Study On Biological Activities Of Proanthocyanidins Extract From Black Poplar (Populus Deltoids) Bark

The extraction conditions of proanthocyanidins, purification method, relation between biological activities and the chemical components of different extract fractions were systematically investigated in this dissertation, and the heavy metals contents of the bioactive extract fraction were also detected, Main results are summarized as follows:The pre-examination results of chemical components detection showed that black poplar bark contained protein, saccharides, organic acid, phenols, tannins, flavones, anthraquinones, steroids, alkaloids and without coumarins, cardiac glycosides, saponins, volatile oils.Suitable extraction conditions were:ethanol concentration 60%, liquid-solid ratio 10:1 mL/g, extract temperature 65℃, extract time 6 h, The extraction yield of proanthocyanidins was 2.1% under this condition.The fractionation and purification effects of 4 kinds of macroporous adsorbent resins (AB-8,D-101,BS-45,BS-30) on proanthocyanidins from poplar bark were investigated and AB-8 showed the most efficient adsorption and desorption properties. The chromatographic column was internally filled with AB-8 as stationary phase and the purified proanthocyanidins were obtained by eluting with increasing ethanol concentration and isolated with solvent evaporation.HPLC-ESI-MS analysis results indicated that the main components of 15% ethanol elution fraction were Procyanidin dimer (Mw 578) and monomer (Mw 290), and the 45% ethanol elution fraction consisted of Myricetin glucoside (Mw 480), eriodictyol (Mw 288) and 5,6,6',7,-tetrahydroxy-4'-methoxy flavanone (Mw 318).The crude extract of ethyl acetate fraction had much stronger biological activities than water fraction.15% ethanol elution fraction had the best anti-oxidation and anti-tumor activities whilst 45% ethanol elution fraction had the best anti-microbial activity among the three purified fractions. These results illustrated that anti-oxidation and anti-tumor activities were related to phenolic hydroxyl groups whereas anti-microbial activity was related to C ring structure of the molecule. Proanthocyandins with more phenolic hydroxyl groups had higher anti-oxidation and anti-tumor activities and the flavonoids with ketone group had higher anti-microbial activity than Proanthocyandins.Heavy metal test indicated contents of heavy metals (Pb, Cu, Hg, As, Cd, total amount) of ethyl acetate fraction were well consistent with the criterion of Green Trade Standards of Importing and Exporting Medicinal Plants and Preparations.