Study On The Preparation Of Lipid-soluble Dihydromyricetin And Its Antioxidant Activity Itdihydromyricetin

Dihydromyricetin (DMY) is an important flavonoid which has obvious effects in anti-oxidation, anti-bacterial, anti-inflammatory and so on. The molecular structure of DMY contained six hydroxyl groups, which are not only the reasons for its novel antioxidant function, but also the reasons for its poor lipid-solubility. Thus, we intended to prepare lipid-soluble Dihydromyricetin (LDMY) by chemical modification to retain the biological activity of DMY and increased the possibility of using effectively in the lipidic environment.1. Study on the Synthesis of LDMYIn this paper, we prepared LDMY by oxygen acylation and carbon acylation. This study determined the optimal reaction conditions to form oxygen acylation dihydromyricetin product (ODMY) as follow:the temperature was 80℃, the dosage DMY:catalyst:chloride=1:0.75:2.5, the reaction time was 8h. The optimal reaction conditions to form carbon acylation dihydromyricetin product (CDMY) were as follow: the temperature was 40℃, the dosage DMY:catalyst:chloride=1:1.5:3, the reaction time was 10h.2. Study on structure of LDMYUV absorption and infrared absorption were used to detect the structure of acylated products. The result of UV scannings showed that CDMY’s two characteristic absorption peak separately shifted 8nm and 12nm, but ODMY appeared differently. The result indicated that the branched-chain was directly connected with the carbon atom of CDMY, rather than with the phenol hydroxyl oxygen atoms, so the hydroxyls in CDMY were retained.We analyzed the infrared spectra and obtained results. After acylation CDMY carbonyl molecules still existed and formed a new carbonyl group. Phenolic hydroxyls and carbonyl of ODMY still existed, but the number of phenolic hydroxyls reduced.3. Study on LDMY antioxidant activityWe studied the antioxidant activity of LDMY in DPPH radical scavenging, superoxide anion scavenging rate, fat oxidation. LDMY had good antioxidant performance which was close to TBHQ’s in DPPH radical scavenging. Their IC50 were as follow:TBHQ 7.419μg/mL, DMY 6.014μg/mL, ODMY 8.011μg/mL, CDMY 5.871 μ.g/mL. In super oxide anion study, CDMY’s clearance effect was better than DMY’s and CDMY’s. Their IC50 were as follow:DMY 13.913mg/mL, ODMY 33.592mg/mL, CDMY 219.62μg/mL. Different concentrations of LDMY played different antioxidant roles in oil system. In the case of low concentration, ODMY was weaker than DMY and CDMY in lard antioxidant capacity. In the medium concentration case, ODMY and CDMY were weaker than DMY in lard antioxidant capacity. In the case of high concentration, ODMY and DMY had similar antioxidant capacity in lard. But CDMY played a role to promote lard oxidation.