Preliminary Study On Antitumor Activity Of 37 Natural Diterpenoids

ObjectiveExamination of the antitumor activity of thirty seven natural diterpenoids in vitro and vivo.Preliminary analysis of thirty seven natural diterpenoids structure-activity relationship.Furthermore,Examination the immunity toxicity of Zhao1(one of diterpenoids) and its mechanism of action.Rearch the change of Bcl-xl, Mcl-1 and Caspase-3 while HL-60 was dealed with Zhaol.MethodsThe cytotoxicity of thirty seven natural diterpenoids in five human tumor cell lines and in Kunming mice' spleen cells was measured by MTT assay .The immunity function effect of Zhaol against the murine spleen cells was tested by ³H-TdR assay . Mice with sarcoma (S180) and hepatocarcinoma (H22) were established to observe the antitumor activity and the effect on the weight of main organs and bone marrow cells of mice after ip Zhao1.Observation cell shape variety through phasecontrast microscope and electron microscope.FCM examined the variety of cell cycle , the content of DNA, and apoptosis rate of multi-tumor cells.Results1 Consequences in vitroAmong thirty seven natural diterpenoids thirteen compounds' IC₅₀ values against K562 are less than 30ug/mL. Zhao1's IC₅₀ values were less than 30ug/mL against five substantiality tumor. The IC50 values of the other 12 compounds were less than 30ug/mL against some substantiality tumor. Zhaol presented strong cytotoxicity againstfive tumor cell lines, particularly K562> OVCA2780.The IC50 values of Zhaol against murine T and B lymphocyte were 12.60 ug/mLN 13.68ug/mL repectively.2 Therapeutic efficacy in vivoZhaol showed dose-dependent inhibitory activity against mice bearing sarcoma (S180) and hepatocarcinoma (H22).The inhibition rate of Zhaol against the growth of S180 and H22 was 43.50% and 39.42% respectively.Within the dose of 8-30mg-kg"\ the inhibition rate of Zhaol against the growth of sarcoma (S180) and hepatocarcinoma (H22) was 5.21-43.50% and 3.19-39.42% respectively.The life extending rate of mice bearing ascites of S180 and H22 was 142.33% and 107.10% at the dose of 30 mg-kg"1 and 24 mg-kg"1 respectively. Zhaol could evidently restrain the growth of mice's BM cell and represent dose-dependence. The inhibition rate of mice's BM cell of was 48.34% and 45.49% at the dose of 30 mg-kg'1 and 24 mg-kg"1 respectively.3 mechanism of actionCell cycle block in S+G2-M were found in multi-cells cultured with Zhaol representing dose-dependence and that effect was avisible at about 24 hours.Multi-tumor cells in particular leukemia appeared typical apoptosis character after dealed with the dose (5ug/mLN lOug/mL) of Zhaol. Gel electrophoresis found the appearence of DNA ladder. FCM turned up cell cycle block in S+G2-Mn the the appearence of sub-diploid apoptotic pea^ the increased number of sub- diploid along with time prolonged.FCM examined HL-60 apoptosis was related with the activation of Caspase-3.The result of Western blot showed that Bcl-xl and Mcl-1 expression level failed along with action time of Zhaol against HL-60 increasing.ConclusionZhaol exhibited strong dose-dependent inhibitory activity in five human tumor cells lines tested and a little immunity toxicity. The other 12 compounds showed significant cytotoxicity in some human tumor cell lines. These 13 compounds deserved more research. And their structure-activity relationship indicated a -methylene cyclopentanone in molecule structures was cytotoxicity center.Zhaol showed obviousinhibitory activity against sarcoma (S180) and hepatocarcinoma (H22).Moreover,Zhaol prolonged the living time of mice bearing ascites of SI80 and H22.The mechanism of action could be related with Cell cycle block in S+G2-M. Zhaol could availably inhibit the growth of leukaemia cell and accelerate its apoptos. The leukaemia cell's sensitivity against Zhaol was related with the high expression of Caspase-3 n the depress expression of Bcl-xl and Mcl-1.Zhaol could become newly high efficiency medicine against leukaemia.