Studies On The Chemical Consituents Of Diterpenoids Toxin From Tow Ericaceae Species

Composing of three chapters, this dissertation investigated the chemical constituents of two plants of the family Ericaceae, which were Pieris formosa and Rhododendron spiciferum. Moreover, relevant effects on immunocyte of mice of some of the compounds were evaluated.Many species of the family Ericaceae contain diterpenoids possessing several specialized skeletons with highly oxygenated functionalities, which results in the toxicity of these species. Some of these diterpenoids possess significant biological properties, such as potent acute toxicity in mammals, antifeedant, growth inhibitory, and insecticidal activities. These diterpenoids occur mainly in the genera Pieris, Rhododendron, Lyonia, Leucothoe and Kalmia. Up to the present, more than 130 diterpenoids have been reported from the family Ericaceae and their structures include four types:(1) the grayanane-type with a 5/7/6/5 ring system; (2) the leucothane-type with a 6/6/6/5 consecutive carbocycle; (3) the 10/6/5 carbon ring grayanol-type; and (4) the kalmane-type with a 5/8/5/5 ring system. To date, over 100 belong to grayanane-type,20 are leucothane-type and kalmane-type, while there are only 4 diterpenoids of grayanol-type were found in natural products.In the course of searching for diterpenoids with structural diversity and biological importance,31 compounds have been isolated from the flowers of P. Formosa, and 8 compounds were new ones. Pierisformosines K-P (1-6) were new grayanane-type diterpenoids, all of them have some oxidated substituting groups at C-15. In addition, we have firstly isolated four new metabolites containing the rare 3,4-seco grayanane diterpenoid skeleton with a cell of y-lactone group, namely Pierisformosine M to P, and what is more, there was a three-member ring which is composed of C-O-C exhibiting between C-4 and C-19 in Pierisformosines M and N. The grayanol-type was considered as the intermediate of all the structural types mentioned above, and up to now, there are only 4 diterpenoids of this kind were found in natural products, and grayanotoxinⅩⅫ(7) was the forth one. Compound 8 was the first disaccharide compound from this species. The known compounds were identified as:Asebotoxin IV(9), Grayanotoxin-Ⅰ(10), Grayanotoxin-Ⅲ (11), Pierisformosin B(12), AsebotoxinⅧ(13), AsebotoxinⅤ(14),5,6-acetonyl grayanotoxin-Ⅰ(15),5,6-acetonyl grayanotoxin-Ⅴ(16), Oleanolic acid(17), ursolic acid(18),β-sitosterol(19), Bayogenin(20), Arjunolic acid(21), (2S,3R)-ent-catechin(22), 2',4-dihydroxy-4'-methoxy-6'-O-β-glucopyranoside dihydrochalcone (23), bis-8,8'-catech iny-lmethane(24), epicatechin-(2β→O→7,4β→8)-ent-epicatechin(25), proanthocyanidin A-1(26), Benzyl o-β-D-glucopyranoside(27),2-Hydroxybenzylβ-D-glucopyranoside(28) and 2,6-dimethoxy-4-hydroxyphenol 1-o-β-D-glucopyranoside(29).From R. spiciferum,16 known compounds were isolated and identified as: quercetin-3-O-α-L-arabinfuranside (30), quercetin-3-O-α-L-rhamnopyranoside (31), trans-taxifolin-3-O-α-arabinopyranoside (32), astilbin (33),3-O-rhamnoside engeletin (34), naringenin (35), (2S)-5,7,4'-trihydroxy-8-methylflavanone (36), epicatechin-(2β→O→7, 4β→8)-ent-epicatechin(37), proanthocyanidin A-1 (38), bis-8,8'-catechiny-lmethane(39), (2S,3R)-ent-catechin(40), epicatechin (41), ursolic acid(42),β-sitosterol(43) 4-(2-hydroxyethyl)phenol (44), (-)-lyoniresinol-9-O-β-D-glucopyranoside (45). All of these compounds were firstly isolated from this species.The results showed that compound 37,38,39 alone or comined with ConA or LPS can significantly enhance the proliferation of spleen lymphocytes in a certain dose range.