The release characteristics and structural changes of CS-SA-MBP NPs and GE-SA-MBP NPs during gastrointestinal digestion were investigated by establishing an in vitro gastrointestinal digestion model,respectively.The results showed that both CSSA-MBP NPs and GE-SA-MBP NPs exhibited a decrease in mean particle size during gastrointestinal digestion,a constant composition of protected MBPs and a targeted slow release in the small intestine.The bioavailability of CS-SA-MBP NPs encapsulated MBP was up to 36.74%,which was 3.6 times higher compared to free MBP.(3)The in vivo metabolomic properties of CS-SA-MBP NPs were investigated by establishing a mouse model.The results showed that CS-SA-MBP NPs were non-toxic and mainly distributed in the gastrointestinal fluid and faeces;during digestion,CS-SA-MBP NPs contributed to the absorption of some polyphenolic compounds into the bloodstream by the small intestine,where they were distributed in various organs and metabolized by colonic microorganisms,and had a positive impact on the intestine by promoting the synthesis of SCFAs;and CS-SA-MBP NPs exhibit excellent intestinal targeting release properties,resist the degradation of MBP in gastric juice,deliver MBP to the intestine smoothly,improve bioavailability and potentially enhance their bioactivity.This thesis constructs MBP-NPs based on biomolecules and demonstrates through in vitro and in vivo gastrointestinal digestion studies that CS-SA-MBP NPs can effectively protect MBP against degradation by gastrointestinal digestion and exhibit slow-release properties,potentially promoting the absorption of MBP in the intestine and thus enhancing the bioavailability of MBP in vivo.This thesis provides a theoretical basis for the application of MBP as a dietary nutrient,as well as a theoretical reference for the construction of other bioactive polyphenol nano-transport systems.