The Extraction And Separation Techniques Of Gallic Acid From Acer Ginnala Maxim Leaves

Acer ginnala Maxim is an important landscape tree, its leaves and seeds contain avariety of medicinal ingredients. Gallic acid is one of a variety of medicinal constituentswhich exists in the form of tannin with20%content in leaves. Gallic acid has beenwidely used in chemical, pharmaceutical, food and military fields, which can behydrolyzed from taninn. In this article we have studied the processes of extraction,isolation and identification of gallic acid from Acer ginnala Maxim leaves, the stabilityof gallic acid also has been studied.UV spectrophotometry （UV） and high performance liquid chromatography （HPLC）methods were established to detect gallic acid from Acer ginnala Maxim. The detectionwavelength of UV was at266nm, there was a good linear relation within the range of0²2.61g/mL. The chromatographic conditions included BDS C₁₈column（4.6mm×200mm,5m）and mobile phase consisted of methanol:0.05%phosphoricacid=10:90（v/v）. Detection wavelength was at266nm. The flow rate was1.0mL/min.There was a good linear relation within the range of0⁰.26mg/mL.UV is simple, rapid and suitable for qualitative and online detection. HPLC is suitto determinate the precise content.Water extraction, acid hydrolysis and alkaline hydrolysis were adopted to extractgallic acid. A constrast of three extraction methods used the quality of extraction gallicacid from per gram of dry leaves as an index. The optimum extraction conditions forgallic acid from Acer ginnala Maxim leaves are: material-to-liquid ratio of1:60（g/mL）,4mol/L HCl as solvent in boiling water extracting for4h.Liquid-liquid extraction and macroporous resin were adopted to purify the crudeextracts. The content of the sample after the two purification methods was60.03%and25.88%, respectively. So liquid-liquid extraction was chose to purify the crude extracts.The content of sample after liquid-liquid extraction, decolorization and crystallizationwas96.32%. The spectroscopic characteristics of the crystal of sample are very similarto reference substances on absorption peak and the basic frameworks. The sample isgallic acid through extraction, purification and identification.The stabilities of gallic acid from Acer ginnala Maxim leaves were studied underheat, pH, oxygenant, reducing agent and metal ions conditions. The results show thatthe gallic acid is stable under heat and strong acid （pH<3） and unstable for alkalioxygenant and reducing agent. The metal ion Mn²⁺, Mg²⁺and low concentration of Ca²⁺,Cu²⁺on the stability of gallic acid have minor effect, Fe²⁺has negative effect, Fe²⁺should be avoided in the extraction processing, application and storage.