Sweet Potato Leaves Flavonoids Extraction, Separation, Purification, And Its Volatile Chemical Composition Of The Study

Sweetpotato is the fourth foodstuff crops in our country and the cultivated area ranks first in the world. Sweetpotato as the high value-added content of sweetpotato crop is lack of processing and using. Most of them were discarded in the ridge of field, which not only wasting resource, but also polluting environment. We should think about that how to effectively utilize these resources and make it exerting its functions. In order to effectively use this resource, the bioactive components flavonoids and volatile oils were discussed and investigated using morden extraction separation techniques in our study. The results can provide a theory reference and practicing guidance at some extent for the research of officinal functions, healthy food and beverage of sweetpotato leaves. This paper can be divided into three parts as follows:In the first part, extraction and assaying total flavones (the chapter two of this paper), the contents of total flavones in sweetpotato leaves were determined by visible spectrophotometry. The main influencing factors, such as maximal absorbing wavelength, chromogenicogent volume, chromogenic time, were discussed. Meanwhile, after carrying out a single factor test, an orthogonal test was used to study the influence of solvents, time, concentration of solvent, ratio of material to solvent for the extraction of total flavnoes. The optimal extraction conditions for total flavones in sweetpotato as follows:ethanol concentration,80%; ratio of material to solvent,1:40; extraction time,30 min; pH value,9, and the yield rate is 8.22% at this best condition.In part two, separated and identification of flavones monomer (the chapter three of this paper), flavones monomer was separated and prepared through column chromatography using polyamide and sephadex LH-20 as the filler and ethanol—water and methanol as eluant. Finally, three yellow powder monomers were separated and purified from the sweetpotatao extract. The purity was processed on high performance liquid chromatography. It can be tentatively identified as flavonoids from their corresponding ultraviolet spectrometry. The monomers may use as reference substances for quantitative analysis by high performance liquid chromatography.In the third part, qualitive and quantitative analysisi of volatile components in sweetpotato leaves (the chapter four of this paper), the volatile components of sweetpotato leaves was extracted by water distillation and inverstigated by gas chromatography-mass spectrometry with the help of two chemometric resolution methods, say heuristic evolving latent projections (HELP) and selective ion analysis, and temperature-programmed retention indices. As for quantitative analysis, overall volume integration technique was performed. Eighty-four and forty-five components which account for 89.39% and 98.08% were tentatively identified from the two cultivars, respectively. Furthermore, thirty-four of the components were identical in both of the cultivars. Major constituents of purple leaves were germacrene D (21.83%), germacrene B (15.17%), caryophyllene (12.44%) and n-hexadecanoic acid (11.24%), while caryophyllene (28.73%),γ-muurolene (13.07%) andβ-caryophyllene epoxide (9.04%) were the major components of green leaves.