Studies On Bound Chemical Constituents And Anti-bacteria Activity Of Pomegranate Peel

Generally speaking,pomegranate peel is the outermost shell and the inedible thin layer inside of a pomegranate,which is the by-product during the process of manufacturing of grenadine juice,and contains more than seventy kinds of active substance such as polyphenol,brass,organic acid etc.As recorded in the history research,part of these substance have the functions of antioxidant,scavenging free radical,cancer antitumor,anti-bacteria,anti-inflammatory activity,which can prevent or release cardiovascular and cerebrovascular disease,leukemia,Alzheimer's disease etc.In this study,we use modern isolation technics to identify bound phytochemicals of pomegranate peel,and make preliminary evaluation on the antioxidant activity of free,bound,and isolated monomeric compound.The optimized extraction conditions of bound-polyphenols from pomegranate peelare as follows:take polyphenols as the index,on the basis of single element,optimize the acid degradation condition of bound-polyphenols from pomegranate peel by adopting Response surface method,and achieve the optimum parameters:6.10mol/L hydrochloric acid,acidolysis time is 2.01h,acidolysis temperature is 44.17?,solid-liquid ratio is 1:20.The gallic acid equivalent is 30.76?mol GAE/g according to the same condition,the regression is y = 30.60 +0.95 A +0.27 B +2.07 C +0.62 D-0.13 AB-0.63 AC-1.09 AD +0.075 BC-0.085 BD-1.21 CD-7.89 A2-8.06 B2-7.67 C2-8.51D2,2Adj=0.9779.Comparative analysis on pomegranate peels polyphenols before and after acid degradation.Analyze the difference in finger prints of polyphenols by HPLC technology,and identify the main polyphenols in the pomegranate peels before and after acid degradation by adopting the method of comparison between MALDI-TOF-MS and literature.These results suggest that in little polar phenolic compounds,species of free compounds are more than bounds,meanwhile,in medium polar phenolic compounds,species of bound compounds are more than free ones in pomegranate peels.By analyzing the main ion fragment,it is found that at least six bound polyphenols compounds have been released,which are Punicacortein?Granatin B?Valoneic acid bilactone?Delphinidin-3-O-glucoside?Caffeic acid hexoside?Vanillic acid hexoside.Bound compound isolated identification.After eliminating the free compounds in the pomegranate peels by organic reagent,acid degrade the residues with the optimized index above,then extract the degraded liquid by using organic reagent,and obtain extracted full of bound compounds.The antibiotic test indicates that extracted can distinctly restrain the golden staphylococcus.We isolate and purify these extracted by tracking the activity and separated by silica gel column chromatography and Sephadex LH-20,then obtain six monomeric compounds,identify the structure of these compounds using modern spectrum and comparing the existed data,we consider these compounds as(1)?-Stitosterol,(2)Ursolic acid(3)?corosolic acid(4)?asiatic acid(5)?arjunolic acid(6)were identified by modern spectroscopic techniques such as mass spectrometry(MS)and nuclear magnetic resonance(NMR).Evaluation of the bacteriostatic activity of bound compounds.Make preliminary bacteriostatic test for the six monomeric compounds isolated from extracted in pomegranate peels,the results demonstrate that,compounds 2,3,5 have selectivity bacteriostatic activity.Compound 2 can restrain the growth of Enterobacter aerogenes?Staphylococcus aureus?Escherichia coli,compound 3 can restrain the growth of Mycobacterium smegmatis?Staphylococcus aureus,compound 5 can distinctly restrain the growth of Staphylococcus aureus and Mycobacterium smegmatis,the MIC values are 1?g/ml and 64?g/ml,compound 5 and compound 6 generates bacteriostatic effect synergistically to restrain the activity of Mycobacterium smegmatis?Staphylococcus aureus,Escherichia coli,which shows prior effect than compound 5 individually.The result of this study indicates that,clear difference exists between free polyphenol compounds and bound polyphenol compounds in pomegranate peels,the main bacteriostatic composition in bound compounds is Pentacyclic triterpene compounds.This study establish the theory foundation for further processing and comprehensively utilizing the pomegranate peels,which has significant value in practical application.