Studies On Antioxidant Capacity And Body-weight Control Effect Of Extracts From The Leaves, Branches And Barks Of Myrica Rubra

Myrica rubra Sieb.et Zucc.belongs to one of the six species of Myricaceae family, genus Myrica Linn.It is of abundant resources and has a long history of cultivating,but the research and development of this traditional plant resource,especially for the non-fruit parts,is extremely shortage.In the present study,the leaves,branches and barks of Myrica rubra were extracted with ethanol/water(70:30,v/v) solution at first step,defatted by petroleum ether and then fractional extracted with ethyl acetate and n-butanol,and finally nine extracts were given out and written as YY,YZ,YS;ZY,ZZ, ZS;PY,PZ,PS,respectively.DPPH method,ABTS method,Rancimat method and whole blood antioxidant method were adopted to evaluate the antioxidant ability of the extracts.HPLC method was used to detect the contents of myricitrin and quercitrin in the ethyl acetate fractions. After there,the fast deactived capacity on fatty acid synthase(FAS) about all of samples were detected in order to discover the most effective fraction of FAS inhibition. Finally,a mouse animal test was figured out to verify the effect of this fraction.Results showed that the water-phase fraction made of the barks of Myrica rubra displayed significant bioactivities both on reducing blood-lipid and controlling body weight in vivo.The main results were summarized as follows:Nine Myrica rubra extracts(YY,YZ,YS;ZY,ZZ,ZS;PY,PZ,PS) demonstrated favorable activity in scavenging free radicals and antioxidant ability to oil in various antioxidant assay systems.DPPH and ABTS⁺ scavenging capacity of Myrica rubra extracts exhibited the descending order:ethyl acetate fraction＞n-butanol fraction＞water fraction.Among the samples of n-butanol and water fraction,the scavenging capacity on DPPH and ABTS⁺ exhibited the descending order:PZ＞ZZ＞YZ, PS＞ZS＞YS.Among the samples of ethyl acetate fraction,the scavenging capacity on DPPH lined up as ZY＞YY＞PY,and on ABTS⁺ as YY＞ZY＞PY.As to the ability of reducing oxidation of camellia oil,the ethyl acetate fraction showed the greatest activity at 0.03%dosage level,which was comparable with 0.02%TBHQ.Moreover, there was significantly positive correlation between the total phenol contents and scavenging capacity on DPPH and ABTS⁺(p＜0.05).HPLC method was used for quantitatively analysis two representative flavonol glycosides in the ethyl acetate fraction of non-fruit extracts.The myricitrin and quercitrin contents exhibited the descending order:branches＞leaves＞barks and leaves＞branches＞barks,individually.Both of them are the lowest in the barks extract.The test of FAS inhibition in vitro elucidated that the water fraction made of Myrica rubra barks(PS) was of the strongest deactived ability to fatty acid synthase with an IC₅₀ value at 0.4μg/mL.In the animal model of preventing obesity from mice, PS significantly decreased the level of body weight,body lipid,TG,TC and LDL-c, and inhibited the FAS activity of liver tissue in experimental animals.At the same time,PS still reduced the quantity of fat cells in mice liver and decreased the cell volume in the adipose tissues.According to our research,it could be concluded that the non-fruit parts of Myrica rubra,i.e.leaves,branches and barks,are important plant resources of polyphenols due to their good characteristics on antioxidant ability and body weight control effect.Particularly,with excellect FAS inhibition and anti-obesity capacities, the water fraction of bark's extract has a great potentiality to be developmented as functional food factor and dietary supplement in the future.