Studies On Dolabrane Diterpenoids Of Ceriops Tagal

Mangrove plants are rich sources of bioactive secondary metabolites with novel chemical structures,because of its special growth environment.C.tagal is the only species of Ceriops genus distributed in China,mainly in Hainan Island.The decoction of its leaves has been used for the treatment of malaria in China,and its bark has been utilized for the treatment of hemorrhage and malignant ulcers in India.Previous phytochemical investigations of this mangrove plant afforded mainly pentacyclic triterpenoids and diterpenoids.Furthermore,105dolabranes have been characterized from the plants.49 of these reported dolabranes have been identified from the mangrove,Ceriops tagal,which is obviously a valuable source for the production of dolabranes.As a part of our search for structurally unique and biologically interesting compounds from mangrove plants,the specimen of the stems and twigs of C.tagal was recollected from Hainan Island.Until now,24 compounds were isolated and purified by some chromatographic methods,such as normal phase silica gal,ODS,Sephadex LH-20 gel column chromatograpies and HPLC.We have identified 21 compounds by their physical properties and spectroscopic data,tagalphenylpropinoidin A?1?;tagalphenylpropinoidin B?2?;tagalene K?3?;tagalene J?4?;together with sixteen known compounds,Ent-5?,2,15-Dioxodolabr-3-ene-3,16-diol?5?;Ent-5?,3,15-DioxodoIabr-1,4?18?-diene-2,16-diol?6?;Ent-5?,2-Oxodolabr-3-ene-3,15,16-triol?7?;Ent-16-nor-5?,2-Oxodolabr-3-ene-3-ol-15-oic?8?;tagalene I?9?;Ceriops diterpenoids C?10?;tagalsin P?11?;tagalsin T?12?;tagalsin S?13?;tagalsin Q?14?;tagalsin X?15?;1,7-phenanthrenedimethano?16?;dehydroabietieacid?17?;2,3,6-Trimethoxy-5-?1-propenyl?phenol?18?;falcarindiol?19?;clemaphenol A?20?,tagalsin J?21?.In these identified compounds,compounds 1-4 are new chemical compounds.Compounds16-19 were isolated from C.tagal for the first time.Cytotoxicities of isolated diterpenoids against HCT-15,MCF-7,SW480,HepG2,HeLa,PANC-1 and A2058 cancer cell lines were also evaluated.Compound 6 exhibited moderate cytotoxic activity against SW480,HeLa and PANC-1 cell lines with IC₅₀ values of 27.7,22.2,and 17.6?M,respectively.