Study On Antioxidant Activities And The Hepatoprotective Effects Of The Extract Of Tibetan Medicine

It has been well documented that the bio-antioxidants can scavenge free radicals,prevent and cure diseases.However,the synthetic antioxidants are highly toxicin vivo,natural ones definitely catch scholar's attentions and research interests.Tibetan medicinal herbs are important ethnic drugs in China,which possess the special and unique biological activities because of the Tibetan natural environment.In recent years,Tibetan medicinal herbs have become a popular natural source to find the extracts or small molecule compounds conferring higher bio-activities.We studied the antioxidant activities of 40 water extracts from Tibetan herbs in vitro.Firstly,the yin or yang nature of extracts was classified based on the medicinal theories of "cold-hot" and "yin-yang".Secondly,the total phenolics and flavonoids were estimated by Folin-Ciocalteuand NaNO2—Al(NO3)3—NaOH methods.The total antioxidant capacity was evaluated by the following mathods:ABTS·+(2,2'azinobis-(3-ethylbenz-thiazoline-6-sulfonic acid),O2·-(super-oxide anion),and Ferric-reducing antioxidant power(FRAP).Joyfully,we found that the herbs with higher total phenolic and flavonoid contents displayed higher activities.Five herbs here,PhyllanthusembicaL.,Rhodiolacrenulata(Hookf.et Thoms.)H.Ohba.,Myricariapaniculata P.Y.Zhang et Y.J Zhang.,Corallodiscuskingianus(Craib)Burttand Rhododendron capitatum Maximhad highest activities and higher total phenolics,including total flavonoids.Secondly,the positive linear correlations(R2)existed between the antioxidant activities and total phenolics,namely,R2=0.8463 for ABTS·+,R2=0.8202 forO2·-and R2=0.8017 for FRAP,while there was no correlation found between the total flavonoids and antioxidant activity.Thirdly and importantly,the yin-tonic herbs showed higher activity than the yang-tonic ones,corresponding to the higher total phenolic contents by up to nearly three-fold.In the vitro antioxidant studies,we found out that although the Terminalia billerica(Gaertn.)Roxb did not have the highest levels of flavonoids and polyphenols contents among the 40 kinds of traditional Chinese medicine,but its antioxidant activities were very strong.So we further studied its antioxidant activities in vivo with mice liver injury model by CC14,we detested the activities of the Alanine aminotransferase(ALT/GPT),Amda aminotransferase(AST/GOT)and superoxide dismutase(T-SOD)in liver.Then we demonstrated its protect effects against INH injuries by detecting the activities of ALT/GPT,AST/GOT,T-SOD and Glutathion peroxidase(GSH-PX),the contents of Malonaldehyde(MDA)in the liver and and the plasma of different mice groups,we studied the pathological slices of the liver tissue as well.Finally,the protecting mechanisms were studied by determining the mRAN contents of genes CYP2E1 and CYP1A2 with methods of extracting total RNA,reverse transcription and PCR.The results suggested that Terminalia billerica(Gaertn.)Roxb showed good antioxidant activities in vivo,had protection against liver damage by INH with significant different levels of CYP1A2 mRNA.The results suggested that the phenolic compounds other than the flavonoids in the cold-nature herbs play the major role in antioxidant capacities and the herbs studied here are good sources of natural antioxidants.We believe that our findings could bring new and important light in the field of theory research in the Tibetan medicine.