英语翻译.Under this condition,the dried extract was9.025%,the co

英语翻译
.Under this condition,the dried extract was
9.025%,the content of polysaccharide in the extract was 20.9%,and the yield of
polysaccharide in Ginkgo biloba leaves was 1.887%.
Kraus (1991) isolated water-soluble polysaccharide from Ginkgo biloba leaves,
separated the polysaccharide mixture into a neutral and two acidic polysaccharide
fractions,and analyzed their structural features simply.The method for extracting
polysaccharide was not exactly the same as ours.After removed pigment and thelike with organic solvent,the leaves was then extracted with water for 24 h at 202C
(conc.5%,i.e.,water to sample approximately 19:1),and polysaccharide was
deposited with EtOH (final conc.75%,i.e.,a threefold volume).After dialysis the
yield of the high Mr.fraction was 1.1%.A UV/Vis scan was performed to a blank from 400 to 900 nm for determining
hydroxyl radical inhibition and the maximum absorption at 554 nm was obtained
(Fig.1).
The results in Fig.2 were obtained with five polysaccharide concentrations of the
extract,and indicated that the extract may be a powerful hydroxyl radical scavenger.
Indeed the extract was able to give an inhibition of 10.46% at concentration of
polysaccharide as low as 0.836 lg ml-1.At higher concentration,the inhibitory
effect was more marked and reached 64.05% at 4.18 lg ml-1,much better than
vitamin C (Fig.2).This may be better than the extracts containing polysaccharide
from other plants.For example,Herba houttuynia,a traditional Chinese medicine,
Agrocybe cyclindracea and Pleurotus ostreatus,two mushrooms,were able to
inhibit hydroxyl radical (Cheng and Li,2006).The scavenging rate of the
polysaccharide from Herba houttuynia was 15.9% at 2 mg ml-1,from Agrocybe
cyclindracea 9.85% at 120 lg ml-1,and from Pleurotus ostreatus 3.34% at
25 lg ml-1 (Cheng and Li,2006).Shao et al.(2007) had demonstrated that
Sarcandra glabra,a traditional Chinese medicine,could inhibit hydroxyl radical.
The scavenging rate of the polysaccharide from Sarcandra glabra was 60% at
2 mg ml-1.The scavenging activity of the extract from Ginkgo biloba leaves
seemed correlated with the presence of polysaccharide in the extract.