Study On Bioavailability And Metabolism Of Purple Sweet Potato Anthocyanins In Vivo

Anthocyanins from purple sweet potato are green natural pigments.Studies have shown that they have multiple functions and pharmacological activities such as anti-tumors,anti-oxidation,anti-mutation,and protective effects on the liver,cardiovascular and cerebrovascular.Additionally,they are considered to be a kind of natural compound low toxicity and health care functions.Moreover,they are even known an oral “skin cosmetic”.In China,researches are mainly focused on the sources,types,synthetic pathways,structure and biological functions of anthocyanins in the present,while other countries in the world tend to report the bioavailability of anthocyanins.At present,there are relatively few articles on the bioavailability of polyphenols and flavonoids,and even less on the single-component metabolic and bioavailability of anthocyanins.Why is there such a situation? The main reason is that the composition of purple sweet potato anthocyanins is very complex,and it is difficult to separate a single component from the anthocyanins.Therefore,the detection and separation conditions of purple sweet potato anthocyanins were optimized,and the main components of the anthocyanins,from the No.3,4,6,and 7 peaks,were analyzed in this work.In addition,we conducted preliminary studies on the absorption and ingestion of these components through in vivo absorption,metabolism and excretion studies,and the transmembrane transport and absorption model in Caco-2 cells.Importantly,this work can provide insight into the pharmacokinetics of the purple sweet potato anthocyanins.1.Through repeated experiments,this work has established and optimized the detection conditions of anthocyanins in purple sweet potatoes grown in the northeast China.Finally,we confirmed that the detection conditions of purple sweet potato anthocyanins were Phase C(1% phosphoric acid/water solution by volume),and the best separation conditions were Phase D(1% phosphoric acid/35% acetonitrile by volume).Under these conditions,we obtained not only much more kinds of anthocyanin components but also they are clearly distinguishable.This work provides favorable conditions for the successful development of follow-up experiments.2.The main components of the purple sweet potato anthocyanins,obtained from the No.3,4,6,and 7 peaks,were analyzed using UV-Visible full-wavelength spectral scanning and internal standard calibration method.After preliminary analysis,we finally determined that the No.3 peak was a diacylated double-glycosylated structure,the No.4 peak was a diglycosylated monoacylated structure,the No.6 peak was Paeoniflorin,and the No.7 peak was a diglycosidic double-acylated structure.3.In order to remove the interference peaks in serum,this work compared the heating method,salting out method and organic solvent extraction method.Finally,we found that only the equal volume acetonitrile treatment can minimize the impurity peaks.Therefore,this method will be used to subsequently detect other samples in the serum4.Absorption of the purple sweet potato anthocyanins(A,absorption):(1)After three different concentrations,the low(5 mg/ml),medium(10 mg/ml),and high doses(20 mg/ml),of purple sweet potato anthocyanins were gastric administered to the experimental animals,their blood concentrations were measured at different time points.Based on the above results,we calculated the main pharmacokinetic parameters of the purple sweet potato anthocyanins,including the highest plasma concentration,peak time and bioavailability.These parameters have led us to discover that by increasing gavage concentration,the bioavailability can be increased in a short time,but it declines rapidly over time.At the same time,we also found that the bioavailability of purple sweet potato anthocyanins was below 7%.(2)We explored the transport mechanism of the purple sweet potato anthocyanins in small intestinal epithelial cells through the study of transmembrane transport and absorption of them in Caco-2 cell monolayer.Additionally,we calculated their apparent permeability coefficients by calculating the transport volumes on the AP-BL and BL-AP sides.The results showed that the different types of purple sweet potato anthocyanins are all passively transported.5.Metabolism of purple sweet potato anthocyanins(M,metabolism)To study the biotransformation of purple sweet potato anthocyanins by hepatocytes,the THLE-2 cells(immortalized hepatocyte)were used instead of the primary hepatocytes in this study.It was found that the metabolism of different types of purple sweet potato anthocyanin in the primary hepatocytes was not significant at their different concentrations.6.Excretion of purple sweet potato anthocyanin(E,excretion)After the mice were given different components of purple sweet potato anthocyanin at different concentrations,we studied the urine excretions at different time points.This study found that the cumulative amounts of different types of purple sweet potato anthocyanins in urine reached a maximum within 2 h,and the excretion of purple sweet potato anthocyanins could not be completed until 12 h(except for the component of the No.6 peak).