The Activity Evaluation And Physiological Disposition Of Exquisite Ginkgo Biloba Extract

Ginkgo biloba L.is the sole surviving species of the once large plant division Ginkgophyta.All other species have become extinct.Fossils of plants quite similar to G.biloba date back to 150 million years ago and thus it has been called a "living fossil".Our country is the birthplace of G.biloba,and the resources of G.biloba rank first in the world.G.biloba extract(GBE),the acetone-water or ethanol extraction of G.biloba L.leaves and then through degreasing,removing the ginkgo acids,biflavone,and enrichment flavonoids and terpene lactones etc.15 processes.Our current understanding of the active principles suggests that the terpene lactones-the ginkgolides and bilobalide,as well as the flavonol glycosides-have been proved to be clinically effective in the treatments of peripheral vascular disease,Alzheimer's disease(AD),protection of central nervous system(CNS),antioxidant,inhibition of platelet activating factor and other health-related conditions.Therefore,strict standardisation and quality control specifications have been defined to control the reproducible production of GBE for therapeutic purposes.The standardized GBE termed "EGb 761"consists of 22-27%flavone glycosides(glycosides of quercetin,kaempferol,and isorhamnetin),5-7%terpene lactones(ginkgolides A,B,C,and bilobalide)and less than 5 mg/kg(5 ppm)ginkgolic acid.Meanwhile,the species of non-flavonoid and non-lactone in GBE are still unknown;whether the non-flavonoid and non-lactone have pharmacodynamic,have influences on pharmacodynamic,pharmacokinetics and toxicology to flavonoids still unclear.The main objectives of this research were helpful to guide the design of new drugs to improve the efficacy and safety of GBE in clinical,and provide the basis of refmedpreparation.A detailed review was given to the research progress of GBE including chemical constituents,pharmacological effects,the process in vivo study,it is helpful to improve the current quality standards and analyze the effects of non-flavoinoid and non-lactone constituents in GBE.First of all,through the polyamide separation and preparation of flavonoids site,lactones site,non-flavonoid and non-lactone site,and then merge parts of flavonoids and lactones to get the high quality of G.biloba extract(HQGBE).Compare and evaluate pharmacological activity of GBE and HQGBE.The antioxidant activities of GBE and HQGBE were assessed by three vitro experiments of eliminating DPPH,eliminating ABTS.and deoxidizing Fe3+;the influence of action of PAF(ADP)in rabbits was observed by PAF(ADP)test induced by PAF(ADP),the results showed that GBE and HQGBE both possess strong activities of antioxidantion,abilities of inhibiting platelet aggregation,and there was no significant difference between the two groups.Rat myocardial ischemia was induced by injection of isoprenaline(5 mg/kg).The descent of J point at different time after injecting isoprenaline were examined,and the serum creatine kinase(CK),lactate dehydrogenase(LDH),superoxide dismutase(SOD)and malondial dehyde(MDA)were detected.GBE(150 mg/kg)and and HQGBE(80 mg/kg,160 mg/kg)can obviously inhibit descent of J point in ratmyocardial ischemia induced by isoprenaline,enhance serum SOD activity,and inhibit the activities of serum CK.LDH.and MDA.The results showed that GBE(150 mg/kg)and HQGBE(80 mg/kg,160 mg/kg)may obviously ameliorate myocardial ischemic injury induced by isoprenaline in rat,and non-flavonoid and non-lactone components had no significant effect on the treatment of myocardial ischemic.Secondly,a selective and sensitive UPLC-MS/MS method was established to determine the plasma concentrations of the fourteen compounds to compare the pharmacokinetic parameters when orally administered FF,TLF,FF-WEF,FF-TLF,TLF-WEF,FF-TLF-WEF with approximately the same dose.At different time points,the concentration of rutin(1),isoquercitrin(2),quercetin 3-0-[4-0-(-?-D-glucosyl)-?-L-rhamnoside](3),ginkgolide C(4),bilobalide(5),quercitrin(6),ginkgolide B(7),ginkgolide A(8),luteolin(9),quercetin(10),apigenin(11),kaempferol(12),isorhamnetin(13),genkwanin(14)in rat plasma were determined and main pharmacokinetic parameters including T1/2,Tmax,Cmax and AUC were calculated using the DAS 3.2 software package.The statistic alanalysis was performed using the Student's t-test with P<0.05 as the level of significance.The result showed that FF and WEF have no effect on the pharmacokinetic behaviors and parameters of the four terpene lactones,but the pharmacokinetic profiles and parameters of flavonoids changed when co-administered with non-flavonoid components.It was found that Cmax and AUC of six flavonoid aglycones in group FF-WEF,FF-TLF and FF-TLF-WEF had varying degrees of reduction in comparison with group FF,especially in group FF-TLF-WEF.On the contrary,the values of Cmax,Tmax and AUC of four flavonoid glycosides in group FF-TLF-WEF were significantly increased by comparison with group FF.These results indicate that non-flavonoid components in GBE could increase the absorption and improve the bioavailability of flavonoid glycosides but decrease the absorption and reduce the bioavailability of flavonoid aglycones.An investigation was carried out to compare the tissue distribution of thirteen compounds(rutin,isoquercitrin,quercetin 3-0-[4-0-(-?-D-glucosyl)-?-L-rhamnoside],ginkgolide C,bilobalide,quercitrin,ginkgolide B,ginkgolide A,luteolin,quercetin,apigenin,kaempferol,isorhamnetin)to clarify the influences of coexisting ingredients on the tissue distribution profile of the flavonoids and the terpene lactones in GBE extracts by using a specific and sensitive ultra-performance liquid chromatography coupled with a UPLC-TQ/MS,and the histograms were drawn.The result showed that the overall trend was CLiver>CKidney>CBrain>CLung>CSpleen>CThymus>CHeart.This study showed that coexisting ingredients could promote the distribution and had no effect on the elimination of these four terpene lactones in most organs,and it also could promote the distribution and accelerate the of elimination of flavonoid aglycones in most tissue but delay the distribution in some organs such as lung and thymus of flavonoid glycosides.The results demonstrated that coexisting ingredients had obvious influence on the thirteen components in some organs and time points.This study was the first report about tissue distribution investigation of flavonoid aglycones,flavonoid glycosides and terpene lactones of GBE and discussed the tissue distribution affect of coexisting components on the thirteen bio-active components in rats which supply a useful information about the safety of clinical therapy and provide reliable evidences for extrapolate correlation with the pharmacodynamic activity of GBE.