Preliminary Studies On The Physico-chemical Properties And Physiological Activity Of Abelia Englerina Leaf Pectin

Abelia englerina is a special plant resource in China, and they are mainly growing inShanxi, Sichuan, Hubei and so on. Results showed that pectin is the most important solubledietary fiber in Abelia englerina leaf. This paper compared the effects of different extractionon pectin yield and quality, then studied the effects on the blood lipid and blood glucose.To obtain the optimal processing conditions of ultrasound-assisted extraction, the factorsincluding extracion temperature, extraction time, pH value and liquid/solid were investigatedwith a four-factor Box-Behnken center-united design based on single-factor experiments.Then the comparisons of physicochemical properties between the Abelia englerina leaf pectinunder the best optimal conditions and commercial citrus pectin （CP） were performed. Theresults showed that the optimal conditions of extraction temperature, pH value, extractiontime, liquid/solid ratio and ultrasonic power were75℃,1.7,30min,1:30and400W,respectively. The predicted yield was18.56%and observed yield was18.79%. The pectinconsisted of68.78%galacturonic acid content with DE value of62.50%, and had thesolubility and oil holding capacity of98.45%and1.98g/g, respectively. The DPPH freeradical-scavenging activity and FRAP value were78.81%and5.13mmol/L（pectinconcentration:2mg/mL）, respectively. Therefore, The pectin under the optimal conditionsbelonged to the high methoxyl pectin（DE＞50%）, had a high oil holding capacity, andcertain antioxidant ability.The pectin from Abelia engleriana leaf were extracted by using four different extractionmethods, including conventional acid, water, enzyme and ultrasound-assisted extraction. Thedifferences were studied by measuring the yield, degree of esterification, galacturonic acidcontent, solubility, pH value, DPPH free radical-scavenging activity and FRAP value. Resultsshowed the main components from four extraction methods were high methoxyl pectin（DE:63.7-87.8%） together with high solubility （94.83-97.03%）. Compared to other extracts, waterextracted pectin had higher galacturonic acid content （69.4%） and DE （87.8%）. Higher antioxidative properties were shown in water and ultrasound-assisted extracted pectincompared to other extracts. Water and ultrasound-assisted extracted pectin（concentration:1mg/mL） exhibited percent of DPPH free radical scavenged of5.79%and5.97%, gave FRAPvalue of2.24and2.05mM FeSO₄. Therefore, it was suggested that water andultrasound-assisted extraction have the potential in producing functional pectin.The effects of Abelia engleriana leaf pectin and water extract on regulating lipidmetabolism had been investigated in high-fat diet mice. Mice in control group were allowedfree access to standard feed, water and orally administrated with physiological saline for4weeks. Mice in model control group were allowed free access to high-fat diet, water andtreated with physiological saline for4weeks. Mice of pectin-treated group were allowed freeaccess to high-fat diet, water and were treated by oral infusion with pectin at a dose of585mg/kg·d,1170mg/kg·d,2340mg/kg·d for4weeks. Mice of water extracts-treated groupwere allowed free access to high-fat diet, water and were treated by oral infusion with waterextract at a concentration of19.5g/L,39.0g/L,78.0g/L for4weeks. This investigationdemonstrated TG, TC, LDL-C, HDL-C content in serum, MDA levels and elevated enzymicantioxidants, including SOD and GSH-Px activities in serum. The results showed that Abeliaengleriana leaf pectin and water extract could decrease the content of TG, TC and LDL-C,and increase the content of HDL-C in serum of high-fat diet mice compared to model controlgroup. At the same time, Abelia engleriana leaf pectin and water extract treatment coulddecrease the level of MDA in serum and increase the activities of SOD and GSH-Px.However, both of samples presented better effects in low dose. Compared to the Abeliaengleriana leaf pectin treatment, water extract had an efficacious amelioration effect,preventing hyperlipidemia. Therefore, it was concluded that Abelia engleriana leaf pectin andwater extract could regulate lipid metabolism, enhance antioxidant capacity and relieve theinjury induced by high-fat diet.The effects of Abelia engleriana leaf pectin and water extract on regulation of bloodglucose metabolism had been investigated in alloxan-induced diabetic mice. Pectin groupswere given orally with Abelia engleriana leaf pectin at the dose of585mg/kg·d,1170mg/kg·d,2340mg/kg·d. While water extract groups were given orally with water extract at aconcentration of19.5g/L、39.0g/L、78.0g/L. After four weeks of treatment, fasting bloodglucose level, serum insulin content, glucose tolerance, serum MDA level and SOD activitywere measured. The results showed that Abelia engleriana leaf pectin and water extract couldreduce the fasting blood glucose levels, increase serum insulin content, and improve glucosetolerance in alloxan-induced diabetic mice. However, the hypoglycemic effect was better inlow dose both of samples. Moreover, Abelia engleriana leaf pectin and water extract could effectively reduce MDA level and increse SOD activity in serum of diabetic mice. Therefore,it was concluded that Abelia engleriana leaf pectin and water extract could promote bloodglucose metabolism and enhance antioxidant capacity of diabetic mice.