Antioxidant And Free Radical Scavenging Activities Of Extracts From Scutellaria Barbata D.Don, Hedyotis Diffusa Willd And Their Herb Pair

Scutellaria barbata D.Don is a wild perennial plant endemic to southern China, which has been widely used for medicinal purposes,such as inflammation,hepatitis, osteomyelitis,gynecological,lung,and rectal tumors in traditional Chinese medicine. On the other hand,Oldenlandia diffusa(Willd.) Roxb.(Syn.Hedyotis diffusa Willd.) is a wellknown folk medicine in Southern China and has been used for the treatment of hepatitis,tonsillitis,sore throat,appendicitis,urethral infection and malignant tumors of the liver,lung and stomach.Fresh or dried Hedyotis diffusa Willd leaves are used to make an aromatic tea or as a tonic or health drink by the local inhabitants. These two plants have been frequently used together,named 'Herb Pair' in traditional Chinese medicine,to achieve mutual enhancement or mutual assistance for the treatment of cancer and tumor in the clinical practice.It is indicated that the Herb Pair of these two plants may contain some new chemical components that result in the enhancement of antitumor activities.In the first chapter,the progress in the study of medicinal herbs differentiate, chemical elements,pharmacology effect and clinical application of Scutellaria barbata D.Don,Hedyotis diffusa Willd and their Herb Pair in recent years was summarized Herb,to provide a reference for further studies in these fields.By examining the change in activity after compatibility,the role of the components could be explained in whole prescription.This attempt would he helpful for the research on the drug combination theory and the interaction between components in traditional Chinese prescription.In the second chapter,Aqueous,hydroalcoholic and organic extracts of Scutellaria barbata D.Don,Hedyotis diffusa Willd and their Herb Pair were prepared. Multi-components library of organic extracts from Herb Pair was constructed.Extract yield,total phenolics and total flavonoids content in the aqueous,hydroalcoholic and organic extracts were also determined.Results showed that organic reagent can enrich phenolic and flavonoid compounds more effectively.In the third chapter,the antioxidant and free radical scavenging activities of Aqueous,hydroalcoholic and organic extracts of Scutellaria barbata D.Don,Hedyotis diffusa Willd and their Herb Pair were evaluated.The results showed that the antioxidant and free radical scavenging activities of extracts was significantly related to the total content of phenolic and flavonoid compounds.In the fourth chapter,the antioxidant and free radical scavenging activities of organic extracts from Scutellaria barbata D.Don,Hedyotis diffusa Willd and their Herb Pair were contrasted.The reducing power,DPPH and hydroxyl radicals scavenging of Scutellaria barbata extract were much stronger than those of other tested extracts;The chelating activity of the Herb Pair extract on ferrous iron and protecting effect on DNA damage caused by hydroxyl radicals were the strongest. The anticancer mechanism of their combination may be associated with its chelating activity on ferrous iron and protecting effect on DNA damage caused by hydroxyl radicals.In the fifth chapter,the structures of flavonoids in aqueous,hydroalcoholic and organic extracts of Scutellaria barbata D.Don were elucidated by UV,LC-MS, MS/MS.The coefficients of correlations were calculated between antioxidant and free radical scavenging activities and contents of phenolic,flavonoid compounds of extracts.The results showed that the reducing power,DPPH and hydroxyl radical scavenging activity of extracts was statistically correlated with their contents of total phenolic,total flavonoid compounds and especially with the content of Luteolin and Apigenin.Correlation between ferrous ion-chelating efficacy and total phenolics and flavonoids contents of all samples in this study was moderate to lower,but significant. The containing of Scutellarein-7-O-β-D-glucuronide and Baicalin may be with relation to the ferrous ion-chelating efficacy of extracts.