Studies On Extraction, Detection, Purification, Antioxidant Activity And Structure-Activity Relationship Of Flavonoids From Bamboo Leaves

The bamboo leaves flavonoids is a new developing natural plant flavone prepration.It has many fine functions, such as anti-free radical, oxidation resistance and protecting vasular system etc. Nowadays, it has received broad attention from all over the world. In order to review roundly the characters of bamboo leaves flavonoids, the next systematical work had been done in the paper: taking the leaves of phyllostachys bamboo as raw material, studying on the extraction, purification, antioxidant activity and the relationship between the structure and antioxidant activity of flavonoids in the bamboo leaves. The main reseach contents and results are as follows: HPLC and UV-VIS spectrophotometry were applied to detect the content of total flavonoids in the experiment and two detection results were compared . The method of quantitative detection was established By good single factor selecting experiment and Orthogonal Design, the best technology for extracting bamboo leaves was established.The best extraction conditions was 70% ethanol as solvent, three times of extraction, 1.5 hours per time and the 1:30(w/v) of material and alcohol ratio. By reviewing for several resins, the separation and purification effect of AB-8 resin was best .After enriched by AB-8 resin, the total flavonoids content was enhanced greatly, from 9.80% to 28.94%, increased 2.95 times. The goal of enrichment and isolation was realized. The result was better than of the solvent extraction patent provided by Zhang Ying, in which the result was 24%. The abilities of scavenging and O2-.and ·OH of the extract of bamboo was detected by chemiluminescence. The results showed that antioxidant activity of the extract was excellent; the flavonoids was not the only antioxidant effective position in the extract of bamboo, tannin and δ-OH-Lys had also quite strong antioxidant ability; the extract of bamboo leaves was a complex and synergistic mixture and it was no effective on antioxidant activity to purify further. Finally, relationship between flavonoids structure and bioactivity was been discussed. Quercetin was selected to be a deputy. A DFT study was performed on quercetin and its possible radicals, and the geometry, the frontier orbitals, the distribution of unpaired electron and the dissociation energy were employed to elucidate the antioxidant activity-structure relationship of flavonoids. From the above series experiments, it was proved that the bamboo leaves flavonoids was a excellent flavonoids prepration. The research provided important theoretical and pratical guidances for exploiting and using of bamboo resource.