Studies On Extraction, Separation And Coordination Antioxidant Ability Of Flavonoids From Morus Nigra L. In Xinjiang

Morus nigra L., one of the folk herbs in Xinjiang, which was used as raw materials, was studied on chemical composition and the extraction process of total flavonoids in Morus nigra L..Besides, it was studied on the flavonoids that were isolated and identified from the ethanol extract of ethyl acetate and n-butanol phase.Also,the anti-oxidation activities in vitro of flavonoid monomer were studied in this paper.A chemical preliminary examination was carried out on the chemical composition of Morus nigra L., and the result showed that the Morus nigra L. contained a large number of chemical components, such as sugar, phenols, organic acids, flavonoids, volatile oil, alkaloids, steroids and terpenes and other chemicals.Based on single factor tests,the orthogonal experiment was employed to optimize the ultrasonic extraction method to extract the flavonoids in Morus nigra L.,the results indicated that the optimum extraction processes were as follows:solid to liquid ratio of 1:25,ultrasonic time 45 min,ethanol concentration 80%,return time 60 min.What’s more,under this optimum extraction processes conditions, the yield of total flavonoids isolated was 2.24%.Adopting chromatographic separation technology, we could isolate eleven flavonoid compounds from Morus nigra L., and they were identified by nuclear magnetic resonance(NMR) and HPLCMS-MS as Rutin(1), Isoquercitrin(2), Hyperin(3),Kaempferol-1-3-O-β-D-glucopyranoside(4),Herbacetin-7-O-(3"-O-β-D-glucopyranosyl)-rhamnopyranoside(5),Quercetin-3-O-β-(2"-O-acetyl)galacto-pyranoside-7-O-α-arabinpyranoside(6),Salidroside(7),Kaempf-erol-3-O-β-(2"-O-α-L-rhamnopyranosyl)-glucuronide(8),Rhamnetin-3-O-galactoside(9), Quercetin-3′-O-β-glucoside(10), Quercetin-3-O-β-D-glucopyranoside(11),respectively. And, compounds(3)-(10)were isolated from Morus nigra L. for the first time.Regarding free radical scavenging rate as evaluation index, and 1,1-diphenyl-2-nitrobenzene hydrazine(DPPH) and 2,2-alnitrogen base-double-(3-ethyl benzothiazole Lin-6-sulfonic acid) 2 amm-onium salt(ABTS) radical-scavenging assays were applied for the evaluation of the anti-oxidant activity of monomer compounds which were separated from the ethanol extract of ethyl acetate ph-ase.The result showed that 4 monomer compounds isolated from ethyl acetate part of alcohol extract were rutin, Isoquercitrin, Hyperin, Kaempferol-1-3-O-β-D-glucopyranoside,respectively.In addition,the inhibition concentration(IC50) of free radical scavenging rate of DPPH were 0.0083 mg/mL,0.0237 mg/mL, 0.0060 mg/mL, 0.0510 mg/mL, respectively. What’s more, the ABTS free radical scavenging rates IC50 were 0.0172 mg/mL,0.0210 mg/mL,0.0120 mg/mL,0.0870 mg/mL,respectively.Four monomer compounds have strong antioxidant activity, and the order of anti-oxidant activity was Hyperin > rutin>Isoquercitrin> Kaempferol-1-3-O-β-D-gluco-pyranoside.The anti-oxidant activity of the flavonoids was assessed by 1,1-diphenyl-2-nitroben-zene hydraz-ine(DPPH) free radical scavenging method. There were four kinds of monomer compounds Rutin,Hyperin, Herbacetin-7-O-(3"-O-β-D-glucopyranosyl)-rhamnopyranoside, salidroside,respectively, which were better than other flavonoids in anti-oxidant activity,and selecting these to study the synergistic anti-oxidant effect,the results showed that salidroside had the antagonism against other compounds in scavenging free radicals and the other three flavonoid compounds had a synergistic effect with each other.