The Active Components And Antioxidant Activity Of Coreopsis Tinctoria Were Detected By Near Infrared Spectroscopy

Coreopsis tinctoria has been used as a popular tea raw material and an important Chinese medicine in China for many years.It has the functions of antibacterial and anti-inflammatory,regulating "three high",softening blood vessels,detoxification and beautification,and anti-aging.There are many beneficial substances in Coreopsis tinctoria,such as fluorine flavonoids,phenolic acids,flavonoids and terpenoids,etc.Flavonoids have good hypoglycemic activity and fluorine flavonoids have good antioxidant activity.The chemical substances extracted from Coreopsis tinctoria include saponins,flavonoids,tannins,polyacetylene and other main substances.Among all kinds of compounds contained in Coreopsis tinctoria,flavonoids are the main chemical substance with the largest content.Therefore,the study of flavonoids in Coreopsis tinctoria has a high application prospect.Separation and purification of bioactive substances from natural compounds has become a key step in the preparation of bioactive products.Adsorption,as a separation method with high adsorption efficiency and low cost,is widely used in various technologies for the separation of natural compounds.The determination of flavonoids usually depends on chromatography.Due to the cumbersome operation and long use time,the near-infrared spectrum is fast,non-destructive,and simple preprocessing is a good method for compound determination.However,because the sensitivity of NIR analysis is generally low,it is difficult to determine the analyte at low concentration.Therefore,adsorbent combined with NIR spectroscopy is used to improve the sensitivity of NIR spectrum and then to determine the flavonoids of Coreopsis tinctoria.In this paper,two common flavonoids luteolin and luteoloside,zn-doped silica adsorbent and arginine-functionalized attapulgite adsorbent were prepared,and luteoloside and luteolin were enriched by effective adsorption.Existing studies have shown that the antioxidant activity of Coreopsis tinctoria is good,but the traditional antioxidant activity measurement method is mostly used,and the process is cumbersome.Therefore,in this paper,a correction model was established by using near-infrared spectroscopy to achieve a rapid prediction of antioxidant activity of Coreopsis tinctoria.The main research work is as follows:（1）In order to determine the content of luteoloside in Coreopsis tinctoria,a new adsorbent zn-doped silica was prepared by doping zinc ions with silica as raw material.Luteoloside was adsorbed by the adsorbent through complexation.The effects of the amount of zinc-doped silica adsorbent,p H value and oscillating adsorption time on the adsorption properties were studied.The results showed that when the mass was 0.25 g,p H was 7 and the oscillation time was 20 min,the adsorption efficiency of luteoloside was 87.1%.The chemical bond in the adsorbent was analyzed by Fourier Transform infrared spectroscopy（FTIR）and the morphology of the adsorbent was analyzed by scanning electron microscopy（SEM）.The adsorbent was determined by NIR without desorption and the quantitative correction model was established.After the standard normal transformation（SNV）treatment,the correlation coefficient between the reference concentration and the predicted concentration of luteoloside correction model was0.9909.The model results showed that luteoloside could be effectively enriched by zinc-doped silica adsorbent and could be quickly and selectively determined.These results provide some reference value for determining the content of trace active components in other plants.（2）In order to determine the content of luteolin in Coreopsis tinctoria,an arginine-functionalized attapulgite adsorbent was prepared by impregnation method in this paper.The adsorbent realized the pre-enrichment of trace luteolin in aqueous solution through complexation and electrostatic action.In addition to ft-IR and SEM experimental methods to characterize the adsorbent materials,The composition of the material was also determined by X-ray diffraction（XRD）.At the same time,the influence factors on the adsorption of luteolin by arginine-functionalized attapulgite were investigated during the adsorption test.The maximum adsorption rate was obtained when the mass was 0.2 g,p H was 7,and the oscillation time was 10 min.And the isotherm can be better described by Langmuir equation.The quantitative model of arginine functionalized attapulgite adsorbent was established by near infrared spectroscopy without elution.The best pretreatment method was SNV,and the main parameter R of the model was 0.9914.The model results showed that the arginine functionalized adsorbent could be used for the rapid,sensitive and selective determination of luteolin.The above experimental results indicate that arginine functionalized attapulgite adsorbent has a good enrichment effect on luteolin.（3）To quickly predict the antioxidant activity of Coreopsis tinctoria,in this study,near infrared spectroscopy was used to quickly and nondestructively determine the antioxidant activity of the samples from different habitats.1,1-diphenyl-2-picrylhydrazyl radical（DPPH）and2,2’-biazbis（3-ethylbenzothiazoline-6-sulfonic acid）ammonium salt（ABTS）were used to determine the antioxidant activity of the extracts from 10 different habitats.The partial least squares（PLS）algorithm was used to establish the calibration model between the near infrared spectra and the antioxidant activity data obtained by the above two methods.Based on the cross validation root mean square error（RMSECV）,correlation coefficient（R）and prediction residual（RPD）as the main parameters,the optimal NIR spectral band and spectral pretreatment method were determined.The results showed that under the optimal spectral band and pretreatment conditions,the RMSECV of the model for predicting anti-DPPH activity by NIR spectroscopy was 0.772,the correlation coefficient R was 0.948,and the prediction residual RPD was 3.17.The correlation parameters of anti-ABTS activity model were 0.365,0.884 and 2.52,respectively.The above data indicate that the prediction effect of anti-DPPH activity model is better than that of anti-ABTS activity model.The results show that NIR spectroscopy can be used to predict the antioxidant activity of Coreopsis tinctoria samples.In this study,two adsorption materials were prepared and combined with near infrared spectroscopy for the determination of luteoloside and luteolin in Coreopsis tinctoria,and the antioxidant activity of Coreopsis tinctoria extract was predicted by near infrared spectroscopy.It provides research ideas for the analysis of active components and rapid determination of biological activity in other plants.