Study On Cyclodextrin Inclusion Compound Of Anthocyanins From Kadsura Coccinea(Lem.)A.C. Smith And Melanin From Leaves Of Vaccinium Bracteatum Thunb

Kadsura coccinea（Lem.）A.C.Smith is kind of plant of vines which belongs to the family Schisandrace.The peel is rich of anthocyanins,polyphenols,flavonoids and trace elements,with a variety of bioactivities.To increase its stability and antioxidant activity,anthocyanin extract（AE）/cyclodextrin（CD）complexes were prepared usingβ-cyclodextrin（β-CD）and its derivative 2-hydroxypropyl-β-cyclodextrin（2-HP-β-CD）.By using the 1%hydrochloric acid ethanol and AB-8 macroporus resin,the anthocyanin extract was obtained from K.coccinea.The content of anthocyanins,polyphenols and flavonoids in the extract were determined by pH differential method,Folin-Ciocalteau method and NaNO₂-Al（NO₃）₃ method.Their inclusion complexation behavior and characterization were investigated by UV,FT-IR,SEM,and encapsulation efficiencies of anthocyanins,polyphenols and flavonoids in the AE/CDs complexes were estimated.Thermogravimetric analysis（TGA）was used to compare the thermal stability of the extract and inclusions,The antioxidant activities of the all samples were determined by DPPH,ABTS and ferric reducing ability in vitro.The mouse model of Potassium bromate（KBrO₃）-induced kidney damage were used to verify antioxidant effects in vivo.The content of anthocyanins,polyphenols and flavonoids were 40.95±0.115 mg/g,107.75±2.482 mg/g and 185.57±0.883 mg/g.The morphologic and spectral studies indicated the formation of inclusion complexes,and encapsulation efficiencies were more than 80%for anthocyanins,polyphenols and flavonoids in the AE/CDs complexes.Moreover,TGA revealed that the AE powder was approximately linear rapidly decomposed between room temperature and 360°C,AE/CDs inclusion degraded at a slowly rate and had less weight loss before 300°C,suggested the presence of CDs significantly improved the stability of anthocyanin extract.The AE/2-HP-β-CD inclusion complexes（weight lost was 32.66%between 25°C and 314°C）was more stable thanβ-CD inclusion（weight lost was 34.01%between 25°C and 290°C）.The antioxidant assays in vitro showed that the complexation of AE with cyclodextrin could increase its antioxidative effects in an order of AE/2-HP-β-CD complexes>AE/β-CD complexes>free AE.β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin themselves have no antioxidant activity.KBrO₃ caused oxidant stress kidney damage mice model was established,intragastric administration of AE,AE/2-HP-β-CD complex,AE/β-CD complex at 100 mg/kg,protective effect of renal injury mice under the same dose condition was in an order of AE<AE/β-CD complexes<AE/2-HP-β-CD complexes.Vaccinium bracteatum Thunb.belongs to the the family Ericaceae.The melanin extract of leaves of Vaccinium bracteatum Thunb.contains very rich and effective ingredients,such as anthocyanins,flavonoids et al,and strong coloring ability,but susceptible to metal ions and preservatives agent and easily get discoloration.In this paper,the effects of different extraction methods on the chemical composition and antioxidant activity of fresh and dried leaves were studied,and the antioxidant activity and stability of the melanin extracts leaves of Vaccinium bracteatum Thunb.and CDs inclusion complexes were compared.The chemical constituents of fresh and dried leaves of Vaccinium bracteatum Thunb.were extracted by water or ethanol,impregnation or reflux.The contents of total flavonoids were determined by ultraviolet spectrophotometers and the antioxidant activities of these samples were determined by DPPH and ABTS in vitro,and the best way to extract melanin from Vaccinium bracteatum Thunb.leaves was obtained.The melanin of Vaccinium bracteatum Thunb.inclusion complexes were prepared withβ-CD and 2-HP-β-CD.The difference between the thermal stability of the extract and its inclusion complex by TGA,the effects of Fe³⁺and potassium sorbate on the melanin extract and its inclusion complex were studied,and the changes of the samples antioxidant activity were compared.Results showed that the total flavonoids content of the alcohol reflux extracts of fresh leaf was the highest（19.48%）,but the antioxidant activity of the water reflux extracts of fresh leaf was the strongest.Cyclodextrin inclusion complexes could improve the antioxidant activity of melanin extract,especially 2-HP-β-CD inclusion complexe.The results of TGA showed that the appearance of cyclodextrin expanded the thermal stability range.The absorbance of the cyclodextrins inclusions and melanin extract were increased by adding of Fe³⁺and potassium sorbate,but the absorbance of the inclusion compound got more increased by adding Fe³⁺,and the potassium sorbate had a great effect on the absorbance of the melanin extract.The inclusion of melanin on the metal ions and preservatives stability had not improved,but the pigment color of the inclusion compounds under the influence of Fe³⁺were improved than the melanin extract.