Extraction And Bioactivity Of Total Flavonoids, Peptides And Polysaccharides From Hawk Tea (Litsea Coreana Var. Lanuginosa)

Hawk tea is one of the most popular traditional beverage in southwest of China for hundreds of years. It is made from a evergreen tree which belongs to Lauraceae. Hawk tea infusion with a slight camphor-aromatic smell looks red-brown and it is good for health.According to the maturity degree of the raw materials, Hawk tea can be divided into three types:Hawk bud tea (HB, made from the most tender shoots), Hawk primary leaf tea (HP, made from new leaves), and Hawk mature leaf tea (HM, made from mature leaves). Their price varies dramatically according to their harvest time. Currently, there are few reports on Hawk teas’bioactive components, particularly for peptides and polysaccharides. In this study the extracted conditions of total flavonoids were optimized. Also, the physicochemical property and bioactivity of peptides and polysaccharides from three kinds of Hawk tea were analyzed. This research could provide a scientific basis for the further exploitation of this herb tea. The main results are as follow:1. The optimal extraction parameters of total flavonoids were microwave time,61s; microwave power,560W; ratio of water to solid,10:1 (mL:g); ethanol concentration, 80.3%. The maximum extraction yield of total flavonoids was 6.52%. At 20 mg/mL, DPPH radical scavenging activity and FRAP value was 66.66% and 2.05 mmol/L, respectively. Total flavonoids extracted from HM had a good bioactivity.2. After 270 min of incubation, the degree of hydrolysis of BPH (Hawk bud tea protein hydrolysates), PPH (Hawk primary leaf tea protein hydrolysates) and MPH (Hawk mature leaf tea protein hydrolysates) was 13.79,18.10 and 17.67%, respectively. PPH and MPH were mainly composed of low molecular weight peptides (<10 kDa), but BPH mainly contained high molecular weight peptides (>10 kDa). They all were rich in His, Tyr, Leu, Phe and Lys. MPH showed better antioxidant activities, metal chelating activities and functional properties than BPH and PPH.3. The texture of three polysaccharides detected by scanning electron microscopy were very different from each other. The polysaccharides of Hawk mature leaf tea (HMP) had a flat surface while the polysaccharides of Hawk primary leaf tea (HPP) and Hawk bud tea (HBP) had a rough surface. Erythrocyte hemolysis inhibition of HMP was the highest. HPP had better ferric reducing activity power (FRAP) value and hydroxyl radical scavenging activity than HMP and HBP. HBP showed the best DPPH radical scavenging activity.4. Considering the costs of raw materials and bioactivity of polysaccharides together as a whole in order to maximize the business profits, HM was selected for the further analyzing. The optimal extraction parameters of HMP were obtained by using a Box-Behnken design as follows:extraction temperature 88.9℃, extraction time 128.2 min and ratio of water to solid 11.4:1 (mL:g). The maximum extraction yield of HMP was 12.74%. Two purified fractions, HMP-1 and HMP-2, were obtained by chromatography of DEAE-52. Their average molecular weights were 133 and 100 kDa, respectively, and HMP-1 exhibited stronger antioxidant activity than HMP-2.