Studies On Triterpenoids From Two Cucurbitaceae Species Plants

This paper basically consists of two parts.PartⅠ:Study on the molecular mechanisms and active components of anti-hyperglycemic activity of Siraitia grosvenorii Swingle.AMP-avtivated kinase (AMPK) as a key controller in the regulation of whole-body energy homeostasis, plays an important role in protecting the body from metabolic diseases. Recently, improved glucose, lipid utility and increased insulin sensitivity were observed on several diabetic rodent models treated with crude mogrosides isolated from the fruit of Siraitia grosvenorii Swingle, but the precise active compounds responsible for the anti-diabetic activity of this plant have not been clearly identified. In our current work, acid hydrolysis of crude mogrosides provided five new cucurbitane triterpenoids (1-4,8), along with three known ones (5-7). The main aglycone mogrol (7) and compounds 4 and 8 were found to be potent AMPK activators in the HepG2 cell line. This result suggested AMPK activation by the mogroside aglycones 7 and 8 was proved to contribute at least partially to the anti-hyperglycemic and anti-lipidemic properties in vivo of Siraitia grosvenorii.PartⅡ:Study on isolation, structural elucidation and their structure-cytotoxcity relationship of cucurbitacin triterpenoids from HemsleyaXue dan is the rhizomes of Hemsleya (Cucurbitaceae) and is used to cure bronchitis, bacillary dysentery, stomachache, tuberculosis, whooping cough and bile duct infection in China. Rencently, the anti-cancer activity and mechanism of hemslecin was reported by Q Lu, we will further study the anti-cancer activity and structure-activity relationship of hemslecin. We have isolated and determined three new compounds from 95% ethanolic extraxt of the rhizomes, named 2β,3α,16α,20(R),24(S),25-hexahydroxy-9-methyl-19-norlanost-5-en-11, 22-dione (15),7-hydroxy-cucurbitacin F-25-O-acetate (19) and 16α,23α-epoxy-2β,3β,20β,26,27-pentahydroxy-10α,23α-cucurbit-5,24-dien-11-one (23), along with thirteen kown compounds, including 23,24-dihydrocucurbitacin F-25-acetate (Hemslecin A) (10), 23,24- dihydrocucurbitacin F (11),23,24-dihydrocucurbit-acin B (12), 23,24-dihydrocucurbitacin E (13),23,24-dihydro-3-epi-isocucurbitacin B (14), 7-hydroxy-23,24-dihydrocucurbitacin F-25-O- acetate (16),2β,3β,6α,20(R),25-pentahydroxy-9-methyl-19-norlanost-5-en-7,11,22-trione (17),2β,3α,16α,20(R),24,25-hexahydroxy-9-methyl-19-norlanost-5-en-11,22-dione (18),23,24-dihydrocucurbitacin E-2-O-D-glucoside (20),2-O-β-D-glucopyranosyl cucurbitacin (21), Scandenogenin D (22),23, 24-dihydrocucurbitacin F-2-O-D-glucoside (24) and 23,24-dihydrocucurbitacin D-2-O-D-glucoside (25). Compounds 10-14 exhibited the significant cytotoxicity against HeLa cell line, the IC50 of main component hemslecin A was 0.389 pM. compounds 15,18 and 19 showed moderate effects, while compounds 16,20,21 and 22 had no effects.