Studies On The Cytotoxic Neo-clerodane Diterpenoids Of Scutellaria Barbarta From Anhui Province

Scutellaria barbarta D. Don, a kind of traditional Chinese Herbs, also hassome alias such as Twinflower Skullcap Herb, etc. This perennial herb is nativelydistributed throughout Korea and southern China such as Jiangsu, Zhejiang,Anhui, Fujian, Guangdong, and so on. Since1985, this herb was adopted in thePharmacopoeia of People’s Republic of China and considered as a kind oftraditional Chinese drug for its many physiologi-cal activities such as of clearingheat, activating blood circulation and anti-tumor.Scutellaria L.(Labiatae) is a large subcosmopolitan genus with360currently recognized species. Recently, plants belonging to this genus haveattracted attention owing to interesting biological activities to anti-tumor.The studies of Scutellaria barbarta D. Don are mainly focused on thechemical constituents and activities. A lot of compounds such as Flavonoids,Polysaccharides, Diterpenois, Alkaloids and Steroides are purified. Scutellarin isthe most typical Flavonoid in this species, it’s also the indicator in the assay ofScutellaria barbarta D. Don in the Pharmacopoeia of People’s Republic of China.SPS Ⅰand SPS Ⅱ are the main Polysaccharides, they are consisted of arabinose,rhamnose, ribose, xylose, mannitose, fructose, galactose, glucose, and β-glycosidic linkage and pyran ring are observed in these Polysaccharides. Study ofDiterpenois is a new hot spot, several Diterpenois such as scutellone A~I，scuterivalactone A, B, C, D etc. are purified and determinated.Modern pharmaceutical researches show that the extracts of Scutellariabarbarta have evident activities which can be used in the curing of lung cancer,digestive system cancer, breast cancer and epithelial cell carcinoma etc., but it isuncertain to discrimiate the exact composition for these activities. For a certaintime many studies were focusing on the Flavones and polysaccharides which are contained in Scutellaria barbarta D. Don, and these substances really showcertain activities in relative experiments, but these activities are not strong enough.A newly emerged opinion considers that some diterpenes are the effectiveconstitutes for anti-tumor. In this thesis30neo-clerodane diterpenoids ofScutellaria barbarta from Anhui Province are purified and studied, thesesubstances show evident activities to anti-tumor.The results of this study are as follows:1: Systematic chemical study of Scutellaria barbarta from Anhui Provincehave been executed and30neo-clerodane diterpenoids are obtained anddeterminated.Many literatures considered that Scutellaria barbarta from Anhui Provincediffer from others, but further research is deficient, especially those onneo-clerodane diterpenoid. From a chemotaxonomic point of view, it is of interestto note that these neo-clerodane diterpenoid alkaloids lack an oxygenatedsubstituent at C-19found in almost all of the neo-clerodane diterpenoids fromEuropean Scutellaria species. By means of many chromatographic separationtechnologies (silica gel, silica gel RP-18, Sephadex LH-20, preparative TLC,HPLC, MPLC, and so on),30neo-clerodane diterpenoids were isolated from thewhole plant of Scutellaria barbata (collected from Linquan district, AnhuiProvince), the structures were established on the basis of chemical methods anddetailed spectral analyses (including UV, IR, MS, HR-MS,1D-NMR and2D-NMR),6of which were new compounds (LB23, LB30, LB11, LB22, LB12,and LB13). These compounds are identified as follows: LB1(Barbatin C), LB2(Scutebarbatine C), LB3(Scutebarbatine D), LB4(Scutebarbatine E), LB5(Barbatin D), LB6(Barbatin E), LB7(Scutebarbatine K), LB8(Scutebarbatine L),LB9(Scutebarbatine O), LB10(Scutebarbatine B), LB11(Scutelinquanine C),LB12(6-Acetoxybarbatin C), LB13(6-(2,3-Epoxy-2-isopropyl-n-propoxyl)barbatin C), LB14(Barbatin A), LB15(Barbatin B), LB16(Scutebarbatine G),LB17(Scutebarbatine F), LB18(6-O-Nicotinoylscutebarbatine G), LB19 (6-O-Nicotinoyl-7-O-acetoxylscutebarbatine G), LB20(6,7-Di-O-nicotinoyl－scutebarbatine G), LB21(Scutehenanine H), LB22(Scutelinquanine D), LB23(Scutelinquanine A), LB24(Scutebarbatine I), LB25(Scutebarbatine J), LB26(Scutebarbatine H), LB27(7-O-Nicotinoylscutebarbatine H), LB28(Scutebarbatine M), LB29(Scutebarbatine N), and LB30(Scutelinquanine B).2: The activities of the neo-clerodane diterpenoids have been evaluated andthe anti-tumor mechanism of scutebarbatine B has been illuminated.By using methylene blue dye assay and anti-tumor drugs, etoposide andcisplatin as positive controls,30neo-clerodane diterpenoids were evaluated forcytotoxity against three tumor cell lines (HONE-1nasopharyngeal, KB oralepidermoid carcinoma, and HT29colorectal carcinoma cells), with IC50valuesbeing in the range of2.0-8.1μΜ. HPLC proved the content of scutebarbatine Bwas relatively high, but lts polarity were low. In order to increase their polarity, itsstrctures was modified and anti-tumor mechanism study was then carried out.Pharmacological experiment showed that scutebarbatine B inhibited the growth ofA549cells by inducing G1phase cell cycle arrest and apoptosis. Furthermore,stress fiber assembly and cell migration in A549cells was markedly suppressedby scutebarbatine B.All of our researches are focused on the neo-clerodane diterpenoids inScutellaria barbarta. We made a further exploration on the material basis of theanti-tumor activities of Scutellaria barbarta by purification, structuredetermination and activity screening. These researches can be great helpful to thefurther application of Scutellaria barbata in modern clinic, and also provide anew valuable idea such as exploiting a new anti-tumor drug by chemical synthesisor partial synthesis.