A new neo-clerodane diterpenoid, barbatin H (1), together with fifteen known analogues (2 -16) were isolated from Scutellaria barbata D.DON. Their structures were determined on the basis of NMR and HR-MS spectral analysis and comparison with the reported data. All of those compounds were comparatively predicted for their cytotoxic activities against four human tumor cell lines, i. e. LoVo (colon cancer), MCF-7 (breast cancer), SMMC-7721 (hepatoma cancer), and HCT-116 (colon cancer) cells by MTT method in vitro. The results turned out that the series of neo-clerodane diterpenoids exhibited varying degrees of cytotoxic activities against the growth of the tested tumor cell lines, and most of them exhibited selective cytotoxicity against LoVo cell lines. Scutebata A (14) showed significant cytotoxic activities against four tested tumor cells with IC 50 values of 4.57, 7.68, 5.31, and 6.23 μM, respectively, which indicated that it might be a potential chemotherapeutic agent.

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10 kinds of annonaceous acetogenins were selected for antitumor activity testing against human lung cancer cell line A549/Taxol and the structure activity relationship was analyzed.MTT assay was used to detect the inhibitory activities of 10 kinds of annonaceous acetogenins and positive drugs against A549/Taxol cells, respectively uvariamicin-Ⅲ(1), uvariamicin-Ⅱ(2), annosquacin D(3), desacetyluvaricin(4), annosquatin A(5), squamostatin D(6), bullatacin(7), squamocin(8), motrilin(9), annosquatin B(10), verapamil and cisplatin. Annonaceous acetogenins showed significant inhibitory activities against A549/Taxol cells, and were more potent than the positive drug verapamil and cisplatin.The more carbon atoms between the tetrahydrofuran ring and the lactone ring of annonaceous acetogenins exhibited more potency.Besides,ACGs with two substituted hydroxyl showed more potency than the compounds with three substituted hydroxyl in the bis-adjacent-THF ACGs. Furthermore, ACGs with three substituted hydroxyl showed more potency than the compounds with four substituted hydroxyl among the no bis-adjacent-THF ACGs.